Geologic guides to oil accumulations in metamorphic rocks

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GEOLOGIC GUIDES TO OIL ACCUMULATIONS IN METAMORPHIC ROCKS

A D issertatio n P resented

to

th e F a c u l t y o f t h e G raduate School The U n i v e r s i t y o f S o u t h e r n C a l i f o r n i a

In P a r tia l F u lfillm e n t o f th e R eq u irem en ts f o r the Degree D o cto r of P h ilo so p h y

by D u n c a n A* M c N a u g h to n F e b r u a r y 1950

UMI Number: DP28521

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This dissertation, written by

Duno8.n A. j'.'icMoiiuA'ton

/

under the guidance of h.±C... Facult y C o m m itt ee on Studies, and a p p r o v e d by all its members, has been presented to and a cce p ted by the Co u n ci l on Graduate S tu d y and Research, in partial fu l­ fillment of requirements f o r the degree of DOCTOR

OF P H IL O S O P H Y

Dean

D a t e S b 2 3

J

C o m m it te e on S tu d ies

Chairman

7

J

TABLE OF CONTENTS PAGE SUMMARY....................................................................................................

i

IN T R O D U C T IO N ....................................................................................

v

HISTORY OF BASEMENT OIL DISCOVERIES IN CALIFORNIA .

.

v

OCCURRENCES OF OIL IN CRYSTALLINE ROCKS IN C A L IFO R N IA ...............................................................................

v iii

ACKNOWLEDGEMENTS.................................................................. PART I .

x iii

ANALYSIS OF THE PROBLEM OFMIGRATION AND

ACCUMULATION OF OIL IN BASEMENT

.

1

I.

Source of o i l

£.

Openings i n

b a s e m e n t r o c k s ............................................

E

3.

T r a p s ............................................................................................

E

PART I I .

.

R O C K S ......................

........................

1

CLASSIFICATION OF OPENINGS IN CRYSTALLINE

R O C K S ....................................................................................................

4

1.

P r i m a r y o p e n i n g s ..................................................................

S.

Secondary openings

PART I I I .

..............................................

4

. . .

5

GEOLOGIC CONTROLS OF SECONDARY OPENINGS

DUE TO MECHANICAL DISRUPTION OF

R O C K S ...............

7

1.

E nvironm ental c o n d itio n s of d efo rm atio n

.

7

E.

Dynamic h i s t o r y .................................................................

II

3.

P h y s i c a l p r o p e r t i e s o f r o c k s ..................................

IE

4.

The n a t u r e o f s e c o n d a r y s t r u c t u r e s .......................

17

PART I V .

•

GEOLOGIC PROCESSES THAT DESTROY SECONDARY

OPENINGS I N R O C K S ......................................................................

S3

1.

C o m p a c t i o n .................................................................................

S3

5.

M e t a m o r p h i s m ............................ ..............................................

S3

PAGE 3.

W e a t h e r i n g ...................................

23

4.

C e m e n t a t i o n ..................................................................................

23

PART V.

DIFFERENTIAL PERMEABILITY IN METAMORPHIC

R O C K S ...................................................................................................................... PART V I .

25

THE ROLE OF DILATANCY IN THE MIGRATION OF

FLUIDS IN METAMORPHIC R O C K S .............................................................. PART V I I .

27

THE "UP SLOPE" THEORY OF MIGRATION OF OIL

IN METAMORPHIC R O C K S ............................................................................. PART V I I I .

29

PRODUCTIVE AREAS IN METAMORPHIC ROCKS IN

THE WESTERN PART OF THE LOS ANGELES B A S I N ..........................

33

P l a y a d e l R e y o i l f i e l d ..............................................................

39

E l Segundo o i l f i e l d

. .

W ilm ington o i l f i e l d PART IX . PART X.

...................................

47

........................................................

SANTA MARIA VALLEY OIL F I E L D ....................................

61

THE BASEMENT COMPLEX IN THE SOUTHEASTERN PART

OF THE SAN JOAQUIN VALLE Y ...................................................................

72

G e n e r a l g e o l o g y ........................................

72

M eta-v o lcan ics

74

.......................................................................................

M e t a - s e d i m e n t s ................................................................................. ..

.

77

Age and c o r r e l a t i o n o f t h e m e t a - s e d i m e n t s and m eta-v o lcan ics

..................................................................................

78

P l u t o n i c r o c K s .......................................................................................

81

S t r u c t u r e .................................

82

O i l - b e a r i n g p r o p e r t i e s o f rocics i n th e

basement

com plex i n the

s o u t h e a s t e r n p o r t i o n o f th e San

Joaquin V alley

. . . . . . .

86

PAGE PART X I .

EDISON OIL F I E L D ...................................................................

88

CONCLUSIONS...................................................................................

103

BIBLIOGRAPHY

106

..............................................................

. . . . .

LIST OF TABLES TABLE I*

PAGE W ells w hich p e n e t r a t e

the

s c h i s t i n the

w e s t e r n Lo s A n g e l e s B a s i n ............................................... II.

D e e p n o n s c h i s t w e l l s i n t h e w e s t e r n Los A ngeles B asin • • • . . »

III.

S tratig rap h ic

...............................................

S tratig rap h ic

36

t a b l e o f th e P l a y a d e l Rey

o i l f i e l d ....................................................................................... IT.

36

t a b l e o f the E dison o i l f i e l d

.

•

41 90

LIST OF FIGURES FIGURE 1.

PAGE

Map o f S o u t h e r n C a l i f o r n i a s h o w i n g t h e l o c a t i o n o f f i e l d s producing o i l

from f r a c t u r e d m eta-

mo r p h i c r o c k s .............................. 2.

ix

H y p o t h e t i c a l example o f p o s s i b l e

s c h i s t accumu­

" c o n d e m n e d a r e a " .............................................

la tio n in

30

3.

Map o f w e s t e r n Lo s A n g e l e s B a s i n .............................. . .

35

4.

P la y a d e l Rey o i l

42

5*

P l a y a d e l Rey o i l f i e l d :

. . .

42

6.

E l S e g u n d o o i l f i e l d ..................................................................

48

7.

S tratig rap h ic

10.

.

.

com posite s e c tio n

T o r r a n c e and W ilm ington

o il fie ld s

9.

s t r u c t u r e map .

.

.

v a r i a t i o n c h a r t : P l a y a d e l Rey,

E l Segundo,

8.

fie ld :

. . . . . . .

W ilm ington o i l

fie ld

(w est)

....................................................

s h o w i n g b a s e m e n t zo n e

53

. . in pocket

C o m p o s i t i o n o f t o p o f R a n g e r Bank . . . . . . .

59

G e n e ra liz e d s k e tc h s e c t i o n a c r o s s S an ta M aria V alley o i l f ie ld

.

.

.

....................................................

11.

Producing

. . .

68

12.

S a n t a M a r i a V a l l e y o i l f i e l d .............................................

69

13.

Map o f s o u t h e a s t e r n p o r t i o n o f S a n J o a q u i n V a l l e y

2D

ne o f t h e S a n t a M a r i a d i s t r i c t

66

s h o w i n g b a s e m e n t l i t h o l o g y ................................................i n p o c k e t 14.

Edison o i l f i e l d :

15.

E dison f i e l d :

sch em atic s e c t io n

.........................

com pilation o f data r e la tin g

94

to

b a s e m e n t p r o d u c t i o n .............................................................

.in pocket

Summary The d i f f i c u l t i e s re se rv o ir co n d itio n s m

in h eren t

to t n e p r e d i c t i o n o f p o t e n t i a l

basem en t r o c k s c u r l e d by a c o n c e a l i n g

m a n tle o f s e d im e n ts a r e a p p a r e n t to a i l g e o l o g i s t s and c o n s t i t u t e th e main cau se f o r p r e j u d i c e a g a i n s t basem en t e x p l o r a t i o n *

Con­

s e q u e n tly g e o l o g i s t s have n o t p la y e d an im p o rta n t r o l e i n d is c o v e ry o f o i l accu m u latio n s in basement ro c k s .

the

A ll of the

m a j o r d i s c o v e r i e s h a v e b e e n a c c i d e n t a l an d o n l y o n e m i n o r d i s ­ c o v e r y ( W e s t e r n G u l f O i l C o m p a n y ’ s D i G i o r g i o No. 1 w e l l ) credited

to geology*

The in

can be

c o n d itio n s n e c e s sa ry f o r tn e fo rm a tio n o f an o i l pool

basem ent ro c k s a r e d is c u s s e d and the fo llo w in g c o n c lu s io n s a r e

reached: (1) capping the

Some s o u r c e o f o i l m u s t b e p r e s e n t i n t h e s e d i m e n t s basem ent.I t

is

the w r i t e r ’s o p in io n

s o u rc e beds o r " c a r r i e r ” beds o f o i l basement

to c k s

th at e ith e r

th a t are in c o n ta c t w ith

over ex ten siv e areas s a t i s f y

th is

co n d itio n .

M arine s h a l e s cap p a r t s o f t n e p r o d u c t i v e a r e a s i n th e b a se m e n t com plex i n E d i s o n , W ilm in g to n , E l Segundo and P l a y a d e l Rey f i e l d s . I n i t i a l p r o d u c t i o n s from w e l l s i n t h e b a s e m e n t complex i n E d is o n fie ld the

a r e r e l a t i v e l y n ig h i n th e a r e a where th e E d is o n s h a l e c a p s

basem ent.

there

They d e c r e a s e m a r k e d ly i n b o r d e r i n g a r e a s .

i s good r e a s o n t o b e l i e v e

t n a t some o f t h e o i l i n t h e b a s e ­

m ent complex o r i g i n a t e d i n c o n t i g u o u s s o u r c e b e d s . o il-b e a rin g sandstones,

c o n g l o m e r a t e s , and f r a c t u r e d

p a r t s o f th e b a se m e n t complex m

Thus,

the v a rio u s f i e l d s .

S im ilarly s h a le s cap Some,

ii p o s s i b l y m ost, o f the o i l

i n th e basem en t complex m

W ilm ington

a n d S a n t a M a r i a V a l l e y f i e l d s , m i g r a t e d dow nward f r o m t h e s e f r a c t u r e d m e t a m o r p h i c tocks.

beds in to (2)

S u i t a b l e o p e n in g s must e x i s t i n

th e basement ro c k s .

These o p e n in g s a r e t n e r e s u l t s o f m e c h a n ic a l d i s r u p t i o n o f r o c k s i n g e o l o g i c e n v ir o n m e n ts where o p p o r t u n i t i e s e x i s t e d f o r b o th v e r t i c a l and l a t e r a l e x p a n s i o n o f d e f o r m e d r o c k m a s s e s . The p h y s i c a l p r o p e r t i e s o f r o c k s e x e r t a n i m p o r t a n t c o n ­ t r o l on t h e i r r e s p o n s e fractu re flow .

to d e f o r m a t i o n .

Some c o m p e t e n t t y p e s

r e a d i l y w h e r e a s o t h e r i n c o m p e t e n t t y p e s d e f o r m by p l a s t i c

M assive r o c k s ,

such a s g r a n i t e ,

have a ten d en cy to l o c a l i z e f a i l u r e defined p lan es of slip p a g e ,

q uartz d i o r i t e ,

and g ab b ro

a lo n g w id e ly sp aced and w e ll

w hereas a n i s o t r o p i c r o c k s ,

such as

m eta m o rp h o s e d s e d i m e n t a r y and m e ta m o rp h o sed v o l c a n i c members o f tn e b a se m e n t com plex, p la n e s of w eakness. lished

tend to f a i l a lo n g numerous p r e - e x i s t i n g Th us d i f f e r e n t i a l p e r m e a b i l i t i e s a r e e s t a b ­

by d e f o r m a t i o n o r t n e v a r i o u s m em bers o f t n e b a s e m e n t

com plex.

B a s e m e n t e x p l o r a t i o n n a s shown t h a t d e f o r m e d m e t a m o r p h i c

r o c k s may c o n s t i t u t e r e s e r v o i r r o c k s b u t t n a t p l u t o n i c r o c k s do no t co ntain a p p reciab le q u a n titie s of o i l . Large f a u l t s a re g e n e r a l l y p e r s i s t e n t f e a t u r e s and, fore,

p r o v id e u s e f u l g u id e s to seco n d ary o p e n in g s i n r o c k s .

ro le of fa u ltin g in a c teristics

th ere­ The

tne fo rm a tio n o f d e s i r a b l e r e s e r v o i r c h a r­

in basement ro ck s i s

e v i d e n t i n E d is o n f i e l d where th e

m ost p r o d u c t i v e p a r t o f th e b asem en t com plex b o r d e r s t h e E d is o n fa u lt.

iii F o l d i n g e x e r t s a n i m p o r t a n t c o n t r o l on t n e f o r m a t i o n o f s e c o n d a ry o p e n in g s i n th e f o l l o w i n g ways:

(a)

f r a c tu r e s deve­

l o p a s a r e s u l t o f movements b e tw e e n b e d s d u r i n g f o l d i n g , d i s t r i b u t i o n and shape o f r o c k u n i t s may b e d e t e r m i n e d b y f o l d i n g ,

wnere c o n t r a s t i n g (3)

to f r a c t u r i n g

and to a l e s s e r e x t e n t i n tn e

and (d) f r a c t u r e s a r e c o n c e n t r a t e d i n a r e a s

stru ctu ral

t r e n d s im pinge upon one a n o t h e r .

T r a p s o f some n a t u r e m u s t be a v a i l a b l e f o r

ten tio n of o i l .

tne

(o) f r a c t u r e s a r e c o n c e n t r a t e d

l o c a l l y on tn e c r e s t s o f a n t i c l i n e s troughs of s y n c lm e s ,

su scep tib le

(b)

tne r e ­

These t r a p s a r e t h r e e - d i m e n s i o n a l i n c h a r a c t e r .

An i m p e r m e a b l e z o n e i n t n e u p p e r p a r t o f t h e b a s e m e n t c o m p l e x se p a ra te s re s e rv o irs in

th e s e r o c k s from r e s e r v o i r s in th e o v e r -

l y i n g s e d im e n ts and t h u s p r e v e n t s t n e e s c a p e o f o i l from t n e b a s e ­ m ent.

The w r i t e r ’ s o p i n i o n i s

upper p a r t o f th e basement i s m in e ra ls along f r a c t u r e s

in

due to

the

tne d e p o s i t i o n o f s e c o n d a ry

the r o c k s .

p o s i t e d from m i g r a t i n g f l u i d s accom panying d i l a t a n c y

t h a t the im perm eable n a t u r e o f

These m i n e r a l s were d e ­

as a resp o n se to d e c re a se d p r e s s u r e s

(in c re a se s m

volume due to d e f o r m a t i o n )

of rock m asses. D e c r e a s e i n th e number and c o n t i n u i t y o f s e c o n d a r y o p e n in g s i n m etam orphic ro c k s a p p e a r s to c o n s t i t u t e w ith in th e basem ent. may c o n s t i t u t e

S t r u c t u r a l l y high s e c tio n s of b u ried h i l l s

t r a p s wnere tn e

o rie n te d a t an angle

"p erm eab ility " tra p s

" g r a i n ” o f m etam orphic r o c k s i s

to t n e s l o p e o f t n e

buried h i l l .

The com m on ly a c c e p t e d "Up S l o p e " t h e o r y o f m i g r a t i o n o f o i l m

m etam orphic ro c k s i s d i s c u s s e d and i t

is

concluded t h a t t h i s

th e o r y i s an u n s a t i s f a c t o r y e x p l o r a t i o n t o o l i n most a r e a s . Em phasis i s p l a c e d upon tn e r o l e o f d i i a t a n c y i n o i l from so u rc e ro c x s i n t o im p o rtan t f a c t o r s

tne m ig r a tio n o f

tne u n d e rly in g basem ent ro c k s .

i n f lu e n c in g the m ig ra tio n of o i l ,

g ra p h ic r e l i e f o f tn e basement s u r f a c e , o r edge w a te r a r e n o t d i s c r e d i t e d .

sucn a s to p o ­

and n y d r a u l i c p r e s s u r e s

However,

tne w r ite r i s of

t n e o p i n i o n t n a t t n e y commonly p l a y a l e s s i m p o r t a n t r o l e m ig ratio n o r f lu id s

O ther

in the

i n m etam orphic r o c k s th an i n c o n v e n tio n a l

sandstone r e s e r v o i r s .

INTRODUCTION The d i s c o v e r y o f s i z e a b l e a c c u m u l a t i o n s o f o i l i n t h e basem ent rocxs u n d e rly in g fo u r o i l f i e l d s in C a lif o r n ia nas s t i ­ m ulated i n t e r e s t in of

tn is

t n e p o s s i b i l i t i e s o f f i n d i n g new o i l p o o l s

type elsew nere in

gatio n is

tne

state.

The p u r p o s e o f t i n s

in v esti­

t o d e v e l o p g u i d e s t n a t may r o c u s b a s e m e n t e x p l o r a t i o n

on a r e a s wnere c o n d i t i o n s a r e f a v o r a b l e f o r o i l a c c u m u l a t i o n . Such g u id e s a re n o t a v a i l a b l e a t tn e p r e s e n t

time i n s o f a r a s can

be d e t e r m i n e d f r o m t n e r e c o r d o f b a s e m e n t d i s c o v e r i e s .

A ll m ajor

d i s c o v e r i e s have been a c c i d e n t a l and tn e o n l y m in o r d i s c o v e r y w n i c n c a n be c r e d i t e d

t o g e o l o g y i s W e s t e r n G u l f O i l C ompan y’ s

D i G i o r g i o No. 1 w e l l i n M o u n t a i n View f i e l d

s o u tn e a s t o f B akers­

fie ld . HISTORY OF BASEMENT OIL DISCOVERIES IN CALIFORNIA Tne d i f f i c u l t i e s re s e rv o ir conditions in

i n h e r e n t to t n e p r e d i c t i o n o f p o t e n t i a l b asem en t r o c x s b u r i e d by a c o n c e a l i n g

m an tle o f sedim ents a r e a p p a re n t to a n

g e o l o g i s t s and c o n s t i t u t e

tne m am cause f o r p r e ju d ic e a g a in s t t h i s P r i o r to tne d is c o v e ry o f tne l a r g e fie ld

in ly4h,

basement p o o l i n E d iso n

t n i s p r e j u d i c e was a u g m e n t e d by t n e c o n v i c t i o n

t n a t o i l i n Dasement some s c i e n t i f i c

type o f e x p lo r a tio n .

to ck s

in terest

i s a vagary of n atu re p o ssessin g

b u t s l i g h t economic i m p o r t a n c e .

d a n g e r s o f b a s i n g e x p l o r a t i o n on n e g a t i v e are w eil i l l u s t r a t e d

in

basement d is c o v e r ie s m

The

th e o rie s of th is nature

tne fo llo w in g review o f the h i s t o r y o f C alifo rn ia.

vi P ro b a b ly tne f i r s t

com m ercial p r o d u c t i o n o f o i l from m e ta ­

m o r p h i c r o c k s i n C a l i f o r n i a was o b t a i n e d i n P l a c e r i t a C a n y o n , n e a r N ew hall, C a l i f o r n i a . 77?),

A c c o r d i n g t o Brown a n d Kew ( 1 9 3 1 , p .

s m a ll q u a n t i t i e s o f l i g h t g r a v i t y o i l were p ro d u c e d from

fiv e w ells d r ille d

b e t w e e n 18 9 9 a n d 1 9 0 1 .

The b a s e m e n t c o m p l e x

in the v i c i n i t y o f th e w e lls c o n s i s t s c h i e f l y o f s c h i s t s . The n e x t d i s c o v e r y o f o i l made i n P l a y a d e l Re y f i e l d

i n t h e b a s e m e n t c o m p l e x was

a t Y enice,

C alifo rn ia,

T h is d i s c o v e r y a p p e a r s to have b een f o r g o t t e n i n of years,

for i t

is

(Huey, 1 947,

1946) d e a l i n g w i t h basem en t d i s c o v e r i e s .

The f o l l o w i n g q u o t a t i o n f r o m B a r t o n

(1931, p . 11)

is of h isto ric a l

He s t a t e s :

"The s c h i s t i s t h e l o w e r m o s t member o f zone. O r i g i n a l l y i t w as n o t c o n s i d e r e d a s th e zone, but s in c e w e lls deepened in to i t c r e a s e d t h e i r p r o d u c t i o n i t h a s h a d t o be co n sid e ra tio n ." The f i r s t fie ld

the passag e

n o t m entioned i n r e c e n t r e p o r t s

an d C a b e e n a n d S u l l w o l d ,

in terest.

in 1929.

in 1937.

the low er a p a rt of have i n ­ taken in to

i m p o r t a n t b a s e m e n t d i s c o v e r y was made i n E l S e g u n d o I t was a c c i d e n t a l i n t h a t t h e o b j e c t i v e o f t h e

t e s t w e l l was t h e s c h i s t c o n g l o m e r a t e c a p p i n g t h e b a s e m e n t . am ination o f c o re s rev ealed s c h is t co n taining o i l .

th at

E x­

th e w e ll bottom ed i n f r a c t u r e d

The w e l l p r o v e d t o be h i g h l y p r o d u c t i v e

and t h i s d i s c o v e r y was f o ll o w e d by i n t e n s i v e d e v e lo p m e n t o f t h e basem ent r e s e r v o i r in t h i s

fie ld .

The s i g n i f i c a n c e o f t h i s d i s ­

c o v e r y was n o t a p p r e c i a t e d b y g e o l o g i s t s , and S u l l w o l d

(1946, p .

a c c o r d i n g to Cabeen

1 7 - 1 8 ) , who s a y :

" I n s p i t e o f t h e f a c t t h a t s c h i s t w e l l s came i n f o r i n i t i a l p r o d u c t i o n s o f up t o 450 0 b a r r e l s p e r d a y , f r a c ­ t u r e d b asem en t r o c k s were n o t a c c e p t e d as t e s t w o r t h y

v ii r e s e r v o i r s e x c e p t in th e im m ediate v i c i n i t y of E l Segundo, where s e v e r a l o u t l y i n g s c h i s t t e s t s were d rille d .n A n o t h e r b a s e m e n t p o o l wa s d i s c o v e r e d i n 1 9 4 2 i n M aria Y a lle y f i e l d . the f o r t u n a t e

the S a n ta

T h i s d i s c o v e r y was a l s o a c c i d e n t a l ,

being

consequence of ig n o ran ce co n cern in g the e x a c t

depth of the basement m

the c e n t r a l p a r t of th e f i e l d .

One o f

th e m a jo r o p e r a t o r s had abandoned o p e r a t i o n s i n t h i s p a r t o f t h e fie ld

some t i m e p r e v i o u s

to the d is c o v e r y .

t h i s o p e r a t o r to a c c e p t th e d i s c o v e r y

The r e l u c t a n c e o f

(Cabeen and S u l l w o l d , 1946,

p . 17} was p e r h a p s u n d e r s t a n d a b l e a t t h e t i m e ,

but l i t t l e

ju sti­

f i c a t i o n rem ains f o r s k e p tic is m a f t e r fo u r y e a rs o f p r o f i t a b l e e x p lo ita tio n of th e basement p o o l.

N ev erth eless,

in g the im portance of th e d is c o v e ry s t i l l

doubt concern­

l i n g e r s i n th e minds

o f some o p e r a t o r s i n t h e S a n t a M a r i a d i s t r i c t . H i s t o r y w as r e p e a t e d i n 1 9 4 5 when e x p l o r a t i o n o f a s i m i l a r n a tu r e in E dison f i e l d ,

so u th east of B ak e rsfield ,

in f r a c t u r e d m etam orphic r o c k s .

disclo sed o il

I n te n s iv e developm ent o f th e

basement r e s e r v o i r fo llo w e d t h i s d is c o v e ry .

Beach and Campbell

(1946)

c o v e rin g the r e s u l t s

of

furnished

the f i r s t

into

some i n t e r e s t i n g

y e a r ’ s work.

th e basem ent and a l l

com m ercial p r o d u c e r s .

sta tistic s

One h u n d r e d a n d t h r e e w e l l s w e r e d r i l l e d but six of

th e s e were c o m p le te d a s

O il p r o d u c t io n from th e s e w e l l s d u r in g

t h e f i r s t 18 m o n t h s a f t e r d i s c o v e r y a m o u n t e d t o f o u r a n d o n e - h a l f m i l l i o n b a r r e l s and t h e e s t i m a t e d r e s e r v e i n t h e b a s e m e n t p o o l wa s t w e n t y - f i v e m i l l i o n b a r r e l s

(Huey, 1 9 4 7 ).

A b a s e m e n t o i l p o o l was d i s c o v e r e d i n t h e W i l m i n g t o n f i e l d 1945.

The i m p o r t a n c e o f t h i s

disco v ery is u n c e rta in

d e v e l o p m e n t , p a r t i c u l a r l y on t h e

due

c r e s t o f the s t r u c t u r e .

in

to l i m i t e d

v iii The f i r s t

basement d is c o v e r y i n C a l i f o r n i a c r e d i t e d

to

g e o l o g y was made i n 1 9 4 6 by W e s t e r n G u l f O i l Company i n M o u n t a i n View f i e l d ,

so u th east of B a k e rsfie ld .

work i n t h i s a r e a h a s d i s c l o s e d t h a t occur in th e basement ro ck s

S ubsequent developm ent sm all q u a n t i t i e s o f o i l

in sev eral l o c a l i t i e s ,

m u la tio n s are n o t o f s u f f i c i e n t s iz e

but

the ac c u ­

to re p a y developm ent and

p ro d u ctio n c o s ts . OCCURRENCES OF OIL IN CRYSTALLINE ROCKS IN CALIFORNIA The l o c a t i o n o f t n e f o u r o i l f i e l d s h a v i n g s i z e a b l e p r o ­ d u c tio n o f o i l from m etam orphic r o c k s i s S eg u n d o an d W i l m i n g t o n o i l

f ie ld s are s itu a te d

p a r t o f t h e Lo s A n g e l e s B a s i n , situ ated

in

situ ated

in the

shown o n F i g u r e 1 .

El

in the w e ste rn

S a n ta M aria V a lle y o i l f i e l d

m e S a n t a M aria d i s t r i c t and E d is o n O il f i e l d

is

is

s o u t h e a s t e r n p a r t o f t h e S an J o a q u i n V a l l e y .

S m a lle r p r o d u c tio n o f o i l from th e s e ro c k s has been d ev elo p ed in P l a y a d e l Rey o i l f i e l d Segundo o i l f i e l d Canyon o i l

lo c a te d fiv e m ile s northw est o f El

i n t n e L os A n g e l e s B a s i n a n d a l s o

f ie ld lo cated

m P lacerita

20 m i l e s n o r t h w e s t o f L o s A n g e l e s .

The t o t a l p r o d u c t i o n o f o i l f r o m m e t a m o r p h i c r o c k s i s n o t kno w n.

However, i t

c o n s t i t u t e s o n ly a v e r y sm all p e r c e n ta g e of

the cu m ulative p ro d u c tio n from C a l i f o r n i a o i l

fie ld s.

E stim ating

p r o d u c tio n from w e lls com pleted in basem ent ro c k s i s d i f f i c u l t because of com pletion p r a c tic e m ost deep w e lls

i n some f i e l d s .

For in s ta n c e ,

in W ilm ington f i e l d pro d u ce from th e

sch ist

r e s e r v o i r an d f r o m r e s e r v o i r s i n t h e o v e r l y i n g s e d i m e n t s .

A

ix

SANTA

MARIA

V> W ILM IN GTON

jvlElXlCO

Map

of

Southern

producing

oil

California from

showi ng

fractured

Figure

1

the

location

metamorphic

of

fields

rocks

X

s i m i l a r p r a c t i c e h a s b e e n a d o p t e d b y some o p e r a t o r s i n t h e S a n t a M aria Y a lle y f i e l d .

O bviously i t

is d iffic u lt

to d e te rm in e th e

t o t a l p r o d u c t io n from basem ent ro c k s i n th e s e f i e l d s .

This d i f f i

c u l t y d o e s n o t e x i s t i n E d i s o n f i e l d w h e r e Huey ( 1 9 4 7 )

estim ated

th e o i l r e s e r v e i n th e basem ent p o o l to

be t w e n t y - f i v e m i l l i o n

b arrels. S e v e r a l m inor o c c u r re n c e s o f o i l in c r y s t a l l i n e C a l i f o r n i a a r e r e p o r t e d by Powers p ilatio n of lo c a litie s

rocks in

( 1 9 3 2 , p . 8 3 7 - 8 3 9 ) w h o s e com­

fo llo w s:

"C o lu sa C o u n ty . - At W ilbur S p r in g s , C olusa C ounty, i s a l i v e o i l s e e p a g e i n s e r p e n t i n e (E. L . I c k e s ) .

there

"L o s A n g e l e s C o u n t y . - A s p h a l t i c o i l s e e p s o u t o f s c h i s t o n t h e s o u t h e r n e d g e o f t h e S a n t a M o n ic a M o u n t a i n s i n t h e a r e a now a p a r t o f W e s t H o l l y w o o d (E. L . I c k e s ) . "Mon t e r e y C o u n t y . - S e e p a g e s o f h e a v y o i l o c c u r i n a f a u l t b lo c k o f ~ c r u s h e d g r a n i t e a lo n g th e San A ndreas r i f t z o n e 5 m i l e s n o r t h w e s t o f P a r k f i e l d , i n S e c . 3 1 , T. 22 S . , R. 1 4 E . , M o n t e r e y C o u n t y . The o i l s e e p e d i n t o t h e c r u s h e d , and t h e r e f o r e p o ro u s , g r a n i t e from the a d j a c e n t p e t r o l i f e r o u s M iocene s h a l e s ( E n g l i s h , 1 9 1 9 , p . 2 4 8 ) . "A nother o c c u r re n c e o f o i l i s i n c a v i t i e s a s s o c i a t e d w ith c in n a b a r o re i n tn e P a t r i q u i n m ine, 4 m ile s n o r th o f P a r k f ie ld , in tne F ra n c isc a n fo rm atio n , m ile northw est of an o u tc ro p o f i n t r u s i v e p e r i d o t i t e . The o i l p r o b a b l y s e e p e d i n from s u b s e q u e n t l y ero d e d o v e r l y i n g d ia to m a c e o u s s h a l e s (F. 0. M a rtin ) . "Mono C o u n t y . - A s e e p a g e o f p e t r o l e u m h a s b e e n r e p o r t e d o n P a o h a I s l a n d , i n t n e Mono L a k e , w h e r e t h e r e a r e s t e a m v e n t s and s o l f a t a r a s i n R e c e n t v o l c a n i c r o c k s . A w e l l was d rille d for o il. There a r e a n c i e n t s e d im e n ta r y r o c k s i n t h e I n y o R an g e e a s t o f Mono B a s i n ( H a r r y R. J o h n s o n ) . "S a n t a B a r b a r a C o u n t y . - O i l i s found in f r a c t u r e c a v i ­ t i e s i n s e r p e n t i n e i n t h e o l d c i n n a b a r mine i n S a n t a I n e z R iv e r Canyon. The o i l r o s e w i t h t h e o r e a l o n g a f a u l t z o n e ( C l a r e n c e B. O s b o r n e ) . " S a n B e n i t o C o u n t y . - I n t h e New I d r i a c i n n a b a r m i n e n a t u r a l g a s m’wasm' e n c o u n t e r e d i n r o c k s o f t h e F r a n c i s c a n s e r i e s (R ie s, 1910, p. 603).

xi " S a n t a C l a r a C o u n t y , - A t New Alm aden h e a v y a s p h a l t i c o i l o c c u r s m g e o d e s and f r a c t u r e s i n th e m etam orphosed r o c k s and s e r p e n t i n e s o f th e F r a n c i s c a n s e r i e s ( J u r a s s i c ? ) a s s o c ia te d w ith cin n ab ar d e p o s its . Gas was f o u n d i n t h e m ine. A r h y o l i t e d ik e p a r a l l e l w ith tn e o r e body h as b r e c ciated th e s e r p e n t i n e (R ie s , 1910, p . 6 0 3 ). " S a n M ate o C o u n t y . - P e t r o l e u m f i l l s v e s i c l e s i n d i a b a s e d i k e s o n B o g e s s and H a r r i n g t o n c r e e k s , n e a r La H o n d a , S an M ateo C o u n ty . The o i l i s f o u n d i n s i d e o f t h e c a l c i t e o r c h a l c e d o n y l i n i n g s o f t h e c a v i t i e s . ( H a e h l an d A r n o l d , 1*04, p. 39). " Sonoma C o u n t y . - P e t r o l e u m o c c u r s i n t h e v e s i c u l a r c a v i ­ t i e s o f a b a s a l t ( ? ) a t a l o c a l i t y about; 7 m i l e s e a s t o f Petalum a (D ickerson, ly 2 2 , p. 527-bQ l). " S u t t e r C o u n t y . - A g a s s e e p a g e i s Known a t t h e s o u t h s i d e o f the M a r y s v i ll e B u t t e s , S u t t e r County, a t th e c o n t a c t of C retaceous sedim entary ro ck s w ith the a n d e s ite core o f th e l a c c o l i t h ( S t a l d e r , 1*32, p. 362). "T u la r e C ounty. - I n the T e rr a B e l l a o i l f i e l d , w e l l s b e g in n in g m the h e rn R iv e r fo rm a tio n o f P lio c e n e age have found o i l i n th e b a s a l a r k o s e and i n th e u n d e r l y i n g basem en t c o m p l e x r o c k s o f t h e S i e r r a N e v a d a (G. C l a r k G e s t e r ) . " V e n t u r a C o u n t y . - The C o n e j o P a s s O i l f i e l d , p ro d u c e s from b a s a l t a g g lo m e r a te . r e p r i n t e d from T a l i a f e r r o ,

V e n tu ra County,

The f o l l o w i n g d e s c r i p t i o n i s

Hudson, and Craddock (ly 2 4 , p .

808-809).

"The Cone j o f i e l d , a t t h e f o o t o f t n e C o n e j o g r a d e , i s o n e o f th e most u n u su a l in C a l i f o r n i a as th e o i l i s o b ta in e d from b a s a l t a g g lo m e r a te . The o n l y r o c k s e x p o s e d i n t h e v i c i n i t y o f t h e f i e l d b e l o n g t o i h e u p p e r p a r t o f t h e Cone j o v o l c a n i c s , which h e r e c o n s i s t o f flo w s o f b a s a l t and a n d e s i t e , and c o a r s e v o l c a n i c a g g l o m e r a t e . The l a t t e r , w h i c h i s t h e m o s t a b u n d a n t t y p e , i s made u p o f l a r g e a n g u l a r b l o c k s a n d sm all fragm ents of b a s a l t in c lo s e d in a m a trix of b a s a l t or b asaltic tu ff. These v o l c a n i c r o c k s form th e s t e e p h i l l s s o u t h e a s t o f t h e to w n o f C a m a r i l l o a n d a l s o u n d e r l i e t h e s m a l l a l l u v i u m - f i l l e d v a l l e y s w i t h i n and a l o n g t h e f r o n t o f t h e h ills. The s t r u c t u r e i s s i m p l e , t h e d i p b e i n g u n i f o r m l y t o 0 t h e n o r t h a t a n g l e s o f 2 u ° - 28 ; t h e s t r i k e i s N. 60 - 70 S . "The o c c u r r e n c e o f o i l i n t h i s r e g i o n i s u n u s u a l f o r t h r e e r e a s o n s : one i s th e f a c t t h a t th e r e s e r v o i r ro ck i s s h e a re d b a s a lt, b a s a lt agglom erate, or alluvium o v e rly in g these ro ck s; a n o t h e r i s th e v e r y s h a ll o w d e p th a t which th e o i l i s en ­ c o u n t e r e d , 60-250 f e e t ; and th e t h i r d i s t h a t s t r u c t u r e a p p a r e n tly p la y s l i t t l e p a r t in the accu m u latio n .

x ii "Not f a r n o r t h o f tn e f i e l d th e Conejo v o i c a n i c s a r e i n f a u l t e d c o n t a c t w ith tn e T e r t i a r y s e d im e n t s , and i t i s p r o ­ bably along t h i s f a u l t t h a t tne o i l r i s e s in to tn e v o lcan ic rocKs. Tnere a re th re e p o s s i b l e s o u rc e s f o r tn e o i l : (1) i t may n a v e o r i g i n a t e d m t h e E o c e n e s n a i e s b e l o w t n e v o i c a n i c s ; { 2 ) i t may h a v e m i g r a t e d i n t o a f a u l t , a n d t h u s i n t o t n e v o i c a n i c s , f r o m t n e s a n d s i n t h e S e s p e ; ^3) o r i t may h a v e come f r o m o r g a n i c s h a i e s i n t e r d i g i t a t e d w i t h t h e f l o w s an d agglom erates. T n e r e i s no d i r e c t e v i d e n c e a s t o w h i c h o f these h y p o th esis i s c o r re c t. S m all am ounts o f o i l have e v i d e n t l y moved u p w a r d a l o n g t h e s o m e w h a t p o r o u s a g g l o m e r a t e s and a c c u m u l a t e d i n th e a l l u v i u m w hich o v e r l i e s them m t h e s h a l l o w v a l l e y s a t t h e e d g e o f t h e h i l l s . QT h e r e i s no g a s o ­ l i n e m t n e o i l , w h i c h h a s a g r a v i t y o f 16 Baume. The average p ro d u c tio n i s about o n e - fo u r th o f a b a r r e l a day. S i x m n e s w e s t o f t h e C o n e j o f i e l d two w e l l s d r i l l e d by t h e W e s t e r n G u l f O i l Company on t h e S p r m g v i i l e a n t i c l i n e f o u n d heavy o i l i n f r a c t u r e s i l l tn e lo w e r 2,uuu r e e t o r th e h o le w h i c h was m b a s a l t i c b r e c c i a , a g g l o m e r a t e , a n d f l o w m a t e r i a l ” ( E . L. I c i c e s ) .

ACKNOWLEDGEMENTS T h is r e p o r t i s a c o m p i l a t i o n and a n a l y s i s ot‘ b o th p u b l i s h e d and o r i g i n a l d a t a c o n c e r n in g o i l i n c r y s t a l l i n e

rocKs.

C ooperation

o f g e o l o g i s t s o f many d i f f e r e n t o i l c o m p a n i e s w as e s s e n t i a l p ro g re ss in t n i s g ratitu d e

tnat

in v estig atio n ,

and i t

to

i s w ith a f e e lin g of s in c e re

th e w r i t e r a c k n o w le d g e s th e c o u r t e s y and c o o p e r a t i o n

o f t n e s e men. The w r i t e r i s

in d e b te d e s p e c i a l l y to n i s o l d

L e d i n g h a m , who s u g g e s t e d cial

frien d ,

t h e p r o b l e m an d l a t e r e n l i s t e d

s u p p o r t o f W e s t e r n G u l f O i l Company m

tne

Glen

tne f i n a n ­

in v estig atio n .

R. L . H e w i t t a n d J o h n May, f o r m e r l y o f T i d e w a t e r A s s o c i a t e d O i l Company a l l o w e d t n e w r i t e r t o s t u d y t h e i r c o l l e c t i o n o f t h i n s e c t i o n s o b t a i n e d from b asem ent ro c k s m

th e San J o a q u i n V a l l e y ;

J . H. B e a c h an d A. H. H u ey c o n t r i b u t e d v a l u a b l e d a t a c o n c e r n i n g o i l p r o d u c t i o n and g e o l o g i c a l r e l a t i o n s h i p s i n E d is o n o i l f i e l d ; Aden H u g h e s c o n t r i b u t e d m o s t o f t n e u n p u b l i s h e d i n f o r m a t i o n c o n ­ c e r n i n g S a n t a M a r i a V a l l e y o i l f i e l d ; M. Mayuga a n d R. W i n t e r b u r n e a llo w e d th e w r i t e r to nave f r e e a c c e s s to u n p u b lis h e d i n f o r m a t i o n c o n c e rn in g W ilm ington o i l f i e l d O i l Company a s s i s t e d

and g e o l o g i s t s o f W e ste rn G ulf

the w r i t e r in

th e c o l l e c t i o n and c o m p i l a t i o n

o f d a t a c o n c e r n i n g w e l l s p e n e t r a t i n g b a s e m e n t r o c k s i n t h e S an Jo aq u in V a lle y . S p e c i a l t h a n k s a r e d u e t o Thomas C l e m e n t s , W i l l i a m E a s t o n a n d K e n n e t h Emer y who n a v e r e a d t h i s r e p o r t a n d o f f e r e d many h e l p ­ fu l criticism s.

F in ally

the w r i t e r w ishes

to e x p r e s s h i s g r a t i t u d e

to the l a t e R o b e rt C la rk f o r h i s K in d ly g uidance d u rin g the e a r l y stag e s of

the i n v e s t i g a t i o n .

PART I ANALYSIS OF THE PROBLEM OF MIGRATION AND ACCUMULATION OF OIL IN BASEMENT ROCKS The c o n d itio n s n ece ssa r y ror the form ation o f an o i l p o o l

in basement tocks are the same as m sedim entary r e s e r v o ir s . They a r e :

(l)

some s o u r c e o f o i l m u s t be p r e s e n t m

cap p in g the basem ent,

(2)

s u i t a b l e openings in

the se d im en ts

tne basem ent r o c k s

m u st e x i s t f o r m i g r a t i o n and a c c u m u l a t i o n o f o i l ,

and (3)

traps

o f some n a t u r e m u s t oe a v a i l a b l e f o r t h e r e t e n t i o n o f o i l .

Each

o f t h e s e c o n d i t i o n s w i l l be c o n s i d e r e d s e p a r a t e l y . 1.

S o u r c e o f O i l . - The p o s s i b i l i t y t h a t o i l i s

to th e b asem en t r o c k s i n wnich i t co n sid eratio n .

is

The b a s e m e n t r o c k s i n

round does n o t w a r ra n t s e r i o u s the p ro d u c in g r i e l d s c o n s i s t

o f m etam orphosed v o l c a n i c and s e d im e n t a r y r o c k s . have been p r e s e n t o r i g i n a l l y in

o il

t n a t may

t h a t i s now p r e s e n t i n

casem ent r e s e r v o i r s must have m ig r a te d i n t o

a d ja c e n t younger sed im en ts.

Any o i l

th e s e d im e n t s would h a v e been

d e s t r o y e d d u r in g m etam orphism ; h e n c e , the

indigenous

th e s e r o c k s from

A ll g e o l o g i s t s f a m i l i a r w ith basement

p o o ls are in agreem ent w ith t h i s c o n c lu sio n . The q u e s t i o n a r i s e s a s t o w h e t h e r t h e o i l p r e s e n t i n b a s e m e n t ro c k s has m ig r a te d d i r e c t l y from s o u rc e beds i n t o r o c k s o r was f i r s t c o n c e n t r a t e d i n basem ent and th e n m ig r a te d i n t o p o ssib ilitie s

" c a r r ie r beds" o v e rly in g

the p r e s e n t r e s e r v o i r .

the

The two

a r e n o t m u t u a l l y e x c l u s i v e an d j u d g i n g f r o m t n e e v i ­

dence r e l a t i n g trib u ted o il

the u n d e r ly in g

to

th is

q u e s tio n both ty p e s o f m ig ra tio n nave con­

to basement r e s e r v o i r s .

2 2.

O penings m

basement rocks a re ings e x i s t m

Basement R ooks* - R e s e r v o i r c o n d i t i o n s i n

restricted

the ro c k s .

the fo llo w in g c a u se s: (b)

t o l o c a l i t i e s where s e c o n d a r y o p e n ­

These o p e n i n g s a r e due to one o r more o f

(a) m e c h a n ic a l d i s r u p t i o n o f rocics,

c h e m ic a l and p h y s i c a l p r o c e s s e s i n t h e zone o f w e a t h e r i n g ,

and (o)

so lu tio n .

of rocxs are

Of t h e s e , o p e n i n g s due t o m e c h a n i c a l d i s r u p t i o n

th e o n ly ones o f im portance i n th e basem ent r e s e r v o i r s

p rod u ctiv e of o i l in C a lifo rn ia a t openings,

tn at is ,

in terg ran u lar

the p r e s e n t tim e.

s p a c e s form ed a t

P rim ary

t h e same t i m e

a s tne e n c lo s in g rock a r e n o t o f im p o rtan ce because o f t h e i r su b cap illary siz e . R e g io n a l and l o c a l g u i d e s t h a t w i l l

se rv e as c lu e s to th e

l o c a t i o n o f p o r o u s and p e rm e a b le z o n e s i n b asem en t r o c k s a r e essen tial

to o ls f o r o i l e x p lo r a tio n in these ro c k s.

W ith o u t them,

t h e s e a r c h f o r o i l w i l l i n d e e d be c o m p a r a b l e t o l o o k i n g f o r t h e p r o v e rb ia l n eed le in the h a y s ta c k . of th is in v estig atio n is geologic fe a tu re s rocks.

One o f t h e m a i n o b j e c t i v e s

to d e te rm in e th e u t i l i t y o f v a r io u s

as g u id es

to s e c o n d a ry o p e n in g s i n basem ent

This p h ase o f th e i n v e s t i g a t i o n i s d e s c r ib e d i n p a r t I I I

o f the r e p o r t . 3.

T r a p s . - The m a j o r o i l p o o l s i n b a s e m e n t r o c k s i n C a l i f ­

o rn ia are lo cated sed im en ts. p o ssib le.

below a c c u m u l a t i o n s o f o i l i n trie o v e r l y i n g

Several in te rp re ta tio n s of th is

re la tio n s h ip are

They i n c l u d e :

(1) basem ent r e s e r v o i r s .

The t r a p c o n d i t i o n i s

common t o b o t h s e d i m e n t a r y a n d

T h i s may b e t r u e o f o i l p o o l s l o c a t e d o n t h e

c r e s t s of bu ried h i l l s ;

such as th o s e u n d e r l y in g W ilm ington,

E l Segundo and P l a y a d e l Rey f i e l d s .

I t d o e s n o t a p p e a r t o be a

s a t i s f a c t o r y e x p la n a tio n f o r o i l p o o ls in basement ro ck s lo c a te d b en eath com bination s t r u c t u r a l - s t r a t i g r a p h i c

trap s,

such as th ese

i n E d is o n and S a n t a M a r ia V a l l e y f i e l d s . (2) is

due t o

The r e l a t i o n s h i p

i s apparent ra th e r

th a n r e a l and

the p a u c i t y o f basem ent t e s t s beyond th e l i m i t s o f

pro d u ctiv e a re a s m

tne o v e r ly in g s e d im e n ts .

T h i s may a l s o b e

t r u e as basem ent e x p l o r a t i o n has b een c o n fin e d l a r g e l y to a r e a s where p o t e n t i a l l y p r o d u c t i v e i n t e r v a l s e x i s t i n

th e sedim ents

c ap p in g the basem ent. (3)

The m o v em en t o f o i l

in

th e b a s e m e n t was r e s t r i c t e d

due t o t h e a b s e n c e o f p r e s s u r e g r a d i e n t s w i t h i n t h e f r a c t u r e d m etam orphic r o c k s .

T his e x p la n a tio n i s

fav o red by the w r i t e r f o r

b a s e m e n t o i l p o o l s i n E d is o n and S a n t a M a ria V a l l e y f i e l d s . reasons fo r fav o rin g

th is

in terp retatio n

are p resen ted

The

in the

a n a l y s i s o f p r o d u c tio n d a t a from E dison f i e l d . The t h r e e d i m e n s i o n a l n a t u r e o f b a s e m e n t t r a p s i s n o t commonly a p p r e c i a t e d b y g e o l o g i s t s . been w ith s t r u c t u r a l b a r r i e r s

th a t w ill a r r e s t m igration o f o i l

tow ards th e c r e s t o f b u r ie d h i l l s . given to th e n a tu re o f the basement r e s e r v o i r . e x is t in w ells

The p r i n c i p a l c o n c e r n h a s

L ittle

c o n s id e ra tio n has been

"capping" c o n fin in g tne o i l

to t h e

G r e a t l y d i f f e r e n t bottom h o l e p r e s s u r e s

ta p p in g p a r t l y d e p le te d sand r e s e r v o i r s

im m ediately

above th e b a se m e n t and i n w e l l s c o m p le te d i n t h e u n d e r l y i n g b a s e ­ ment r e s e r v o i r s ,

thus i n d i c a t i n g

sep arated w ithin

t h e b a s e m e n t r o c k s b y some t y p e o f b a r r i e r .

b a r r i e r developed e i t h e r a f t e r

t h a t t h e two r e s e r v o i r s a r e

th e o i l had e n t e r e d

This

the basement

r o c k s f r o m o v e r l y i n g r e s e r v o i r s o r i t w as a b s e n t f r o m t h a t s e c t i o n o f t h e b asem ent where i n f l u e n t se e p a g e fro m th e s e d i ­ m e n t s was l o c a l i z e d .

The e v i d e n c e r e l a t i n g

p re s e n te d f o r each of tne f i e l d s

m

to

t h i s problem i s

p a r t s V I I I t o XI o f t n e

rep o rt. PART I I CLASSIFICATION OF OPENINGS IN CRYSTALLINE ROCKS: The v a r i o u s k i n d s o f o p e n i n g s t n a t a r e f o u n d m lin e

cry stal­

r o c k s may be c l a s s i f i e d a s f o l l o w s : P rim a ry O penings 1.

In te rg ra n u la r spaces.

2.

Openings m

volcanic rocks.

S eco n d ary O penings 1.

F r a c t u r e s due to m e c h a n ic a l d i s r u p t i o n o f r o c k s .

2.

O p e n in g s due to c n e m i c a i and p h y s i c a l p r o c e s s e s i n

the zone o f w e a th e rin g . 3.

O p e n in g s due t o s o l u t i o n . P r im a r y O penings

1.

I n t e r g r a n u l a r S p a c e s . - I n t e r g r a n u l a r s p a c e s p l a y an

u n im portant ro le in rocks.

th e movement o f f l u i d s

O r i g i n a l p o r o s i t i e s a re low , o p e n in g s a r e

i n s i z e and t n e y a r e n o t i n t e r c o n n e c t e d . cites

through c r y s t a l l i n e

F u ller

su b cap illary (1906, p .

61)

t n e r e s u l t s o f t h i r t y - s i x p o r o s i t y d e t e r m i n a t i o n s on

g ran ite ,

scn ist,

to 1 .8 5 p e r c e n t.

and g n e i s s .

P o ro sities

M einzer (1923, p .

ill)

ranged from 0 .019 p e r c e n t and T olm an(1937, p .

100)

co nclude t h a t tn e ground w a te r s to r a g e c a p a c i t y o f th e s e ro c k s i s lo w d u e t o

the m ic ro s c o p ic

s i z e o f o p e n i n g s and tn e a b s e n c e

o r c o n n e c t i o n s between th e i n t e r g r a n u l a r p.

v v ) and Rule

fic a n t size

in

developed s in c e 2.

(1937, p .

28-30) ag re e

spaces,

E ckis

(1934,

th a t a l l openings o f s i g n i ­

the basem ent com plex i n s o u t h e r n C a l i f o r n i a have form ation of the ro ck s, Openings in V o lc a n ic R ocks, - V e s i c u l a r o p en in g s m

l a v a s an d o p e n i n g s m

volcanic

breccias are fe a tu re s

e i t h e r destroyed o r g r e a tly m odified

th a t are

by m e t a m o r p h i c p r o c e s s e s .

V o l c a n i c members o f t h e b a s e m e n t co m plex i n C a l i f o r n i a have been metam orphosed*

P rim ary openings i n

t h e s e r o c k s were e i t h e r

c l o s e d o r f i l l e d w i t h s e c o n d a r y m i n e r a l s such a s q u a r t z and epidote. tu re s

O il b e a r i n g seams i n tn e m e t a - v o l c a n i c s occupy f r a c ­

th a t are c le a r ly secondary m

o rig in .

O bviously t h i s c o n c lu s io n does not a p p ly

to y o u n g e r v o l c a n i c

ro c k s i n t e r c a l a t e d w ith s e d im e n ts c a p p in g the basem ent com plex. The s t o r a g e c a p a c i t y o f t h e s e r o c k s h a s n o t b e e n r e d u c e d b y m e t a m orphism ; n e n c e ,

they c o n s titu te p o te n tia l r e s e r v o ir rocks. S e c o n d a ry Openings

A ll o p en in g s developed a f t e r

the f o r m a tio n of the e n c lo s in g

rock a re c l a s s i f i e d as secondary openings T h e y may be c l a s s i f i e d

(M einzer, 1923, p .

on t h e b a s i s o f o r i g i n i n t o

109),

the fo llo w in g

catego ries. 1. tu re s are stress.

F r a c t u r e s due to M e c h a n i c a l D i s r u p t i o n o f r o c k s . - f r a c ­ the r e s u l t of f a i l u r e F o ld in g and f a u l t i n g

i n a r o c k mass t h a t h a s e x p e r i e n c e d

a r e common c a u s e s o f f r a c t u r e s .

T h eir r o le in sid ered

in

th e l o c a l i z a t i o n o f f r a c t u r e s in r o c k s w i l l be con­

the f o llo w in g s e c t i o n o f th e r e p o r t d e a l i n g w ith

g eologic c o n tro ls of 2.

secondary openings.

O p en in g s due to C h em ical and P h y s i c a l P r o c e s s e s i n

Zone o f W e a t h e r i n g . - O p e n i n g s i n r e g o l i t h i c

the

d eb ris p resen t

a l o n g t h e u n c o n f o r m i t y b e t w e e n b a s e m e n t r o c k s an d o v e r l y i n g s e d i ­ m e n t s may be d u e c h i e f l y t o w e a t h e r i n g p r o c e s s e s .

S izeable o i l

p r o d u c t i o n from th e u p p e r w e a tn e re d s u r f a c e o f b u r i e d basem ent h ills

is

r e p o r t e d by Powers and C lapp

(1932, p .

o v e r ly in g the b u rie d A m arillo M ountains, from th e s c h i s t c o n g lo m e ra te o v e r l y i n g E l S e g u n d o , a n d P l a y a d e l Hey f i e l d s

Texas.

725)

from f i e l d s

O il i s produced

th e basem ent i n W ilm ington,

in the Los A ngeles b a s in .

R e s e r v o i r s o f t h i s n a t u r e h a v e f e w f e a t u r e s i n common w i t h r e s e r ­ v o i r s i n f r a c t u r e d m etam orphic r o c k s ; h e n c e , in any d e t a i l in 3.

they are no t d isc u sse d

th is rep o rt.

O p e n i n g s E n l a r g e d by S o l u t i o n . - S e c o n d a r y o p e n i n g s

e n l a r g e d b y s o l u t i o n a r e w e l l Known f e a t u r e s by l i m e s t o n e .

in areas underlain

L i m e s t o n e a n d m a r b l e a r e n o t common r o c k s in t h e

b a s e m e n t c o m p l e x i n C a l i f o r n i a a n d a r e n o t p r e s e n t in a n y o f t h e b a s e m e n t c o r e s e x a m i n e d by t h e w r i t e r . th e fo rm a tio n o f open sp a c e s m to be u n i m p o r t a n t .

The r o l e o f s o l u t i o n i n

these rocks i s

thus co n sid e red

PART I I I GEOLOGIC CONTROLS OF SECONDARY OPENINGS DUE TO MECHANICAL DISRUPTION OF ROCKS S econdary o p en in g s r e s u l t i n g from m e c h an ical d i s r u p t i o n o f rocks,

are not a c c id e n ta l.

The y a r e

the r e s u l t s o f f a i l u r e

i n a ro c k mass t h a t h a s e x p e r ie n c e d s t r e s s . d ete rm in e d by: (2)

(1) e n v ir o n m e n ta l c o n d i t i o n s o f d e f o r m a t i o n ,

dynamic h i s t o r y o f t h e r e g i o n ,

rocks,

T h e ir developm ent i s

and ( 4 )

(3) p h y s i c a l p r o p e r t i e s o f

th e n a t u r e o f s e c o n d a r y s t r u c t u r e s im posed on

the rocks* 1.

E nvironm ental C o n d itio n s o f D efo rm atio n . - S econdary

openings a re

ch aracteristic

co n fin in g p re s s u re s .

f e a t u r e s o f d e f o r m a t i o n u n d e r low

They a r e l e s s

common i n d e e p s e a t e d e n ­

v i r o n m e n t s w h e r e t h e y t e n d t o be l o c a l i z e d a l o n g s h e a r z o n e s . The r e s p o n s e o f a r o c k t o d e f o r m a t i o n i s pressure

and t e m p e r a t u r e .

th a t are s ta b le

at

in flu e n c e d by

A s e d i m e n t a r y r o c k co m p o s e d o f m i n e r a l s

the e a r t h ’s s u r f a c e w i l l undergo m o rp h o lo g ic a l

a n d m i n e r a l o g i c a l c h a n g e s a s t e m p e r a t u r e s an d p r e s s u r e s i n c r e a s e w ith b u r ia l.

In te rstic e s

in the rock w ill tend

to d e c r e a s e i n

s i z e due to r e - a r r a n g e m e n t o f p a c k i n g p a t t e r n o f t h e g r a i n s , p u lsio n of w ater,

and c e m e n t a t i o n .

ex­

D eep b u r i a l c a r r y i n g t h e r o c k

i n t o a g e o l o g i c e n v i r o n m e n t f a v o r i n g r e c r y s t a l l i z a t i o n o f some or a il of its

c o m p o n e n t m i n e r a l s w i l l be a c c o m p a n i e d b y a f u r t h e r

r e d u c t i o n i n p o r o s i t y i n r e s p o n s e to h ig h c o n f i n i n g p r e s s u r e s . S im ilarly ,

its

r e s p o n s e to d e fo rm a tio n in t h i s e n v iro n m e n t w i l l

be l i m i t e d

to s t r u c t u r e s

t h a t a r e econom ical in

t h e i r space

requirem ents.

F r a c t u r i n g r e q u i r e s an in c r e a s e

(N evin, 1949, p . 1 7 7 ), h e n c e , i t

i n r o c k v o lu m e

ten d s to be r e s t r i c t e d

to zones

where s t r e s s e s can be s u f f i c i e n t l y c o n c e n t r a t e d t o overcom e th e r e s t r i c t i o n s im posed by h i g h c o n f i n i n g p r e s s u r e s . siste n t fau lts

(com monly d e s c r i b e d a s

in th e m etam orphic r o c k s .

sh e a r zones) a re developed

These s h e a r zo n es a r e i n h e r e n t l y open

s t r u c t u r e s r e a d i l y p e n e t r a t e d by s o l u t i o n s , (1948, p . 3 9 ) . th is

Strong p er­

a c c o r d i n g to G i l l

L o c a liz a tio n of ore d e p o sits along s tr u c tu r e s of

type i n t h e C a n a d ia n S h i e l d c e r t a i n l y s u b s t a n t i a t e s t h i s

s t a t e m e n t and i n d i c a t e s oped

t h a t p o ro u s and perm eab le zones are d e v e l­

by f a u l t i n g i n m o st g e o l o g i c e n v i r o n m e n t s . O t h e r s e c o n d a r y s t r u c t u r e s i m p o s e d on r o c k s i n d e e p

s e a te d environm ents a r e : in n atu re),

(b)

(a)

com plex f o l d i n g

s t r u c t u r e s due to p l a s t i c

( co m m o n ly i s o c l i n a l

flow i n in co m p eten t

r o c k s - e l o n g a t i o n o f ro c k b o d ie s tow ards th e s u r f a c e w hich i s the d ir e c tio n of e a s i e s t r e l i e f , tio n

a common r e s p o n s e ,

( s c h i s t o s i t y and s l a t y c l e a v a g e ) ,

o rie n te d a t r ig h t angles rock m asses. stru ctu res o il

is

are

reserv o ir.

and (d) c r o s s

(c) f o l i a ­

jo in ts

to t h e d i r e c t i o n o f e l o n g a t i o n o f

S e c o n d a ry o p e n in g s accom panying m ost o f th e s e sm all in s i z e . However,

The y do n o t c r e a t e

a p o ten tial

they c o n s t i t u t e p la n e s o f weakness in

t h e r o c k s w h i c h may be u t i l i z e d

d u rin g a l a t e r deform ation o f

t h e r o c k mass u n d e r low c o n f i n i n g p r e s s u r e s .

Under t h e s e c o n d i­

t i o n s t h e y may " o p e n u p " a n d c r e a t e d e s i r a b l e o p e n s p a c e s i n t h e rocks.

9 U p l i f t a n d d e e p e r o s i o n may e v e n t u a l l y e x p o s e a m e t a m orphic t e r r a i n a t tia l

decrease m

the

surface.

T his change in v o lv e s a s u b s t a n ­

co n fin in g p re s s u re ;

r e a d j u s t m e n t s due to

h en ce, m inor s t r u c t u r a l

the r e l e a s e o f e l a s t i c

c o m p r e s s i o n may be a n t i c i p a t e d .

energy s to r e d d u rin g

S h e e t i n g i n p l u t o n i c r o c k s and

s i m i l a r s t r u c t u r e s i n m e t a m o r p h i c r o c k s may be d u e t o e l a s t i c expansion o f rocks a t These f l a t - l y i n g

the e a r t h t s s u r f a c e

stru ctu res co n stitu te

g r a n i t e s of G eorgia (L egrand, 1949). sta te s

(Lobeck, 1939, p . 8 5 ) .

im p o rta n t a q u i f e r s in the Jah n s (1943, p .

77-78)

t h a t i n t h e g r a n i t e s o f New E n g l a n d t h e s h e e t s b e c o m e

th ick er,

fla tte r

an d more r e g u l a r w i t h i n c r e a s i n g d e p t h .

The

s p a c e s b e t w e e n s h e e t s be com e p r o g r e s s i v e l y t h i n n e r w i t h i n c r e a s i n g d e p th , making th e o c c u r r e n c e o f a p p r e c i a b l e q u a n t i t i e s o f ground w ater le s s l i k e l y a t depths g r e a te r reductions

t h a n £50 f e e t .

F u rth er

i n t n e s i z e o f o p e n i n g s may be a n t i c i p a t e d w h e r e t h e

c r y s t a l l i n e rocks a re su b seq u en tly d eep ly b u ried under younger sedim ents a s in The w e i g h t o f

lying

the c a se i n the basem ent o i l p o o ls o f C a l i f o r n i a ,

t h e o v e r l y i n g s e d i m e n t s i s c o n c e n t r a t e d on f l a t -

s t r u c t u r e s such a s t h e s e and i t

i s d o u b tfu l i f open spaces

c a n be m a i n t a i n e d f o r a n y a p p r e c i a b l e d i s t a n c e C atac la stic

deform ation of ro ck s

(R ule, 1937, p .

33).

( r u p t u r e and r o t a t i o n o f

i n d i v i d u a l m i n e r a ls and m e c h a n ic a l d i s r u p t i o n o f ro c k m asses) takes p lace low .

i n s h a llo w e n v iro n m e n ts wnere c o n f i n i n g p r e s s u r e s a r e

Open s p a c e s a r e f o r m e d i n a l l

p o s sib le exception of lim esto n e, resu lt,

c r y s t a l l i n e rocks w ith

g ypsum a n d h a l i t e ,

and,

the

as a

t h e v o l u m e o f t h e r o c k m a s s commonly i n c r e a s e s ; Mead

(1925) u s e s th e

term d i l a t a n c y f o r a l l

increases

i n r o c k volume

10 due t o d e f o r m a t i o n *

H is d is c u s s io n of tne g e o lo g ic r o le o f

d i l a t a n c y i s an o u t s t a n d i n g c o n t r i b u t i o n

to g e o l o g i c a l l i t e r a t u r e ,

but, u n fo rtu n a te ly ,

th e a t t e n t i o n w hich i t

deserves.

i t has

Rove ( 1 9 4 7 , p .

178)

co n cep t to th e developm ent w ays m

cry stallin e

not received

rocks.

h a s a p p l i e d M ead 's d i l a t a n c y

and m a in te n a n c e o f p e rm e a b le c h a n n e l He s t a t e s :

"The a n a l o g y m i g h t be draw n b e tw e e n a f i n e - g r a i n e d d e n s e b r i t t l e r o c k an d a s a n d m c l o s e p a c k i n g ; a n y d e f o r m a t i o n t e n d s t o c r e a t e new o p e n i n g s a n d n e c e s s i ­ t a t e s an i n c r e a s e in v o lu m e ." D ilatan cy is

c o n t r o ll e d by c o n fin in g p r e s s u r e ;

in f r a c tu r e p a t t e r n s a t depth are e x p e c ta b le . q u o t a t i o n from M cK in stry (1948, p . t h i s n a tu r e in m ining d i s t r i c t s ,

396)

and,

changes

Tne f o l l o w i n g

concerns changes of

thus,

fo r s im ila r fe a tu re s in r e s e rv o ir rocks.

th erefo re,

f u r n i s h e s a guide

He s a y s :

"Many b u l k y d e p o s i t s , i n c l u d i n g some t h a t a r e c a l l e d d i s s e m i n a t e d c o n s i s t o f a com plex s y s te m o f s m a l l , c l o s e l y - s p a c e d f r a c t u r e s an d d i f f e r f r o m l o d e s o n l y i n b e i n g m ore o r l e s s e q u i d i m e n s i o n a l i n p l a n r a t h e r t h a n lo n g or narrow . When o r e b o t t o m s , i t i s u s u a l l y by d e c l i n e m n u m b e r a n d s i z e o f f r a c t u r e s . • • W ith g r e a t c h a n g e s i n d e p t h , t h e n a t u r e o f f r a c t u r i n g may be e x p e c t e d to c h a n g e c o r r e s p o n d i n g l y . This fo llo w s n o t o n l y fro m t h e o r e t i c a l c o n s i d e r a t i o n s o u t from a com parison of e p ith e rm a l ( n e a r - s u r f a c e d ep o sits!) w ith hypotherm ai d e p o s i t s ( d e e p -s e a te d d e p o s its !). Tension c r a c k s and b r e c c i a s , s i n c e t h e y i n v o l v e i n c r e a s e m th e volume o f t h e m ass a s a w h o le , a r e t h e p r e d o m in a n t mode o f f r a c t u r i n g c l o s e to t h e s u r f a c e , w h e r e a s s h e a r ­ i n g i s m o s t common i n d e e p s e a t e d d e p o s i t s . . . I t is i m p o s s i b l e to a s s i g n an y d e f i n i t e d e p t h to t h i s c h a n g e , s i n c e i t o c c u r s a t much g r e a t e r d e p t h m c o m p e t e n t r o c k s th a n in c o m p e te n t o n e s , and f u r t h e r m o r e , i t p r o b a b l y v a r i e s w ith th e n a t u r e o f l o a d i n g and r a t e o f a p p l i c a t i o n o f force. " ( U n d e r l i n i n g and e x p l a n a t o r y t e x t e n c l o s e d i n b r a c k e ts i n s e r t e d by th e w r i t e r ) . The w e i g h t o f o v e r b u r d e n on d i l a t a n c y .

t h u s c o n s t i t u t e s an i m p o r t a n t c o n t r o l

11 D ilatancy is

f a v o r e d i n r e g i o n s w n e r e tooth v e r t i c a l and

l a t e r a l movements o f r o c k s a r e p o s s i b l e .

The i n f l u e n c e o f t o p o ­

g r a p h i c r e l i e f o n d i l a t a n c y i s e m p h a s i z e d by R u l e i n an i n t e r e s t i n g cry stallin e

rocks.

(1937, p .

25)

d i s c u s s i o n o f the developm ent o f a q u i f e r s in He s t a t e s :

”Open j o i n t s an d f r a c t u r e s a r e m o re l i k e l y t o toe f o u n d i n a r e a s o f h i g h r e l i e f , w here t h e r e i s an o p p o r t u n i t y o f t n e l a t e r a l movem ent o f r o c k m a s s e s t h a n w h e r e t h e rocks are l a t e r a l l y c o n ta in e d .” S i m i l a r o p p o r t u n i t i e s f o r l a t e r a l e x p a n s i o n may e x i s t o n b u r i e d h ills

on t h e basem en t s u r f a c e .

ta ry rocks)

surrounding

rocks c o n s titu tin g

the h i l l

The r e s t r a i n i n g m edium ( s e d i m e n ­ is

m

f a v o r e d by low c o n f i n i n g

n e a r - s u r f a c e environm ents o f d e fo rm a tio n .

Secondary openings a re occurs,

than c r y s t a l l i n e

the basem ent f l o o r .

C onclusions. - D ila ta n c y i s pressures ex istin g

less rig id

formed a t a l l

d e p t h s where f r a c t u r i n g

b u t a r e f a r m o r e common i n e n v i r o n m e n t s w h e r e o p p o r t u n i t i e s

f o r u p w a r d and l a t e r a l m o v e m e n t s o f r o c k m a s s e s e x i s t . h ills

B uried

o f f e r g r e a t e r o p p o r tu n i t i e s f o r l a t e r a l expansion than f l a t -

l y i n g o r g e n tly s lo p in g basement s u r f a c e s .

R ed u ctio n i n c o n fin in g

p r e s s u r e s accom panying rem oval o f o v e rb u rd e n a llo w s r o c k m asses to expand by d ev elo p m en t of s e c o n d a ry o p e n in g s a lo n g p r e - e x i s t i n g p l a n e s o f s t r u c t u r a l w e a k n e s s o r a l o n g e n t i r e l y new f r a c t u r e s i n rocks. 2. c h a ra c te ristic

Dy n a m ic H i s t o r y . featu res

c r u s t a l movements a r e

m

still

- Secondary openings m ro c k s are

re g io n s such a s C a l i f o r n i a , in progress.

where

The y a r e l e s s common

i n r e g i o n s o f c r u s t a l s t a b i l i t y a t t h e p r e s e n t time r e g a r d l e s s o f

12 th e p r e v i o u s dynamic n i s t o r y o f t h e r e g i o n . differen ce rocks

is

The r e a s o n f o r t h i s

t h a t c e m e n t a t i o n ( s e e P a r t IY o f r e p o r t )

of the

t a k e s p l a c e and o p e n in g s a r e r e d u c e d i n s i z e and r e s t r i c t e d

in th e ir co n tin u ity .

U n l e s s f u r t h e r movement i n t e r v e n e s t o

c r e a t e new o p e n i n g s t h e r o c k may b e c o m e i m p e r m e a b l e t o f l u i d s (R ule, 1937, p .

27).

3. response

P h y s i c a l P r o p e r t i e s o f R ooks. - Rocks d i f f e r to s t r e s s .

in t h e i r

Some f r a c t u r e r e a d i l y a n d t h u s c o n s t i t u t e

fa v o ra b le h o s t rocks fo r o i l a c c u m u latio n , whereas o th e r s , under id en tical s tre ss in response are

c o n d itio n s , deform by p l a s t i c

flow .

D ifferen ces

due l a r g e l y t o v a r i a t i o n s i n t h e p h y s i c a l p r o ­

p e r tie s of rocks. Iso tro p ic

vs.

an iso tro p ic

rocks.

Some l a r g e m a s s e s o f i g n e o u s r o c k s t e n d t o a p p r o a c h s t a ­ t i s t i c a l hom ogeneity a c c o r d in g to M cK instry (1948, p .

3 0 3 ) , who

states: " I r r e g u l a r i t i e s such as g r a in s o r c r y s t a l s are sm all i n p r o p o r t i o n t o t h e d i m e n s i o n s u n d e r o b s e r v a t i o n an d a r e o r i e n t e d a t r a n d o m so t h a t t n e d i r e c t i o n a l p r o p e r t i e s o f i n d i v i d u a l g r a i n s te n d to c a n c e l each o t h e r o u t . " T h e s e r o c k s may b e c l a s s i f i e d p ro p e rtie s are alik e

as is o tr o p ic ,

in a ll d ire c tio n s.

o t h e r hand a r e w eaker m

th at is ,

th e ir ela stic

A n i s o t r o p i c r o c k s on t h e

some d i r e c t i o n s t h a n o t h e r s .

n e s s may b e d u e t o b e d d i n g p l a n e s ,

co n tact su rfa c e s,

T h is weak­ fo lia tio n ,

and numerous s e c o n d a ry s t r u c t u r e s im posed on th e r o c k s . Large b o d ie s o f i s o t r o p i c r o c k s such a s g r a n i t e d io n te

an d q u a r t z

are u n fa v o ra b le h o st rocks f o r o i l accum ulation.

openings a r e r e s t r i c t e d

l a r g e ly to

Secondary

s h a tt e r e d zones along f a u l t s

13 and th e r e m a in d e r o f t h e r o c k m ass i s

t i g h t an d i m p e r m e a b l e .

The w a t e r - b e a r i n g p r o p e r t i e s o f g r a n i t i c M einzer (1923, p .

ro c k s a r e d i s c u s s e d by

1 4 3 ) , who s t a t e s :

" T h e y a r e p o o r w a t e r b e a r e r s and a t c o n s i d e r a b l e d e p t h s a re alm ost devoid o f a v a i l a b l e w a t e r ." E ckis

(1934, p .

77) r e a c h e s a s i m i l a r c o n c l u s i o n c o n c e r n i n g

m a s s iv e r o c k s i n th e b a s e m e n t complex i n s o u t h e r n C a l i f o r n i a . L a rg e f lo w s o f w a t e r e n c o u n t e r e d i n th e San J a c i n t o

tunnel near

B anning, C a l i f o r n i a , were c o n f in e d l a r g e l y t o m etam orphic r o c k s a c c o r d i n g to R ule

(1937, p .

g r a n itic rocks

the E d iso n f i e l d

p.

m

32).

The o i l - b e a r i n g p r o p e r t i e s o f a r e c o n s i d e r e d by Beach (1948,

6 4 ) , who s t a t e s : "No w e l l h a s y e t f o u n d o i l m

tne g r a n i t i c

ro ck s."

A n i s o t r o p i c r o c k s such a s m etam orphosed s e d im e n ta r y and m e ta m o rp h o s e d v o l c a n i c members o f t h e b a s e m e n t com plex c o n s t i t u t e the r e s e r v o i r ro c k s in a l l basem ent p o o ls in C a l i f o r n i a . i s n o t m e r e ly c o i n c i d e n t a l b u t i s due to these ro c k s.

A ll o f

t h e mode o f f a i l u r e

R e l a t i v e l y low s t r e s s w i l l c a u s e m ove­

ment a lo n g th e s e p la n e s o f w eakness u n l e s s th e y happen to w i t h t h e p l a n e o f maximum o r minimum n o r m a l s t r e s s

th e le a v e s o f the s c h i s t t h r o u g h which f l u i d s 368),

co incide

(M cK instry,

Movement i s d i s t r i b u t e d o v e r a l a r g e n u m b e r o f

these p lan es p a r t i c u l a r l y in s c h is to s e ro ck s.

1939, p .

in

th em p o s s e s s p l a n e s o f w e a k n e s s t h a t i m p a r t

a " g r a in " to the basem ent.

1948, p . 3 0 3 ).

This

(G rill, 1948, p .

can p a s s r e a d i l y .

S h e a r i n g may o p e n

40 ) a n d p r o d u c e c h a n n e l s Bedding,

an d p r e - e x i s t i n g f a u l t s a l s o

contacts

(Bruce,

c o n s titu te planes of

w e a k n e s s t h a t may b e u t i l i z e d b y l a t e r m o v e m e n t s .

14 The d e g r e e o f o p e n i n g i n

tn ese a n i s o t r o p i c rocks depends

on t h e f o r c e s o p p o s in g d i l a t a n c y .

F r a c t u r e s w i l l b e t i g h t when

formed u n d e r c o n d i t i o n s o f h i g h c o n f i n i n g p r e s s u r e and d i r e c t e d s t r e s s o r i e n t e d a t a n g l e s i n e x c e s s o f 50 d e g r e e s o f weakness.

to t h e p l a n e s

Low c o n f i n i n g p r e s s u r e s an d d i r e c t e d s t r e s s o r i e n t e d

a t low a n g l e s to th e p l a n e s o f w eakness w i l l thus c re a te p o te n tia l r e s e r v o ir C om petent v s .

f a v o r d i l a t a n c y and

co n d itio n s.

incom petent r o c k s .

S e c o n d a r y o p e n i n g s a r e m o re a p t t o b e d e v e l o p e d a n d m a i n ­ tained

i n com petent th an m

com petent a r e r e l a t i v e stress.

incom petent ones.

term s based on the b e h a v io r o f r o c k s u n d er

The f o l l o w i n g d e f i n i t i o n s o f

(1948, p .

Com petent and i n ­

term s a r e q u o ted from M cK instry

2 8 2 ) , who s a y s :

”C om petent a s th e t e r m i s u s e d h e r e , r e f e r s t o r o c k s t n a t a r e r e l a t i v e l y s t r o n g , b u t , when t h e y do f a i l , b r e a k a s though th e y were b r i t t l e m a t e r i a l . Incom petent r e f e r s t o r o c k s w n i c n a r e w ea k a n d h a v e a t e n d e n c y t o d e f o r m p l a s t i c a l l y o r by f lo w .” The r o l e o f c o m p e t e n t r o c k s i n l o c a l i z i n g o r e n a s b e e n in v estig ated

by m ining g e o l o g i s t s .

M cK instry (1948, p.

m a riz e s the r e l a t i o n s h i p s o f com petent ro c k s d istric ts listed

b y Newhouse

284)

to o re m m in in g

(1942, pp. 45-48)

i n t h e symposium

”0 r e D e p o s i t s a s R e l a t e d t o S t r u c t u r a l F e a t u r e s , ” b y s t a t i n g tne odds a r e G ill

sum­

th at

t h r e e to one i n f a v o r o f c o m p e te n t r o c k s . (1 9 4 8 , p . 44) d i s c u s s e s f a v o r a b l e r o c k s i n t h e C a n a d ia n

pre-C am brian S h i e l d and a r r i v e s

a t sim ilar

co n clu sio n s.

He s t a t e s :

”Weak s e m i - p l a s t i c r o c k s l i k e s e r p e n t i n e a n d t a l c c h l o r i t e s c h is ts are l e a s t fa v o ra b le because they w ill n o t r e t a i n openings e x c e p t under ra re c irc u m s ta n c e s , bordering s tro n g ro ck s. However, t h e i r w eak n ess f a v o r s

15 f r a c t u r i n g o f s t r o n g e r r o c k s n e a r b y and ch an ces f o r o re o c c u r r e n c e i n the v i c i n i t y o f such m a sse s a r e , t h e r e f o r e , b e t t e r than elsew h ere, o th e r th in g s being e q u a l." It is

in tere stin g

pentine

to n o te t n a t G i l l ’ s s ta te m e n ts c o n c e rn in g s e r ­

do n o t a p p l y t o t h e T e x a s o i l f i e l d s

co n stitu tes

the r e s e r v o i r ro c k

(see S e l l a r d s ,

The w o r k o f Rove ( 1 9 4 v , p . d iscu ssio n of fav o rab le rocks.

I n which s e r p e n t i n e 1932).

177) i s p e r t i n e n t t o t h i s

He made a nu m b er o f l a b o r a t o r y

t e s t s on t n e c r u s h i n g s t r e n g t h o f d i f f e r e n t r o c k s an d n o t e d t h e ty p e o f f a i l u r e which o c c u r r e d . c o m p e te n t rocics w i t h h ig h e l a s t i c o f openings t n a t are r e l a t i v e l y

R upture o f f in e g ra in e d

lim its re su lts

in the form ation

f r e e o f gouge, whereas r u p tu r e of

c o a r s e g r a i n e d i n c o m p e t e n t r o c k s w i t h lo w c r u s h i n g s t r e n g t h r e s u l t s i n th e f o r m a t i o n o f h eav y gouge seam s. The r e s u l t s o f R o v e ’ s e x p e r i m e n t a l w o r k c a n b e c o m b i n e d w i t h G i l l ’s c o n c l u s i o n to F racturing b rittle

fo rm u la te th e f o llo w in g w orking h y p o th e s is .

s h o u ld be c o n c e n t r a t e d i n r e g i o n s where f i n e g r a i n e d

r o c k s a r e i n t e r c a l a t e d w i t h weak,

sem i-p lastic rocks.

T h i s h y p o t h e s i s was t e s t e d i n t h e E d i s o n f i e l d w h e r e t h e m e t a m orphic r o c k s h av e oeen d i v i d e d by t h e w r i t e r i n t o co n sistin g of:

(l)

m assive m e ta - v o lc a n ie s ,

(2)

i n t e r c a l a t e d m e ta - s e d im e n t s and m e t a - v o l c a n i c s fie ld ,

pigure 15).

th ree u n its

sla te ,

and (3)

( s e e map o f E d i s o n

The t h i r d u n i t c o n s i s t s o f r e l a t i v e l y c o m p e t e n t

m em ber s ( m e t a - v o l c a n i c s ) t h a t a r e i n t e r c a l a t e d w i t h r e l a t i v e l y i n c o m p e t e n t m em ber s ( m e t a - s e d i m e n t s ) . re tic a l

It

th u s answ ers the th e o ­

r e q u i r e m e n t s o u t l i n e d above f o r a l i t h o l o g i c u n i t s u s c e p t i b l e

to th e developm ent o f sec o n d a ry o p e n in g s by f r a c t u r i n g .

An a n a l y s i s

16 o f p ro d u c tio n d a ta in E dison o i l f i e l d i s m o re p r o d u c t i v e o f o i l slates,

shows t n a t t h i s t h i r d u n i t

th an tne m assiv e m e ta - v o lc a n ic s o r the

( S e e d e s c r i p t i o n o f E d i s o n f i e l d p a r t XI o f t h e r e p o r t

for fu rth er

d is c u s s io n of the r e l a t i o n s h i p o f p r o d u c t iv i t y in d ic e s

and c o m p e te n c y o f r o c k s ) . The r o l e o f c o m p e t e n t r o c k s i n l o c a l i z i n g o i l a c c u m u l a t i o n is

c o n s i d e r e d b r i e f l y b y C a b e e n and S u l l w o l d

( 1 9 4 6 , p . 2 5 ) , who

say: "The r e s e r v o i r i s a p p a r e n t l y c o n f i n e d t o b r i t t l e ro c k w hich can h o ld open f r a c t u r e s . S h a l e s . . . , a t S anta M a r i a an d s o f t w e a t n e r e d s c h i s t a s a t E d i s o n a r e t i g h t and b a r r e n . " I n t h e S a n t a M a r ia V a l l e y f i e l d Regan and Hughes (1 9 4 9 , p.

51) n o t e

p ro d u ctiv e.

t n a t basem ent w e lls com pleted i n " s a n d s to n e " a r e However, a i l g e o l o g i s t s a r e n o t i n a g r e e m e n t t h a t

any r e l a t i o n s h i p e x i s t s

betw een r e s e r v o i r c h a r a c t e r i s t i c s and

l i t h o l o g y i n the basement o i l p o o ls o f C a l i f o r n i a .

For in s ta n c e ,

Hu ey (1947), a n d May a n d H e w i t t ( 1 9 4 6 , p .

th at

o f m etam orphic ro c k h as l i t t l e of o il th is

in E dison f i e l d .

153) a g r e e

tne type

i f a n y c o n t r o l on t h e a c c u m u l a t i o n

Beacn (1946, p .

79-80) a l s o

co n sid ers

q u e s t i o n and s t a t e s : "W hether o r n o t a c e r t a i n t y p e o f m etam orphic r o c k i s m o re l i k e l y t o c o n t a i n o i l t h a n a n o t h e r t y p e i s d i f f i c u l t to d e te r m in e from p r e s e n t d a t a . A substantive s t a t e m e n t c a n b e made t h a t a n y r o c k i n t h e b a s e m e n t zone a t E d is o n w h ich c o n t a i n s in te r - c o m m u n ic a b le v o id s p a c e i s a p o t e n t i a l o i l r e s e r v o i r and c o n t a i n s o i l i f o th e r c o n d itio n s are f a v o ra b le fo r the accu m u latio n of p etro le u m ." W hite

in

( 1 9 4 6 , p . 4)

in h is d is c u s s io n o f basement o i l p o o ls

th e Los A n g e le s B a s i n s a y s :

17 " E x p e r i e n c e h a s sh ow n t h a t t h e t e x t u r e an d c h a r a c t e r o f t h e s c h i s t h a v e l i t t l e o r no r e l a t i o n t o i t s a b i l i t y t o c a r r y o i l an d t h a t o p e n f r a c t u r e s a r e t h e d e t e r m i n i n g feature of i t s re se rv o ir capacity. The e x t e n t o f t h i s f r a c t u r i n g h a s a l s o b e e n fo u n d to v a r y g r e a t l y from w e ll t o w e l l so t h a t e a c h w e l l d r i l l e d i s r e a l l y a w i l d c a t w e ll," T hese s t a t e m e n t s show t h a t t h e r e i s

little

a g r e e m e n t among

g e o l o g i s t s a s t o t h e r o l e p l a y e d by l i t h o l o g y i n t h e d e v e l o p m e n t and m a in te n a n c e o f s e c o n d a r y o p e n in g s i n C a l i f o r n i a o i l p o o l s , 4.

The N a t u r e o f S e c o n d a r y S t r u c t u r e s , - The s t r u c t u r e s

c o n s id e r e d u n d e r t h i s h e a d in g a r e f a u l t s and f o l d s .

They a r e

c a p a b l e o f r e p r e s e n t a t i o n on m aps a n d s e c t i o n s ,

th erefo re,

and,

s e r v e a s p r a c t i c a l g u i d e s to e x p l o r a t i o n . F au lts. When f a u l t i n g o c c u r s i n

the o u t e r p a r t o f the e a r t h ’ s c r u s t ,

open zones a re c r e a te d e i t h e r alo n g th e cent w all rock

(G ill,

1948, p, 3 9 ).

p e r s i s t e n t f e a t u r e s and t h e y ,

f a u lt or w ith in

the a d ja ­

Large f a u l t s a re g e n e r a l l y

t h e r e f o r e , p r o v id e u s e f u l g u id e s to

seco n d ary openings in ro c k s. Tne g e o l o g i c l i t e r a t u r e ro le of fa u ltin g rocks.

m

i s r e p l e t e w ith d e s c r i p t i o n s o f th e

c h a n n e l i z i n g t h e m ovem ent o f f l u i d s t h r o u g h

The f o l l o w i n g q u o t a t i o n f r o m R u l e ( 1 9 3 7 , p .

p a r t i c u l a r i n t e r e s t as i t the w ater-b earin g C alifo rn ia.

i s based on d e t a i l e d

capacity of c r y s ta llin e

43-45)

is of

in v estig atio n s of

rocks in so u th ern

He s t a t e s :

" F a u l t s i n c r y s t a l l i n e r o c k s a r e th e s i n g l e most im portant s t r u c t u r a l f e a tu re r e l a t e d to w ater sto ra g e and p e r c o l a t i o n . . . F a u l t s a c t i n a d u a l r o l e , b e in g b o t h dam s a n d a q u i f e r s . Tne p r a c t i c a l l y i m p e r m e a b l e gouge seams a r e c a p a b l e o f e f f e c t i v e l y p r e v e n t i n g l a t e r a l p a s s a g e o f w a te r from one s i d e o f a f a u l t to th e o t h e r , a n d , w h e re su ch seams a r e c o n t i n u o u s f o r g r e a t d i s t a n c e s , they d iv id e a f a u l t e d a r e a in to a s e r i e s o f ground w a te r

18 r e s e r v o i r s s e p a r a t e f r o m one a n o t h e r . On t h e o t h e r h a n d ,th e f r a c t u r e d zones n e a r l y alw ays on one o r b o th s id e s o f f a u l t s of any m agnitude o f f e r th e m ost perm eable m edia f o r l o n g i t u d i n a l p e r c o l a t i o n to be found w i t h i n a c r y s t a l l i n e rock m a s s . . . i t has been custom ary e x p e rie n c e ( i n t u n n e l s ) to p i c k up i n c r e a s i n g h e a v y f l o w s o f w a t e r in the f r e s h b u t f r a c t u r e d rock a p p ro a c h in g a f a u l t a n d t h e n , p a s s i n g i n t o t h e f a u l t p r o p e r , to f i n d c o m p a r a ­ t i v e l y l i t t l e w ater in the h ig h ly crushed a l t e r e d s o f t m a t e r i a l o f t h e zo ne o f s l i p . . . I n g e n e r a l t h e q u a n t i t y o f w a t e r t o be e x p e c t e d f r o m a g i v e n f a u l t z o n e w i l l b e in p r o p o rtio n , o th e r th in g s bein g e q u a l, to th e e x te n t o f the d i s l o c a t i o n . ” E x tre m e ly heavy flo w s o f w a te r have been e n c o u n te re d a lo n g fau lts

during tu n n e lin g o p e r a tio n s .

Flows up to 1000 g a l l o n s p e r

m i n u t e w ere e n c o u n t e r e d i n t h e San J a c i n t o

tunnel in southern

C a l i f o r n i a u n d e r a r o c k c o v e r o f 2000 f e e t

(R ule, 1957, p.

T his tu n n e l d ra in e d resu lt,

the c r y s t a l l i n e ro c k r e s e r v o i r ,

and,

24).

as a

s p rin g s w ith in a r a d iu s of s e v e ra l m ile s o f the tu n n el

ceased flow ing.

R ule (1937, p .

h e a v ie r flow s e n c o u n tered m from M cK in stry (1948, p .

21) a l s o

c i t e s i n s t a n c e s o f much

o th e r tu n n els.

521-522)

The f o l l o w i n g q u o t a t i o n

d e s c r i b e s th e d e g r e e to w hich

f l o w s o f w a t e r may b e c o n c e n t r a t e d a l o n g f i s s u r e s .

He s a y s :

” The M a h r . . . t u n n e l , 3 0 , 0 0 0 f e e t l o n g , d r a i n s t h e M orococha m in es by c o n n e c t i n g w i t h t h e i r w o r k in g s a b o u t 1700 f e e t below th e s u r f a c e . D u rin g the d r i v i n g o f t h i s t u n n e l th e w a te r em erging from i t s p o r t a l i n c r e a s e d g r a d u a l l y , r e a c h i n g 1 7 , 0 0 0 g a l l o n s p e r m i n u t e when t h e f a c e h a d a d v a n c e d to a b o u t 2 3 , 0 0 0 f e e t . At t h a t p o i n t th e tu n n e l c u t a f i s s u r e from w hich a flo w o f 50,000 g a l l o n s p e r m in u te gushed w ith such f o r c e as to p r e v e n t f u r t h e r advance f o r s ix m o n th s.” F ractu rin g o f c r y s ta llin e

r o c k s may n o t be c o n f i n e d t o

f a u l t z o n e s b u t may e x t e n d o v e r a c o n s i d e r a b l e a r e a w h e r e g e o ­ lo g ic

c o n d i t i o n s have b e e n f a v o r a b l e .

ground w ater i n t o

The i n f l u e n t s e e p a g e o f

c r y s t a l l i n e ro ck s has been s tu d ie d i n

Tim oteo w a t e r s h e d n e a r Beaumont, C a l i f o r n i a by T r o x a l says:

th e San

( 1 9 4 2 ) , who

19 "The c r y s t a l l i n e r o c k s i n t h e b a s i n o f S a n T i m o t e o Creek have an i n o r d i n a t e l y l a r g e c a p a c i t y to ab so rb r a i n f a l l a n d t o d e t a i n much o f t h e i n f i l t r a t e a s g r o u n d w ater s t o r a g e . . . In e x te n s iv e p a r t s of the a r e a , th e y t r a n s m i t w a t e r m o re f r e e l y t h a n t h e f i n e r a l l u v i a l m a t e r ­ i a l s a lth o u g h s u b s t a n t i a l l y l e s s f r e e l y th a n the c o a r s e r a l l u v i a l m a t e r i a l s . . . Storm r u n - o f f from t h e s e r o c k s i s r e l a t i v e l y s m a ll even though t h e s e r o c k s foim the h i g h e s t p a r t o f t h e b a s i n and t h e r e r e c e i v e t h e g r e a t e s t a m o u n t of ra in fa ll." C ry stallin e b a sin are

r o c k s u n d e r l y i n g t h e h i g h e s t p a r t o f t h e San T i m o t e o

t r a v e r s e d b y s e v e r a l s t r a n d s o f th e San A n d reas f a u l t .

L a r g e s c a l e movements a l o n g t h e s e f a u l t s c o u p le d w i t h o p p o r t u n i t i e s f o r b o t h v e r t i c a l an d l a t e r a l are resp o n sib le

e x p a n s io n o f deform ed rock m asses

f o r the t h o r o u g h l y f r a c t u r e d

c ry s ta llin e rocks.

c h a ra c te r o f the

C o m p a r a b l e g e o l o g i c c o n d i t i o n s may be a n t i c i ­

p a t e d i n the b asem en t where b u r i e d h i l l s

are lo c a te d along m ajor

fau lts. F o ld s . - Secondary openings a re f o l l o w i n g ways:

(l)

f r a c t u r e s d e v e l o p a s t h e r e s u l t o f movements

betw een beds d u rin g f o l d i n g , ro ck u n i t s s u s c e p t i b l e to (3)

(2)

th e d i s t r i b u t i o n and shape o f

f r a c t u r i n g may be d e t e r m i n e d b y f o l d i n g ,

f r a c t u r e s a r e c o n c e n t r a t e d l o c a l l y on th e c r e s t s o f a n t i c l i n e s

and to a l e s s e r e x t e n t i n t h e are

c o n t r o l l e d by f o l d i n g i n th e

troughs of s y n c lin e s ,

and (4) f r a c t u r e s

c o n c e n t r a t e d i n a r e a s where c o n t r a s t i n g s t r u c t u r a l

im pinge upon one a n o t h e r .

trends

F o l d i n g may t h u s p l a y a n i m p o r t a n t r o l e

i n th e developm ent o f s e c o n d ary o p e n in g s . U n fo rtu n ately ,

the e x i s t i n g s u b su rfa c e d a ta are

in ad eq u ate f o r d ec ip h e rin g fo ld ed s tr u c tu r e s in p lex.

en tire ly

t h e b a s e m e n t com­

S t r u c t u r a l t r e n d s have been e s t a b l i s h e d i n th e E d iso n -

M o u n t a i n View f i e l d

a r e a s due i n l a r g e m e a s u r e t o t h e d i l i g e n c e

a n d f o r e s i g h t o f J . May, R. L . H e w i t t ,

a n d G. W. L e d i n g h a m , who

20 c o l l e c t e d and s a v e d b a s e m e n t c o r e s fro m w e l l s i n V alley.

E lsew here i n

s o u th e r n C a l i f o r n i a o p e r a t o r s have n o t ta k e n

many b a s e m e n t c o r e s b e c a u s e tossed

th e San J o a q u in

" t h e y a r e o f no v a l u e " o r t h e y h a v e

them i n a c o n v e n i e n t sump b e c a u s e " t h e y n a d t o c o n s e r v e

sto rag e spaceJ" The r e s u l t o f t h i s l a c k o f g e o l o g i c a l f o r e s i g h t i s b e s t e x e m p l i f i e d i n t h e S a n ta M aria V a l l e y f i e l d where o i l i n b asem en t rocks i s confined

t o a c o m p e t e n t " s a n d s t o n e " member ( o r m e m b e r s )

i n t e r b e d d e d w i t h " s q u e e z e d and s l i c k e n s i d e d

sh ale s."

i s r e c o g n i z e d by m o st o p e r a t o r s i n t h e d i s t r i c t , h a s b e e n made t o d e t e r m i n e s t r u c t u r a l C onsequently,

trends

This c o n t r o l

yet l i t t l e

effort

in the basem ent ro c k s .

th e s p a ti a l d is tr ib u t i o n of the fav orab le r e s e r v o ir

r o c k s c a n n o t be a s c e r t a i n e d i n a d v a n c e o f d r i l l i n g .

The c o s t o f

i n v e s t i g a t i n g and p r o b a b l y f i n d i n g an an sw er to t h i s r a t h e r i n t e r ­ e s t i n g s t r u c t u r a l q u e s t i o n would amount o n l y to a s m a l l f r a c t i o n o f the an n u al e x p e n d itu r e tu n ities

fo r u n s u c c e ss fu l basement t e s t s .

f o r a p p l y i n g some o f

the p r i n c i p l e s

d iscussed in

Oppor­ th is

s e c t i o n o f th e r e p o r t p r o b a b l y a r e n o t c o n f in e d to th e S a n ta M aria V alley f ie ld . F r a c tu re s develop as d u rin g fo ld in g .

th e r e s u l t o f m ovements b e tw e e n b ed s

These f r a c t u r e s a re c o n fin e d l a r g e l y

members, e a c h t h i n enough to f a i l , fractu res.

but b rittle

thus confined c h ie f ly F olding d eterm ines

lith o lo g ic

enough to form good

A d j a c e n t i n c o m p e t e n t m em bers may d e f o r m by p l a s t i c

flow age w ith o u t th e developm ent o f open sp a c e s. are

to co m p eten t

u n its

to r e l a t i v e l y

Secondary openings

t h i n c o m p e te n t members.

t h e d i s t r i b u t i o n and s h a p e o f f a v o r a b l e

in th e basem ent com plex.

I t i s much e a s i e r

21

to fin d fa vo rab le i i t h o l o g i c u n it s i f we Know wnere to I ook fo r them.

T herefore, a Knowledge o f s t r u c t u r a l trends c o n s t i t u t e s

a va lu a b le guide to e x p lo r a tio n i n areas where I i t h o l o g i c c o n tr o l o f o i l accumulation has been demonstrated by development worK. F ractu res

a r e c o n c e n t r a t e d l o c a l l y on th e c r e s t s o f a n t i ­

c l i n e s and t o a l e s s e r e x t e n t i n

tne tro u g h s of s y n c iin e s .

T his

s p a t i a l c o n t r o l o f f r a c t u r i n g i s w e ll e s t a b l i s h e d and m ig h t p ro v e t o be a u s e f u l g u i d e t o e x p l o r a t i o n i n f i e l d s w h e r e s u f f i c i e n t subsurface data are a v a ila b le .

F or exam ple, an i n t e r s e c t i o n

b e t w e e n a n a n t i c l i n a l a x i s an d a f a v o r a b l e I i t h o l o g i c u n i t w o u l d c o n s t i t u t e a t a r g e t w e ll w o rth i n v e s t i g a t i o n i n a f i e l d where o i l is present in

the basement rocK s.

F ractures are stru ctu ral tren d s,

concentrated

i n a r e a s where c o n t r a s t i n g

t r e n d s im pinge upon one a n o t h e r .

Changes i n r e g i o n a l

i n t e r s e c t i o n o f m a jo r f a u l t s and i n t e r s e c t i o n s o f l i n e s

o f f o l d i n g may c r e a t e f o c a l p o i n t s o f d e f o r m a t i o n . openings w ill

be c o n c e n t r a t e d a t t h e s e f o c a l p o i n t s i f

m ental c o n d itio n s fav o r d il a t a n c y . E dison f i e l d

is

environ­

The t e c t o n i c p o s i t i o n o f

in te re s tin g in th is resp ect.

i n an a r e a where e a s t e r l y

The f i e l d

tre n d s in the basem ent ro c k s are n o r t h e a s t e r l y ,

and,

Local thus,

be a c o m p r o m i s e b e t w e e n t n e two c o n t r a s t i n g r e g i o n a l

In ad d itio n

tne f i e l d

is

l o c a t e d on t h e

n o rth w esterly tren d in g f a u lt

th at in tersects

a s iz e a b le o i l a ccu m u latio n w ith the tre n d s w arrants

appear

trends.

southw est s id e o f a m ajor

in th e m etam orphic ro c k s a t a l a r g e a n g l e .

stru c tu ra l

is lo cated

t r e n d i n g T ehachapi s t r u c t u r e s im pinge

on n o r t h w e s t e r l y t r e n d i n g S i e r r a Nevadan s t r u c t u r e s .

to

Secondary

the s t r u c t u r a l

"g rain ”

This a s s o c i a t i o n o f

ju n c tio n of c o n tr a s tin g

the c o n c lu s io n t h a t o th e r a r e a s

22

possessing s im ila r s tr u c tu r a l co n d itio n s a t t e n t i o n by g e o l o g i s t s engaged m

should r e c e iv e

sp ecial

basem ent e x p lo ra tio n .

A p p l i c a t i o n . - The m o s t d i f f i c u l t p r o b l e m i n b a s e m e n t ex p lo ratio n is

to d e t e r m i n e t h e p o s i t i o n o f e x t e n s i v e l y f r a c t u r e d

rocks in advance of a c tu a l d r i l l i n g .

The w r i t e r b e l i e v e s t h a t

some o f t h e u n c e r t a i n t y r e g a r d i n g f o c a l p o i n t s o f f r a c t u r i n g c a n b e e l i m i n a t e d by t n e a p p l i c a t i o n o f p r i n c i p l e s d i s c u s s e d in the p re c e d in g s e c tio n o f th e r e p o r t .

For in s ta n c e ,

regions

w it h a com plex s t r u c t u r a l h i s t o r y can be s e p a r a t e d from r e g i o n s o f l o n g q u i e s c e n c e by t h e p r e s e n c e o r a b s e n c e o f f a u l t s , an d u n c o n f o r m i t i e s m

the sed im en ts o v e r ly in g

th e basem ent.

d i s t r i b u t i o n o f f a v o r a b l e and u n f a v o r a b l e i i t h o l o g i c be p l o t t e d o n a b a s e m e n t m ap , it

The

ty p es should

and wnere f a v o r a b l e r o c k s a r e p r e s e n t ,

i s w o r t h w h i le to d e t e r m i n e t h e i r d i p and s t r i k e

sucn a s m agnetic o r i e n t a t i o n o f c o re s . tu ral lin es

fo ld s,

b y some m e t h o d ,

C a r e f u l m apping o f s t r u c ­

f r o m b o t h s u r f a c e and s u b s u r f a c e d a t a m ay d e f i n e a

t a r g e t f o r d r i l l i n g a t the i n t e r s e c t i o n of c o n tr a s tin g tre n d s . F in ally ,

t h e i m p o r t a n t r o l e o f d i l a t a n c y s h o u l d be b o r n e i n mind

d u rin g a i l p la n n in g of basement e x p lo r a tio n . of rocks w ill

be f o u n d o n l y i n a r e a s w h e r e o p p o r t u n i t i e s f o r a p p r e ­

c i a b l e e x p a n s io n o f r o c k volum es e x i s t e d . by p l a s t i c in clin ed lateral

W idespread f r a c t u r i n g

B uried h i l l s

s e d i m e n t s a r e more f a v o r a b l e l o c a l i t i e s

surrounded

tnan g e n tly

basement s u r f a c e s because o f the o p p o r tu n ity f o r b o th and v e r t i c a l e x p a n s i o n o f th e c r y s t a l l i n e

ro ck m ass.

PART IT GEOLOGIC PROCESSES THAT DESTROY SECONDARY OPENINGS IN ROCKS Secondary openings m

rocKs a r e n o t p e rm a n e n t f e a t u r e s *

They a r e m o d i f i e d o r d e s t r o y e d cesses.

by t h e f o l l o w i n g g e o l o g i c p r o ­

( T o l m a n 193V, p* 1 0 2 ) . 1.

C o m p a c tio n * - S e c o n d a r y o p e n in g s formed a s

o f m e c h a n i c a l d i s r u p t i o n o f r o c its m are reduced in s iz e i f tner e s u l t 2.

n e a r - s u r f a c e en v ironm ents

tne w eight o f overburden i s

o f subsidence

tne r e s u l t

in creased as

and d e p o s i t i o n o f s e d i m e n t s .

M e t a m o r p h i s m . - H ig h t e m p e r a t u r e s a n d n i g h p r e s s u r e s

a t t e n d i n g deep b u r i a l e f f e c t i v e l y d e s t r o y b o th p rim a ry o p en in g s a n d a n y s e c o n d a r y o p e n i n g s t n a t may h a v e d e v e l o p e d p r i o r t o m e t a ­ m orphism . 3.

W e a t h e r i n g . - F o r m a t i o n o f c l a y m i n e r a l s and p r e c i p i t a ­

t i o n o f m i n e r a l s a l t s i n t h e z o n e o f w e a t h e r i n g may r e d u c e p o r o s i t y of rocks. rocksi s

N orm ally, how ever,

increased in 4.

the

s iz e o f secondary openings in

t h e zone o f w e a t h e r i n g .

C e m e n ta tio n . - This p r o c e s s i s

re d u c in g secondary openings m

M icroscopic exam ination of cores

commonly p r e s e n t i n f r a c t u r e s

The a g e o f t h e c a l c i t e v a r i e s w i t h r e f e r e n c e t o o i l present m

the f r a c t u r e s .

w hile in o th e rs i t

in

f r a c t u r e d m etam orphic r o c k s i n the

basem ent o i l rocks o f C a lif o r n ia . shows t h a t c a l c i t e i s

tne m ost im p o rta n t

I n some c a s e s i t

is

m

these

that is

tocks

.

also

d e f in ite ly o ld er

a p p e a rs to nave s e a le d f r a c t u r e s

containing o i l .

D e v e l o p m e n t work i n t n e d i f f e r e n t o i l p o o l s m rocks nas dem onstrated

tn at b a rrie rs

th e u p p er p a r t o f tn e basem ent.

to o i l m i g r a t i o n e x i s t i n

G r e a tly d i f f e r e n t bottom h o le

p r e s s u r e s a r e found i n w e l l s t a p p in g p a r t l y d e p l e t e d v o irs

basement

sand r e s e r ­

im m e d i a t e l y ab ove th e b a s e m e n t and i n w e l l s c o m p le te d i n t h e

u n d e rly in g basement r e s e r v o i r s .

A s i m i l a r c o n d i t i o n was n o t e d

i n W e s t e r n G u l f O i l Com pany*s Di G e o r g i o #1 w e l l i n M o u n t a i n View fie ld .

H ere,

t h e u p p e r p a r t o f t h e b a s e m e n t was t i g h t a n d i m p e r ­

m eable above th e p r o d u c t i v e zo n e. d e s c r i p t i o n o f tne

B a r t o n (1931, p . 11)

in h is

s c h i s t z o n e i n P l a y a d e l Hey o i l f i e l d

states:

"W ells d r i l l e d i n to i t nave g e n e r a l l y found tne f i r s t 100 t o 300 f e e t e x t r e m e l y h a r d . B elo w t h i s i s a f r a c ­ t u r e d zone i n w nicn th e o i l h a s a c c u m u l a t e d . n The w r i t e r b e l i e v e s

tnat

the im perm eable n a t u r e o f th e u p p e r p a r t

o f t h e b a s e m e n t i s due t o t h e d e p o s i t i o n o f s e c o n d a r y m i n e r a l s along f r a c t u r e s

in tne r o c k s .

The c a u s e o f m i n e r a l d e p o s i t i o n i n f r a c t u r e d r o c k s i s d i s c u s s e d by W a l d s c h m i d t ( 1 9 4 1 , p .

1 8 7 b ) who s a y s :

" I f p r e s s u r e i s r e le a s e d m any a r e a w ith in th e san d ­ s t o n e b y f r a c t u r i n g o r f a u l t i n g , t h e m o v em en t o f t h e c o n t a i n e d f l u i d s m u s t be t h r o u g n t h e s a n d s t o n e , t o w a r d s a r e a s o f p r e s s u r e r e l i e f , an d i n t o an d t h r o u g h o p e n f r a c t u r e s and f a u l t s . Because o f p r e s s u r e r e l i e f , p r e c i p i t a t i o n o f m in e ra ls w ith in th e v o id s , w hether r a p i d o r s l o w , w i l l c a u s e a d d i t i o n a l f l u i d t o be d i s ­ p l a c e d , and th u s c o n t in u e to f o r c e the f l u i d s tow ard t h e low p r e s s u r e a r e a . " D i l a t i o n o f r o c k s th u s a p p e a r s a s an im p o r ta n t f a c t o r i n p r o ­ m oting m ig r a tio n o f f l u i d s along f r a c t u r e s

and p r e c i p i t a t i o n o f s e c o n d a r y m i n e r a l s

in deform ed r o c k s .

PART V DIFFERENTIAL PERMEABILITY IN METAMORPHIC ROCKS D iffe re n tia l p erm eab ility e x ists m The m o s t p e r m e a b l e z o n e s i n t h e r o c k s a r e planes of f o lia tio n .

Thus f l u i d s

m ost m etam orphic r o c k s . commonly p a r a l l e l

c a n be e x p e c t e d t o m i g r a t e

more f r e e l y a l o n g t n e " g r a i n ” o f t h e r o c k t h a n a c r o s s t n e This r e l a t i o n s h i p

to

"g rain ".

i s n e g le c te d i n m ost d i s c u s s io n s c o n c e rn in g th e

d i r e c t i o n o f m i g r a t i o n o f o i l i n m etam orphic r o c k s . M etam orphic r o c k s o r i g i n a t e from s e d i m e n t a r y , v o l c a n i c and o th e r igneous ro c k s . d i f f e r w idely p r io r of

the o r i g i n a l

The p h y s i c a l p r o p e r t i e s o f t h e s e r o c k s to m etam orphism .

M e t a m o r p h i s m d e s t r o y s some

d if f e r e n c e s b u t in th e basem ent o i l p ools o f

C a l i f o r n i a enough o f them h a v e s u r v i v e d

the r e l a t i v e l y

o f m etam orphism to i m p a r t a m a rk e d ly a n i s o t r o p i c

l i g h t wave

c h a r a c t e r to th e

re se rv o ir rocks. O penings i n th e m etam orphic ro c k s i n th e o i l f i e l d s o f C a l i f o r n i a a r e d ue l a r g e l y t o m e c h a n i c a l d i s r u p t i o n o f r o c k s . H e n c e m o s t o p e n i n g s a r e l o c a l i z e d a l o n g p l a n e s o f m ovem ent w h i c h in

t u r n te n d to f o l l o w p r e - e x i s t i n g p l a n e s o f w e a k n e ss i n a n i s o ­

tro p ic rocks.

T h e s e p r e - e x i s t i n g p l a n e s o f w e a k n e s s may i n c l u d e

man y s t r u c t u r e s , tio n p lanes. to the

b u t commonly t h e y a r e b e d d i n g ,

contact or f o l i a ­

Thus r e l a t i v e l y p e r m e a b l e z o n e s a r e d e v e l o p e d p a r a l l e l

" g r a in " o f m etam orphic r o c k s . The f o l l o w i n g b r i e f r e v i e w o f t h e l i t e r a t u r e

j e c t should be o f i n t e r e s t e x p lo r a t ion.

on t h i s

to g e o l o g i s t s engaged i n basem ent

sub­

26 E llis

(1906, p .

2 1 - 2 3 ) made a d e t a i l e d

bearing c a p a c ity o f c r y s t a l l i n e fra c tu re d planes p a r a lle l im p o rta n t w ater c a r r i e r s wa s r e a c h e d by R u l e

stu d y o f the w a te r­

ro c k s i n C o n n e c tic u t and found

to th e s c h i s t o s i t y

t o be t h e m o s t

i n m e t a m o r p h i c r o c it s .

(1937, p .

A s im ila r co n clu sio n

3 0 ) who s a y s :

"The i m p o r t a n c e o f f o l i a t i o n and s c h i s t o s i t y w i t h r e g a r d to g ro u n d w a te r i s p r o b a b l y l a r g e l y due to j o i n t s p a r a l l e l ­ in g th e p la n e s of f i s s i l i t y . . . T his has been w e ll e s t a b l i s h e d i n th e San J a c i n t o T unnel w here m eta m o rp h ic r o c k s c o m p r is e a c o n sid e rab le p o rtio n of the rock tu n n e le d ." E ckis

(1934, p.

78)

stu d ied

the w a te r - b e a r in g c a p a c i t y o f

m etam orphic ro c k s i n s o u th e r n C a l i f o r n i a .

He s t a t e s :

"A n u m b e r o f t u n n e l s h a v e b e e n d r i v e n i n t o t h e s e r o c k s a l o n g t h e s o u t h e r n b a s e o f t h e S a n G a b r i e l an d S a n B e r n a r ­ dino m o u n ta in s , fro m w hich s m a ll c o n tin u o u s flo w s a r e obtained. The w a t e r s e e p s i n t o t u n n e l s f r o m c r a c k s a n d crushed zones, g e n e r a lly along p la n e s o f s c h i s t o s i t y . " Legrand (1949, p .

Ill)

says:

" M e t a m o r p h i c r o c k s , o w i n g t o d e f o r m a t i o n , c o n t a i n many s t r u c t u r a l p l a n e s , some o f w h i c h a f f e c t t h e c i r c u l a t i o n o f ground w a te r. The m o s t p r o m i n e n t p l a n e s a l o n g w h i c h g r o u n d w a t e r m ov es a r e t h o s e d u e t o f o l i a t i o n . " The r e l a t i o n s h i p s M cK instry (1948, p .

i n m ining d i s t r i c t s

a r e summ arized by

3 0 6 ) who s t a t e s :

" A l t h o u g h f u r t h e r s t u d y o f t h e mode o f f a i l u r e o f a n i s o t r o p i c m a t e r i a l i s n e e d e d , e v e r y o n e knows t h a t f a i l u r e t e n d s to t a k e a d v a n ta g e o f s l a t y c l e a v a g e and sc h isto sity ." These s t a t e m e n t s a r e a p p l i c a b l e to t h e m etam orphic r o c k s in

the S i e r r a Nevada.

lelin g

S p rin g s is s u e alo n g crushed zones p a r a l ­

t n e s c h i s t o s i t y o f m e t a m o r p h i c r o c k s i n many l o c a l i t i e s

v i s i t e d by th e w r i t e r d u r i n g th e f i e l d

seaso n in 1947.

T herefore,

c o m p a r a b l e c o n d i t i o n s o f d i f f e r e n t i a l p e r m e a b i l i t y may b e e x p e c t e d i n s i m i l a r r o c k s u n d e r l y i n g t h e a d j a c e n t S an J o a q u i n V a l l e y .

PART VI THE ROLE OF DILATANCY IN THE MIGRATION OF FLUIDS IN METAMORPHIC ROCKS The m o s t c o m p l e t e s t a t e m e n t o n t n e g e o l o g i c r o l e o f d ilatan cy is m

M e a d 's

d ilatan cy fo r a l l

(1925)

in creases

c l a s s i c a l paper*

He u s e s t h e t e r n

i n r o c k volu m e d u e t o d e f o r m a t i o n .

F r a c t u r i n g i n r o c k s i s a c c o m p a n ie d by d i l a t a n c y - t h e n e t volume o f t h e f r a c t u r e d m a s s b e i n g i n c r e a s e d b y t h e volum e o f t h e o p e n ­ ings produced.

The f o r m a t i o n o f o p e n s p a c e s w i l l r e d u c e h y d r o ­

s t a t i c p r e s s u r e s and t h u s w i l l

s e t up p r e s s u r e g r a d i e n t s

in

r o c k s t h a t w i l l t e n d t o p r o d u c e f l u i d m o v em en t t o w a r d s f o c a l p o i n t s of fractu rin g .

Tne w r i t e r b e l i e v e s

t h a t d i l a t i o n o f m etam orphic

r o c k s i n t h e b a s e m e n t o i l p o o l s i n C a l i f o r n i a was a n i m p o r t a n t f a c t o r i n p r o m o t i n g m i g r a t i o n o f o i l an d g a s f r o m o v e r l y i n g s o u r c e rocks in to un derly ing r e s e r v o ir s .

The t e r m s o u r c e r o c k s

in th is

u s a g e i n c l u d e s b o th " c a r r i e r " b e d s and s o u r c e beds o f o i l . The r e l a t i o n o f m i g r a t i o n an d a c c u m u l a t i o n o f o i l t u r e s was n o t e d by M i l l s

(1923).

to f r a c ­

He c o n d u c t e d a s e r i e s o f e x p e r i ­

m ents u s in g o i l and gas d is s e m in a te d through w a t e r - s a t u r a t e d in g lass

tubes.

When t n e g l a s s t u b e s w e r e c r a c k e d a c c i d e n t a l l y ,

t h e g a s i m m e d i a t e l y e x p a n d e d a n d moved t o w a r d s pressure rele a se .

sands

the p o in t o f

B o t h w a t e r an d o i l e s c a p e d a t t h e f r a c t u r e .

S i m i l a r e x p e r i m e n t s b y W. T u y l, P a r k e r and S k e e t e r s

A. W a l d s c h m i d t a r e d e s c r i b e d b y Van (1945).

They s t a t e :

"In th ese ex p e rim e n ts, a c o n tr o lle d o i l - w a t e r m ixture was i n t r o d u c e d i n t o an i n c l i n e d g l a s s t u b e , so p a c k e d a s to r e p r e s e n t a p o ro u s r e s e r v o i r sand t e r m i n a t e d u p d ip by an im pervious m a t e r ia l ( b e n t o n it e ) . By m e a n s o f a n e x t r a

o u t l e t t u b e , so p l a c e d a s t o a f f o r d p o i n t o f p r e s s u r e r e l e a s e down d i p s a n d c o n t a c t , W a l d s c h m i d t w as a b l e l a t i o n s e n t i r e l y in d e p e n d e n t o f the re se rv o ir,"

a predeterm ined from t h e b e n t o n i t e to o b t a i n accumu­ te rm in a tio n o f the

L e v o r s e n (1 9 4 3 , p . b y 9 ) a p p e a r s to h av e had a s i m i l a r c o n c e p t i n m i n d i n h i s s t i m u l a t i n g p a p e r on " D i s c o v e r y T h i n k i n g He s a y s : "A nother e x p l a n a t i o n ( f o r tne f a v o r a b l e c h a r a c t e r o f wedge b e l t s o f p o r o s i t y ) i s t h a t w i t h i n t h e wedge b e lts of p o ro s ity , p re ssu re g ra d ie n t fa c to rs are s e t u p w h i c h may b e i n s t r u m e n t a l i n e x t r a c t i n g t h e o i l a n d g as fro m th e s u r r o u n d i n g s h a l e s , l i m e s t o n e s , and th e o th er p o ssib le o i l sources. In the r e g io n a l h i s t o r y o f a lm o s t any r e s e r v o i r r o c k , from th e tim e o f i t s d e ­ p o s i t i o n t o t h e p r e s e n t , i t h a s e x p e r i e n c e d many e f f e c t s of u p l i f t , f a u l ti n g , t i l t i n g , b u r i a l , e ro s io n , o r in o t h e r te rm s , the p r e s s u r e s w i t h i n i t , w h e th e r h y d ro ­ s t a t i c o r ro ck p r e s s u r e s , have f l u c t u a t e d alm o st a s a b e l l o w s due t o i t s g e o l o g i c h i s t o r y , d i a s t r o p h i s m , and t e m p e r a t u r e v a r i a t i o n s . The w edge e d g e , b e c a u s e i t i s e f f e c t i v e l y s e a le d in one d i r e c t i o n , o f f e r s r e s i s t a n c e to t h e s e p r e s s u r e c h a n g e s , and th e o p e r a t i o n and e f f e c t o f p r e s s u r e s i n s u c h a r e a s may b e d i f f e r e n t f r o m w h a t th e y a re m th e c e n t e r o f th e b a s i n wnere c i r c u l a t i o n i s f r e e and t h e r e i s r e l i e f fro m p r e s s u r e i n a l l d ire ctio n s. T h e r e may t h e n r e s u l t , i n t h e v i c i n i t y o f t h e w edg e e d g e , a s u c t i o n e f f e c t o n t h e s u r r o u n d i n g r o c k s w hen t h e p r e s s u r e s a r e l o w e r e d m t n e n e i g h b o r i n g r e g i o n s due to e r o s i o n , l o w e r i n g o f h y d r o s t a t i c h e a d , o r d iastrophism . T h i s s u c t i o n e f f e c t may p u l l t h e h y d r o c a rb o n s o u t o f tn e s u r r o u n d in g f o m a t i o n s end t h e y w o u ld t h u s r e p l a c e t h e w a t e r w h i c h was p u l l e d t o a r e a s o f low er p r e s s u re d eep er i n the b a s i n . " The d i l a t a n c y c o n c e p t a p p e a r s a l s o o r e d e p o s i t i o n b y Ro ve ( 1 9 4 7 , p . 1 7 8 ) .

i n a r e c e n t p a p e r on

He s a y s :

"Any d e f o r m a t i o n t e n d s t o c r e a t e new o p e n i n g s ( s p e a k i n g o f b r i t t l e r o c k s ) a n d n e c e s s i t a t e s an i n c r e a s e i n v o l u m e . " D ila ta n c y c r e a te s a "ten d en cy to suck i n any s o l u t i o n s a v a i l a b l e to th e o p e n in g s ." The w r i t e r

( M c N a u g h to n , 1 9 4 7 , p .

18)

stated :

"A p o t e n t i a l b a s e m e n t r e s e r v o i r c o m p l e t e l y s a t u r a t e d w i t h w a t e r w ould n o t bec om e a n a c t u a l o i l r e s e r v o i r u n l e s s

29 the w ater ta b le d e c lin e d as a r e s u l t o f: (l) u p lif t, o r (2) an i n c r e a s e i n t h e amount o f v o id s p a c e p ro d u c e d by f u r t h e r d e fo rm a tio n o f th e r o c k s . ” T h e s e s t a t e m e n t s may b e s u m m a r i z e d i n

t h e f o l l o w i n g way:

f r a c t u r i n g o f r o c k s i n v o lv e s d i l a t a n c y w hich i n t u r n r e d u c e s h y d ro s ta tic p re ssu re in fo c a l areas of d eform ation. entrapped in a d ja c e n t ro ck s w ill

O i l and g a s

t e n d t o move t o w a r d s t h e s e a r e a s

o f reduced p r e s s u re . PART V I I THE ”UP SLOPE" THEORY OF MIGRATION OF OIL IN METAMORPHIC ROCKS A ll g e o l o g i s t s f a m ila r w ith basement p o o ls a r e in agreem ent t h a t o i l i n m etam orphic ro c k s i n C a l i f o r n i a o r i g i n a t e d

in sed im ents

c a p p i n g o r f l a n k i n g b u r i e d h i l l s on t h e b a s e m e n t s u r f a c e a n d t h a t i t m i g r a t e d l a t e r a l l y o r do wnwar d a c r o s s

the u n c o n fo rm ity a t th e

to p o f th e b asem en t com plex and e n t e r e d th e m etam orphic r o c k s . However,

t h e y do n o t a g r e e on t h e s u b s e q u e n t h i s t o r y o f m i g r a t i o n

o f o i l i n t h e m e t a m o r p h i c r o c k s n o r do t h e y a g r e e on t h e c a u s e o f tr a n s v e r s e m ig ra tio n a c ro s s the u n c o n fo rm ity .

The w r i t e r b e l i e v e s

t h a t t h e commonly a c c e p t e d t h e o r y o f m i g r a t i o n o f o i l r o c k s , which i s

s t a t e d below ,

t o o l i n many a r e a s . in

th is

in m etam orphic

i s u n s a t i s f a c t o r y a s an e x p l o r a t i o n

The t h e o r y a n d i t s l i m i t a t i o n s a r e c o n s i d e r e d

s e c tio n of the r e p o r t .

in g the m i g r a t i o n of o i l

An a l t e r n a t i v e

ex p lan atio n concern­

in m etam orphic r o c k s i s p ro p o sed by the

w r i t e r i n P a r t XI o f t h e r e p o r t . The "Up S l o p e ” t h e o r y o f m i g r a t i o n . - T h i s d e s c r i p t i v e b u t o t h e r w i s e a w k w a r d name i s h e r e b y s u g g e s t e d b y t h e w r i t e r f o r t h e

W /L D C A T D R /1 LED /N SEA PC /V OF B U T T R E S S S A /v D O N N O SE PR O V E S STRUCTURE BU,

■ p/n d s

Sa n d

I su g g e ste d s / te I FO R S E C O N D TE ST

asA r

B A S E M £ A/ T

FAU LT OR LO SS OF P E R M E A S /L /T Y

O/L M A Y H AVE M /G R A T E D /N T O S C H /S T FRACTURES A N D BECO M E

H ypothetical possible

schist

Cabeen

TRAPPED U P D )P

example

accumulation

and

Sullwold

Figure 2

of

in " c o n d e m n e d " a r e a

(1946,

p .2 5 )

31 commonly a c c e p t e d t h e o r y o f m i g r a t i o n o f o i l rocks.

The t h e o r y i s

of m igration of o i l in b u ttre ssin g against

clo sely p attern ed a f te r

the a c c e p te d th e o r y

co n v en tio n al sandstone

the s id e o f a b u r ie d h i l l .

t h a t t h e m o st p e rm e a b le zone m along th e i r upper s u rfa c e . the h i l l ,

i n m etam orphic

" c a r r i e r ” beds The t h e o r y a s s u m e s

the basement ro ck s i s lo c a te d

T h e r e f o r e o i l m oves u p t h e s l o p e o f

p a s s i n g t h r o u g h t h i s p o r o u s and p e rm e a b le zone u n t i l i t

reaches

t h e c r e s t o f t h e s t r u c t u r e o r u n t i l i t e n c o u n t e r s some

b arrier

to m i g r a t i o n on th e f l a n k s o f th e s t r u c t u r e . One o f t h e e a r l y p r o p o n e n t s o f

the

t h e o r y was J .

E. E a t o n

who c o n t r i b u t e d a b r i e f s t a t e m e n t c o n c e r n i n g P l a y a d e l Hey f i e l d t o t h e symposium e d i t e d b y Tan T u y l and P a r k e r

(1941, p .

99).

He s a y s : "At t h e P l a y a d e l Rey o i l f i e l d i n C a l i f o r n i a t h e s t r u c t u r a l c o n tro l i s a p p a re n tly in p a r t a b u rie d s c h is t r i d g e , th e lo w e r o i l zone e m b r a c in g f l a n k i n g s t r a t a and c r e v ic e s in the s c h i s t . In t h i s f i e l d the o i l s o b v io u s ly o r ig in a te d above the u n co n fo rm ity . H o o t s , B l o u n t , an d J o n e s ( 1 9 3 5 ) b e l i e v e t h a t t h e y m i g r a t e d dow nw ard s f r o m t h i n o i l s h a le s above th e low er o i l zone. I co n sid er t h e m mor e l i k e l y t o h a v e m i g r a t e d l a t e r a l l y f r o m a th ic k su ccessio n of fla n k in g organic s h a l e s . ” A m ore d e t a i l e d a n d e x p l i c i t s t a t e m e n t advanced by

Cabeen and S u l l w o l d (1 9 4 6 , p .

25)

o f the

t h e o r y was

who s t a t e :

"O il m ight have m ig ra te d o u t o f th e sand (se e F ig u re 2 i n t h i s r e p o r t ) i n t o s c h i s t f r a c t u r e s and p o s s i b l y b een tr a p p e d h i g h e r up d i p by a f a u l t w i t h i n th e s c h i s t , by a r e v e r s a l o f d ip a t th e top o f th e s c h i s t , by l e s s e n i n g o f f r a c t u r e p e r m e a b i l i t y , o r by a n y o n e o f s e v e r a l r e a s o n s . " May a n d H e w i t t regarding

(1948, p .

1 5 3 ) do n o t e x p r e s s a n o p i n i o n

t h e d i r e c t i o n o f m o v em en t o f o i l

in Edison f i e l d .

The y s a y :

in the basem ent rocks

32 ”The s o u r c e o f o i l i s t h e w e s t e r l y e x p a n d i n g T e r t i a r y sedim entary b a s in . The o i l m i g r a t e d u p d i p a n d moved i n t o p o r e and f r a c t u r e s p a c e s o f th e s t r u c t u r a l l y h i g h e r s c h i s t , much a s i t w o u ld i n t o a d o l o m i t i e l i m e ­ sto n e under s im i l a r c o n d i t i o n s . ” Beach (1 9 4 8 , p . stru ctu ral

75)

stresses

th e im portance o f l o c a l

”h i g h s ” b u t a l s o d r a w s a t t e n t i o n t o some o f t h e

u n u su al f e a t u r e s of a c c u m u la tio n in E dison f i e l d .

He s a y s :

”A 1 t h o u g h o i l a c c u m u l a t i o n i n t h e m e t a m o r p h i c r o c k s o c c u r s on a s t r u c t u r a l h i g h , n o t e v e r y w e l l d r i l l e d i n to the m etam orphics in th e s t r u c t u r a l l y h ig h a r e a i s a com m ercial o i l w e l l . P ro d u ctiv ity in d ices of base­ ment zone w e l l s v a r y g r e a t l y from l o c a t i o n to l o c a t i o n reg ard less of lo c a l s tru c tu ra l p o sitio n . The s o u t h ­ e a s t e r n p a r t of the f i e l d i s s t r u c t u r a l l y h ig h b u t t h e r e i s no c o m m e r c i a l p r o d u c t i o n f r o m t h e m e t a m o r p h i c rocks throughout t h i s a r e a . ” A d m i t t e d l y o u r know ledge c o n c e r n in g m i g r a t i o n o f o i l i s incom plete m

many r e s p e c t s .

t h a t o i l w ill follow

H o w e v e r , we a r e r e a s o n a b l y c e r t a i n

th e m ost p erm eable channelw ays in ro c k s

i n i t s movem en t f r o m a r e a s o f h i g h p r e s s u r e pressure.

to a r e a s o f low er

The ”U p S l o p e ” t h e o r y a p p e a r s t o b e b a s e d o n t h e q u e s t i o n ­

a b l e a s s u m p t i o n t h a t t h e m o st p e r m e a b le zone i n th e m etam o rp h ic rocks l i e s

i m m e d i a t e l y b e l o w t h e u n c o n f o r m i t y a n d i s m ore o r

less p a ra lle l

to t h i s

stru ctu re.

m orphic r o c k s a re n o t ta k e n i n t o

S t r u c t u r a l tr e n d s in th e m eta­ co n sid eratio n ,

hence d i f f e r e n t i a l

p e r m e a b i l i t y i n m etam orphic ro c k s i s n e g l e c t e d as a p o s s i b l e p lic a tin g f a c to r in th is

co n cep t o f the m i g r a t i o n o f o i l .

com­

F ailu re

t o c o n s i d e r t h i s f a c t o r may n o t be s e r i o u s i n a f i e l d w h e r e a b u ried h i l l

is

in c o n ta c t w ith p e tr o lif e r o u s

sid es - o i l

can e n t e r perm eable zones in m etam orphic r o c k s in a

f a v o r a b l e l o c a t i o n on t h e h i l l sch ists

and f o l l o w t h e

s t r a t a on two o r m o r e

”g r a i n ” o f th e

i n i t s m o v em en t t o w a r d s a r e a s o f l o w e r p r e s s u r e .

However,

33 the s i t u a t i o n

i n Edison f i e l d

e n tire ly d iffe re n t. of o il

Here

the

where the

s u r p r i s i n g to on th e

In view o f t h i s fin d th a t

flan k s r a th e r

situ a tio n ex ists

is

"Up S l o p e " d i r e c t i o n o f m o v em en t

i s alm ost a t r ig h t an g les

m orphic r o c k s .

theory has been a p p lie d

to t h e

" g ra in " in the m eta­

relatio n sh ip i t

i s perhaps not

the o i l p o o l i n the b asem en t r o c k s i s

than a t the c r e s t o f s tr u c tu r e .

A com parable

i n th e S a n ta M aria V a lle y f i e l d where the o i l

a c c u m u l a t i o n i n b a s e m e n t r o c k s i s l o c a t e d on t h e n o r t h f l a n k o f th e S a n ta M aria V a lle y s y n c l i n e .

In th is f i e l d

the o i l

in m eta­

m orphic r o c k s i s below a c o m b in a tio n s t r u c t u r a l - s t r a t i g r a p h i c trap

i n s e d im e n ts o f M iocene a g e .

i s th e f r a c tu r e d m eta-sandstone in

These b e d s a re p r o d u c t i v e a s the u n d e rly in g basem ent.

T o p o g r a p h i c a l l y h i g h e r s e c t i o n s o f t h e b a s e m e n t do n o t c o n t a i n o i l where t h e y a r e o v e r l a i n b y n o n - p e t r o l i f e r o u s b e d s o f P l i o c e n e age.

(See d e s c r i p t i o n o f S a n ta M aria V a lle y f i e l d

rep o rt).

It is

in terestin g

to note

i n P a r t IX o f

th a t basement e x p lo ra tio n

b a s e d on t h e " U p s l o p e " t h e o r y o f m i g r a t i o n o f o i l p r o b a b l y w o u l d have f a i l e d

to l o c a t e

and E dison f i e l d s .

the o i l p o o l s i n both S a n ta M aria V a lle y

Therefore

the w r i t e r b e l ie v e s

w orking h y p o th e s is c o n c e rn in g m ig r a tio n o f o i l m

that a b e tte r m etam orphic

rocks i s needed. PART V I I I PRODUCTIVE AREAS IN METAMORPHIC ROCKS IN THE 7/ESTERN PART OF THE LOS ANGELES BASIN Com m ercial p r o d u c t i o n o f o i l i n m e ta m o ip h ic r o c k s h a s been developed in th re e f i e l d s

i n th e Los A n g e le s B a s in :

E l Segundo and P l a y a d e l R ey.

W ilm ington,

Some o f t h e c h a r a c t e r i s t i c

34 g e o lo g ic a l f e a tu r e s o f the p ro d u cin g a r e a s a r e w ell i l l u s t r a t e d on F ig u r e 3 w hich i s a s t r u c t u r a l

c o n t o u r map o f t h e s u r f a c e o f

t h e b a s e m e n t r o c K s i n t h e w e s t e r n p a r t o f t h e Lo s A n g e l e s B a s i n . T h i s m a p , a s w e l l a s t a b l e s I an d I I a r e r e p r o d u c e d f r o m W h i t e (1946).

These f e a t u r e s a r e : (1)

They a r e a l l l o c a t e d on b u r i e d h i l l s

on t h e s u r f a c e

o f th e basem ent. (2)

These b u r ie d h i l l s

Inglew ood f a u l t .

nave an o b liq u e

t r e n d to t h e

T h i s f a u l t i s n o t s ho wn o n t h e map b u t i t s

a p p r o x i m a t e p o s i t i o n c a n b e d e t e r m i n e d by t h e a l i g n m e n t o f p r o ­ d u c i n g a r e a s e x t e n d i n g f r o m In g le w o o d f i e l d on t h e n o r t h w e s t to Lo n g B e a c h f i e l d h ills

on t h e

so u th ea st.

I t w i l l be n o t e d

th at

the b u r ie d

t r e n d 15 t o 20 d e g r e e s m ore w e s t e r l y t h a n t h e I n g l e w o o d

fa u lt. (3)

The p r o d u c t i v e a r e a s a r e l o c a t e d b e t w e e n t h e I n g l e w o o d

f a u l t and th e e x te n s io n o f th e f a u l t bounding P a lo s V erdes H i l l s on t h e i r n o r t h e a s t e r n s i d e . (4) to th e

The b u r i e d h i l l s

are

He n e c h e l o n " s t r u c t u r e s p l u n g i n g

s o u t h e a s t to w ard s th e Inglew ood f a u l t . (5)

relativ e ly

The b u r i e d h i l l s h a v e c o m p a r a t i v e l y f l a t s u m m i t s a n d steep fla n k s.

This l i s t anticip atin g

of ch a ra c te ristic

f e a t u r e s may b e e x t e n d e d b y

g e o lo g ic a l d e s c rip tio n s of the in d iv id u a l f i e l d s .

A d ditional c h a r a c te r is tic

f e a t u r e s o f the p ro d u c in g a r e a s in c lu d e

the fo llo w in g : (6) M iocene a g e .

The b u r i e d h i l l s

a re capped by se d im e n ts o f u p p er

The b a s a l member o f

th e se sed im en ts i s a s c h i s t

\\ X N x^ \ VI \\ ' \ ,\M*\ \ \ \ x" \\'l 29S2* \ V , S'w \ V V \ \ \J \ x] X s V XX ,0-

———L i

32S

«*-

1

SOUTHEASTERN PORTION OF SAN-JOAQUIN VALLEY SHOWING BASEMENT LITHOLOGY WESTERN GULF OIL CO.

I

37 conglom erate

t h a t i s p r e s e n t on t h e f la m e s o f th e s t r u c t u r e ,

p a r t i c u l a r l y i n d e p r e s s i o n s a l o n g t h e f l a m e s w h e r e i t may b e s e v e r a l hundred f e e t in th icien ess. o f the

stru ctu re.

It

is

C onform ably o v e r l y i n g

a b s e n t from th e c r e s t the b a s a l c o n g lo m erate

i s a dark-brow n compact n o d u la r s n a le c o n t a i n i n g sm all b u t abundant s t r e a k s and n o d u l e s composed c h i e f l y o f c a l c i u m p h o s p h a t e iy43, p.

2y2).

The t h i c k n e s s o f

the s h a le and the p e rc e n ta g e o f

i n t e r b e d d e d s a n d s t o n e v a r i e s f ro m one s t r u c t u r e S im ilarly ,

to th e o t h e r .

d isco n fo rm ities occur in d if f e r e n t p a r ts of

m e n t a r y s e c t i o n s ±n t h e v a r i o u s f i e l d s N evertheless th e ir s tr a tig r a p h ic (?)

(M etzner,

(W issler,

the s e d i ­

ly43, p .

227).

reco rd s are a lik e .

The t h i c k n e s s o f t h e b e d s o f M i o c e n e a g e i n c r e a s e s

m a r k e d l y down t h e f l a n k s o f t h e s t r u c t u r e s .

(See i s o p a c h o u s

l i n e s on F i g u r e 7 - Map o f W i l m i n g t o n O i l F i e l d ) . (8) sedim ent m

Trie h i l l s tne

cause a n t i c l i n a l fe a tu re s m

th e o v erly in g

s e n s e t h a t t h e l a t t e r d i p aw ay f r o m trie s u m m it

areas. (9) bu ried h i l l s

S i z e a b l e o i l a c c u m u l a t i o n s a r e fo u n d on a l l o f th e l o c a t e d on th e w e s t e r n s i d e o f tn e Inglew ood f a u l t

w i t h th e e x c e p t i o n o f th e T o rra n c e s t r u c t u r e w here th e m etam orphic rock s a re perm eable b u t w et. F ro m t h e f o r e g o i n g i t (buried)

h ills

appears

to the w r i t e r t h a t th e

h a v e h a d a common t e c t o n i c o r i g i n a n d t n a t t h e i r

s u b s e q u e n t h i s t o r i e s o f e r o s i o n and b u r i a l a r e a l i k e . o b liq u e tre n d o f folded tren d m g s trik e

slip

s t r u c t u r e s w ith r e f e r e n c e to n o r th w e s te r iy -

fa u lts

in so u th ern C a lifo rn ia

The

i s a w ell e s ta b lis h e d

tecto n ic featu re

( S e e G e n e r a l i z e d T e c t o n i c Map o f S o u t h e r n

C a l i f o r n i a b y Heed and H o l l i s t e r , e c h e lo n group o f

1936).

Trends o f th e en

b uried h i l l s w ith r e fe re n c e

to

tne Inglew ood

f a u l t seem t o a g r e e w i t h t h e t r e n d s o f f o l d s o c c u p y i n g s i m i l a r p o s i t i o n s w ith r e f e r e n c e to m ajo r f a u l t s elsew here C a lifo rn ia , hence, iar

in o rig in .

cussed a f t e r

ther© i s r e a s o n to b e l i e v e

in so u th ern

t h a t th e y a r e sim i

The h i s t o r y o f e r o s i o n a n d b u r i a l w i l l be d i s ­

t h e p r e s e n t a t i o n o f m o re d e t a i l e d g e o l o g i c a l

m a t i o n o n P l a y a d e l R e y , HI S e g u n d o an d W i l m i n g t o n f i e l d s .

in fo r­

PLAYA DSL RSY OIL FIELD L o c a t i o n - The P l a y a d e l R e y o i l f i e l d c o a s t a b o u t 12 m i l e s w e s t o f L o s A n g e l e s . reference B asin i s

to o t h e r o i l f i e l d s

in

Its

is

s i t u a t e d on t h e

lo c a tio n w ith

the w e s t e r n p a r t o f th e Los A ngeles

shown o n F i g u r e 3 .

H i s t o r y - The L o w er P r o d u c t i v e Zone i n

th is

fie ld

was d i s ­

c o v e r e d i n 1 9 2 9 a n d t h e U p p e r P r o d u c t i v e Zon e w a s d i s c o v e r e d two years l a t e r .

The f o l l o w i n g q u o t a t i o n f r o m W h i t e ( 1 9 4 6 p . 4 - 5 )

d e s c r i b e s t h e e x p e r i e n c e s o f some o p e r a t o r s i n c o n n e c t i o n w i t h th e developm ent o f

basement p r o d u c tio n i n

th is

fie ld .

He s a y s :

" I n t n e O h io O i l Company w e l l No. B I o c k L 2 a t P l a y a d e l R e y ( T h i s w e l l i s n o t shown o n F i g u r e 3 . It is l o c a t e d on t n e O c e a n F r o n t A r e a on F i g u r e 4 ) . . . a 534 f o o t s e c t i o n o f b a s e m e n t was p e n e t r a t e d and t n e c o r e r e c o v e r y a v e r a g e d a p p r o x i m a t e l y 14 p e r c e n t . This p o o r c o r e r e c o v e r y was p r o b a b l y d u e t o t h e s c h i s t s b e i n g b a d l y f r a c t u r e d . . . Tne t o p o f t h e n o d u l a r s h a l e ( s e e c o m p o s i t e s e c t i o n o n f i g u r e 4) w as f o u n d a t 5 , 5 0 5 f e e t and tne top o f tne s c h i s t conglom erate a t 5,b72 f e e t , and th e top o f th e s c h i s t a t 5 , 6 8 5 f e e t . The h o l e was d r i l l e d to a d e p th o f 5,719 f e e t and 8 5 / 8 - i n c h c a s in g was c e m e n t e d a t 5 , 5 0 6 f e e t . A 6 5 /8 -in c h l i n e r w ith p e r ­ f o r a t i o n s f r o m 5 , 5 0 9 t o 5 , 7 1 9 f e e t was l a n d e d a t 5 , 7 1 9 feet. The w e l l was c o m p l e t e d i n F e b r u a r y 1 9 3 1 , f l o w i n g a t t h e r a t e o f ±23 b a r r e l s a d a y w i t h a 25 p e r c e n t c u t . The w e l l was K i l l e d and d e e p e n e d i n s c h i s t t o 6 , 2 1 9 f e e t , t h u s h a v i n g a t o t a l o f 534 f e e t o f s c n i s t f o r m a t i o n . A 5 3 / 4 - i n c h , p e r f o r a t e d l i n e r was l a n d e d f r o m 5 , 4 6 8 t o 6 , 2 1 9 f e e t s o t h a t t n e w e l l was o p e n t o t h e o r i g i n a l p e r f o r a t e d zone and to the a d d i t i o n a l s c h i s t z o n e . It was t h e n r e c o m p l e t e d f l o w i n g 1 , 9 6 8 b a r r e l s i n t h e f i r s t 24 h o u r s , c u t t i n g 12 p e r c e n t . This w e ll pro d u ced from t h e Lower Zone u n t i l M a r c h , 1 9 3 8 , when i t was p l u g g e d b a c k -co t h e U p p e r Z o n e . At t h a t tim e i t had p r o d u c e d i n e x c e s s o f 2 6 0 , 0 0 0 b a r r e l s o f o i l f r o m t h e Low er Z o n e . " The m a r x e d i n c r e a s e

m

p r o d u c t i o n when t h e p e n e t r a t i o n o f f r a c t u r e d

m e t a m o r p h i c r o c k s was i n c r e a s e d f r o m 34 f e e t t o 5 3 4 f e e t i s w o r t h y of note as i s

the

curam ulative p r o d u c t i o n o f o i l fro m t h i s w e l l i n

a n a r e a o f to w n l o t s p a c i n g o f w e l l s .

40 The u p p e r 3 4 f e e t o f im perm eable, from th e

the b a s e m e n t w as p r o b a b l y t i g h t a n d

t h e o r i g i n a l 125 b a r r e l s a d a y p r o b a b l y b e i n g d e r i v e d

s c h i s t conglom erate.

Long (1946, p .

s t a n c e s where d e e p e n in g o f w e l l s r e s u l t e d a n d he a l s o

cites

5) c i t e s o t h e r i n ­

in in creased pro d u ctio n

i n s t a n c e s o f u n s u c c e s s f u l w ork o f t h i s n a t u r e .

F o r exam ple, he s a y s: ”B a r n s d a l l O i l Company w e l l No. B u r k s 12 was d e e p e n e d f r o m t h e U p p e r Zone i n S e p t e m b e r , 1 9 3 2 d r i l l i n g 4 5 9 f e e t i n t o the s c h i s t . I t w as c o m p l e t e d o n t h e pump f o r 148 b a r r e l s a d a y , c u t t i n g 26 p e r c e n t , w h i c h p r o d u c t i o n declined r a p i d l y . ” S t r a t i g r a p h y - T a b le 3 w hich i s on P l a y a d e l Rey o i l

fie ld

re p ro d u c e d from th e

by H o o ts , B l o u n t , and J o n e s

p . 173) g i v e s th e s t r a t i g r a p h i c

report

(1935,

column o f t h e P l a y a d e l Rey f i e l d .

The d i s t r i b u t i o n a n d t h i c k n e s s e s o f t h e

s c h i s t conglom erate

a r e shown o n F i g u r e s 4 a n d 5 , r e p r o d u c e d f r o m M e t z n e r ’ s ( 1 9 4 3 , p.

2 9 3 ) r e p o r t on t h i s o i l f i e l d .

conglom erate i s

I t w i l l be n o t e d t h a t t n e

a b s e n t from th e c r e s t o f t h e s t r u c t u r e

and t h a t i t

a p p e a r s on t h e f l a n k s o f t n e h i l l w h e r e t h i c k a c c u m u l a t i o n s a r e found l o c a l l y

i n d e p r e s s i o n s on t h e

A c c o r d i n g to H o o t s , is

s u r f a c e o f tne basem ent.

B lo u n t, and Jo n es

(1935, p .

commonly a s s o c i a t e d w i t h t n e c o n g l o m e r a t e .

182)

c o a r s e sand

Some o f t h e

c o b b le s and b o u ld e r s i n

the c o n g lo m erate a re w e ll rounded b u t th e

above m entioned a u th o r s

state:

” I t i s common t o f i n d b o u l d e r s u p t o 6 i n c h e s i n d ia m e te r t h a t a re s u b -a n g u la r w ith o n ly the c o rn e rs s l i g h t l y ro u n d ed .” A nodular black sh ale o v e r lie s flan k s of

th e c o n g l o m e r a t e on th e

the b u r i e d h i l l and e x te n d s a c r o s s th e s c h i s t s u r f a c e

on t h e c r e s t o f the h i l l .

The n o d u l e s i n

the s h a le a r e h i g h l y

41

TAHLE I I I S t r a t ic . r a p h i c T

Age Pl ei st ocene —

able of th e

P laya

del

R

ey

O il F ie l d

Thickness

Group or Formation

Description

? A rnold’s u pper and lower San P edro and D eadm an Island “ P liocene” ?

Loose gray sand w ith som e clay and line conglom ­ erate

M egascopic shells of m arine m olluscs a b u n d a n t near to p . F oram inijera fairly a b u n d a n t a t some horizons

Soft light g ray clay shale, and m icaceous s iltsto n e an d san d sto n e. D ark carbonaceous or bitu m in o u s appearance is en tirely ab sen t

O nly Foram inijera are ab u n d a n t

2 ,0 0 0 -3 ,0 0 0

Foram inijera are ab u n d a n t a t some horizons. O th e r­ wise clay shale appears to be co m p arativ ely lean in organic m a terial

2 ,4 0 0 -2 ,8 0 0

Oil Zones

Organic Contents

? io o -

500

M P ico

Pliocene

Soft light gray silty clay shale and m icaceous siltstone and sandstone w ith im p o rtan t oil zone oc­ cupying m iddle 1,000 feet. Sands below m ain oil zone are less ab u n d a n t, b u t all are s a tu ra te d w ith oil in area near crest of anticline. F ractu res in clay shale w ithin the oil zone co n tain oil, b u t otherw ise clay shale is devoid of carbonaceous or bitu m in o u s appearance

R e p e tto f

Low er m em ber of M odelo} U pper u n it

U p p er M io ­ cene

M iddle u n it

Low er unit!!

J u rassic (? )?

M ajor unconform ity— F ranciscan

UPPER

O IL

ZONE

n ear m iddle; thin oil sands occur th ro u g h o u t lower p a rt

H a rd g ray and brown siliceous shale, b ea u tifu lly la m in a ted in g reater p a r t. In te rcala ted th in beds of sand a re sa tu ra te d w ith oil in a rea n e a r crest of anticline. Brow n lam inae a p p e a r bitum in o u s

T h in beds of oil san d locally

F ish scales com m on, pelecypods rare,a n d F o ra m in i­ jera of arenaceous and calcareous ty p e s com m on. Brow n lam inae yield some oil w hen h eated

H a rd black a nd dark brow n shale co n tain in g a b u n ­ d a n t ta n an d light g ray p h o sp h ate nodules a n d ’ lam inae. VVell bedded, w ith bedding p lan es and fractu re p lanes com m only co n tain in g h ea v y black oil. H as highly bitum inous ap p earan ce

O IL SH A L E

H igh p h o sp h ate c o n ten t resu lts from a b u n d a n ce of organic life. Scales an d bones of fish fairly com m on, F oram inijera rare. A bu n d an ce of finely dissem i­ n ated organic m a terial, now larg ely u n id en tifiab le, produces black color. C o n tain s h eav y black oil and m uch p y ro b itu m in o u s m aterial

C oarse conglom erate and san d w ith a b u n d a n t detrita l fragm ents of schist u p to several feet in d i­ am eter; calcareous and irre g u larly m ineralized w ith p j rite

L O W E R O IL Z O N E

Schist, highly m etam orphosed

Oil in fractures near top

U nidentifiable shell frag m en ts ap p e ar to be rare

N one recognizable

• E vidence of th is u n conform ity in th e P la y a del R ey field is not positiv e due to scarcity of cores. A t th e m o u th of P o tre ro C an y o n , 3 miles n o rth w est of P la y a

300-

700

75-

200

o-

120

?

del R ey,

gently d ipping lower P leistocene or upper Pliocene conglom erate rests d irectly upon alm ost v ertical u p p er Pliocene rocks w ith an g u lar discordance of ab o u t 60°. t A nam e proposed by the C orrelation C om m ittee of th e Pacific Section of th e Society of Econom ic P aleontologists an d M ineralogists an d described in In ternational Geological

Congress Guidebook A'o. 15 (1933), p. 31, for low er Pliocene s tr a ta exposed in th e R e p e tto H ills, Los Angeles C o u n ty .

t T h is u n conform ity is su p p o rted by a strik in g difference betw een th e s tru c tu re of th e u p p er oil zone (P liocene) an d th e lower oil zone (M iocene), an d b y th e ap p a re n t absence in th is field of 3,500-4,000 feet of u p p er M odelo s tr a ta which crop out on th e n o rth llank of th e S an ta M onica M o u n tain s, 12 miles n o rth of P la y a del R e y .H . L. D riv e r, S ta n d ­ a rd O il C om pany of C alifornia, s ta te s th a t faunal evidence does n o t indicate to him th e presence of an u n co n fo rm ity . 5 T h e M odelo form ation of th e S a n ta M onica M ountains h as been sub d iv id ed in to an u p p er an d a low er m em ber. O nly th e lower p a r t of th e low er m em ber ap p ears to be p resen t a t P lay a d el R e y . II Age u n ce rtain . M ay be M iddle M iocene or older. An unco n fo rm ity m ay o ccur a t its top. ^ G e n e r a lly c o n s id e re

i

J u r a s s ic b u t m a y in c lu d e o ld e r ro c k s of e v e n P a le o z o ic a n d p r e - C a m b ria n ag e .

H o o t s , B l o u n t and J o n e s

(1935, p .

173)

42 PLAYA DEL REY OIL FIELD LOS ANGELES CO. CALIF. SHOWING

CONTOURS ON TOP OF SCHIST FIELD AREAS AND ISOPACHS OF THE OIL SAND-CONGLOMERATE ZONE ACCOMPANYING

REPORT BY LOYDE H M ET2N ER SCALE rt

Contour interval ao o Ijopech

O CEAN

F R O N T .. . AREA

P la y a del R ey oil field : s tr u c tu r e m ap.

F igure 4

DEL F E Y H /L L S A F E A ~DCL * t Y H/LLS

Sandy

S h a /g

*

C /a y . S t r e a k s

o f

Sane/ •4 0 0 - 600

S k a /e

& ■ S tre a k s o f S a n d

Ska/m

& S trea k s

Upper nco

S a n d y

°f

San at

S k a te

— 2600

S c h / s f upper MOCCNC (MOOCUO)

P LA Y A D E L REY O IL F IE LD

COM POSITE ACCOMPANYING

SECTION

sca le

HORIZONTAL 1 VERTICAL

400

o

400

too

itoo ft

REPORT BY. LOYDE H METZNER

P l a y a del R ey oil field : c o m p o site sectio n .

F i g u r e s 4 and 5

Figure 5 E e tz n e r (1943, p .

293)

Lower

43 p h o s p h a t i c and a r e a s s o c i a t e d w i t h t h i n ,

d i s c o n t i n u o u s b e d s and

l a m i n a e o f t h e same c o m p o s i t i o n ( H o o t s , B l o u n t an d J o n e s , 1 9 3 5 , p. 130).

The s h a l e s a r e h i g h l y b i t u m i n o u s an d a r e c o n s i d e r e d b y

H o o t s , B l o u n t and J o n e s

(1935, p . 181)

to be t h e s o u r c e o f o i l

i n t h e u n d e r ly in g s c h is t - c o n g lo m e r a t e and s c h i s t r e s e r v o i r .

The

r e m a i n d e r o f M i o c e n e t i m e i s r e p r e s e n t e d b y h a r d g r a y a n d brow n s ilic e o u s sh ale P lio c e n e age

th at is

c o n f o r m a b l y o v e r l a i n by s e d i m e n t s o f

(M etzner, 1943, p .

u n i t on t h e f l a n k s o f

292).

the s tr u c t u r e

is

T hickening o f t h i s

shale

shown on t h e c o m p o s i t e

s e c t i o n i n F i g u r e 5. S t r u c t u r e - The s t r u c t u r e o f P l a y a d e l R e y o i l f i e l d a n t i c l i n a l in the sense

th a t the

s e d i m e n t s o f u p p e r M iocene and

P l i o c e n e ages a rc h o v e r th e c r e s t o f the h i l l . tn e b e d s i s due to c o m p a c tio n o f f i n e g r a i n e d ad jo in in g

T his a t t i t u d e

of

sedim ents in b a s in s

th e b u r i e d h i l l a s w e l l a s to o r o g e n i c movements i n l a t e

M iocene t i m e .

M etzner

(1943, p .

2 93) d o e s n o t show a n y f a u l t s

o n h i s map a n d s e c t i o n o f t h e f i e l d B arton

is

(1931, p .

11)

(see Figure 4 ).

However,

says:

"While t h e r e i s c o n s i d e r a b l e e v i d e n c e o f f a u l t i n g i n th e f i e l d , i t i s i n s u f f i c i e n t to d e f i n i t e l y p l a c e a f a u l t i n any one l o c a l i t y . " S tru c tu ra l E v o lu tio n . - Several d iff e r e n t in te rp r e ta tio n s of tne e v o lu tio n of (1943, p .

227 )

t n e P l a y a d e l Rey f i e l d a r e p o s s i b l e .

W issler

states:

" I n e a r l y u p p e r M ohnian t i m e , f o l l o w i n g t h e d e p o s i ­ tio n o f tne b a s a l sed im en ts o f D iv is io n D (a fo ra m in if e r a l d i v i s i o n w i t h i n t n e lo w e r s h a l e m em ber), t h e P l a y a d e l Rey, E l S e g u n d o , and T o r r a n c e s t r u c t u r e s s t a r t e d to d e v e lo p ." ( U n d e r l i n i n g by w r i t e r ) .

44 In c o n t r a s t to th e f o re g o in g s ta te m e n t M etzner

(1943, p .

292 )

says: "The s t r u c t u r e o f t h e P l a y a d e l R e y f i e l d c o n s i s t s o f a r i d g e o f s c h i s t r e p r e s e n t i n g an o l d e r o s i o n s u r f a c e , on t h e f l a n k s a n d o v e r t h e c r e s t o f w h i c h t h e o i l - b e a r i n g and o t n e r s e d i m e n t a r y r o c k s o f tn e r e g i o n were d e p o s i t e d , t o f o r m a n o r t h w e s t - t r e n d i n g a n t i c l i n e o r e l o n g a t e d o m e. D uring tne lo n g i n t e r v a l o f e r o s i o n p r i o r to the d e p o s i­ t i o n o f t h e s e d i m e n t s t h e s c h i s t r i d g e w as p a r t o f a m o u n ta in s y s te m p r o b a b l y c o m p a ra b le i n h e i g h t and e x t e n t w i t h t h e p r e s e n t - d a y S a n t a M o n i c a M o u n t a i n s , an d s i m i l a r l y d i s s e c t e d by d r a in a g e c h a n n e ls , • , D u rin g submergence o f t h i s r i d g e i n u p p e r M iocene t i m e , an a p r o n o f s c h i s t b e a r i n g e l a s t i c s , composed c h i e f l y o f s c h i s t s a n d and a n g u l a r s c n i s t fra g m e n ts from n e a r a t hand, and q u a r t z s a n d a n d r o u n d e d q u a r t z p e b b l e s , was d e p o s i t e d i n t h e l i t t o r a l zone a t th e f o o t o f t h e r i d g e a n d i n embayments formed by t h e submerged d r a i n a g e . T his l i t t o r a l type o f d e p o s i t i o n ended a b r u p t l y w h i l e th e m ain r i d g e and many o f t h e s u b s i d u a r y l a t e r a l r i d g e s s t i l l r e m a i n e d above s e a l e v e l . " U n f o r t u n a t e l y he d o es n o t o f f e r any e x p l a n a t i o n f o r th e p a r a d o x depicted in

the l a s t s ta te m e n t.

S t i l l another in te r p r e ta tio n is

t h a t t h e s u m m it a r e a o f P l a y a d e l Re y wa s a s u b m a r i n e b a n k d u r i n g t h e e a r l y p a r t o f u p p e r M iocene t i m e . i n t e r p r e t a t i o n s follow s

D iscussion of these v ario u s

tn e d e s c r i p t i o n o f W ilm ington o i l f i e l d .

P r o d u c t i v e Z o n e s . - O il i s p ro d u c e d from an Upper and Lower Zon e m

P l a y a d e l Rey o i l f i e l d .

800 f e e t a b o v e t h e

b asem ent r o c k s and th u s i t

i n t e r e s t ir u ^ s o - ^ f a r a s t h i s Zone i n c l u d e s

The U p p e r Zone i s

in v estig atio n is

f r o m 400 t o

i s not of p a r tic u la r

concerned.

The L o w er

th e f r a c t u r e d m etam orphic ro c k s form ing t h e b u r ie d

h i l l and th e o v e r l y i n g m a n t l e o f s c h i s t c o n g lo m e r a te on t h e f l a n k s of tne h i l l .

The m a i n p r o d u c i n g f o r m a t i o n i s

the co n g lo m e ra te .

The c h a r a c t e r o f t h e m e t a m o r p h i c r o c k s i n t h e u n d e r l y i n g r e s e r v o i r i s noted in

t n e c o r e r e c o r d f r o m t h e Ohio O i l Company w e l l No.

" B l o c k L " 2 ( W h i t e , 1 9 4 o , p . 4)

45 D epth in f e e t F r om

To

5685 570 7 5770 5811

570 7 5770 5811 5847

5847 5947

5929 6001

6016 6053 6071 6142

6053 6071 6074 6219

D escriptio n G reen-grey h ard w eathered s c h i s t B lue g r e y h a rd s c h i s t Same w i t h s t r e a k s o f s o f t t a l c y s c h i s t G r e y an d g r e e n - g r e y s o f t v e r y t a l c y s c h i s t w i t h a few o i l s t a i n e d s t r e a k s B lu e-g rey hard s c h is t w ith t a l c y s tr e a k s Grey and b r o w n i s h - r e d m o t t l e d h a r d g r a n i t o i d rock. Red m a t e r i a l i s p o s s i b l y h e m a t i t e . E n tir e core s lic k e n s id e d w ith ta lc y m a te r ia l in f a u lt p lanes. G reen-grey o i l - s t a i n e d hard s c h is t G r e e n an d o l i v e b row n s o f t w e a t h e r e d t a l c y s c h i s t D a r k g r e y a n d br ow n o i l - s t a i n e d s c h i s t Green and g r e y s c n i s t f r a g m e n t s

I t w i l l be r e c a l l e d

t h a t d e e p e n i n g o f t h i s w e l l f r o m 5719 f e e t t o

6219 f e e t p r o d u c e d a n i n c r e a s e b a r r e l s p e r day.

i n p r o d u c t i o n fro m 123 to 1968

B a rto n (1931, p .

I I ) in d isc u ssin g

these deep­

ening o p e ra tio n s s ta te s : "W ells d r i l l e d i n t o i t ( th e s c h i s t s ) have g e n e r a l l y f o u n d t h e f i r s t 100 t o 300 f e e t e x t r e m e l y h a r d . Below t h i s i s a f r a c t u r e d zone i n w hich o i l h a s a c c u m u l a t e d . " W hite

(1946, p .

5) d o e s n o t b e l i e v e

of developing p ro d u ctio n of o i l adequately te s te d .

th a t the p o s s i b i l i t i e s

in the m etam orphic have been

He s a y s :

" I n t h e O c e a n F r o n t A r e a 131 w e l l s w e r e d r i l l e d t o t h e " L o w e r Z o n e " , a n d l e s s t n a n 10 o f t h e s e p e n e t r a t e d mor e t h a n 200 f e e t o f s c h i s t f o r m a t i o n . In view o f th e e x c e l ­ l e n t r e s u l t s o b t a i n e d f r o m some w e l l s when d r i l l e d d e e p i n t o t h e s c h i s t , i t d o e s n o t a p p e a r to th e w r i t e r t h a t t h e s c h i s t was a d e q u a t e l y t e s t e d i n t h i s a r e a . " The w r i t e r i s

in clin ed

to a g re e w ith

t h i s e v a l u a t i o n b u t the la n d

p i c t u r e i n t h i s a r e a i s n o t e n c o u r a g i n g due to

town l o t

S i g n i f i c a n t F e a t u r e s . - Since the purpose of tio n is

th is

su b d iv isio n . in v estig a­

to d e v e lo p g u id e s to o i l a c c u m u la tio n s i n basem en t r o c k s ,

there

f o ll o w s a r e v ie w o f g e o l o g i c a l f e a t u r e s which th e w r i t e r c o n s i d e r s to be s i g n i f i c a n t i n s o f a r a s b asem ent e x p l o r a t i o n i s

concerned.

46 (1)

The c l o s e a s s o c i a t i o n o f

r e s e r v o i r r o c k s , - H oots,

s o u r c e b e d s and u n d e r l y i n g

B l o u n t an d J o n e s

nodular o i l sh a le o v e rly in g

(1935) n o te

th a t the

th e s c h i s t - c o n g l o m e r a t e on th e f l a n k s

o f t h e h i l l a n d t h e s c h i s t on t h e c r e s t o f t h e h i l l

c o n t a i n s an

abundance of f r e e o i l and p y ro b itu m in o u s m a t e r i a l .

They b e l i e v e

t h a t o i l f r o m t h e s h a l e m i g r a t e d do wnwar d i n t o

the u n d e r l y in g

re se rv o ir rocks, (2)

The f r a c t u r e d c h a r a c t e r o f m e t a m o r p h i c r o c k s on a h i l l ,

D ila ta n c y o f rock m asses i s

fa v o re d by the o p p o r t u n i t y f o r b o th

l a t e r a l and v e r t i c a l e x p a n s i o n on a h i l l . (3) sc h ists.

The i m p e r m e a b l e c h a r a c t e r o f t h e u p p e r p a r t o f t h e An i m p e r m e a b l e zo ne i n

r o c k s c a n be e x p e c t e d , m eab ility m

th is

the u p p er p a r t o f the f r a c t u r e d

as a lre a d y s ta te d .

The a b s e n c e o f p e r ­

s e c t i o n does n o t n e c e s s a r i l y i n d i c a t e

u n d e r ly in g ro c k s a r e a l s o im perm eable.

t h a t the

EL SEGUNDO OIL FIELD L o c atio n . south of P lay a d e l H isto ry .

E l Segundo o i l f i e l d Rey o i l f i e l d .

Its

- E l Segundo f i e l d

i s lo cated

a b o u t foxr

lo catio n is

m iles

shown o n F i g u r e 3 .

was d i s c o v e r e d i n 1 9 3 5 b y t h e

R e p u b l i c P e t r o l e u m C o m p an y ’ s w e l l , Mo. " E l S e g u n d o " 1 i n t h e NWj, Sec.

18, T.3 S . ,

estim ated r a te

R. 14 W . , S . B. B. M.

o f 400 b a r r e l s p e r d a y .

d e p t h and th e p r o d u c t i v e zone a t

T h i s w e l l f lo w e d a t an The w e l l w a s 7402 f e e t i n

the bottom o f th e w e l l c o n s i s t e d

o f 72 f e e t o f s c h i s t c o n g l o m e r a t e a n d 20 f e e t o f s c h i s t . and Sullw old, 1946, p. 1 8 ).

D uring the f o llo w in g

68 p r o d u c i n g w e l l s and 8 d r y h o l e s w e r e d r i l l e d a r e a o f 950 a c r e s .

three years,

d e fin in g a producing

M o st o f t h e s e w e l l s p r o d u c e d f r o m t h e c o n g l o ­

m erate b u t 6 o r 8 w e lls the conglom erate i s

(Cabeen

i n th e w e s te rn p a r t o f the f i e l d ,

a b s e n t , p ro d u ced from th e s c h i s t .

where

A to ta l of

1 1 ,5 3 9 ,0 0 0 b a r r e l s o f o i l had been p ro d u ced to J a n u a ry 1 , 1946. Cabeen a n d S u llw o ld

(1 9 4 6 , p . 18) r e p o r t

w e lls p ro d u cin g o n ly from the

s c h i s t had i n i t i a l

h ig h as 4 ,000 to 5,000 b a r r e l s a d ay. tio n o f th e se high

t h a t some o f t h e p ro d u ctio n s as

They do n o t

s ta t e the d u ra­

producing r a t e s .

S t r a t i g r a p h y . - The d i s t r i b u t i o n o f s e d i m e n t s on t h e b u r i e d h i l l u n d e r l y i n g E l Segundo o i l f i e l d c ro ss s e c tio n in F igure conglom erate,

ra n g in g in

shown on t h e g e n e r a l i z e d

6 (R eese, 1943, p .

296).

t h i c k n e s s up to 100 f e e t ,

the f la n k s o f the s t r u c t u r e . rests

is

The b a s a l s c h i s t i s p r e s e n t on

I t i s o v e rla in by n o d u lar sh ale th a t

d i r e c t l y on m e t a m o r p h i c r o c k s on t h e c r e s t o f t h e h i l l .

L A R C O O IL CO Mm

/

.R IC H F IE L D OIL C O R P

xr

'se™ ~ T T J h d e r l i n i n g b y t h e w r i t e r ) . S i g n i f i c a n t F e a t u r e s . - These i n c l u d e : (1)

The c l o s e a s s o c i a t i o n o f s o u r c e b e d s a n d u n d e r l y i n g

reserv o ir rocks. (2)

The a s s o c i a t i o n o f f a u l t i n g w i t h a f r a c t u r e d

zone i n

the m etam orphic r o c k s . (3)

The s t a t e m e n t by R e e s e

(1943, p.

245)

th a t p ro d u ctiv ity

v a r i e s a c c o r d in g to the p e r m e a b i l i t y o f th e r o c k s r a t h e r th ick n ess or s tru c tu ra l p o s itio n .

than t h e i r

WILMINGTON OIL FIELD L o c a t i o n * - W ilm ington o i l f i e l d

i s lo cated

i n t h e Los

A ngeles H arbor d i s t r i c t betw een th e c e n t e r o f th e c i t y o f ? /ilm in g to n a n d t h e L o s A n g e l e s C o u n t y F l o o d C o n t r o l C h a n n e l i n Lo n g B e a c h . H i s t o r y . - W i l m i n g t o n f i e l d was d i s c o v e r e d i n 193 6 b y G e n e r a l P e t r o l e u m C o r p o r a t i o n ' s w e l l No. T e r m i n a l 1 i n t h e n o r t h ­ w e ste rn p a r t o f the f i e l d .

(See F i g u r e 6 ) •

o b t a i n p r o d u c t i o n from f r a c t u r e d m etam orphic P a c i f i c No. E 47 o n t h e c r e s t o f t h e d rilled

i n May, 1 9 4 5 .

W hite

(194o p .

The f i r s t w e l l t o tocks

stru ctu re.

was U n i o n

T h i s w e l l was

b) p r e s e n t s some i n t e r e s t i n g

d e t a i l s r e g a rd in g the h i s t o r y o f th e se e a r l y basement t e s t s .

He

says: " C o r e r e c o r d s ( f r o m U nion P a c i f i c w e l l No. E 47 s e e F i g u r e 8 f o r l o c a t i o n ) show t h a t i n t h e 1 9 - f o o t i n t e r v a l from 5,787 to 5 ,8 0 6 f e e t , th e c o r e r e c o v e r y was o n l y 1 f o o t 10 i n c h e s o f s o f t a n d h a r d g r e e n s c h i s t . The t o p o f t h e s c h i s t was d e t e r m i n e d f r o m e l e c t r i c lo g to be a t 5,680 f e e t . The w e l l was b o t t o m e d a t 5,806 f e e t . A f i v e in c h l i n e r w ith p e r f o r a t i o n s from 5,682 to 5,796 f e e t was landed a t 5,796 f e e t . D uring a th re e hour p ro d u c tio n t e s t of t h i s p e r f o r a te d i n t e r ­ v a l t h e w e l l flo w e d a t th e r a t e o f 376 b a r r e l s a day o f 31.0 - d eg ree, A .P .I . g r a v i ty o i l , c u ttin g 0 .2 p e r c e n t w a t e r . . . U n i o n P a c i f i c R a i l r o a d Company com­ p l e t e d w e l l No. O n i o n P a c i f i c 369 i n J u n e 194 6 f o r a n i n i t i a l p r o d u c tio n of 2,839 b a r r e l s a day of 29.0 d e g re e , A .P .I . g r a v i ty o i l , c u t t i n g 0.1 p e r c e n t w a t e r . . . F orm ation t e s t s of th e s c h is t fo rm a tio n in o th e r w e lls i n t h e f i e l d h a v e shown p r o d u c t i o n r a t e s a s h i g h a s 2,300 b a r r e l s o f o i l a d a y . ” D e v e l o p m e n t worK: i n t h e s c h i s t z o n e s i n c e 1 9 4 6 h a s be e n d i s a p p o i n t i n g to th e Company.

e n g i n e e r s o f t h e Long B e a c h O i l D e v e l o p m e n t

Many o f t h e i r d e e p w e l l s w e r e on m u l t i p l e z o n e p r o ­

d u c t i o n an d t h e e n t r y o f b o t t o m w a t e r i n t h e b a s e m e n t r o clcs

dam ag ed p r o d u c t i o n z o n e s i n t h e o v e r l y i n g tnese

engineers regard

the d isc o v e ry of o i l

ro ck s as a dubious b le s s in g , little

sed im en ts.

it

m

H en ce

the m etam orphic

is perhaps f a i r

to

state

th at

a t t e n t i o n has been giv en to pro b lem s a s s o c i a t e d w ith th e

d i s c o v e r y and d e v e l o p m e n t o f o i l

in

h as been done,

t h a t were t a k e n , few have been

saved.

and, o f the c o re s

The f i r s t

the s c h i s t s .

s t r u c t u r a l c o n t o u r map o f

b a s e m e n t was made b y t h e w r i t e r m years a f te r

the o r i g i n a l

in th is f ie ld .

L ittle

coring

tne s u r f a c e o f th e

t h e summer o f l y 4 e - t h r e e

discovery o f o i l

in m etam orphic ro c k s

A l t h o u g h n e g l e c t o f t h e b a s e m e n t z o n e may b e

u n d e r s t a n d a b l e , due to i t s the h ig h ly p r o l i f i c

lim ited

reserv o irs

im portance in com parison w ith

in the o v e rly in g sands,

it

does

i n d i c a t e a c e r t a i n l a c k o f g e o l o g i c a l f o r e s i g h t among t h e o p e r ­ ato rs

±n t h e

rie ld .

The e x p e n d i t u r e

in ly4b o f a r e l a t i v e l y

sm all

sum o f money f o r r e s e a r c h w o r k o n p r o b l e m s a s s o c i a t e d w i t h t h e developm ent o f

t h e B a s e m e n t Z on e a t W i l m i n g t o n o i l f i e l d

c e r t a i n l y would have been r e p a i d

alm ost

s e v e ra l f o ld d uring subsequent

o p eratio n s. S t r a t i g r a p h y . - F i g u r e 7 from W i s s l e r ' s r e p o r t on t n e p r o d u c i n g z o n e s m stra tig ra p h ic fie ld s.

(1943, p .

227)

t n e Lo s A n g e l e s B a s i n s h o w s t h e

v a r i a t i o n rroin P l a y a d e l Rey to W ilm in g to n o i l

T h i s c h a r t was c o m p i l e d p r i o r

t o much o f t n e d e e p d e v e l ­

opment work i n W ilm in g to n f i e l d h e n c e i t f o r the deeper zones.

For in s ta n c e ,

conglom erate o v e rly in g

the basem ent.

i s not e n tir e ly accu rate

W i s s l e r d o e s n o t show s c h i s t T his u n i t i s p r e s e n t a t

the

b a s e o f t h e M i o c e n e a n d o c c u p i e s t h e same r e l a t i v e p o s i t i o n i n th is It

is

f i e l d as i t

does m

P l a y a d e l Rey a n d F I S e g u n d o o i l f i e l d s .

a b s e n t on t h e c r e s t o f t h e h i l l

a n d p r e s e n t on t h e f l a n k s

PLAYA DEL REY

EL SEGUNDO

2 500

“i

-2000

-

.O

1500

W IL M IN G T O N

TORRANCE

(W E S T )

-1000

-

50 0

lj~

8A

D ATUM * T OP MIOCENE

DIVISION A DIVISION A i 4 -

500

-1 0 0 0

-1 5 0 0

-2000

LEGEND

□

SHALE WITH PHOS NOOULCS

-2 5 0 0

PERCENT o r SAND

|< £ b ? o |

CONGLOMERATE WlTh SCHIST BOULDERS

^

SCH'ST

-3 0 0 0

-3500

HO SAM PLES UNCONEORMf T Y

COMPILED BT - STANLEY G. W /S SL C R AUGUST IS, 1 9 4 0

S tr a tig ra p h ic v a r ia tio n c h a r t : P la y a del R ey, El Segundo, T orrance, an d W ilm in g to n ( w e s t ) oil fields. F ig u re 7.

.7is s l o r

(1943, p .

227)

54 o f th e h i l l where t h i c k a c c u m u l a t i o n s l o c a l l y i n d e p r e s s i o n s on th e

(80-100 f e e t )

su rface o f the

N otew orthy d i f f e r e n c e s betw een th e W ilm ington f i e l d

sed im en tary s e c tio n in

in c lu d e the f o llo w in g :

o f t h e b e d s o f M i o c e n e a g e i s much g r e a t e r fie ld ,

basement r o c k s .

and t h e s e d i m e n t a r y s e c t i o n s m

and S I S e g u n d o f i e l d s

a re found

P l a y a d e l Rey

(l)

the th ic k n e s s

in W ilm ington o i l

(2)

the p e rc e n ta g e

o f sand m th e

beds o f M iocene age i s

g re a te r in

W ilm ington o i l

f i e l d a n d ,(3)

n o d u l a r s h a l e i s more

restricted

of the

in

t h i c x n e s s and e x t e n t i n W i l m i n g t o n f i e l d .

S t r u c t u r e . - The s h a p e o f t h e b u r i e d h i l l

on t h e s u r f a c e

basement ro c k s i n W ilm ington o i l f i e l d

sh ow n i n F i g u r e

8.

The h i l l

is

its

flan k s.

The u p p e r l i m i t o f t h e

r e l a t i v e l y f l a t on t o p and i s r e l a t i v e l y s t e e p on

heavy d o tte d lin e

conglom erate i s

n e a r t h e summit o f t n e h i l l .

n e s s o f th e lo w e r p r o d u c t i v e zone shown b y t n e i s o p a c h o u s l i n e s .

(237 Zone)

s u r f a c e o f the

down t h e d i p .

th at

sed im ents a r e

i n t e r v a l betw een

t o p o f t h i s Zone a n d t h e

the h i l l was i n e x i s t e n c e a t

t h e tim e o f d e p o s i t i o n o f th e s e b e d s .

fie ld .

in the

basement rocks in c r e a s e s in th ic k n e s s

T his in d ic a te s

237 Zone i s r e l a t i v e l y

shown by t h e

Changes i n t h i c k ­

The s t r a t i g r a p h i c

th e B A ( e l e c t r i c lo g ) m arker a t tne u n d erly in g

is

thin a t

I t w i l l be n o t e d

the s o u th e a s te r n e x tr e m ity of th e

T h i s may h a v e b e e n a t o p o g r a p h i c " h i g h ” a t t h e

d e p o sitio n of

these beds and,

th a t the

if

t h i s was t h e c a s e ,

tim e o f

ex p lo ratio n

f a r t h e r to th e s o u t h e a s t b e n e a t h t h e c o a s t a l w a t e r s would o f f e r h o p e o f e x t e n d i n g t h e p r e s e n t l i m i t s o f p r o d u c t i o n i n t h e 237 Z o n e . The h i l l

is

d i v i d e d i n t o d i f f e r e n t s t r u c t u r a l u n i t s by

nor th e r ly - tr e n d in g f a u l t s .

W in te rb u rn (1943, p . 304)

says:

55 MA11 trie p r i n c i p a l f a u l t s a r e n o rm a i_ pa u l t s , h a d i n g to the e a s t , w ith tn e e x c e p t i o n o f th e lo w e r i-ine f a u l t , w hich h a d e s to th e w e s t . The a n g l e o f i n c l i n a t i o n o f t h e f a u l t p l a n e s r a r g e s b e t w e e n 50 a n d 60 d e g r e e s f r o m the h o r i z o n t a l , w ith a g e n e r a l te n d e n c y to s te e p e n as the f a u l t i s tra c e d n o rth w a rd from th e a x i s of the s t r u c t u r e . . . A much t h i c k e r R e p e t t o s e c t i o n i s f o u n d on th e downthrown s i d e o f a l l th e f a u l t s t h a n on t h e im m e d ia te ly a d j a c e n t upthrow n b la c k . I n t e r v a l s i n the M i o c e n e a r e m ore n e a r l y u n i f o r m t h r o u g h o u t t h e f i e l d . . T his r e l a t i o n s h i p o f tn e v a r i a b l e t h i c k n e s s o f the R e p e tto s e c t i o n to th e s t r u c t u r a l f e a t u r e s u g g e sts t h a t the f o l d i n g and f a u l t i n g o c c u r r e d p r o g r e s s i v e l y d u rin g the d e p o s i t i o n o f th e R e p e tto b e d s, which a t t a i n e d v a r y i n g t h i c k n e s s e s , d e p e n d i n g on t h e r e l a t i v e d e p r e s s i o n of ad ja c e n t a re a s du ring d e p o s it io n .” Some m o d i f i c a t i o n s o f t h e s e s t a t e m e n t s a r e n e c e s s a r y d e v e lo p m e n t work h a s d i s c l o s e d

t h a t the

as r e c e n t

th ick n esses of s t r a t i -

g r a p h i c i n t e r v a l s i n b e d s o f M iocene age v a r y m a r k e d ly a c r o s s some f a u l t s . the B

For exam ple,

the

thickness of

the i n t e r v a l b etw een

A m a r k e r an d m e b a s e m e n t i s 250 f e e t o n t h e c r e s t o f t h e

stru ctu re

to

the f a u l t

the

the w e s t o f tn e Power L ine f a u l t . t h i c k n e s s i s 450 f e e t .

in th ic k n e ss i s

A s i m i l a r a b r u p t change

a p p a r e n t a lo n g the s o u th w e s t e r l y t r e n d i n g s t r a n d

o f t h e Termo f a u l t . relatio n sh ip s

Im m ediately a c r o s s

A lthough a l t e r n a t i v e

ex p lan atio n s f o r these

a r e p o s s i b l e the w r i t e r b e l i e v e s

t h a t the f a u l t s w ere a l r e a d y i n e x i s t e n c e a t t i o n o f th e b e d s o f u p p e r M iocene a g e .

th a t they in d ic a te

th e tim e o f d e p o s i ­

A d d i t i o n a l movements

along th e se f a u l t s o c c u rre d d u rin g d e p o s itio n o f the younger R epetto

beds.

F a u l t s and f o l d s i n t h e b e d s o f u p p e r M i o c e n e

age and i n th e o v e r l y i n g R e p e t t o f o r m a t i o n a r e n o t r e f l e c t e d the younger sed im en ts

(M iddle P ic o )

th e top o f th e R ep etto f o rm a tio n The f a u l t s

in

m igration of f lu id s

ov erly in g

(W interburn,

the u n c o n fo rm ity a t 1943, p.

304).

t h i s f i e l d a c t e d a s im perm eable b a r r i e r s a c c o rd in g to W interburn

in

(1943, p .

to

3 0 4 ) who s t a t e s :

56 "The f a u l t s a p p a r e n t l y a r e s e a l e d an d a c t a s b a r r i e r s t o t n e m o v em en t o f f l u i d t h r o u g h t n e s a n d s . . . At many p l a c e s w a t e r s a n d s on one s i d e o f t h e f a u l t a r e i n c o n ­ t a c t w ith o i l sands on th e o p p o s ite s i d e . " S t r u c t u r a l E v o l u t i o n . - The h i s t o r y o f stru ctu re

is

d isc u sse d b r i e f l y by W issle r

the W ilm ington

(1943, p .

2 2 6 ) who s a y s :

" D u rin g the m id d le M iocene th e s e a g r a d u a l l y e n ­ c r o a c h e d f r o m t h e s o u t h w e s t o v e r t h e a r e a now o c c u p i e d by th e P a l o s V erdes H i l l s u n t i l , by e a r l y u p p e r L u i s i a n t i m e , i t h a d t r a n s g r e s s e d o v e r w h a t a r e now t h e W i l m i n g t o n and Inglew ood o i l f i e l d s . A p p aren tly the tr a n s g r e s s io n was f o l l o w e d by a s h o r t p e r i o d o f l o c a l e m e r g e n c e a n d e r o s io n r e s u l t i n g i n the u n co n fo rm ity betw een D iv is io n s E an d F . F o llo w in g t h i s em ergence th e s e a advanced c o n s i d e r a b l y be yond t h e p r e s e n t b o u n d a r i e s o f t h e B a s i n , an d a l o n g p e r i o d o f d e p o s i t i o n b e g a n . . . A p p a r e n t l y d e p o s i t i o n was c o n t i n u o u s o v e r t h e m a i n p a r t o f t h e W ilm ington a r e a . • . u n t i l m id d le R e p e tto t i m e ." P ro d u c in g Z ones. - S ix p r o d u c tiv e zones have been e n c o u n te re d i n th e W ilm ington f i e l d .

Of t h e s e ,

o n l y t h e 237 Z o n e a n d S c h i s t

Zone a r e o f i m p o r t a n c e i n s o f a r a s t h i s i n v e s t i g a t i o n i s c o n c e r n e d . The 237 Zone i n c l u d e s

sands t h a t b u t t r e s s a g a in s t th e u n d e rly in g

b asem ent s u r f a c e and a l s o it

in clu d es

i s p r e s e n t on th e s t r u c t u r e .

t h e s c h i s t - c o n g l o m e r a t e where

T h i s Zone i s

s e p a r a t e d from th e

u n d e r l y i n g S c h i s t Zone b y a p e r m e a b i l i t y b a r r i e r i n t h e m e t a m o r p h i c rocks.

? / e l l s c o m p l e t e d i n t h e S c h i s t Zone a r e

c h a r a c te r iz e d by

h i g h b o t t o m - h o l e p r e s s u r e s a n d h i g h i n i t i a l p r o d u c t i o n s a s com­ p a r e d to w e l l s

com pleted in th e

im m ediately o v e rly in g

sands o f the

237 Z o n e . A few s p e c im e n s o f t h e m etam o rp h ic r o c k s were exam ined by the w r i t e r .

The y c o n s i s t e d o f w e l l f o l i a t e d

s c h is ts p o s s ib ly o f m eta-v o lcan ic o r ig in . a v a i l a b l e hence i t

green c h l o r i t i c

V ery few c o r e s a r e

i s n o t p o s s i b l e t o make a d e t a i l e d l i t h o l o g i c

s tu d y such a s h a s been done a t E dison o i l f i e l d .

57 S i g n i f i c a n t F e a t u r e s # - A lth o u g h W ilm ington o i l f i e l d h a s many f e a t u r e s it

i n common w i t h P l a y a d e l Key an d

E l Segundo f i e l d s ,

d i f f e r s i n t h a t th e p r o d u c t i v e s e c t i o n i n b e d s o f u p p e r M iocene

a g e i s much t h i c k e r

than i n the l a t t e r

fie ld s.

O il in the S c h is t

Zone i n W i l m i n g t o n f i e l d may h a v e b e e n d e r i v e d f r o m e i t h e r o v e r ly in g source beds o r r e s e r v o i r san d s b u t t r e s s i n g a g a i n s t the s id e o f the b u rie d h i l l . An a n a l y s i s o f p r o d u c t i o n d a t a i n W i l m i n g t o n f i e l d i s p r e ­ s e n te d g r a p h i c a l l y on F ig u re 8 .

The f o l l o w i n g c o n c l u s i o n s a r e

b a s e d on t h e e v i d e n c e p r e s e n t e d m (1)

th ese graphs.

The p r o d u c t i v i t y o f a w e l l i s

p e n e tra tio n into

Th ey a r e :

related

to

the d e p t h o f

the basem ent - th e w e lls w ith lo n g e r i n t e r v a l s

open i n t h e b a s e m e n t h a v i n g h i g h e r i n i t i a l p r o d u c t i o n s . (2) lated

The p r o d u c t i v i t y o f a w e l l d o e s n o t a p p e a r

t o th e t o p o g r a p h i c p o s i t i o n o f t h e w e l l on th e (3)

The o i l - w a t e r

in terface

th r o u g h o u t the S c h i s t Zone. cells

is irre g u la r

t o be r e ­

stru ctu re.

in e le v a tio n

T h i s may b e d u e to a n u m b e r o f s e p a r a t e

i n t h e r e s e r v o i r r o c k s o r i t may be due t o b y - p a s s i n g o f o i l

b y w a t e r d u r i n g e a r l y s t a g e s o f f l u s h p r o d u c t i o n f r o m some w e l l s . (4 )

Deep p e n e t r a t i o n o f t h e

p ro d u ctio n o f o i l but i t wet w e l l s .

T his l a t t e r

also

resu lts

in h ig h e r i n i t i a l

in a h ig h e r percen tag e o f

re la tio n sh ip in d icates

a r e p r e s e n t below a zone o f o i l (5)

sch ist re su lts

t h a t bottom w a te rs

saturated f ra c tu re s .

The v a r i a t i o n s i n i n i t i a l p r o d u c t i o n w i t h d i r e c t i o n s o f

s la n t holes are not o f s la n t w ells.

s i g n i f i c a n t due p o s s i b l y t o t h e l i m i t e d n u m b e r

58 O rig in o f the B uried H i l l s . - S e v e ra l a l t e r n a t i v e e x p la n a ­ tio n s

c o n c e rn in g th e o r i g i n o f b u r ie d h i l l s have been p r e s e n te d

i n the fo re g o in g s e c t io n of ap p aren tly b eliev es

the r e p o r t .

t h a t the

graphic u n i t u n d erly in g

the

W issler

schist-conglom erate

(1943, p .

227)

is a s tra ti-

s e d i m e n t s o f u p p e r M iocene age and

t h a t th e a b s e n c e o f t h i s u n i t on th e c r e s t o f t h e s e s t r u c t u r e s i s due i n p a r t ,

at le a st,

to s u b a e r i a l e r o s i o n f o l l o w i n g f o l d i n g

and u p l i f t o f the s t r u c t u r e s . (1943, p.

29 5) a n d W h i t e

M etzner

(1946, p .

(1943, p .

292), Reese

6) s u g g e s t t h a t t h e s c h i s t -

c o n g l o m e r a t e i s a l i t t o r a l d e p o s i t a n d by i n f e r e n c e th at tim e.

the h i l l s

were i s l a n d s i n

R elativ ely rap id

o r f a u l t i n g i s held

t h e s e a s o f e a r l y u p p e r M io c e n e

submergence as a consequence o f f o l d i n g

t o be r e s p o n s i b l e f o r

c o n g l o m e r a t e on t h e c r e s t o f t h e

stru ctu re

The w r i t e r h e r e b y s u g g e s t s

the absence o f the (W hite, 1946, p .

are

s i m i l a r i n many r e s p e c t s

s c r i b e d b y Emery ( 1 9 4 8 , p .

797).

6).

t h a t t h e s e h i l l s may h a v e b e e n

su b m a rin e ban k s d u r i n g e a r l y u p p e r M iocene t i m e . h ills

they suggest

The b u r i e d

t o R a n g e r Bank r e c e n t l y d e ­ The s h a p e o f R a n g e r Bank a n d t h e

d i s t r i b u t i o n o f s u r f a c e m a t e r i a l on t h e Bank a r e show n i n F i g u r e 9 from Emeryr s r e p o r t .

The r e l a t i v e l y

ste e p e r flan k s of th is

s u m m it a r e a a n d t h e

subm arine to p o g ra p h ic f e a t u r e have t h e i r

c o u n t e r p a r t s on t h e b u r i e d h i l l s Los A n g e le s B a s i n .

fla t

S im ilarly

m

the w e ste rn p a r t o f the

tne d i s t r i b u t i o n of s u rfa c e m a t e r ia l

on t h e Ban k i s c o m p a r a b l e t o t h e d i s t r i b u t i o n o f s c h i s t - c o n g l o m e r a t e a n d s c h i s t on t h e b u r i e d h i l l s .

F urtherm ore, p h o sp h atic m a te r ia l

i s r e l a t i v e l y a b u n d a n t b o t h a l o n g t h e t o p o f t h e Bank an d i n t h e b a s a l p a r t o f th e n o d u la r s h a le cap p in g the b u r ie d h i l l s .

59

I5°30'

f

ROCK

RANGER BANK STATUTE

MILES

NOTATIONS OF SAND GRAVEL ROCK R UCDWR BOTTOM PHOTOGRAPH R UCDWR BOTTOM SAM PLE R H O . 1193 BO TTO M NOTATION X VELERO III DREDGING

II5°30'

Composition of top of Ranger Bank based on samples, photographs, and navigational chart notations. Insert is generalized map of surface materials. F i g u r e 9,

Sm ery ( 1 9 4 8 , p .

797)

60

A p p l i c a t i o n s # - The o r i g i n o f t h e b u r i e d h i l l s m ay n o t a p p e a r to

be a t o p i c c l o s e l y r e l a t e d

yet there i s

to o i l i n m etam orphic ro c k s

a n i n d i r e c t c o n n e c t i o n b e t w e e n t h e two s u b j e c t s .

one a c c e p t s W i s s l e r ’ s i n t e r p r e t a t i o n o f t h e o il

th at is present m

have m ig ra te d l a t e r a l l y

stra tig ra p h ic

th e m etam orphic r o c k s i n

If

record,

t h e h i l l s may

in th e sc h is t-c o n g lo m e ra te f o r a long

d i s t a n c e b e f o r e a c c u m u l a t i n g on t h e f l a n k s and c r e s t s o f b u r i e d h ills. th at

the

An e x p e c t a b l e f e a t u r e o f t h e a l t e r n a t i v e sch ist-c o n g lo m erate

and g r a d e s l a t e r a l l y b asin s.

Thus,

ex p lan atio n is

i s l o c a l i z e d around the b u rie d h i l l

in to f i n e r g ra in e d sed im en ts in the a d jo in in g

l e s s o p p o r tu n ity f o r long d is ta n c e l a t e r a l m ig ra­

ti o n o f o i l e x i s t s a c c o rd in g to the l a t t e r co n c e p t o f t r i b u t i o n of sedim ents.

Therefore,

the d i s ­

tran sv erse m igration of o i l

from b itu m in o u s s h a le s d i r e c t l y i n t o u n d e r l y in g r e s e r v o i r ro c k s m u s t be c o n s i d e r e d a s a p r o c e s s r e s p o n s i b l e f o r some o f t h e o i l in the s c h i s t s .

PART IX

SANTA MARIA VALLEY OIL FIELD L o c a t i o n . - The S a n t a M a r i a V a l l e y o i l f i e l d

is

situ ated

i n S a n ta M aria V a l l e y in th e n o r th w e s t e r n c o r n e r o f S a n ta B a rb a ra C ounty.

The l o c a t i o n o f t h e

fie ld

is

shown o n F i g u r e 3 .

H i s t o r y . - The d i s c o v e r y w e l l i n t h e f i e l d w a s d r i l l e d 1 9 3 4 by t h e U n i o n O i l Company. u n t i l the d is c o v e ry of o i l

in

P r o d u c tio n o f o i l from the f i e l d th e b a s e m e n t r o c k s i n 1942 amounted

to a b o u t f o r t y m i l l i o n b a r r e l s . C a b e e n and S u l l w o l d

in

(1 9 4 6 , p . 19)

The f o l l o w i n g q u o t a t i o n f r o m i s p a r t i c u l a r l y i n t e r e s t i n g due

to t h e f a c t t h a t t h e y w ere en g a g e d i n th e e a r l y d e v e lo p m e n t work on t h e f r a c t u r e d b a s e m e n t r e s e r v o i r .

They s a y :

" I n D e c e m b e r o f 1 9 4 2 , N. R. G e r a r d s p u d d e d i n h i s A c q u i s t a p a c e 1 o n a l e a s e q u i t - c l a i m e d by a m a j o r o i l co m pa ny i n t h e n o r t h c e n t r a l p a r t o f t h e f i e l d o f f s e t t i n g a 1 5 - b a r r e l p e r day w e l l . The w e l l w a s i n t e n d e d t o t a k e i n t h e same z o n e a s t h e e a s t e r l y o f f s e t w e l l b u t was on t h e u p t h r o w n s i d e o f a f a u l t a n d w e n t 90 f e e t i n t o t h e b a s e m e n t due t o t h e l a c k o f t e c h n i c a l a d v i c e on t h e job. I t came i n a s a 1 0 , 0 0 0 MCF p e r d a y g a s w e l l , b u t s o o n w e n t t o o i l an d f l o w e d 2500 b a r r e l s p e r d a y o f c l e a n 18.5° g r a v ity o i l . S e v e n i n c h c a s i n g was s e t a t 3 9 8 8 f e e t , t o p M iocene a t 4010 f e e t , to p d e t r i t a l zone a t 4 2 7 0 f e e t a n d t o p K n o x v i l l e ( b a s e m e n t ) a t 429 5 f e e t , t o t a l d e p th 4385 f e e t . S l o t t e d l i n e r was l a n d e d w i t h th e e n t i r e i n t e r v a l below the shoe open to p r o d u c t i o n . C asin g p r e s s u r e s w ere f a r m e x c e s s o f the bottom h o le f o r m a t i o n p r e s s u r e s o f The d e p l e t e d M i o c e n e p r o d u c t i v e z o n e , a n d o i l p r o d u c t i o n was b e y o n d t h e w i l d e s t d r e a m s o f the o p e ra to r . . . In M arch, 1944 th e second w e l l was c o m p l e t e d f o r 2800 b a r r e l s d a i l y f r o m a t o t a l d e p t h o f 4805 f e e t w i t h a p e n e t r a t i o n o f 415 f e e t o f K n o x v i l l e p l u s th e u s u a l M iocene z o n e s . T h i s w e l l was o f f s e t t i n g a 5 - b a r r e l p e r d a y M iocene w e l l on t h e w e s t . . . S u b s e q u e n t d e v e l o p m e n t h a s r e s u l t e d i n o v e r 40 K n o x v i l l e w e l l s , some w i t h o v e r 1200 f e e t o f K n o x v i l l e p e n e t r a t i o n . M o s t o f t h e m h a v e some M i o c e n e o p e n a l o n g w i t h t h e K n o x v i l l e , b u t th e K n o x v i l l e h a s b een i s o l a t e d and fo u n d pro d u ctiv e alo ne. Some o f t h e w e l l s came i n f l o w i n g a s i n t h e G e r a r d a r e a , b u t m o s t a r e b r o u g h t i n o n t h e pump f o r an a v e r a g e o f 200 t o 400 b a r r e l s d a i l y . . . T h e r e a r e now a b o u t 420 a c r e s p r o v e n i n t h e K n o x v i l l e . "

A review o f the g e o lo g ic a l l i t e r a t u r e rev eals 1942.

t h a t o i l had been r e p o r t e d I n 19 3 9 C a n f i e l d

(1939, p.

fie ld

in the basement ro c k s b e fo re 50)

b a se m e n t complex i n a s t r a t i g r a p h i c V alley o i l f i e l d .

on t h i s

sh ow s o i l i n f r a c t u r e s

in

s e c t i o n o f th e S a n ta M aria

On p a g e 68 i n t h e same p a p e r h e s t a t e s :

"Th e F r a n c i s c a n c o n t a i n s no o i l o t h e r t h a n t h a t w h i c h h a s m i g r a t e d i n t o t h e f o r m a t i o n from th e M o n t e r e y . ” It is

in terestin g

to r e c a l l

th a t s iz e a b le o i l accum ulations in

th e m e ta m o rp h ic r o c k s i n P l a y a d e l Rey and S I Segundo f i e l d s h a d b e e n d i s c o v e r e d some y e a r s p r e v i o u s t o

the p u b l i c a t i o n o f

th is paper. STRATIGRAPHY Baseme n t r o c k s . divided in to

The b a s e m e n t r o c k s i n t h e

three general

fie ld

ty p e s a c c o rd in g to C a n f ie ld

c a n be (1943,

p • 4 4 0 ) who s a y s : "The r o c k s . . . a r e o f t h r e e g e n e r a l t y p e s : (l) c a lc ite v e i n e d h a r d g r e e n i s h - g r a y p y r i t i f e r o u s and c a l c a r e o u s s a n d s t o n e ( t h e m ain r o c k ) ; (2) g o u g e - l i k e s t e e l - g r a y p y r itif e r o u s c la y sh ale; (3) im pure s e r p e n t i n e ( d i k e s and v e in s).” The m i n e r a l o g i c a l c o n t e n t o f t h e s a n d s t o n e t o 4431 f e e t

i n t h e i n t e r v a l 4425

i n U n i o n O i l Company w e l l No. B e t t e g a 3 was d e t e r ­

m ined by th e R o siw al m e th o d .

The s a n d s t o n e c o n s i s t s o f t h e

fo llo w in g m in era ls: Q uartz

14.5#

C hert

2.4 #

F eldspar

2.2 #

M ica

0 .6 #

Opaque

0 .5 #

C a l c i t e cement

79.8#

63 T h i s a n a l y s i s was made i n t h e l a b o r a t o r i e s o f

theU n ited S t a t e s

G e o l o g i c a l S u r v e y f o r t h e U n i o n O i l Company. The s a n d s t o n e i s f i l l e d w ith c a l c i t e

commonly f r a c t u r e d a n d t h e f r a c t u r e s a r e

(C anfield,

1 9 4 6 , p . 19; Regan and Hughes,

1943, p . 440; Cabeen andS u l l w o l d , 1949, p .

51).

The s h a l e s i n t e r b e d d e d w i t h t h e s a n d s t o n e a r e h i g h l y slick en sid ed .

Regan and Hughes (1 9 4 9 , p .

"p lastic-ap p earin g te ristic s."

51) r e f e r

t o th e m a s

sh ale a p p a re n tly w ith o u t r e s e r v o ir ch arac­

The y a l s o

state:

"C asts of th e m e g a f o s s il A u c e lla have been r e p o r t e d i n t h e s h a l e s a t t h e e a s t e n d o f t h e f i e l d , a n d on t h e b a s i s o f t h e s e th e zone i s r e f e r r e d to a s t h e K n o x v i l l e (Upper J u r a s s i c ) ” . These rocK s a r e o n l y s l i g h t l y m etam orphosed and s h o u ld p e r h a p s be c l a s s i f i e d a s

sedim ents r a t n e r th a n m e ta -s e d im e n ts .

The w r i t e r d i d n o t make a d e t a i l e d o f the basem ent ro c k s.

C ores from th e basem ent were d i s c a r d e d

b y t h e U n i o n O i l Company p r i o r th is fie ld

in

to

the w r i t e r ’ s b r i e f v i s i t

the v a r i o u s l i t h o l o g i c

i n t h e b a s e m e n t w e r e made b y t h e u s e o f e l e c t r i c

U n f o r t u n a t e l y t h e w r i t e r was u n a b l e t h i s m ethod.

F urtherm ore,

c o r r e l a t i o n c a n be a p p l i e d I t w o u l d be i n t e r e s t i n g

it

is doubtful i f

t h i s method o f (Ford, 1947).

to a t t e m p t c o r r e l a t i o n s b etw een w e l l s on T h i s m e t h o d may b e a p p l i c a b l e

th e basem ent ro c k s in S a n ta M aria V a lle y f i e l d .

if

log s.

t o make a n y c o r r e l a t i o n s b y

to f r a c t u r e d r o c k s

t h e b a s i s o f gamma r a y l o g s .

be p o s s i b l e

to

t h e summer o f 1 9 4 8 .

S e v e ra l a tte m p ts to c o r r e l a t e u n its

study o f th e lith o lo g y

I f not,

to

i t may

t o c o r r e l a t e b e t w e e n w e l l s on t h e b a s i s o f l i t h o l o g y

s e v e r a l co m p lete c o r e s o f th e b asem ent i n t e r v a l were o b ta in e d

64 in ad jacen t w ells. of th e rocks in

N e e d le s s to say

t h i s problem o f c o r r e l a t i o n

the b asem ent i s h i g h l y i m p o r t a n t i n t h i s

fie ld .

S t r u c t u r a l tr e n d s must be d e te rm in e d i n o r d e r to d e te rm in e p o s i t i o n s of the f a v o r a b le of d r illin g .

fractu red

the

s a n d sto n e r e s e r v o i r in advance

This i n f o r m a t i o n i s n o t a v a i l a b l e a t th e p r e s e n t

time i n s o f a r a s th e w r i t e r c o u ld d e t e r m in e from d i s c u s s i o n w ith various o p erato rs in

the f i e l d .

M i d d l e a n d U p p e r M i o c e n e . - The b a s a l member o f m ents unconform ably o v e r ly in g f r o m 2 0 t o 3U f e e t T his l i t h o l o g i c

the s e d i ­

the basement i s a d e t r i t a l m an tle

in th ic k n e ss

(Cabeen and S u llw o ld , 1945, p .

19).

u n i t i s o v e r l a i n by th e M o n terey f o r m a tio n w hich

h as b e e n d i v i d e d by C a n f i e l d

(1943, p . 440)

in to

the fo llo w in g

u n its: " S i l t s t o n e and S h e l l Z o n e . T h i s z o n e , t h e l o w e s t member o f t h e M o n t e r e y , i s c o m p o se d e s s e n t i a l l y o f s o f t to h a r d g r a y s i l t s t o n e , m e d iu m -g ra in e d s a n d , and cavernous or c a lc a re o u s sandstone o r s h e l l . . . ” n0 i l S a n d Z o n e . O v e r l y i n g t h e s i l t s t o n e a n d s h e l l zone b y m o d e r a te u n c o n f o r m i t y i s a b a s a l s a n d o f th e M onterey s h a le s e a t i o n . I t co n sists o f o il-s a tu ra te d s o f t to h a r d f i n e s i l t y to c o a r s e c a l c a r e o u s s a n d . . . ” "D a r k Brown Z o n e . O v e r i y i n g t h e o i l s a n d z o n e w i t h lo c a l d isco n fo rm ity o ccu rs a s e c tio n of m oderately h ard , dark chocolate-brow n sem ip laty f o r a m in if e r a l s h a l e . . . ” ”B u f f and Brown Z o n e . A s e c t i o n o f m o d e r a t e l y h a r d , i n t e r b e d d e d , c h o c o l a t e - b r o w n s e m i p l a t y an d b u f f - c o l o r e d p h o s p h a t i c s h a l e s o v e r l i e t h e d a r k brown z o n e . . . ” "B e n to n itic - B r o w n Zone. D is c o n fo rm a b ly above th e b u f f a n d bro w n z o n e o c c u r s a s e c t i o n o f m o d e r a t e l y h a r d l i g h t t o d a r k br ow n s h a l e , i n p a r t t h i n l y l a m i n a t e d a n d f i s s i l e , and in p a r t s i l i c e o u s and b a n d e d . . . ” ”C h e r ty Z o n e . D i s c o n f o r m a b l y above th e b e n t o n i t i c br ow n z o n e o c c u r s a c h e r t y z o n e , a s e c t i o n o f f r a c t u r e d , h a r d , l i g h t to d a r k b r o w n , p l a t y o r b a n d e d , p a r t l y s i l i c e o u s s h a le t h a t c o n t a i n s numerous bands o f b r o w n is h b l a c k an d b r o w n i s h - g r a y c h e r t . . . ”

65 wA r e n a c e o u s Z o n e , The h i g h e s t M o n t e r e y b e d s f o u n d i n t h e f i e l d c o n s i s t s o f f r a c t u r e d h a r d d a r k brown p l a t y shale. . . ” The S a n t a M a r g a r i t a

(?)

fo im atio n o v e r lie s

zo n e i n some p a r t s o f t h e f i e l d . sem iplaty s h a le , (C anfield,

It

the A renaceous

c o n s i s t s o f h a r d brown

devoid o f n e a r l y a l l

f o r a m i n i f e r a l rem ains

1943, p . 441).

P l i o c e n e . - The S i s q u o c f o r m a t i o n c o n s i s t i n g o f d i a t o m a c e o u s siltsto n e

and f in e

silty

u p p e r M iocene a g e . of f in e

sand unconform ably o v e r l i e s

th e beds of

I t i s o v e r l a i n by th e Foxen fo rm a tio n c o n s i s t i n g

sand and s i l t s t o n e .

B o t h t h e S i s q u o c and F o x e n f o r m a t i o n s

are m arine d e p o s it s . C o n t i n e n t a l d e p o s i t s c o n s i s t i n g o f g r a v e l and c l a y o v e r l i e th e Foxen f o r m a tio n .

They a r e P l e i s t o c e n e

to R e c e n t i n a g e .

S t r u c t u r e . - The S a n t a M a r i a V a l l e y o i l f i e l d on t h e n o r t h l i m b o f sy n clin e.

is

lo cated

the w e s t e r l y t r e n d i n g S a n t a M a r ia V a l l e y

The p o s i t i o n o f t n e o i l f i e l d w i t h r e f e r e n c e

hom oclinal s t r u c t u r e

on t h e l i m b o f r u e s y n c l i n e i s

i n F i g u r e 10 ( H o o t s ,

1943, p .

275).

to

tne

w e l l shown

The m o s t i m p o r t a n t a c c u m u l a ­

tio n of o il

is

in a com bination s t r u c t u r a l - s t r a t i g r a p h i c

betw een the

c a s e m e n t r o c k s and t h e u n c o n f o r m i t y a t t h e t o p o f t h e

p r o d u c tiv e M onterey f o rm a tio n .

The t h i c k n e s s o f t h e M o n t e r e y

f o r m a t i o n d e c r e a s e s up d i p a n d f i n a l l y a t tn e n o r t h edge o f tn e

trap

f i e l d where

t i o n r e s t s d i r e c t l y on t h e b a s e m e n t.

the f o r m a tio n t e r m i n a t e s

tne o v e r l y i n g S is q u o c f o r m a ­ C anfield

(1943, p .

70)

"This s a n d - a n d - s h a le p r o d u c in g o v e r la p type o f t r a p , w i t h m ore t h a n 3 , 0 0 0 f e e t o f c l o s u r e on t o p o f t h e M iocene, d i s t i n g u i s h e s the f i e l d from any o t h e r i n C a lifo rn ia ."

states:

66

GENERALIZED SKETCH SECTION ACROSS SANTA MARIA VALLEY OIL FIELD S H O W IN G

T R U N C A T IO N OF PRO DUCING

M O NTEREY SHALE

AND

CHERT

5 G ra vel and day. /C O O

b e lo n g S e a L e v e l

Cortmen ta>

a*

~ a r S& C1

H o r i z o n t a l s c a le m m ile s

j/4 500

M on t e r e y

10 00

«o 2000

C r e t a c e o u s (’> fr F ra n c isc a n

3000

V2

67 Several stee p re v e rs e f a u lts c lin a l stru ctu re.

com plicate

These f a u l t s a r e

and H ughes, 1949, p . The i n t e r n a l

t n i s s i m p l e homo-

shown o n F i g u r e 1 2 ( B e g a n

49). s tr u c t u r e o f the

b a se m e n t rocics i s n o t

P r o d u c i n g Z o n e s . - The p r o d u c i n g z o n e s i n d istrict

the S a n t a M aria

a r e s hown i n F i g u r e 11 ( R e g a n an d H u g h e s ,

T heir s t r a t i g r a p h i c r e l a t i o n s h i p

Known.

1949, p .

33).

t o t h e b a s e m e n t r o c ic s an d t h e

o v e r ly in g S isquoc f o rm a tio n i n the S an ta M aria V a lle y o i l f i e l d is

s hown i n F i g u r e 1 0 . The s t r u c t u r a l c o n t o u r map ( F i g u r e 1 2 )

show ing f r a c t u r e d

" K n o x v i l l e " s a n d s t o n e p r o d u c t i o n was c o m p i l e d r e c e n t l y by R e g a n and Hughes (1 9 4 9 , p . 4 9 ) . o i l accum ulations in

Some i n t e r e s t i n g r e l a t i o n s h i p s b e t w e e n

t h e b a s e m e n t r o c i c s and o i l a c c u m u l a t i o n s i n

t h e o v e r l y i n g r o c i c s a r e a p p a r e n t o n t h i s m ap . proven p ro d u c tiv e a re a i n the K noxville i s

For in s ta n c e ,

the

s i t u a t e d below th e

p r o d u c t i v e a r e a i n th e o v e r l y i n g r e s e r v o i r b e d s o f M iocene a g e . The o n l y e x c e p t i o n t o t n i s

statem en t is

one b a s e m e n t w e l l l o c a t e d

a few h u n d re d f e e t n o r t h o f t h e M iocene " p i n c h o u t " i n Sec.

13,

istics

T 1 0 S . , R35W,, 3 . B .

between th e

lith o lo g ic u n its m 23,

D ifferences m

t h e SE-J,

re se rv o ir ch aracter­

" f a v o r a b l e " s a n d s t o n e and " u n f a v o r a b l e " s h a l e the

T 1 0 S ., R 3 4 S ., 3.B .

b a s e m e n t a r e a p p a r e n t i n S e c t i o n s 22 a n d W ells p e n e t r a t i n g th e

s a n d s t o n e mem ber s

o f t h e K n o x v i l l e f o r m a t i o n a r e p r o d u c t i v e i n S e c t i o n 22 i n c o n t r a s t t o w e l l s p e n e t r a t i n g t h e s h a l e m em b er s i n S e c t i o n 2 3 . w e lls in both s e c tio n s a re lo c a te d

Basement

below p r o d u c t i v e a r e a s i n th e

o v e rly in g sedim ents hence d i f f e r e n c e s in p r o d u c t i v i t y a re alm o st c e r t a i n l y due to d i f f e r e n c e s

in lith o lo g y of

the basem ent rocics.

68

PRODUCING

I *Z0NE~ STAGE FORMATION Local Terminology

LOWER PLIOCENE

SERIES

ZONES

OF

^

0 -4 0 0 0 '

FRACTURED SHALE ZONES

I

MONTEREY B entonitic Brown

EAST

i

CAT CANYON

SANTA M A RIA VALLEY F IE L 0

i

a.

0 - 2500'

—

•

FOUR 0EER FIE LD

, C h e rt

Luiaian

■

Brown

QtL P O INT

SAL

0 -2 5 0 0 '

Oil Sand and S iltsto n e S h ell

FIE LD S

I

B u ff and Brown Dark

R e lizia n

i

WEST CAT CANYON

C hert

Mohnian

Lower Mehnian

FRACTURED SANDSTONE ZONES

i

.

Upper

DISTRICT

j

i LE MIOCENE

MARIA

SIS Q U O C

O0 UJ CL CL Z>

SANTA

OIL SAND ZONES (Local) !

Arenaceous

oo 2

THE

r

ORCUTT FIELD SANTA M A RIA VALLEY FIELD CASMALIA FIE LD

, Limey Shale

CASMALIA ORCUTT » CAT CANY ZACA CR

W -'

E. END SANTA MARIA VALLEY FIE L D

C A S M A LIA

L MIOCENE

LOSPE

TO 0 - 2600'

JURASSIC ?

UP EOCENE

N C E N TR A L PART SANTA M A R IA VALLEY FIE LD

KNO XVILLE

--- - — ---- ----------- - - ---- —

------—

-------------_ ---

FRANCISCAN

100 7.

CUMULATIVE PRODUCTION JAN. 1.1947 ALL ZONES 250,637.000 Bbls

F igure 11,

50 7. -

23 4 7. 0 R e g a n and H u g h e s ( 1 9 4 9 , p .

74 2 7.

1

33)

,2.4 7

SN A L E N O R T H

34