Pacific Outer Continental Shelf OCS Report

MMS 91-0087

Estimated Oil and Gas Reserves

Pacific Outer Continental Shelf

(as of December 31, 1990)

U.S. Department of the Interior

Minerals Management Service MMS Pacific OCS Region
OCS Report

Pacific Outer Continental Shelf MMS 91-0087

Estimated Oil and Gas Reserves

Pacific Outer Continental Shelf

(as of December 31, 1990)

by

Robert D. Edwards

Scott B. Sorensen

Harold E. Syms

Resource Evaluation Office

Additional copies may be obtained from:

U. S. Department of the Interior

Minerals Management Service

Pacific OCS Region

770 Paseo Camarillo

Camarillo, California 93010

Attn: Public Affairs

(805) 389-7520

U.S. Department of the Interior

Minerals Management Service Camarillo

Pacific OCS Region October 1991
ii

Contents 

Page

Abstract ............................................................... . iv

Introduction .............................................................. . 1

Definition of Resource and Reserve Terminology ................................. . 1

Methods Used for Estimating Reserves ........................................ . 6

Fields Reported ........................................................... . 6

Studies Conducted ........................................................ . 10

Field Size Distribution .................................................... . 10

Status of Field Development ................................................ . 10

Drilling History and Production Rates ........................................ . 10

Crude Oil Prices ................... .................................... . 15

Distribution of Reserves by Relative Age of Reservoir Rock ....................... . 15

Conclusions ............................................................. . 15

References Cited ......................................................... . 18

 

Figures 

1. MMS petroleum reserve classification ..................................... . 2

2. Wells determined to be producible in accordance with 30 CFR 250.11 ........... . 3

3. Pacific OCS MMS reserves classification procedure .......................... . 5

4. Recognized discoveries of federally controlled oil and gas fields 

in the Pacific OCS ..................................................... . 7

5. Annual estimates of remaining recoverable reserves from known fields .......... . 8

6. Annual estimates of original recoverable reserves from known fields ............ . 9

7. Size distribution of oil and gas fields ..................................... . 11

8. Annual drilled footage for wells in the Pacific OCS ......................... . 13

9. Annual production rates for the Pacific OCS .............................. . 14

10. Cumulative production for the Pacific OCS ................................ . 14

11. Average daily production rates for the Pacific OCS ......................... . 16

12. Average monthly crude oil price for the Pacific OCS ........................ . 16

13. Remaining reserves and estimated original recoverable reserves 

 (on a BOE basis) by reservoir age group ................................. . 17
iii

Tables

Page

1. Proved, unproved, and total oil and gas reserves, Pacific OCS, 

December 31, 1990 .................................................... . 8

2. Annual estimates of original recoverable reserves with source 

publication numbers .................................................. . 9

3. Changes in reported reserves and production, Pacific OCS, December 31, 1990 ... . 11

4. Secondary recovery methods used in Pacific OCS fields ...................... . 12

5. Summary of development well borehole status ............................. . 12

6. Annual and cumulative production for the Pacific OCS ...................... . 13

 

7. Geologic formations within each reservoir age group ........................ . 17

Abbreviations

ACT . . . Actively Drilling

API ... . American Petroleum Institute 

bbl ... . Barrel of Oil (42 gallons)

Bcf ... . Billion Cubic Feet of Gas

BOE . . . Barrels of Oil Equivalent 

CFR . . . Code of Federal Regulations

DPP . . . Development and Production 

 Plan PGW . . . Producing Gas Well 

F .... . Degrees Fahrenheit o

GIW . . . Gas Injection Well

GLO . . . Gas Lift Oil Well

GSI ... . Gas Well Shut-in

Mcf ... . Thousand Cubic Feet of Gas

MMcf . . Million Cubic Feet of Gas

Mbbl . . . Thousand Barrels of Oil

MMbbl . Million Barrels of Oil

 WSW . . Water Source Well 

MMS . . . Minerals Management Service

OCS . . . Outer Continental Shelf

OFR . . . Open File Report

OFSHR . Offshore

OSI ... . Oil Well Shut-in

PA .... . Plugged and Abandoned

POW . . . Producing Oil Well 

psia ... . Pounds per Square Inch 

 Absolute 

SPE . . . Society of Petroleum Engineers 

SUSP . . Suspended (includes temporarily

 abandoned and inactive 

 completions) 

WDW . . Water Disposal Well 

WIW . . . Water Injection Well 
iv

Estimated Oil and Gas Reserves

Pacific Outer Continental Shelf

(as of December 31, 1990) 

By Robert D. Edwards, Scott B. Sorensen, and Harold E. Syms

Abstract 

 Proved reserves of oil and gas in the Pacific Outer Continental Shelf (OCS), * **

offshore California, are estimated to be 923 million barrels of oil and 1,478 billion

cubic feet of gas as of December 31, 1990. These reserves are attributed to 13 fields. 

Original recoverable reserves from these fields are estimated to be 1,418 million

barrels of oil and 2,005 billion cubic feet of gas. 

 Unproved reserves of oil and gas in the Pacific OCS, offshore California, are

estimated to be 570 million barrels of oil and 679 billion cubic feet of gas as of

December 31, 1990. These reserves are attributed to 25 fields. Original recoverable

reserves from these 25 fields are the same as the remaining reserves because these

fields have not had any sustained production. 

 Of the 38 fields, reserve estimates for 31 fields were determined by individual

reservoir volumetric studies, while decline-curve and volumetric analyses were used

for the remaining seven. At the end of 1990, nine fields were producing.

-------------------

"Oil," as used in this report, includes crude oil and condensate. * 

 "Gas," as used in this report, includes associated and nonassociated dry gas. **
1

Introduction 

 This report, which supersedes OCS

Report MMS 90-0086 (Flynn and Searls,

1990), presents estimates of original

recoverable oil and gas reserves, cumulative production through 1990, and estimates of remaining reserves as of December 31, 1990, for the Pacific Outer Continental Shelf (OCS), offshore California. 

These estimates were completed in June

1991. The annual update of this report is

part of a Minerals Management Service

(MMS) continuing program to provide a

current inventory of oil and gas reserves

for the Pacific OCS. The estimates presented here were prepared by petroleum

engineers, geologists, geophysicists, and

other personnel from the MMS, Pacific

OCS Regional Office, Camarillo, California. 

Definition of Resource and

Reserve Terminology economic, marginally economic, and

 The MMS has standardized its definitions of resources (Estimates of Undiscovered Conventional Oil and Gas Resources

in the United States - A Part of the Nation's Energy Endowment, U.S. Geological Survey and Minerals Management

Service, 1989). The Society of Petroleum

Engineers (SPE) has also adopted a standardized set of reserve categories and

definitions (1987, p. 577- 578). The

definitions used within this report conform with both these sources. Figure 1

shows how resource and reserve definitions are related.

 

 Undiscovered Resources -- Resources

estimated from broad geologic knowledge

and theory, existing outside of known

fields or known accumulations are undiscovered resources. Undiscovered resources can exist in untested prospects on

unleased acreage, or on undrilled leased

acreage, or in known fields. In known

fields, undiscovered resources occur in

undiscovered pools that are controlled by

distinctly separate structural features or

stratigraphic conditions from the discovered resources (U.S. Geological Survey

and Minerals Management Service, 

1989). 

 Discovered Resources -- Once leased

acreage is drilled and is determined to

contain oil or gas under Code of Federal

Regulations (CFR) Title 30, Part 250,

Subpart A, Section 11, Determination of

Well Producibility (hereinafter referred to

as 30 CFR 250.11), the lease is considered

to have discovered resources. Discovered

resources are the equivalent of identified

resources as reported by Dolton and others (1981). Identified resources are resources whose location and quantity are

known or are estimated from specific geologic or engineering evidence and include

subeconomic components. Discovered resources can be further characterized as

unproved or proved reserves, depending

upon evidence of economic viability. The

number of wells determined to be producible in accordance with 30 CFR 250.11 is

shown in figure 2. 

 Unproved Reserves -- After a lease

qualifies under 30 CFR 250.11, the MMS

Field Naming Committee reviews the new

producible lease to assign it to an existing

field or, if the lease is not associated with

an established geologic structure, to a

new field. Regardless of where the lease

is assigned, the reserves associated with

the lease are initially considered to be

unproved reserves. Unproved reserves

are based on geologic or engineering

information similar to that used in estimates of proved reserves; but 
Undiscovered Resources Discovered Resources

Untested

Prospects

Known

Fields

Unproved Reserves

Possible Probable Undeveloped

Developed

Nonproducing Producing

Proved Reserves

Reserves

of

Nonproducing

Reservoirs

Reserves

of

Producing

Reservoirs

Economic

Recovera

Margina

Economic

Recovera

Uneconom

Increasing Geologic Assurance

Figure 1. MMS petroleum reserve classification (modified from USGS & MMS, 1989; and SPE, 19
68 70 72 74 76 78 80 82 84 86 88 90

0

2

4

6

8

10

Year

2

Figure 2. Wells determined to be producible in accordance with 30 CFR 250.11.

technical, contractual, economic, or regu- Unproved Probable Reserves -- "Unlatory uncertainties preclude such re- proved probable reserves are less certain

serves being classified as proved. than proved reserves and can be estimat-

 Unproved reserves may be divided into indicate they are more likely to be recovtwo subclassifications, possible and prob- ered than not" (SPE, 1987). Reserves in

able, which are similarly based on the fields for which a schedule leading to a

level of uncertainty. Development and Production Plan (DPP)

 Unproved Possible Reserves -- "Un- been classified as unproved probable. 

proved possible reserves are less certain

than unproved probable reserves and can Proved Reserves -- "Proved reserves

be estimated with a low degree of cer- can be estimated with reasonable certainty, which is insufficient to indicate tainty to be recoverable under current

whether they are more likely to be recov- economic conditions, such as prices and

ered than not. Reservoir characteristics costs prevailing at the time of the estiare such that a reasonable doubt exists mate. Proved reserves must either have

that the project will be commercial" facilities that are operational at the time

(SPE, 1987). After a lease qualifies under of the estimate to process and transport

30 CFR 250.11, the reserves associated those reserves to market or a commitwith the lease are initially classified as ment or reasonable expectation to install

unproved possible. such facilities in the future" (SPE, 1987). 

ed with a degree of certainty sufficient to

has been submitted to the MMS have
3

 Proved reserves can be subdivided into category includes reserves contained in

undeveloped and developed. nonproducing reservoirs, contained re-

 Proved Undeveloped Reserves -- Re- ting well workovers or transportation faserves are classified proved undeveloped cilities. A diagram of the reserves classiwhen a relatively large expenditure is re- fication procedure is shown in figure 3. 

quired to install production and/or transportation facilities, a commitment by the Total Reserves -- Total reserves are

operator is made, and a time frame to the sum of proved and unproved reserves. 

commence production is established. 

Proved undeveloped reserves are reserves Original Recoverable Reserves -- The

expected to be recovered from (1) yet amount of oil and gas expected to be

undrilled wells, (2) deepening existing recovered from the original oil in place or

wells, or (3) existing wells for which a the amount equal to the sum of cumularelatively large expenditure is required tive production and remaining reserves is

for recompletion. considered to be the original recoverable

 Proved Developed Reserves -- "Reserves that are expected to be recovered Production Data -- The measured volfrom existing wells (including reserves umes of gross hydrocarbons reported to

behind pipe) are classified as proved de- the MMS by Federal lessees and operaveloped reserves. Reserves are consid- tors. Oil and gas volume measurements

ered developed only after necessary pro- and reserves are corrected to reference

duction and transportation equipment standard conditions of 60 F and 14.73

have been installed or when the installa- psia. Continuously measured volumes

tion costs are relatively minor. Proved from production platforms or leases are

developed reserves are subcategorized as allocated to individual wells and reserproducing or non-producing" (SPE, 1987). voirs on the basis of periodic well tests. 

This distinction is made at the reservoir These procedures introduce approximalevel and not at the field level. tions in both production and reserves

 data by reservoirs and by fields.

 Proved Developed Producing Reserves

-- Once the first reservoir in a field begins

production, the reservoir is considered to

contain proved developed producing reserves, and the field is considered on production. If a reservoir had sustained production during the last year, it is considered to contain proved developed producing reserves. 

 

 Proved Developed Nonproducing Reserves -- Any developed reservoir in a developed field that has not produced or has

not had sustained production during the

past year is considered to contain proved

developed nonproducing reserves. This

serves behind-pipe, and reservoirs awaireserves. 

o
D

R

Proved

Undeveloped

Reserves

Unproved

Probable

Reserves

Unproved

Possible

Reserves

Untested Prospects (Leased Undrilled Acreage)

30 CFR 250.11 Operator Provides Schedule for DPP

Submittal

DPP

Approved

Production and

Transportation Equipment Installed

Increasing Geologic Assurance and Economic Certainty

Figure 3. Pacific OCS MMS reserves classification procedure.
5

Methods Used for Estimating

Reserves 

 

 Volumetric calculation -- For the volumetric calculation of reserves, the amount

of original oil and gas in place is

estimated from the bulk volume of the

reservoir as mapped using data from

boreholes and seismic profiles. Maps of

net oil and gas sand thicknesses are

drawn and measured with a planimeter,

and the results are converted to bulk

volume using the appropriate equations. 

Rock porosity and the amounts of water,

oil, and gas in the pore space are interpreted from well logs and core analyses. 

The estimated amount of original oil and

gas in place is converted to standard

conditions by analyses of pressure, volume, and temperature relationships and

by the use of standard correlations. The

amount of the original oil and gas in place

that can be recovered is estimated from

information about the reservoir

drive-mechanism, spacing of the wells,

analog field recovery factors, and API

recovery factor equations (Arps and others, 1967, p. 19-20). 

 Decline-curve analysis -- In the decline

curve analysis method, future production

is estimated by extrapolating plots of

production rates and fluid percentages

versus time. The ultimate production is

determined by adding past production to

predicted future production. 

Fields Reported 

 As of December 3l, l990, thirty-eight

fields in the Pacific OCS (figure 4) are

recognized as containing reserves under

the established criteria. Two of these

fields are gas fields, 27 are oil fields, and

9 are combination oil and gas fields. The

number of fields increased by one from

the previous report (Flynn and Searls,

1990), and this increase is due to the

initial evaluation of a field discovered in

1989. 

 Thirteen fields were determined to

have proved reserves of oil and/or gas. 

These 13 fields are San Miguel, Point

Pedernales, Point Arguello, Pescado,

Sacate, Hondo, Dos Cuadras, Pitas Point,

Carpinteria Offshore, Santa Clara, Sockeye, Hueneme, and Beta (figure 4, fields

2, 7, 11, 20, 21, 23, 29, 30, 31, 33, 34, 36,

and 38). The remaining 25 fields were

determined to have unproved reserves of

oil and/or gas.

 The current Pacific OCS total estimates for proved, unproved, and total

reserves of oil and gas are shown in table

1. The totals appear as aggregate numbers to protect the proprietary data used

to determine the estimates. Annual

estimates of remaining recoverable reserves from Pacific OCS fields are graphically shown in figure 5. Estimates of

original recoverable reserves for several

individual fields were refined as development drilling continued to delineate the

fields. Previous estimates of original

recoverable reserves are shown in table 2

by year and source publication. Annual

estimates of original recoverable reserves

from Pacific OCS fields are shown in

figure 6. Differences in reported reserves

and production from the previous report

(Flynn and Searls, 1990) are summarized

in table 3.
Figure 4. Recognized discoveries of federally controlled oil and gas fields in the Pacific OCS. (Da

geographical-mile boundary between State and Federal waters.)
76 78 80 82 84 86 88 90

0

500

1000

1500

2000

2500

Oil (MMbbl) Gas (Bcf)

Year

7

Table 1. Proved, unproved, and total oil and gas reserves for Pacific OCS, December 31, 1990.

Reserves of Reserves Production Production Reserves

Number Original Recoverable Cumulative Annual Remaining

Fields Oil Gas Oil Gas Oil Gas Oil Gas

 (MMbbl) (Bcf) (MMbbl) (Bcf) (MMbbl) (Bcf) (MMbbl) (Bcf)

Proved 13 1,418 2,005 494 528 30 50 923 1,478

Reserves

Unproved 25 570 679 0 0 0 0 570 679

Reserves

Total 38 1,988 2,684 494 528 30 50 1,493 2,157

Reserves

Figure 5. Annual estimates of remaining recoverable reserves from known fields.
76 78 80 82 84 86 88 90

0

500

1000

1500

2000

2500

3000

Oil (MMbbl) Gas (Bcf)

Year

8

Table 2. Annual estimates of original recoverable reserves with source publication numbers.

Original Recoverable Reserves

Year Publication Oil Gas

(MMbbl) (Bcf)

1976 OFR 78-387 829 1,530

1977 OFR 79-345 843 1,546

1978 OFR 80-477 875 1,665

1979 OFR 80-1042 920 1,845

1980 OFR 81-623 988 1,853

1981 OFR 82-37 1,082 1,847

1982 OFR 83-559 1,217 1,983

1983 OFR 84-0024 1,433 2,298

1984 MMS 85-0041 1,515 2,400

1985 MMS 86-0066 1,599 2,334

1986 MMS 87-0045 1,670 2,461

1987 MMS 88-0047 1,727 2,501

1988 MMS 89-0085 1,729 2,467

1989 MMS 90-0086 1,987 2,723

1990 MMS 91-0087 1,988 2,684

 Figure 6. Annual estimates of original recoverable reserves from known fields.
9

Studies Conducted

 Reserve estimates for seven of the producing fields were conducted from

volumetric calculations and declinecurve analyses: Hondo, Dos Cuadras,

Pitas Point, Carpinteria Offshore, Santa

Clara, Hueneme, and Beta (figure 4,

fields 23, 29, 30, 31, 33, 36, and 38).

 Individual reservoirs in each field were

grouped for volumetric calculations, while

decline-curve analyses were made on lease-by-lease and platform bases. The 31

remaining fields were studied on a reservoir-by-reservoir basis, and the reserve

estimates were determined solely by the

volumetric calculation method. 

Field Size Distribution

 Figure 7 shows the field size distribution based on current estimated original

recoverable reserves for 36 oil and gas 

fields and 2 gas fields. For convenience of 

comparison, gas reserves are expressed in There were 329 exploratory wells and

terms of barrels of oil equivalent on the 707 development wells spudded by yearbasis of equivalent heating values (5,620 end. For the first year since 1963, no excubic feet of gas has the approximate ploratory wells were drilled in the Pacific

heating value of one barrel of oil), herein- OCS. Table 5 shows the yearend summaafter referred to as BOE. ry of the borehole status for all developStatus of Field Development

 

 As of December 31, l990, five of the

fields in the Pacific OCS have completed

their primary drilling programs: Dos

Cuadras, Pitas Point, Carpinteria Offshore, Hueneme, and Beta (figure 4, fields

29, 30, 31, 36, and 38). Of the 38 recognized fields, nine were producing in December: Dos Cuadras, Pitas Point, Carpinteria Offshore, Santa Clara, Sockeye,

Hueneme, and Beta (figure 4, fields 7, 23,

29, 30, 31, 33, 34, 36, and 38). Additional

exploratory and delineation wells are anticipated in many of the remaining fields

to further define productive limits and

optimize oil and gas recovery.

 Five producing oil and gas fields in the

Pacific OCS are undergoing fluid injection: Hondo, Dos Cuadras, Santa Clara,

Hueneme, and Beta (figure 4, fields 23,

29, 33, 36, and 38). Recovery beyond primary production is occurring or can be

anticipated (table 4). One field, Hondo, is

undergoing gas injection for reservoir

pressure maintenance. One field, Dos

Cuadras, was undergoing polymer injection. Polymer injection at the field ceased

in August 1990. Five fields, Hondo,

Santa Clara, Dos Cuadras, Hueneme, and

Beta, are undergoing water injection. 

 

Drilling History and Production

Rates

ment wells. Drilled footage by year for all

wells in the Pacific OCS is displayed in

figure 8.

 Annual oil and gas production through

1990 is shown in table 6 and figure 9. 

Cumulative production through 1990 is

shown in table 6 and figure 10. Average

daily production rates for each month

during 1990 are shown in figure 11.
0

5

10

15

20

25

30

35

31

4

1 2

0 100 200 300 400

Original Recoverable Reserves

In Million Barrels of Oil Equivalent

10

Table 3. Changes in reported reserves and production, Pacific OCS, December 31, 1990.

 Production and Reserves Oil Gas

 (MMbbl) (Bcf)

Original Recoverable Reserves: 

Estimated as of 12/31/90 (MMS 91-0087) 1,988 2,684

Estimated as of 12/31/89 (MMS 90-0086) 1,987 2,723

Change +1 -39

Cumulative Production:

Through 1990 494 528

Through 1989 464 478

Proved Reserves:

Estimated as of 12/31/90 (MMS 91-0087) 923 1,478

Estimated as of 12/31/89 (MMS 90-0086) 951 1,515

Change -28 -37

Total Reserves:

Estimated as of 12/31/90 (MMS 91-0087) 1,493 2,157

Estimated as of 12/31/89 (MMS 90-0086) 1,523 2,246

Change -30 -89

Figure 7. Size distribution of oil and gas fields. 
11

Table 4. Secondary recovery methods used in Pacific OCS fields.

Field Type Polymer Flood Active Water Active Gas

Injection Injection

Oil Dos Cuadras Dos Cuadras

Beta

Hueneme

Oil & Gas Hondo Hondo

 Santa Clara

Table 5. Summary of development well borehole status.

Platform POW GLO PGW OSI GSI GIW WIW WDW WSW SUSP PA Total ACT

Name

A 42 0 0 5 0 0 2 1 0 0 15 65 0 

B 39 0 0 5 0 0 4 0 0 0 21 69 0 

C 22 0 0 1 0 0 5 0 0 0 0 28 0 

Edith 15 0 0 3 0 0 0 0 0 2 1 21 0 

Ellen 28 0 1 3 1 1 22 1 3 0 7 67 0 

Eureka 28 0 0 0 0 0 14 1 0 0 1 44 0 

Gail 11 2 0 1 0 0 0 0 0 0 0 14 0 

Gilda 39 0 2 2 3 0 14 0 0 2 6 68 0 

Gina 7 0 0 0 0 0 5 0 0 0 2 14 0 

Grace 0 17 0 4 3 0 0 0 0 3 7 34 0 

Habitat 1 0 14 0 2 0 0 0 0 3 1 21 0 

Harvest 0 0 0 8 0 0 0 0 0 11 0 19 0 

Henry 22 0 0 1 0 0 0 0 0 0 2 25 0 

Hermosa 0 0 0 11 0 0 0 0 0 1 0 12 0 

Hidalgo 0 0 0 6 0 0 0 0 0 1 0 7 0 

Hillhouse 16 25 0 4 0 0 1 0 0 0 4 50 0 

Hogan 6 9 0 16 0 2 0 3 0 0 14 50 0 

Hondo 11 11 0 2 0 2 1 1 0 0 9 37 0 

Houchin 14 9 0 9 0 0 0 0 0 1 10 43 0 

Irene 9 4 0 3 0 0 0 0 0 1 2 19 1 

Total 310 77 17 84 9 5 68 7 3 25 102 707 1 
62 64 66 68 70 72 74 76 78 80 82 84 86 88 90

0

200

400

600

800

Year

Total Wells

Development Wells

Exploratory Wells

12

Figure 8. Annual drilled footage for wells in the Pacific OCS.

Table 6. Annual and cumulative production for the Pacific OCS.

 

Year Annual Cumulative Annual Cumulative

Oil (bbl) Oil (bbl) Gas (Mcf) Gas (Mcf)

1968 2,076,160 2,076,160 1,237,180 1,237,180 

1969 9,942,733 12,018,893 6,016,485 7,253,665 

1970 25,035,171 37,054,064 13,757,148 21,010,813 

1971 31,103,681 68,157,745 17,853,055 38,863,868 

1972 22,562,566 90,720,311 12,546,915 51,410,783 

1973 18,818,026 109,538,337 9,157,714 60,568,497 

1974 16,784,100 126,322,437 7,234,937 67,803,434 

1975 15,434,507 141,756,944 5,978,959 73,782,393 

1976 13,977,436 155,734,380 5,533,258 79,315,651 

1977 12,258,013 167,992,393 5,366,181 84,681,832 

1978 11,979,674 179,972,067 5,193,985 89,875,817 

1979 10,971,013 190,943,080 5,430,689 95,306,506 

1980 10,118,614 201,061,694 5,771,792 101,078,298 

1981 19,619,670 220,681,364 12,769,110 113,847,408 

1982 28,471,665 249,153,029 17,814,958 131,662,366 

1983 30,558,866 279,711,895 23,923,258 155,585,624 

1984 30,500,506 310,212,401 45,912,435 201,498,059 

1985 29,673,649 339,886,050 63,523,094 265,021,153 

1986 28,779,936 368,665,986 57,989,035 323,010,188 

1987 31,284,618 399,950,604 54,874,298 377,884,486 

1988 31,529,776 431,480,380 49,132,759 427,017,245

1989 33,067,789 464,548,169 50,872,623 477,889,868

1990 29,885,271 494,310,184 49,950,216 527,796,524
68 70 72 74 76 78 80 82 84 86 88 90

1

10

100

Oil (MMbbl) Gas (Bcf)

Year

68 70 72 74 76 78 80 82 84 86 88 90

1

10

100

1000

Oil (MMbbl) Gas (Bcf)

Year

13

Figure 9. Annual production rates for the Pacific OCS. 

Figure 10. Cumulative production for the Pacific OCS.
14

Crude Oil Prices

 Figure 12 shows the price for Pacific

OCS crude oil (average 19 API) for each o

month during 1990. The price of West

Texas Intermediate crude oil (38 API) is o

shown for comparison. After a general

decline during the first six months of

1990, average crude oil prices rose to a

yearly high level of $26.41 per barrel in

October 1990. A total of 13 lessees sold

Pacific OCS crude oil during the year,

with the four largest firms accounting for

over 80% of all sales.

Distribution of Reserves by

Relative Age of Reservoir Rock 

 

 The reserves of the Pacific OCS can be

divided into three groups based on the

relative age of the reservoirs in which

they exist. The three age groups of reservoir rocks are (1) Pre-Monterey: rocks

older than the Monterey Formation (early

Miocene age and older), (2) Monterey:

rocks of the Monterey Formation (Miocene age), and (3) Post-Monterey: rocks

younger than the Monterey Formation

(late Miocene age and younger). 

 The distribution of remaining reserves

and estimated original recoverable reserves in BOE is illustrated in table 7 and

figure 13. 

Conclusions 

 As of December 3l, l990, the remaining

recoverable proved reserves in 13 known

oil and gas fields in the Pacific OCS are

estimated at 923 million barrels of oil and

1,478 billion cubic feet of gas. Remaining

recoverable unproved reserves in 25

known oil and gas fields in the Pacific

OCS are estimated to be 570 million barrels of oil and 679 billion cubic feet of gas. 

Nine oil and/or gas fields being produced

by 17 platforms have yielded 494 million

barrels of oil and 528 billion cubic feet of

gas since the first Pacific OCS platform

began production in 1968.
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

0

20

40

60

80

100

120

140

160

Oil (Mbbl) Gas (MMcf)

1990

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

$0

$10

$20

$30

$40

POCS Crude West Texas Crude

1990

15

Figure 11. Average daily production rates for the Pacific OCS. 

Figure 12. Average monthly crude oil price for the Pacific OCS.
Remaining Reserves Orig. Rec. Reserves

0%

25%

50%

75%

100%

Pre-Monterey

Monterey

Post-Monterey

10%

79%

11%

24%

67%

9%

16

Table 7. Geologic formations within each reservoir age group.

Reservoir Age Geologic Remaining Estimated Original

Group Formations Reserves Recoverable Reserves *

(MMbbl) (MMbbl)

*

Post-Monterey Pico, Puente, Repetto, Santa

Margarita, Sisquoc 185 586

Monterey Monterey 1,492 1,657

Point Sal, Vaqueros,

Pre-Monterey Topanga, Hueneme, Sespe/ 200 222

Alegria, Gaviota, Sacate,

 Camino Cielo, Jalama

 *Barrels of oil equivalent 

 Figure 13. Remaining reserves and estimated original recoverable reserves (on a BOE basis) by

reservoir age group.
17

References Cited

Arps, J. J., Brons, F., Van Everdingen, A. 

F., Buchwald, R. W., and Smith, A. E.,

l967, A Statistical Study of Recovery

Efficiency: American Petroleum Institute Bulletin D14, 33 p. 

Dolton, G. L., Carlson, K. H., Charpentier, R. R., Coury, A. B., Crovelli, R.

A., Frezon, S. E., Khan, A. S., Lister,

J. H., McMullin, R. H., Pike, R. S.,

Powers, R. B., Scott, E. W., and 

Varnes, K. L., 1981, Estimates of Undiscovered Recoverable Conventional

Resources of Oil and Gas in the United States: U.S. Geological Survey Circular 860, 87 p. 

Flynn, G. L., and Searls, A. W., 1990, 

Estimated Oil and Gas Reserves Pacific Outer Continental Shelf (as of

December 31, 1989): Minerals Management Service OCS Report, MMS 9-

0-0086, 16 p. (Superseded by this 

report.) 

Society of Petroleum Engineers (SPE), 

1987, Definitions for Oil and Gas Reserves: Journal of Petroleum Technology, May 1987, p. 577-578. 

U.S. Geological Survey, and Minerals 

Management Service, 1989, Estimates

of Undiscovered Conventional Oil and

Gas Resources in the United States -

A Part of the Nation's Energy Endowment, 44 p.
As the Nation’s principal conservation

agency, the Department of the Interior

has responsibility for most of our nationally owned public lands and natural

resources. This includes fostering the

wisest use of our land and water resources, protecting our fish and wildlife,

preserving the environmental and cultural values of our national parks and

historical places, and providing for the

enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works

to assure that their development is in the

best interest of all our people. The Department also has a major responsibility

for American Indian reservation communities and for people who live in Island

Territories under U.S. Administration.