. 725 

Geological Estimates of Undiscovered Recoverable 

Oil and Gas Resources in the United States 

GEOLOGICAL SURVEY CIRCULAR 725 

Prepared for the Federal Energy Administration 

Sununary -----------------------------------

Introduction --------------------------------- Acknowledgments _________ ---------------

Sources of data ----------------------------- Guidelines and concepts for resource appraisal --

Definitions of resource terms -------------

Commodities included in the resource 

appraisal estimates --------------------

Role of technology and economics in resource 

appraisal -----------------------------

Geologic framework ----------------------

Onshore United States ---------------

Offshore United States ---------------

Region and province locations and boundaries 

Sedimentary rock areas and volumes -------

Factors related to hydrocarbon occurrence and 

exploration _____ -- ________________ _ 

Characteristics of the habitat of hydrocarbons -----------------------

Trap types ---------------------- Methodology 

Introduction and review of basic resource 

appraisal methods ----------------------

Appraisal procedures for this report --------

General ----------------------------- Specific methodology used by the Resource 

Appraisal Group -------------------

CONTENTS 

1 

6 

6 

7 

8 

8 

9 

9 

10 

12 

14 

14 

16 

17 

17 

18 

18 

18 

20 

20 

20 

Methodology-Continued 

Appraisal procedures-Continued 

Methodology for processing probabilistic 

assessments of undiscovered hydrocarbon resources ---------------------- Summary of appraisal procedures ------

Methodology for estimating natural gas 

liquids resources _ ------------------

Methodology for estimating inferred reserves ---------------------------- Petroleum resources of the United States ------

Summary of results ---------------------

Results-Undiscovered recoverable oil 

and natural gas resources ----------

Results-Undiscovered recoverable IJatural gas liquids resources -·----------

Comparison of hydrocarbon resource estimates 

in the United States -------------------

Conclusions ---------------------------------

Selected references ---------------------------

Appendix ----------------------------------- Revised short form for resource appraisal f'-.,.d 

evaluation by geologic provinces ---------

Form 3, Province summary sheet --------

Forms 4-A and 4-B, Resource appraisalprovince estimate ----------------------

Estimates of Inferred + Indicated Reser·res 

for the United States by States, by R. F. 

Mast and Janet Dingler -----------------

ILLUSTRA'TION.S 

22 

25 

25 

25 

26 

26 

26 

45 

45 

48 

49 

54 

54 

69 

70 

73 

FIGURE 1. Undiscovered recoverable resources of crude oil and natural gas for the United States----------- 3 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

Diagrammatic representation of petroleum resource classification by the U.S. Geological Sur"rey 

and U.S. Bureau of Mines ---------------------------------------------------------- 8 

Tectonic map of North America showing generalized structural elements --------------------- 10 

Index map of North America showing the boundaries of the 15 regions, onshore and offshore, 

covered in this report --------------------------------------------------------------- 11 

Index map of conterminous Lower 48 United States showing the regional boundaries ---------- 15 

Index map of Alaska showing the boundaries of the major onshore and offshore petroleum 

provinces -------------------------------------------------------------------------- 16 

Map of the United States showing the oil and gas fields and the regional boundaries ---------- 19 

Probability distributions by Monte Carlo analysis on undiscovered recoverable resources for 

Alaska: Aggregate probability distributions for three onshore subregions and the trt.al 

Alaska onshore -------------------------------------------------------------------- 24 

Cumulative production and demonstrated reserves of oil and natural gas by regions for the C'lnterminous United States, onshore and offshore to 200 metres------------------------------ 32 

Cumulative production and demonstrated reserves of oil and natural gas by regions for Alae·ka, 

onshore and offshore to 200 metres --------------------------------------------------- 32 

Undiscovered recoverable resources of oil and natural gas by regions for the conterminous United 

States, onshore and offshore to 200 metres---------------------------------------------- 33 

III 
FIGURE 12. Undiscovered recoverable resources of oil and natural gas for Alaska, onshore and offs·hore to 200 

metres ---------------------------------------------------------------------------- 33 

13. Diagrammatic representation of estimated crude oil resources using the U.S. Geological Survey's 

resource classification system. Cumulative oil production is cited below the figure; --------- 34 

14. Diagrammatic representation of estimated natural gas resources using the U.S. Geohgical Survey's resource classification system. Cumulative gas production is cited below the figure ---- 34 

15-20. Lognormal probability distributions of the Undiscovered Recoverable Oil Resources fo ... onshore: 

15. Region 1. Alaska; Region 2., Pacific Coastal States ------------------------------ 36 

16. Region 3. Western Rocky Mountains; Region 4., Northern Rocky MountainS' --------- 36 

17. Region 5. West Texas and Eastern New Mexico; Region 6., Western Gulf B~in ------ 37 

18. Region 7. Mid-continent; Region 8., Michigan Basin ------------------------------ 37 

19. Region 9. Eastern Interior; Region 10., Appalachians ---------------------------- 38 

20. Region 11. Eastern Gulf and Atlantic Coastal Plain ------------------------------- 38 

21, 22. Lognormal probability distributions of the Undiscovered Recoverable Oil Resources fa offshore: 

21. Region lA. Alaska (0-200 m); Region 2A., Pacific Coastal States (0-200 rn) -------- 38 

22. Region 6A. Gulf of Mexico ( 0-200 m) ; Region llA., Atlantic Coa~tal States 

(0-200 m) ---------------------------------------------------------------- 39 

23-28. Lognormal probability distributions of the Undiscovered Recoverable Gas Resources for onshore: 

23. Region 1. Alaska; Region 2., Pacific Coastal States ------------------------------ 39 

24. Region 3. Western Rocky Mountains; Region 4., Northern Rocky Mountains --------- 40 

25. Region 5. West Texas and Eastern New Mexico; Region 6., Western Gulf Pq,sin ----- 40 

26. Region 7. Mid-continent; Region 8., Michigan Basin ----------------------------- 41 

27. Region 9. Eastern Interior; Region 10., Appalachians ---------------------------- 41 

28. Region 11. Eastern Gulf and Atlantic Coastal Plain ------------------------------ 42 

29, 30. Lognormal probability distributions of the Undiscovered Recoverable Gas Resources for offshore,: 

29. Region lA. Alaska (0-200 m); Region 2A., Pacific Coastal States (0-200 I"') ------- 42 

30. Region 6A. Gulf of Mexico (0-200 m); Region llA., Atlantic Coastal States 

(0-200 m) ---------------------------------------------------------------- 42 

31-33. Lognormal probability distributions of the Undiscovered Recoverable Oil Resources for: 

31. Onshore and offshore:Total Lower 48 onshore and total Lower 48 offshore (0-200 m) 43 

32. Onshore and offshore:Total onshore United States (Lower 48 and Alaska) and total 

offshore United States (Lower 48 and Alaska, 0-200 m) ---------------------- 43 

33. Total United States, onshore and offshore (0-200 m) ------------------------------ 44 

34-36. Lognormal probability distributions of the Undiscovered Recoverable Gas Resources for: 

34. Total Lower 48 onshore and total Lower 48 offshore (0-200 m) -------------------- 44 

35. Total onshore United States (Lower 48 and Alaska) and the total offsh'lre United 

States (Lower 48 and Alaska, 0-200 m) ------------------------------------- 44 

36. Total United States, onshore and offshore (0-200 m) ------------------------------ 44 

37. Comparative estimates of oil resources in the United States --------------------------------- 46 

38. Comparative estimates of natural gas resources in the United States ------------------------- 47 

39. Correlation of production and reserve terminology ________________________________ ...... ________ 73 

'TABLES 

TABLE 1. Production, reserves, and undiscovered recoverable resources of crude oil, natural gas, and natural 

gas liquids for the United States (December 31, 1974). (Onshore and offshore to ,~Tater depth 

of 200 metres) -------------------------------------------------------------------- 1 

2. Major stratigraphic and time divisions (modified from Geologic Names Committee, U.S. Geological Survey, 1972) ------------------------------------------------------------------ 13 

3. Sedimentary rock area and volume by regions ____ -------------------------------------- 17 

4. Production, reserves, and undiscovered recoverable oil resources for the United States, December 

31, 1974 (billion barrels) ------------------------------------------------------------ 28 

5. Production, reserves, and undiscovered recoverable gas resources for the United StateS". December 

31, 1974 (trillion cubic feet) -------------------------------------------------------- 30 

6. Estimates of undiscovered recoverable resources for natural gas liquids in the United States ___ 45 

7. Estimated Inferred + Indicated Reserves of crude oil for the United States througl. December 

31, 1972. In thousands of barrels;! derived by application of Hubbert's Correction Factors to 

Ultimate Recovery for each State --------------------------------------------------- 74 

8. Estimated Inferred + Indicated Reserves of natural gas for the United States through December 

31, 1972. In millions of cubic feet; derived by applicationofHubbert's Correctior Factors to 

Ultimate Recovery for each State --------------------------------------------------- 76 

IV 
Geological Estimates of Undiscovered 

Recoverable Oil and Gas Resources in the United States 

By Betty M. Miller, Harry L. Thomsen, Gordon L. Dolton, 

Anny B. Coury, Thomas A. Hendricks, Frances E. Lennartz, 

Richard B. Powers, Edward G. Sable, and Katharine L. Varnes 

SUMMARY 

The estimates in this report of undiscovered 

recoverable oil and gas resources for the United 

States were made: (1) by carefully reviewing 

a large amount of geological and geophysical 

information gathered on more than 100 different provinces by over 70 specialists within the 

Survey; (2) by applying a variety of resource 

appraisal techniques to each potential petroleum province; and ( 3) through group appraisals and the application of subjective probability procedures. These methods provide a 

range of estimates which are summarized in 

terms of low, high, and mean values for the 

various provinces and groups of provinces, or 

regions. The basic data and procedures used 

are documented and are being incorporated 

into a dynamic, data-intensive system that can 

be upgraded, updated, and reevaluated periodically. These data are open to public inspection. 

In this study, the primary emphasis was 

placed on crude oil and natural gas in the onshore provinces and the provinces on the continental shelf out to water depths of 200 

metres; estimates of natural gas liquids were 

derived independently by multiplying estimates 

of natural gas by factors determined from historical data. Excluded from consideration were 

oil shales, tar sands, and heavy hydrocarbons 

and tight gas sands not currently productive. 

Also excluded was offshore potential beyond 

200 metres of water depth. All of these resources or areas for resource development have 

significant future potential measured in tens or 

hundreds of billions of barrels. Time did not 

permit assessment of their recoverability as a 

part of this study, but they will be the subject 

of accelerated study in the immediate future. 

The estimates of undiscovered recoverable resources take into account relevant past history 

1 

and experience and are based on assun1ptions 

that undiscovered recoverable resources will be 

found in the future under conditions represented by a continuation of price-cost rr1ation-

. ships and technological trends generally prevailing in the recent years prior to 197 4. Pricecost relationships since 197 4 were not taken 

into account because of the yet undeter·mined 

effect these may have on resource estimates. 

Clearly a new pattern of exploration economics 

is now under development, and, in cooperation 

with the Bureau of Mines, work to determine 

the effect of this new pattern on discovery and 

recovery of oil and gas is beginning. As8·uming 

an increase in price-cost ratio, undisc1vered 

recoverable resource estimates will expard and, 

at some threshold level, recovery percE:ntages 

on discovered petroleum !may improve. The 

higher price-cost ratios existing in 1~75, if 

they should continue or increase even higher, · 

would likely increase estimates of both undiscovered recoverable resources and reserves significantly-some economists think perhap·s by 

half .again. This possible added potential is 

being considered in a follow-on study planned 

for completion within a year. 

The terms used to categorize past, present, 

and future supplies of oil and gas essentially 

correspond to definitions jointly adopted by the 

U.S. Geological Survey and the Bureau of 

Mines in April 1974; however, specific terminology for oil and gas reporting has not yet 

been standardized. In the present study, the 

following are reported as separate quartities; 

cumulative production; measured, ind~~ated, 

and inferred reserves (all of which fall into 

the identified category); and undiscover~d recoverable resources. The category inferr~d reserves has been included by some estimators as 

part of the undiscovered resources. 

In considering these quantities it is impor-
tant to distinguish between reserves and undiscovered recoverable resources. Reserves are 

identified resources known to be recoverable 

with current technology under present economic conditions. Undiscovered recoverable resources include deposits that are yet to be discovered but are assumed to be economically 

producible. Resources also include deposits that 

have been identified, but cannot now be extracted because of economic or technological 

factors as well as subeconomic deposits that 

are yet to be discovered. 

Table 1 summarizes for the conterminous ~ - - --

u.s. and Alaska, both onshore ;:t~d <>_ffshore, t_he 

current estimates of measured, indicated, and 

inferred reserves and the undiscovered recoverable resources of crude oil, natural gas, and 

natural gas liquids. Cumulative production is 

also shown. The measured and indicated reserves are derived from estimates prepared by 

the American Petroleum Institute (API) and 

the American Gas As.sociation (AGA). The inferred reserves are identified as to field location but have not yet been defined by drilling. 

The undiscovered recoverable resources are reported as a range of values derived by computer analysis of lognormal distribution curves. 

Within the probability levels of 95 percent and 

5 percent, the range of total undiscovered recoverable oil resources is 50 to 127 billion barrels. The range of undiscovered recoverable gas 

is 322 to 655 trillion cubic feet, and the range of 

undiscovered recoverable natural gas liquids is 

11 to 22 billion barrels. Smaller and larger 

volumes, respectively, would be associated with 

probabilities of more than 95 percent and less 

than 5 percent. The regional probability curves 

included with this report show the magnitude 

of est'im·ates for any selected range. For totally 

unexplored frontier areas, the absence of 

already discovered indigenous or adjacent recoverable hydrocarbons render uncertainty 

sufficiently great to weaken probability j udgments at ·either high or low levels, and in those 

areas e·stimates at the 75 and 25 percent levels 

are shown as more ap·pJic.able for some planning 

purposes. 

The disgj~uti~n_b_X_j~gions of the estimated 

undiscovered recoverable resources of-crude oil 

and natural gas is shown as a range of values 

in figure 1. 

2 

The user of these data should be aware that 

the forecasts recorded for measrred, indicated, 

and inferred reserves are singlo.-number estimates of these quantities, derived from API 

and AGA statistics. By contrasL undiscovered 

recoverable resources are treated here as uncertain quantities, the degree of uncertainty 

about each being expressed in the form of 

probabilities. . 

For planning purposes, it is desirable to report 

probabilities for total recoverable resources; 

e.g., the probability that total 1·ecoverable resources are less than a given number or lie 

between two numbers. An intuitively plausible 

approximation, given that only single number 

estimates for measured, indicated, and inferred 

reserves are available, is to add these estimates 

(in this case, 62 billion barrels of oil) to the 

end points of an interval of v~lues of undiscovered recoverable resources (in this case, 

50-127 billion barrels of oil) and then assert 

that the probability assigned to this interval 

for undiscovered recoverable res·1urces is equal 

to the probability that total r~coverable resources lie in the interval so trarQlated. This is 

correct only under the assumption that measured, indicated, and inferred reserves are 

known with certainty and have 1Jalues equal to 

the single-numbe1· estimates cit~d. Given this 

assumption, the probability that the remaining 

total recoverable resources of cr1de oil lie between 112 billion barrels and 189 billion barrels 

is 90 percent. At the 1974 level of domestic 

production of 3.04 billion barrels, this is equivalent to ·a 37 to 62 year production life. Current 

production makes up only about two thirds of 

crude oil consumption. 

Performing a similar computation using the 

sum of single-number estimateE of measured 

r~erves of natural gas and of inferred reserves 

_Qf_natural gas (in this case, 39£ trillion cubic 

feet of gas) and adding this single-number 

estimate to the end points of a range of values 

of undiscovered recoverable resources (in this 

case, 322-655 trillion cubic fee1 of gas), the 

probability that the remaining total recoverable 

resources of natural gas lie in the range of 721 

trillion cubic feet to 1,054 trillion cubic feet is 

also 90 percent. At the 1974 prod·1ction level of 

21.3 trillion cubic feet, this is equivalent to a 

36 to 51 year production life. 
ESTIMATED RANGE OF 

UNDISCOVERED RECOVERABLE RESOURCES 

CRUDE OIL AND NATURAL GAS** 

(Alaska Onshore and Offshore) 

* 2-19 

~ 

~. '""-· aee tJMil' 

Undiscovered Recoverable Oil 12-4 9 Billion Barrels 

Undiscovered Recoverable Gas l~ crllJ~ Trillion Cu Ft 

(Conterminous U.S. Onshore and Offshore) 

Undiscovered Recoverable Oil 36-81 Billion Barrels 

Undiscovered Recoverable Gas l§~ .. 5)~~ Trillion Cu Ft 

* Marginal Probability Applied * * For regional distribution of inferred reserves. see tables 4 and 15. 

FIGURE !.-Undiscovered recoverable resources of crude oil and natural gas for the United States. Report~ as a 

range of values at 95-5 percent probability in billions of barrels for oil and trillions of cubic feet for gas. 

1 Estimates reported at the 75 and 25 percent probability levels because, in these frontier areas, these levels are judged to be more applicable for some planning purposes. It can a:lso be noted that in frontier areas, lacking discovered indigenous or adjacent rePoverable 

hydrocarbons, uncertainty is sufficiently great as to weaken probability estimates at extreme ranges. For purposes of comparison with other 

recorded ranges, the 95-5 percent probability range in the Bering Sea is 0-8 billion barrels of oil and 0-18 trillion cubic feet of ga~; in the 

offshore Atlantic it is 0-6 biUion barrels of oil and o--22 trillion cubic feet of gas. 

3 
.c::a. 

TABLE !.-Production, 'reserves, and undiscovered recoverable resources of crude oil, natural gas, and natural gas Uquids 

for the United States, December 31, 1974 (onshore and offshore to water depth of 200 metres) 

Area 

Lower 48 Onshore-----------

Alaska Onshore-------------

Total Onshore------------

Lower 48 Offshore----------

Alaska Offshore------------

Total Offshore-----------

Total Onshore 

and Offshore-------------

Lower 48 Onshore-----------

Alaska Onshore-------------

Total Onshore------------

Lower 48 Offshore----------

Alaska Offshore------------

Total Offshore-----------

Total Onshore 

and Offshore-------------

Reserves 

Cumulative Demonstrated j 

Production MeasuredLj Indicatedjj Inferred4 

99.892 

0.154 

100.046 

5.634 

0.456 

6.090 

106.136 

Crude Oil 

(billions of barrels) 

21.086 4.315 

9.944 0.013 

31.030 4.328 

3.070 0.308 

0.150 Negligible 

3.220 0.308 

34.250 4.636 

Natural Gasl 

(Trillions of cubic feet) 

446.366 

0.482 

446.848 

33.553 

0.423 

33.976 

480.824 

169.454 

31.722 

201.176 

35.811 Not 

0.145 Applicable 

35.956 

237.132 

Natural Gas Liquids 

(billions of barrels) 

14.3 

6.1 

20.4 

2.6 

0.1 

2.7 

23.1 

119.4 

14.7 

134.1 

67.4 

0.1 

67.5 

201.6 

Undiscovered 

Recoverable 

Resources 

Range5,6 

(95%-5%) 

~9 - 64 

6 - 19 

36 - 81 

5 - 18 

3 - 31 

10 - 49 

50 - 127 

246 - 453 

16 - 57 

264 - 506 

26 - 111 

8 - 80 

42 - 181 

322 - 655 

Total Onshore and Offshore 15.730 7 11- 22 
en 

2 

3 

4 

5 

Cumulative production and estimates of reserves and resources reflect an assumed recovery of 

about 32 percent of the oil and 80 percent of the gas-in-place. Some portion of the remaining 

oil-in-place is recoverable through application of improved recovery techniques. Estimates 

are based on figures released by the American Petroleum Institute (API) and the American Gas 

Association (AGA) in April 1975. 

Identified resources that can be economically extracted with existing technology. Estimates 

are the "proved reserves" of the API and AGA. 

Identified resources, economically recoverable if known fluid injection technology is applied. 

Estimates are from the API. 

Resources estimated to be recoverable in the future as a result of extensions, revisions of 

estimates, and new pays in known fields beyond those shown in indicated reserves. 

The low value of the range is the quantity associated with a 95 percent probability (19 in 20 

chance) that there is at least this amount. The high value is the quantity with a 5 percent 

probability (1 in 20 chance) that there is at least this amount. Totals for the low and high 

values are not obtained by arithmetic summation; they are derived by statistical methods. 

6 The reader is cautioned against averaging ranges. Statistical mean values are shown in 

tables 4 and 5. 

7 

The calculated estimates of undiscovered recoverable resources are derived from natural gas 

estimates by applying historical NGL/Natural Gas ratios. These figures suggest that if 

added to crude oil estimates, natural sas liquids would increase the estimates of petroleum 

liquids by approximately 20 percent. 
INTRODUCTION 

In September 197 4 the Resource Appraisal 

Group of the Branch of Oil and Gas Resources, 

U.S. Geological Survey, was asked to aid the 

Federal Energy Administration (FEA) in its 

legal responsibility to generate by June 1975 an 

independent appraisal of the undiscovered oil 

and gas resources of the United States, both 

onshore and offshore. Under the leadership of 

Harry Thomsen, the Resource Appraisal Group 

accelerated its ongoing efforts to develop sound 

appraisal methods and procedures that would 

permit the systematic collection and evaluation of basic data from petroleum provinces 

throughout the Nation. The results are summarized in this report. 

Great uncertainties are inherent in estimating undiscovered quantities of oil and gas. The 

estimates in this report are derived from j udgments based on a variety of geologic data, 

records of exploration successes and failures, 

production histories, assumptions concerning 

economic and technological conditions, and 

several appraisal m~ethods. Because of the subjective variability in all these factors, estimates 

by various experts may differ considerably even 

when they have access to the sam,e general information. A follow-on phase of this work is 

now being started to quantify the economic and 

technological conditions that affect resource 

appraisal and to integrate this understanding 

with the oil and gas potential of individual 

provinces. 

ACKNOWLEDGMENTS 

As a result of the urgency imposed by the 

legislative charge of the FEA, the Resource 

Appraisal Group obtained the assistance of 

other geologists in the U.S. Geological Survey 

who have broad experience and expertise in 

the particular areas of the United States which 

are either productive or potential future petroleum provinces. Significant contributions were 

made by over 7 0 geologists from the Branch 

of Oil and Gas Resources, the Branch of Alaskan Geology, the Branch of Pacific-Arctic 

Marine Geology, the Branch of Atlantic-Gulf 

of Mexico Marine Geology, and the Conservation Division. 

6 

PRINCIPAL CONTRIBUTORS 

Geologic Division 

Branch of Alaskan Geology, G. Gryc, Chief 

Menlo Park, Califot·nia 

D. F. Barnes 

E. E. Brabb 

W. P. Brosge 

M. Churkin, Jr. 

R. L. Detterman 

G. D. Eberlein 

A. A. Grantz 

J. M. Hoare 

W. W. Patton, Jr. 

G. Plafker 

I. L. Tailleur 

Branch of Pacific-Arctic Marine Geology, D. W. Scholl, 

Chief 

Menlo Park, Califm"nia 

A. K. Cooper 

H. G. Greene 

D. M. Hopkins 

M.S. Marlow 

D. S. McCulloch 

J. E. Schoellhamer 

P. D. Snavely, Jr. 

J. G. Vedder 

H. C. ~Nagner 

Reston, Virginia 

R. E. von Huene 

Seattle, Washington 

R. J. Lantz 

B1·anch of Atlantic-Gulf of Mexico Marine Geology, 

J. C. Behrendt, Chief 

Co'rpus Ch1·isti, Texas 

R. G. Martin, Jr. 

Branch of Oil and Gas Resources, P.R. RC'q,e, Chief 

Menlo Park, Califm·nia 

K. J. Bird 

T. R. Bruns 

R. D. Carter 

H. E. Cook 

L. B. Magoon 

H. McLean 

E. W. Scott 

J. C. Taylor 

Denver, Colorado 

T. D. Fouch 

F. B. Loomis 

W. W. Mallory 

E. K. Maughan 

E. A. Merewether 

D. D. Rice 

R. T. Ryder 

C. A. Sandberg 

C. W. Spencer 
Reston, Virginia 

W. deWitt, Jr. 

R. Q. Foote 

0. Girard 

R. E. Mattick 

W. J. Perry, Jr. 

E. C. Rhodehamel 

D. J. Taylor 

Little Rock, Arkansas 

E. E. Glick 

Conservation Division, R. L. Rioux, Assistant Chief 

Metairie, Louisiana 

J. Courtney Reed 

A. S. Khan 

Reston, Virginia 

G. W. Horton 

CONSULTANTS 

Branch of Alaskan Geology 

Menlo Park, California 

Helen L. Foster 

Fairbanks, Alaska 

Florence C. Weber 

Branch of Pacific-Arctic Marine Geology 

Menlo Park, California 

D. M. Hopkins 

Seattle, Washington 

T. H. McCulloh 

Branch of Oil and Gas Resources 

Reston, Virginia 

K. L. Core 

S. E. Frezon 

Office of Scientific Publicatiom 

Reston, Virginia 

D. M. Kinney 

Technical Reports Unit 

Denver, Colorado 

Ann C. Christiansen 

Conservation Division 

Metairie, Louisiana 

F. T. Bryan 

Wing Gee 

L. G. Hammons 

J. E. Hewitt 

H. McAndrews 

J. R. Pearcy 

The clerical and technical ~staff of the Resource App·raisal Group and the U.S. Geological 

Survey provided us with excellent support in 

the preparation of this report. To them, we 

express our thanks and appreciation for their 

hard work and their many hours of labor. 

7 

In addition to those listed above, w~ are indebted to G. M. Kaufman, Professor of Operations Research and Management, Massachusetts Institute o.f Technology, for his advice 

and assistance in developing methods of handling subjective probability estimates made by 

the Resource Appraisal Group, and to J. R. 

Century, consultant, for his assistance in the 

preparation of maps showing well cortrol, oil 

and gas fields, and regional geology for many 

of the producing provinces in the Lower 48 

States. We are grateful to V. E. McKelvey, 

R. P. Sheldon, and C. D. Masters for their 

critical reviews of the manuscript and for their 

helpful suggestions. Finally, we wish to express 

our sincere appreciation to P. R. Rose for his 

guidance and wholehearted support. 

SOURCES OF DATA 

Data were obtained through thre:~ main 

sources: verbal and written contributions from 

over 70 geologists from various divisions and 

branches of the U.S. Geological Survf.~'; pubHshed references consisting of geological information, exploration and production history 

data and maps; and unpublished U.S. Geological Survey materials. 

Published sources of production and reserve 

data are listed in the "Selected References" at 

the end of this report. Chief among t1' ese are 

the American Petroleum Institute-American 

Gas Association-Canadian Petroleum Association annual reports on reserves and production 

through 197 4. Also used were pub] ications 

of the American Petroleum Institu~, Independent Petroleum Association of North 

America, International Oil Scouts Association, Potential Gas Committee, ·and States of 

Alaska and California. Only major data sources 

on regional geology and map mater~als are 

listed in the references to provide an insight 

into the materials studied and used. Numerous 

published geologic reports and mapr which 

were used in this study are not cited because 

of their great number. They were, never·theles·s, 

important and key contributions to the understanding of the geology of specific ar~.as. 

Basin evaluation maps were generated 

from the Petroleum Information Corporation's Well History Control System (computerized data banks) for many of the 

producing provinces of the lower 48 
PETROLEUM RESOURCES OF THE UNITED STATES 

ICENTFIED 

Demonstrated UNDISCOVERED 

t ~~~ 0 

I 

"[ ~----_.--------------------~------------~~ ~ degree of geologic assurcn::e 

FIGUiu1 2.-Diagrammatic representation of petroleum resource classification by the U.S. Geologic""l Survey and 

the U.S. Bureau of Mines (modified from McKelvey, 1973). 

States. These maps, showing well density, oil 

and gas fields, and productive or tested stratigraphic units, provided background m.aterials 

for province appraisals. Cumulative production 

data for several provinces were derived from 

the U.S. Geological Survey Oil and Gas Pool 

computer data bank at Norman, Oklahoma. 

GUIDELINES AND CONCEPTS FOR 

RESOURCE APPRAISAL 

DEFINITIONS OF RESOURCE TERMS 

The following list defines the terms used in 

figure 2 and in this study. Some are modified 

from. published definitions (McKelvey, 1973, 

1974a, 1974b) to apply specifically to the commodities oil, natural gas, and natural gas 

liquids. In this study, price-cost relationships 

and technological trends generally prevailing 

in the recent years prior to 1974 are assumed. 

Resources.-Concentrations of naturally occurring solid, liquid, or gaseous materials in or 

on the Earth's crust in such form that economic extraction of a commodity is currently 

or potentially feasible. 

Economic resources.-Those resources, both 

identified and undiscovered, which are estimated to be economically recoverable. 

8 

Subeconomic resources.-Identified and undiscovered resources that ~are not presently recoverable because of technologi ~al and economic factors but which may be recoverable in 

the future. 

Identified resources.-Specitic accumulations 

of economic resources whose locr.tion, quality, 

and quantity are estimated from geologic evidence supported in part by engineering measurements. 

Identified sub economic resources.-Known 

resources that may become recovr"."able as a result of changes in technological and economic 

conditions. 

Undiscovered resources.-QuaJJtities of aresource estimated to exist outside of known 

fields on the basis of broad geolorric knowledge 

rand theory. 

Undiscovered recoverable resources.-Those 

economic resources, yet undiscc vered, which 

are estimated to exist in favorable geologic 

settings. 

Reserves.-That portion of the identified resource which can be economically extracted. 

Measured reserves.-That part of the identified resource which can be eco:'lomically ex-
tracted using existing technology, and whose 

amount is estimated from geologic evidence 

supported directly by engineering measurements. In this study, they are considered to be 

equivalent to API and AGA proved reserves. 

Indicated reserves.-Reserves that include 

additional recoveries in known reservoirs (in 

excess of the measured reserves) which engineering knowledge and judgment indicate will 

be economically available by application of 

fluid injection, whether or not such a program 

is currently installed (API, 1974). In this 

study indicated reserves are equivalent to API 

indicated additional rese1·ves. 

Demonstrated reserves.-A collective term 

for the sum of measured and indicated reserves. 

Inferred reserves.-Reserves in addition to 

demonstrated reserves eventually to be added 

to known fields through extensions, revisions, 

and new pays. (See Appendix for explanation 

of derivation of inferred reserves quantities 

used in this study.) 

Cumulative production.-The sum of the production for the current year and the actual 

production for each of the prior years. 

COMMODITIES INCLUDED IN THE RESOURCE 

APPRAISAL ESTIMATES 

Commodities included in this apprai·sal are 

crude oil, natural gas, and natural gas liquids 

(NGL). Crude (unrefined) oil is a natural mixture of hydrocarbons occurring underground 

in a liquid state in porous-rock reservoirs and 

remaining in a liquid state as it flows from a 

well at atmospheric pressure. N·atural gas is a 

mixture of hydrocarbons occurring as: a ''gas 

cap" in contact with and above an oil deposit 

within a reservoir; dissolved in solution with 

the crude oil within the reservoir; or as dry 

gas that is not associated with or in contact 

with crude oil within a reservoir. The American 

Gas Association (1974) defines natural gas 

liquids as those hydrocarbons occurring within 

the natural gas in a res.ervoir which are separated from the natural gas as liquids at the 

surface through the proces·s of condensation, 

absorption or adsorption, or other methods in 

field :separators, scrubbers, gas proces1sing 

plants, and cycling plants. 

9 

In 197 4, the United States natural g.~.s liquids production was 24 percent that of crude 

oil, ·and NGL proved (measured) reserve~ were 

19 percent of those of oil reserves. 

The following commodities were not in~luded 

or were included only in part in this report: 

Heavy oils.-Oils whose specific gravity and 

viscosity (fluidity) are too low for economic 

extraction by conventional primary and secondary production methods. These r~·ources 

are included with reserves of crude oil ir. areas 

that 1are currently producing but are excluded 

in areas that are not developed or are abandoned. 

Tight gas sands.-Gas resources in tight 

sands are included in areas that are currently 

producing and are excluded in areas r'lt developed or abandoned. 

Oil shale.-Resources of this commodity are 

not included in this ·appraisal. 

Tar sands.-Resources of tar sands r.re not 

included in this appraisal. 

Gas occluded in coal.-Resources of this commodity are not included in this apprais<:\.1. 

ROLE OF TECHNOLOGY AND ECONOMIC.~ IN 

RESOURCE APPRAISAL 

In making estimates of undiscovered recoverable oil and gas resources, it is necessary to 

make fundamental assumptions pertairing to 

economics and technology. The estimr.tes of 

undiscovered recoverable resources ta1~e into 

account relevant past history and exp,~rience 

and are based on assumptions that un~iscovered recoverable resources will be found in the 

future under conditions represented by a continuation of price-cost relationships and technological trends generally prevailing in the recent years prior to 197 4. Price-cost relationships since 197 4 were not taken into ~~count 

bec,ause of the yet undetermined effect these 

m·ay have on resource estimates. If fundamental changes in cost-price relationships ~.re imposed or if radical improvements in tecrnology 

occur, estimates of recoverable resourc~s will 

be affected accordingly. 

These assumed conditions permit the appraisal of recoverable oil and gas resources to 

be made on the basis of: ( 1) relevant past 

history and experience concerning r~overy 
ARCTIC OCEAN 

~ 

il 

" .. 

a o 

0 400 800 MILES 

0 400 800 KILOMETRES 

FIGURE 3.-Tectonic map of North America showing generalized structural elements (modified from Eardley, 1962). 

factors; (2) the geology favorable to the occurrence of producible hydrocarbons; and (3) the 

size and type of reservoirs which have been 

found, developed, and produced. 

Recoverable resource potential as reported 

here for the frontier basins of Alaska, and to 

some extent the offshore areas of the Lower 48 

States, is especially uncertain. Many of the 

frontier basins will have very severe economic 

constraints under which oil and gas may be recovered. A certain amount of the recoverable 

10 

oil and gas in basins used for analogs, but 

which lie in areas of favorable ec~nomics (such 

as the Lower 48 States) , may not be economically recoverable in the Arctic or offshore 

basins ; this fact was taken into consideration 

in the estimating process. 

GEOLOGIC FRAMEWOrK 

Interpretation of the geology of all or any 

part of a potential petroleum pre vince provides 

the basis for resource discovery and measure-
{offshore areas extend to 

200-m water depth) 

\ 

~ 

0 400 800 MILES 

0 400 800 KILOMETRES 

FIGURE 4.-Index map of North America showing the boundaries of the 15 regions, onshore and offshore., covered 

in this report. 

ment. The following discussion provides a 

broad outline of the geology of the United 

States as it relates to known and prospective 

petroleum potential. ·The descriptions, onshore 

and offishore, are generally from east to west, 

and are keyed to major geologic structural 

elements of North America (fig. 3). Within, 

and in part coinciding with these elements, are 

the locations of the 11 onshore and 4 offshore 

productive .and prospective regions app~raised 

in this report (fig. 4) . These regions correspond 

closely to province boundaries established in 

11 

AAPG Memoir 15 (Cram, 1971). R~gion 1 

(Alaska) includes three major structural elements; Regions 2 and 3 encompass the Pacific 

Margin Ranges and Intermontane Plateaus and 

Basins; Regions 4, 5, 7, 8, and 9 lie g1~nerally 

within the Central Stable Interior of t'le Midcontinent; Region 10 includes the Appr.lachian 

basin ; ~and Regions 6 and 11 corresp~md respectively to the Gulf and Atlantic Coastal 

Plains. The offshore regions are 1A, Alaska; 

2A, Pacific Coastal States ; 6A, Gulf of Mexico; 

and 11A, Atlantic Coastal States. 
ONSHORE UNITED STATES 

Eastern part 

The oil and gas resources of the northeastern 

and north-central parts of the United States 

are concentrated in fields on and adjacent to 

the Cincinnati arch (fig. 3), a southward extension of the eastern part of the Canadian 

shield from the west end of Lake Erie to central Tennessee. The fields of eastern Indiana 

and northwestern Ohio are related to the crest 

of the Cincinnati arch, whereas the productive 

Appalachian basin adjoins the 'arch on its east 

side, •and the Michigan and Illinois basins flank 

it on the west. The oil and gas in this area 

occur in rocks of Paleozoic age (table 2). The 

oldest reservoirs are sandstones and fractured 

carbonate rocks of Cambrian, Silurian, and Devonian age. The youngest productive beds are 

porous sandstones and carbonate rocks of Mississippian and Pennsylvanian age. 

East of the Appalachian basin, crystalline 

rocks of the Piedmont belt separate the Atlantic Coastal Plain sediments from the other 

onshore sedimentary basins except to the south, 

where the sediments of the Atlantic Coastal 

Plain overlap the rocks of the Piedmont and 

merge with the sediment•s of the Gulf Coastal 

Plain. 

Central part 

In the Central Stable Interior Region of the 

Mid-continent, a western prong of the Canadian 

shield extends southward mostly in the ·subsurface from Lake Superior to central Missouri. The southern part of the region consists 

of a series of basins and uplifts that begin in 

northwestern Missouri and extend southwestward to central and west Texas. These basins 

are productive in southeastern Kansas ·and central Arkansas and are highly productive in the 

Ardmore and Anadarko basins of Oklahoma 

·and in the West Texas Permian basin, as well 

as in central and southwest Kansas. The principal productive rocks are Cambrian ·and Ordovician sandstones and carbonates; Silurian and 

Devonian carbonates; Mississippian and Pennsylvanian sandstones and carbonate reefs; and 

Permian sandstones, granite wash, porous 

bedded carbonates, and reefs. 

12 

Another series of basins and uplifts extends 

westward to the Rocky Mountains' front with 

the highly productive Delaware b.<:tSin of southeastern New Mexico at the southern end. Farther north, the essentially barren Tucumcari 

and Raton basins are followed by the moderately productive Denver and Powder River 

Basins, and this trend continues northward into 

Canada through the Sweetgrass arch •area of 

Montana. The productive Williston basin lies 

in this region, east of the Sweetgrass arch. The 

principal production in this trend comes from 

the Paleozoic rocks in the Delawr.re basin, the 

Cretaceous in the Denver basin, Upper Paleozoic and Cretaceous in the Powder River Basin, 

and Paleozoic rocks in the Willistcn basin. 

Southern part 

South of the area of predominantly Paleozoic production, the highly productive Mesozoic 

and Tertiary strata of the gulf C<''~st cover the 

older strata from the panhandle of Florida to 

the Mexican border. These strata lie in a wedge 

that thickens southward from a thin edge in 

northeast Texas, southern Arkan~s, and central Mississippi to more than 50,000 feet below 

the Gulf of Mexico. There are seven major 

productive trends in the gulf c1astal region 

that •are made up of progressively younger 

strata from north to south, ranging in age from 

Lower Cretaceous to Quaternary. 

Western part 

Within the Rocky Mountains, 2nd extending 

into the eastern part of the Internontane Plateaus and Basins, are several procuctive basins 

extending from the San Juan Basin in northwestern New Mexico to the Bigl: orn Basin in 

Montana and Wyoming. Production in these 

basins comes from reservoirs ranging in age 

from Paleozoic through Mesozoic to early Tertiary. 

West of this productive trend are large areas 

of essentially nonproductive rock~ that extend 

to the Pacific coast. Exceptions are in Californi·a, where the moderately productive Sacramento basin, the more productive San Joaquin, 

Cuyama, Santa Maria and Ventura basins, and 

the highly productive Los Ange]es basin are 

present. These basins produce mostly from 

sandstones that range in age from Late Cretaceous to Quaternary. 
TABLE 2.-Major stratigraphic and time divisions (modified from Geologic Names Committee. U.S. 

Geological Survey, 1972) 

Age estimates of 

Subdivisions in use by the U.S. Geological Survey boundaries (in millions 

years before present) 

Era or Erathem System or Period 

Quaternary 

1. 5-2 - CENOZOIC 

Tertiary 

65 -

Cretaceous 

136 -

MESOZOIC Jurassic 

190-195 -

Triassic 

225 -

Permian 

280 -

Pennsylvanian 

320 -

Mississippian 

345 - PALEOZOIC Devonian 

r- 395 -

Silurian 430-440 -

Ordovician 

ca.SOO --

Cambrian 

570 -

PRECAMBRIAN 4,500 ± 

13 
Alaska 

Most Alaska onshore sedimentary st:r:ata are 

moderately to highly deformed, and most prospective provinces contain sections of more 

than 15,000 feet of sedimentary rocks. Carbonate rocks and sandstones of Late Paleozoic 

age :and sandstones of Mesozoic age are moder-

!ately to highly productive in the foothills and 

coastal ·plain of northern Al·aska. Sandstones 

of TerUary age are productive in Cook Inlet in 

southern Alaska. Prospective rocks in other 

provinces are mostly Mesozoic to Tertiary 

sandstones. Paleozoic and older sedimentary 

r·ooks are prospective in the Yukon-Porcupine 

province of eastern central Alaska. 

OFFSHORE UNITED STATES 

The eastern part of the U.S. continental margin offshore to a water depth of 200 metres, 

essentially the outer edge of the Continental 

Shelf, extends from the Canadian border off 

the Atlantic coast southwestward to include 

the .southern tip of Florida. The northern portion is underlain by clastic sediments which 

thicken southward to more than 40,000 feet in 

the Baltimore Canyon Trough, beyond which 

they thin southward and interfinger with carbonate sediments of M.esozoic and Cenozoic age 

flanking the Florida Peninsula. None of the 

sediments off the eastern coast of the United 

States has been drilled. 

Although Mesozoic carbonate rocks of the 

Florida pl·atform contain moderately to highly 

productive reservoirs onshore, no production 

has been found offshore to date. The Cenozoic 

carbonate :rocks grade wes·tward into clastic 

sediments that are highly productive off the 

coast of Louisiana :and moderately productive 

off the coast of ·Texas. 

'The !basin of the southern Californi·a borderlands and Santa Barbara Channel, which lie 

north of Mexico along the Pacific coast, are 

highly productive, or potentially productive, 

from Cenozoic clastic rocks in offshore extensions of the Los Angeles and Ventura basins. 

The cl·astic sediments off the coast of northern 

California, Oregon, and Washington are unproductive to date. 

Alaska offshore areas contain extensions of 

onshore carbonate and clastic rocks of Paleo14 

zoic age and clastic rocks of l.Vf esozoic age. 

These may have major potentk.l under the 

Arctic Ocean. ·Thick sediments of dastic rocks 

of Tertiary age are also prospective in basins 

under the Arctic Ocean, Bering Sea, and Pacific margin of southern Al·aska. Rocks of the 

same age are productive under Cook Inlet in 

southern Alaska. 

REGION AND PROVINCE LOCATrONS AND 

BOUNDARffiS 

Apprai~s·al of the Nation's p~troleum resources ·requires that the entirE. country be 

covered on a systematic regional b~.sis. Regional 

boundaries were established to facilitate this 

and to orient the reader with reference to the 

geographic distribution of those resources. Fifteen regions, offshore and onshore, .are treated 

in this report and are shown on the accom.panying index m·wp· of North America (fig. 4) . These 

regions correspond closely to province boundaries established in AAPG Memoir 15 (Cram, 

1971). They include Alaska and rqgions of the 

conterminous 48 States. Hawaii. thought to 

have insignificant oil and gas potential, is excluded. The majority of the regions consists of 

two or more individual geologic pr'"lvinces (figs. 

5, 6) which are the basic elements for this 

appraisal. Provinces usually exhibit certain 

common geologic features characteristic of the 

region they occupy. A total of 102 separate 

onshore and offshore provinces were individually appraised. 

In order to provide a ready basis for comparison with studies of petroleum resources 

published by the American Association of 

Petroleum Geologists ( Cra.m, 1971) and the 

National Petroleum Council (1970, 1973), the 

region and province boundaries ertablished for 

the onshore in this .study were designed to generally conform with their boundaries, except 

loc·ally, where appropriate treatrnent dictated 

otherwise, Si~milarly, the numbering system 

used for these regions parallels that of the 

AAPG and the NPC. 

Onshore region boundaries were drawn in 

specific detail to coincide wherever possible 

with local political bounda:ries, such as State 

and county lines, but also to ap.proximate the 
---Petroleum Region 

-------lndividuolly analyzed 

Petroleum Province 

--- 20Q-m water depth line 

Ot--....&.........,..._30...~..0~~.-._.____.600 MILES 

0 600 KILOMETRES 

FIGURE 5.-Index map of the conterminous Lower 48· United States showing the regional boundaries: 

Region 2, Pacific Coastal States; 

Region 2A, Pacific Coastal States Offshore; 

Region 3, Western Rocky Mountains; 

Region 4, Northern Rocky Mountains; 

Region 5, West Texas and Eastern New Mexico; 

Region 6, Western Gulf Basin; 

basic natural geologic boundaries. This was 

done in order to facilitate use of production, 

reserve, and other data which are generally 

published for political subdivisions by various 

State and Federal agencies and private sources. 

Onshore province boundaries within the regions, those elements shown on figures 5 and 

6, ·are hased fundamentally on known limits of 

natural geologic provinces and ~are dra.wn in 

detail along local political boundaries, with the 

exception of the Al·askan provinces which are 

unmodifi·ed by politic,al subdivisions. 

Province boundaries used within the offshore 

regions were also made to approximate natural 

geologic boundaries wherever possible; however, it was necessary to utilize arbitrarily 

straight lines in some instances. 

Only the Continental Shelf out to 200 metres 

of water depth was treated within the offshore 

15 

Region 6A, Gulf of Mexico; 

Region 7, Mid-continent; 

Region 8, Michigan Basin; 

Region 9, Eastern Interior; 

Region 10, Appalachian Basin; 

Regioll 11, Atlantic Coast; ------- ---

Region llA, Atlantic Coastal States Offshore. 

areas in this report. Present technology and 

economics allow for ready exploration and development of petroleum resources of offshore 

areas out to water depths of 200 metres ( 660 

ft) in most areas, except for those having 

extreme sea and ice conditions. Industry is 

already ·actively exploring in water depths 

greater than 200 metres, ~although actuq_l drilling at these depths has been limited to date. 

With reference to the international boundaries of the offshore regions, the United States 

has not yet resolved its Continenta 1 Shelf 

boundaries with its neighboring States. For 

purposes of thi's report, it has been n(leessary 

to make certain arbitrary ·assumptions about 

the extent of areas potentially subject to U.S. 

jurisdiction. ·The lines used in prepar:ng this 

report ·are for purposes of illustration only, and 

do not necessarily reflect the position C"' views 
1 

sso 

5f' 

46" 

IS SO 

As noted in the text, the U.S. has 

not resolved its continental shelf 

boundaries with other States concerned. The lines on this chart 

are for purposes of illustration 

only, and do not necessarily reflect the positions or views of 

the United States with respect to 

the boundary involved. 

0 100 200 300 400 500 MILES 

0 500 KILOMETRES 

13Z" 

Reaion IA 

1480 

':~ 

INDEX 

180" 176° 172" 168° 164° 1600 15SO 152° 148° 144° l••'l" 136" 

FIGURE 6.-Index map of Alaska showing the boundaries of the major onshore and offshore petroleum provinces. 

of the United States with respect to the location of the Continental Shelf boundaries between the United States and other States concerned. The United States expressly reserves 

its dghts, and those of its nationals, in all 

areas in which the Continental Shelf boundary 

has not been resolved, •and these illustrative 

lines are used without prejudice to such rights. 

In this resource assessment, no exclusion of 

lands was made on the basis of current or 

future availability for resource development, 

either in terms of existing or proposed reservations, sanctuaries, or other withheld ~areas. 

SEDIMENTARY ROCK AREAS AND VOLUMES 

Areas of prospective sedimentary rock were 

measuf!ed and the volume of contained sedimentary rock calculated (table 3) within each 

province and region. 

Principal among the several base maps used 

in compilation is the "Tectonic M·ap of North 

Am·erica" (King, 1969). M·ap areas planimetered from this source for the most ·part show 

small deviations of scale owing to the type of 

map projection. Thus, measurec1 areas with 

few exceptions :fall within 6 percent of actual 

global-sur:fac·e measurements. 1\f easurements 

at the western edge of the Bering Sea Continental Shelf ·and the westernmost Alaska Peninsula and the Aleutian Islands Joeally exceed 

true area by as much as 10 perr~nt. Even in 

these areas, however, the provin~e areas and 

derived rock volumes reported h~re generally 

exceed true dimensions by less than 8 percent. 

Measurements on other maps, when checked, 

fell within 5 percent of •actual global-surface 

measurement. 

16 
TABLE 3,-Sedimentary rock area and volume by regions 

ONSHORE OFFSHORE TOTAL 

(Water depths 0-200 metres) 

Region Area in Volume in Area in I Volume in Area in Volume in 

1000 mi2 1000 mi3 Region 1000 mi 2 I 1000 mi 3 1000 mi 2 1000 mi 3 

I 

1. Alaska-------------------- 252.2 644.7 !A. Alaska-------------------- 318.1 501.7 570.3 1,146.4 

2. Pacific Coastal States---- 125.5 192.1 2A. Pacific Coastal States---- 18.4 32.0 143.9 224.1 

3. Western Rocky Mountains--- 329.9 549.1 329.9 549.1 

4. Northern Rocky Mountains-- 360.6 591.6 360.6 591.6 

5. West Texas and 

Eastern New Mexico------ 193.4 283.8 193.4 283.8 

6. Western Gulf Basin-------- 238.7 774.8 6A. Gulf of Mexico------------ 112.8 570.0 351.5 1,344.8 

7. Mid-Continent------------- 446.6 324.2 446.6 324.2 

8. Michigan Basin------------ 122.0 108.0 122.0 108.0 

9. Eastern Interior---------- 166.2 204.0 166.2 204.0 

10. Appalachians-------------- 205.4 501.4 205.4 501.4 

11. Eastern Gulf and 

Atlantic Coastal Plain-- 109.4 127.8 llA. Atlantic Coastal States--- 102.3 233.0 211.7 360.8 

Total Lower 48 Onshore- 2,297.7 3,656.8 Total Lower 48 Offshore-- 233.5 835.0 2,531. 2 4,491.8 

Total Onshore Total Off shore 

United States-------- 2,549. 9 4 ,301. 5 United States---------- 551.6 1,336.7 3,101. 5 5,638.2 

Uplifted areas of crystalline or metamorphic 

rock were excluded from sedimentary areas as 

nonpotential, as were sedimentary rocks which 

were strongly deformed or altered to the point 

of being potentially nonproductive for hydrocarbons. Such rocks were likewise excluded 

from vertical rock sections, thus providing a 

"basement" or floor to an otherwise prospective 

thickness of sedimentary rock. 

In Regions lA, 4, 7, and 8, additional areas 

of very thin sediment cover, with no production history, were considered nonprospective 

and excluded from reported sediment areas and 

volumes; these areas are peripheral to the 

Canadian shield and that part of the Bering 

Shelf lying outside of the recognized basinal 

areas. 

Throughout essentially all regions, with minor exceptions in some of the onshore provinces, only the ·sedimentary rock ·sections less 

than 30,000 feet in depth were considered potentially prospective and calculated for the 

reported total rock volumes. This selection was 

m·ade on the basis of limiting factors of economics and drilling technology, as well as degradation of reservoirs at depth and instability 

and destruction of certain. hydrocarbons 

themselves at temperatures and pressures generally encountered at these depths. The contained volumes of sediments otherwise were 

treated as having petroleum potential, qualified by geologic factors of probable reservoir 

qualitY, generation of hydrocarbons, asrociated 

trapping potential, and other factors related to 

petroleum occurrence. 

FACTORS RELATED TO HYDROC.ARBC'S 

OCCURRENCE AND EXPLORATION 

CHARACTERISTICS OF THE HABITAT OF 

HYDROCARBONS 

A petroliferous province must have: (1) an 

adequate thickness of sedimentary rocl~s; (2) 

source beds containing considerable dispersed 

organic matter; (3) a suitable environment for 

the maturation of organic matter; (4) porous 

and permeable reservoir bed,s; (5) hydrodynamic conditions favorable for both early migration and ultimate entrapment of oil and 

gas; (6) a favorable thermal history; (7) adequate trapping mechanisms; and (8) suitable 

timing of ·petroleum generation and migration 

in relation to the development of trap~·. Many 

other features are favorable but not ·abr~olutely 

necessary. Examples of favorable indications 

in unexplored basins are : the presence of oil 

and gas seeps, a varied sequence of roc]~ type·s, 

some organically rich marine sediments as 

source beds for the generation of oil ari associated gas, nonmarine organically rich sediments for genesis of nona:ssociated gas .. structural features that show progressive growth 

through geologic time, unconformities, and the 

presence of evaporite deposits. For arer;s in an 

early stage of exploration, important indicators 

17 
are: shows of oil and gas in noncommercial 

wells, presence of saline or sulfate water in 

potential reservoirs, commercial production, a 

favorable ratio between wells drilled and oil 

and gas discoveries, ·and traps that are detectable by conventional geological and geophysical 

methods. 

TRAP TYPES 

Most of the oil and gas fields onshore in the 

Lower 48 States occur in structural traps, such 

as anticlines, salt domes, and fault traps. However, many are in stratigraphic traps ·such as 

reefs, porosity pinchout~, or the truncated edges 

of porous strata. The super-giant Hugoton gas 

field and the East Texas oil field (each the 

largest in its own category in the Lower 48 

States) are at least partly stratigraphic in the 

nature of their trapping .mechani,sm. Paleozoic 

reef traps are particularly abundant in salt 

and other evaporite basins, such as the Michigan, Delaware, and Paradox basins and the 

Jurassic reef trend from northeast Texas to 

the panhandle of Florida. In addition, salt 

domes and salt :anticlines are important productive structures. In onshore Alaska, fields 

occur in anticlinal and fault traps as well as 

combination traps like the Prudhoe Bay field 

which consists of structuve and erosional truncation, sealed by impervious rocks. 

The distribution of oil and gas fields of the 

United States, including Ala,ska and the Continental Shelves, is ·shown on figure 7. The 

concentration of these oil and gas fields ranges 

from dense in heavily explored areas (such as 

the Appalachian region, Mid-continent, gulf 

coast, Permian basin, and Los Angeles basin) 

through locally dense in partly explored areas 

like the Continental Shelf of the Gulf of Mexico 

and offshore southern California, to scattered 

in lightly explored areas, such a;s northern 

Alaska and the undrilled Atlantic Continental 

Shelf. 

METHODOLOGY 

INTRODUCTION AND REVmW OF BASIC 

RESOURCE APPRAISAL METHODS 

There ·are many methods for estimating 

petroleum potential, and each requires a certain level of knowledge or degree of information. Each method with its recognized limitations can produce relevant results, but no 

single technique has universal application. The 

strengths and weaknesses of e·z.ch technique 

must be considered in choosing the method or 

methods to be used in making an estimate of 

the petroleum potential of a spe~ific area. 

In the last two decades the many estimates 

of petroleum resources that have been made 

f,an into three basic categories. T,._,~ successful 

application of these methods r3quires some 

knowledge of the geology of the. sedimentary 

province being evaluated. These three basic 

methods are as follows: 

I. Perform·ance or behavioristic extrapolation methods based upon historical data, 

II. Volumetric-yield methods, and 

III. Combined methods-geological and statistical models. 

A fuller discussion of these three basic categories follows : 

18 

I. Performance or behavioristic extrapolation methods based upon historical data. 

·These methods ·are ba'Sed upon the 

extrapolation of past exper·ience such as 

discovery r·ates, cumulathre production 

or productive capacity curves, and the 

fitting of past performanc3s by various 

mathematical derivations into logistic 

or growth curves which are projected 

into the future. These techniques are 

not valid in frontier basinq where little 

history exists or in any area that is 

not ·a geologic and econor•ic replica of 

the historical model. Genet'ally speaking 

they are most applicable to the later 

stages of exploration in a mature area. 

Well known examples of these models 

are: M. K. Hubbert's growth curve projections (1962, 1974) ; C. L. Moore's rate 

of discovery curves (196f) ; and C. R. 

Pelto's rate of discovery curves (1973). 

II. Volumetric-yield methods. 

There are a wide variety of ways in 

which volumetric estimating techniques 

have been used in the past. These range 

from worldwide average yields in barrels of oil or cubic feet of gas per cubic 

mile of sedimentary rock or per square 

mile of surface area applied uniformly 
""""' ~ 

~0 

~= 

I ~w~ p\) 

,. "'""-... . ... .,;~~- ~\ 

-OIL AND GAS 

FIELDS 

FIGURE 7.-Map of the United States showing the oil and gas fields and the regional boundaries (modified from the U.S. Geological Survey, 1967). 
over a sedimentary rock area to more 

sophisticated analyses where the yields 

from a geologically analogous basin 

have be~n used to provide a basis of 

comparison. The pioneer works by 

Weeks (195a), Zapp (1962), and Hendricks (1965) are illustrative of these 

techniques. 

Where a yield factor based upon geologic analogs is used in this report, it 

is done in the context of a reasonably 

sound consideration of the geology of 

the province and the selection of a geologically analogous basin or province. 

III. Combined methods-geological and statistical models. 

These methods consist of more sophisticated techniques which require a large 

·amount of data as well as complicated 

mathematical and computer methods for 

handling the information input. These 

may involve: 

1. Basin evaluation studies with geologic models, 

2. Play analysis techniques, 

3. Statistical and economic models, decisionmaking models, and 

4. Comprehensive petroleum province 

analog systems. 

APPRAISAL PROCEDURES FOR THIS REPORT 

GENERAL 

Estimates of recoverable oil and gas resources are based upon a .series of resource appraisal techniques. These techniques all have 

the common characteristic of having been 

selected on the basis of the available geologic 

information for each province or region. 

The techniques used include: (1) an extrapolation of known producibility into untested 

sediments of similar geology for a well-developed area; (2) volumetric techniques using 

geologic analogs and setting upper and lower 

yield limits through comparisons with a number of known areas; (3) volumetric estimates 

with an arbitrary general yield factor applied 

when direct analogs were unknown ; ( 4) Hendricks' (1965) potential-area categories; and 

(5) comprehensive comparisons of all known 

published estimates for each area to all estimates generated by the above methods. 

20 

SPECIFIC METHODOLOGY USED BY TT·IE RESOURCE 

APPRAISAL GROUP 

Geological appraisal procedures 

Geological data formats were provided to 

the geologist making the primary geologic 

analysis in a specific geological prC'vince so that 

he would accomplish the following: 

1. Provide a summary of the awdlable information, including the inte~pretive geology. 

2. Provide an inventory of the information 

base in a province, such ar maps, logs, 

and reports. 

3. Quantify the summarized information needed to characterize the basi o. geology of 

the province, describe the ba.sic field and 

reservoir information, and describe the 

production, reserves, and re?ource information for the province. 

4. In short, provide the basic input essential 

to the various methods of resource appraisal that would be applie.d by the Resource Appraisal Group to each of the 

provinces. 

Two versions of the data formats were used: 

a long form to be used for the m~re maturely 

developed and productive provinco.s, consisting 

of approximately 85 basic categories of information, and a shorter version designed for the 

less maturely explored or frontier and offshore 

areas, consisting of approximately 60 basic 

categories of information. An example of the 

short form is given in the Appendix with data 

from the Michigan basin, compiled for illustrative purposes. 

Approximately 70 U.S. Geolo:rical Survey 

geologists provided basic geologic data for the 

province, or provinces, in their reEpective areas 

of expertise, and for which they were responsible for the compilation and asse'llbling of all 

the basic geological data. 

Each of the province data for1nats was reviewed critically by the Resour~'?.e Appraisal 

Group and rechecked with the area experts. 

Special emphasis was placed upon accuracy of: 

areal determinations of provinc~s by planimetry using various base maps; determinations 

of thickness and volumes of sedhnents in each 

of the provinces ; and the selection of yield 
values by analog basins or provinces. One-page 

province summary sheets were compiled for 

each province by a Resource Appraisal Group 

representative. (See form 3, Appendix, for an 

example of the province summary sheet for the 

Michigan basin.) 

The most complete and up-to-date information available was compiled for each province 

on oil, natural gas, and natural gas liquids for 

the following classes: cumulative production, 

measured reserves, indicated reserves, .and the 

total cumulative production and identified reserves (see Definitions of Resource Terms). 

Initial'resource appraisal procedures 

In this phase of the resource appraisal procedure, all of the above geological data summary reports and total production and reserve 

information for a particular province were assigned to one of the members of the Resource 

Appraisal Group. These data were then subjected to a series of resource appraisal methods. 

A series of geological and volumetric-yield 

analog procedures was first applied to each 

province to determine a range of hydrocarbon 

yield values. These were calculated for in-place 

estimates, total recoverable resources, and remaining undiscovered recoverable resources. 

Other procedures were also used, such as extrapolating known producibility into untested 

portions of ·a province , or more arbitrary yield 

factors were used when direct analogs were 

unknown or uncertain. In addition, a series of 

Hendricks' productive-area categories was calculated to evaluate a range of potential for 

each of the three commodities. Finally, all 

published and documented resource appraisal 

estimates were compiled on a special summary 

form (see form 4-A, Appendix) with all of the 

above estimates that were calculated for each 

of the methods. These documented estimates 

usually consisted of the following sources : 

American Association of Petroleum Geologists, 

Memoir 15, 1971; National Petroleum Council 

Estimates, 1973; Potential Gas Committee, 

1973; and U.S. Geological Survey or other area 

or province expert's estimates. 

The Resource Appraisal Group representative for each region made a comprehensive 

comparison of all of the above information and 

appraisals and then, assuming the occurrence 

21 

of oil and gas in commercial quantitie~, made 

an initial resource appraisal by a subjective 

probability technique as follows: 

1. A low resource estimate corresponding to 

·a 95 percent probability that the~e is at 

least that amount. 

2. A high resource estimate with a 5 percent 

probability that there is at lea,~t that 

amount. 

3. A modal estimate of the resource wl'ich the 

estimator associates with the highest 

probability of occurrence that th~re will 

be that amount. 

4. A statistical mean which is calculated by 

adding the low value, the high value, and 

the modal value and dividing the sum by 

3. 

These estimates were recorded on the resource appraisal summary sheets for use in the 

final evaluation by the Resource Appraisal 

Group Committee. (See Appendix for example 

of the resource appraisal summary sheets for 

the Michigan basin (forms 4-A and 4-B)). 

Final resource appraisal procedures used by 

the Resource Appraisal Group Committee 

Meetings of the Resource Appraisal Group 

Committee and the appropriate geologic representatives were held to complete the final resource appraisal estimates for each of the 

provinces. The representative for each province 

or region presented a comprehensive summary 

of the geology and pertinent information related to an evaluation of the province's or region's petroleum potential. A collective review 

was made by the committee of all the summary 

sheets and data formats, all the oth~r estimators' figures, and the detailed evaluation of 

the Resource Appraisal Group representative's 

evaluation procedures as previously dE.~cribed. 

Following the detailed reviews, each member 

of the committee and the appropriate representatives and area experts individually made 

their resource appraisal estimates for the 

province by the subjective probability procedures described in the previous section: 

(a) A low estimate with 95 percent probability, 

(b) A high estimate with 5 percent probability, 

(c) A modal estimate with the highest 
probability, and 

(d) A calculated statistical mean. 

All the evaluators' individual estimates (a, 

b, c, and d) were posted for review. If there 

were any major differences in these estimates, 

the reasons for the differences were discussed 

and resolved, and a group consensus arrived at 

for a range of estimates as defined in (a) 

through (d) above. 

The last phase of the resource appraisal 

procedure was a review of the Resource Appraisal Group's estimates by the respective 

representative and the U.S. Geological Survey 

geologist doing the initial geology for each 

province. In those provinces where there was a 

major differenee of opinion between the Resource Appraisal Group's estimates and the 

original geologist's evaluations, the entire resource appraisal procedure was reevaluated 

and analyzed to resolve the differences. 

The final figures as arrived at by the Resource 

Appraisal Group for the low (95 percent), 

high (5 percent), and modal estimates and the 

calculated statistical mean are the estimates 

that were then statistically analyzed, as discussed below in the Monte Carlo simulation 

proc·edures, and were finally incorporated into 

this report. 

METHODOLOGY FOR PROCESSING PROBABILISTIC 

ASSESSMENTS OF UNDISCOVERED HYDROCARBON RESOURCES 

The procedures just described for estimating 

the undiscovered oil and gas for each of the 

102 U.S. petroleum provinces involved subjective probabilities (Raiffa, 1968). Judgments 

were expressed by the Resource Appraisal 

Group Committee for each province as percentile assessments, plus the assessment of a 

modal value and a calculated statistical mean. 

These values were computerized and processed 

as probability distributions by lognormal curves 

(Kaufman, 1962). 

Percentile assessments in this study were 

limited to judgment of quantities associated 

with the 5 and 95 percent range. These moderate intervals were selected to realistically account for at least 90 percent of the range of 

the probable undiscovered oil and gas resources 

for each province. An example of such a cumulative probability distribution curve follows: 

Co) 41V IUSICA ON5HOIII. - NOIIMIIt M.ASU -

22 

l. 

---!'\ 0 .. I s I 

I ~ ........... l<t.r. 

·- I \ ~ •. r·~~ • 0 

0. • 0 

• 

I 1\. I 

I 

~ 

~ 

I " ~ r...... ~ -· 1---- - ·- ... 2.1 7.1 12.=s 17.=s zz.s 

UNDISCOVERED R!tOVERAILE RESOURCE$ 

BILLION BARRELS 

Probability distributions-Monte Carlo 

techniques 

In order to translate these se:')arate probability judgments into a form useful for evaluating resource assessments for totfl regions and 

for the total United States, and to determine 

statistically valid ranges of resource estimate 

summations, the following pro~edures were 

developed for the U.S. Geologic~.! Survey by 

Gordon M. Kaufman of the Alfred P. Sloan 

School of Management at Massachusetts Institute of Technology: 

1. Lognormal probability distributions were 

computed for the assessment for each 

province. A lognormal distribution has 

the following qualitative craracteristics: 

(a) The values can range from zero to 

infinity; 

(b) It has one mode on the distribution curve; 

(c) It is positively skewed (a long 

right tail) ; 

(d) A mean and variancn exist; and 

(e) It is reasonably flexible in shape 

with at least two and no more 

than three parameters. 

The following diagram, showing two 

probability density functiolls, illustrates 

why ranges can not be summed arithmetically or ave~aged to determine the 

mean. 
Mode 

1 

~ 

-.:a 0 

..Q 

e 

a.. 

Undiscovered Recoverable Resources ---+ 

The lognormal distributions were used 

for all provinces except the few for which 

the group assessments of modes placed 

these modes closer to the 5 than to the 

95 percentiles. These exceptions were assessed by subjective probability procedures by the Resource Appraisal Group. 

The first step then was to fit a lognormal distribution to the assessments for 

each province for which the mode was 

closer to the 95 than to the 5 percentile. 

In order to account for the possibility that 

the percentiles are not spaced far enough 

apart, the Resource Appraisal Group's assessments were fitted in three ways to the 

lognormal curve, and that fitted distribution giving the largest spread between 

the 95 and 5 percentiles was chosen. 

2. Monte Carlo techniques were utilized for 

aggregating the probability distribution 

of the sums of undiscovered oil and gas 

resources in regions consisting of two or 

more provinces and the probability 

distributions of the sums of the total undiscovered U.S. oil and gas resources in 

the 15 onshore and offshore regions and 

for the total United States. 

Once the assessments for each individual province were fitted with a distribution, the probability function in each 

region composed of two or more provinces 

was computed by Monte Carlo techniques, 

assuming mutual independence among 

provinces. Following the assessments for 

each region, a Monte Carlo apprm~imation 

was calculated for the total aggregated 

undiscovered oil and gas for all onshore 

areas of the United States, and an aggregate for all the offshore areas, respectively. A Monte Carlo approrimation 

was then computed for an -aggregation of 

the entire United States to give tho. ranges 

and mean values for the undiscoHered oil 

and gas resources. The high and low 

ranges of estimated resources determined 

for each of the above aggregate8' are determined independently and cannot be 

arithmetically summed for a total. Only 

the aggregated range of values for the 

total United States obtained by the 

Monte Carlo technique is valid. 

Software systems for implementation of ( 1) 

and (2) above were devised to include graphic 

displays of the probability distribut: ~ns for 

undiscovered oil and gas resources by province, 

by region, ,and by totals for the Unitei States 

offshore and onshore areas, as well as the 

numerical computation of parameters such as 

the 1, 5, 25, 50, 75, 95, and 99 percentiiE:(i, mean, 

mode, median, and standard deviation of these 

distributions as shown in computer graphic 

display such as those illustrated in figure 8. 

Marginal probability 

23 

In the initial resource appraisal for a given 

province, an assumption was made that oil and 

gas occurred in commercial quantitie~· (see p. 

21). This assumption cannot be m·ade with 

certainty in frontier areas in which r0 petro-
(al 'OJV MAIKA CINIHIIIII. •• ......... M:*A -

)oo 

... 

:::; 

1. 

o. 

~ .. • 0 

-

L 

.. 

•• 

- --~ f'\ 

I \ 1 

I .-:&a~ 1'9." 

I \ v.--s:~ 

I 1\. I 

I 

~--h-- I --- "' 

--~ ~ 

-2.1 7.1 11.5 17.5 

UNDISCOVERED I!C.OVEIAILE RESOURCES 

BILLION BARRELS 

I. 

-

e . . 

)oo 

... •• :::; 

;;; 

<I( 

• 0 

-

L 0. 

r\ !MARGIN I L ~·~ eiLITV• "701e IMca.N: n 

I\ 0":.34 

-· "' -~ 

- 11.1 0

'o.oo •.• 1.11 1.51 2.00 

UNDISCOVERED RfCOVERAILE RESOURC:ES 

BILLION BARRELS 

(etlAn.·.., ALM~CA CINIMDIII - 1'0TM. .... 

:: 

:::; 

• 

;;; 0 <I( 

. 

0 

-

L 

• 

.... 

.. 

·-.. 

-~ 

i\ 114.AN:.u. I \ 0"1 ,.., 

I 

I 

I 

I 

• 

.. 

•.• 

·-j 

I .J~ 1.. ,,.. - 3.01 .... 

UNDISCOVERED lfCOVERAILE RESOURCES 

BILLION BARRELS 

••• 

)oo 

.... 

::::; 

I . 

0 

~ 0 

a 

• &. 

0 

0 

•• --~ 

I 1\ 

: 

I \ IMsaw: ll.!'r 

·- I \ r: :s.• 

I 

I ~ ·-· I "" I 

I --'"I-~---- ----· ~~ 

a.• "· • ••·• a?. s ·•·• 8? .• 

UNOISCOVEIED I!C.OVERAILE RESOuRCES 

BILLION BARRELS 

FIGURE B.-Probability distributions by Monte Carlo analysis on undiscovered recoverable resouroos for Alaska: 

Aggregate probability distributions for three onshore subregions and the total Alaska on~hore. 

leum has been discovered to date. It was necessary, therefore, to assign a marginal probability to the event "Commercial oil found" and 

to the event "Commercial gas found" (Spurr 

and Bonini, 1973). These marginal probabilities were determined by consensus of the Resource Appraisal Group Committee. They were 

then applied to the estimated subjective probability judgments of the undiscovered recoverable resources to determine a final probability 

distribution of those resources. 

Marginal probability can best be described 

by referring to the graph in figure 8 (graph 

b) . At the present time there has been no oil or 

gas found in the onshore provinces of central 

Alaska. The probability of finding oil and/ or 

gas in commercial quantities was calculated as 

approximately 70 percent (corresponding to a 

30 percent probability of finding no oil or gas 

in commercial quantities). This marginal prob24 

ability was obtained by utilizing the Monte 

Carlo approximation technique to aggregate 

the individual provinces, assuming mutual independence among provinces. 

The following example illustrates the logic 

used in the computer program to do.termine the 

marginal probability for the aggre~ated<Monte 

Carlo) central Alaska subregion : 

(a) For the Yukon-Porcupine rrovince the 

probability of no commercial oil or gas 

is 70 percent; that is, 1-0.3=0.7. 

(b) For the Yukon-Koyukuk }Jrovince the 

probability of no commercial oil or gas is 

75 percent; that is, 1-0.26'=0.75. 

(c) Interior Lowlands province (negligible 

·amounts) probability dist~ibution not 

calculated. 

(d) For the Bristol Bay Tertiary province the 

probability of no commercial oil or gas 
is 60 percent; that is, 1-0.4 = 0.6. 

The total probability of no commercial oil or 

gas for the three provinces is 0.70X0.75x 

0.60 = 0.315, or 31.5 percent. The marginal 

probability of any success at all in the total 

subregion is 1-0.315 = 0.685, or 68.5 percent. Therefore, reading the probability distribution graph (fig. 8b) for central Ala,ska onshore at the 95 percent level would give a zero 

reading, as the probability of success is less 

than 70 percent for this subregion. 

Alaskan examples 

Region 1, onshore Alaska, is described here 

and shown in figure 8 for illustrative purposes. 

The region was subdivided into three subregions, which in turn were further subdivided 

into 11 geological provinces. The 11 provinces 

were evaluated, and the -probability distributions for oil and gas resources were determined 

for each. 

The probability distributions for oil were 

aggregated by the Monte Carlo technique for 

each of the three subregions and for the total 

onshore Alaska region as follows : 

1. Subregion aggregate: Alaska OnshoreNorthern Alaska (fig. Sa) Provinces: 

Arctic Coastal Plain 

Northern Foothills 

Southern Foothills and Brooks Range 

2. Subregion aggregate: Central Alaska (fig. 

8b) Jlarginal 

Provinces Probability 

Yukon-Porcupine _______ 30 percent 

Yukon-Koyukuk ________ 25 percent 

Interior Lowlands __ (Negligible ·amounts 

·estimated) 

Bristol Bay Tertiary ____ 40 percent 

3. Subregion aggregate: Southern Alaska (fig. 

8c) Provinces : 

Alaska Peninsula 

Cook Inlet 

Copper River Basin 

Gulf of Alaska 

4. Total region ·aggregate: Alaska Onshore 

(fig. 8d) Provinces: All of the above 

11 provinces 

The following information is noted on the 

graphs for each of the above four aggregated 

probability distribution for the undiscovered 

recoverable oil resources : mean and standard 

deviation and the 95 percent and 5 percent 

ranges. 

SUMMARY OF APPRAISAL PROCEDURES 

Individual and collective appraisals were 

made for each province or region using volumetric-yield procedures, basin analyses, producibility extrapolations, Hendricks' pc tentialarea categories, ·and other published app~aisals, 

thus encompassing the various estimates into 

an overall framework for apprai·sal. A lognormal distribution was fitted to the high, low, 

and modal values of the Resource A]lpraisal 

Group's ·assessments to compute the prol)ability 

distribution for each province. Monte Carlo 

approximation techniques were .appliec1 to derive the probability function for the arrount of 

undiscovered oil and gas in each region composed of two or more provinces and for the 

summation of subtotals and totals of the regions in the United States. 

METHODOLOGY FOR ESTIMATING NATURAL GAS 

LIQUIDS RESOURCES 

Estimates of undiscovered recoverable natural gas liquids were not made in tl'e same 

manner as those for crude oil and natural gas; 

by definition, they are derived from and dependent upon natural gas production. Historical 

ratios of cumulative production (American 

Petroleum Institute, American Gas Association, 

1974) of natural gas liquids in barrels per million cubic feet of natural gas were calculated 

for each region. These factors were then applied to estimates of undiscovered natural gas 

resources for each region to obtain regional 

estimates of undiscovered recoverable resources 

of natural gas liquids. Where no histori~al data 

were available to calculate a NGL/natural gas 

ratio, or where it was felt that future development would substantially affect the calculated 

factor, the national average of 33 barrels of 

NGL per million cubic feet of natural gas was 

used. Results of these calculations are reported 

in the summary section for undiscov1~red recoverable natural gas liquid resources. 

METHODOLOGY FOR ESTIMATING 

INFERRED RESERVES 

In this study, a ratio of API-AGA inferred 

+_indicated reserves to proved (measured). reserves was calculated for each of the. -11 onshore regions and the total U.S. averages for 

onshore and offshore areas, respectirrely, by 

extrapolating the rate of growth of discovered 

volumes for each given region by use of Hubbert's alpha correction factors which are based 

upon the time l~pse since the initial year of 

25 
discovery for the respective States involved 

(Hubbert, 1974). The regional factors were 

determined by combining the data for API 

States and districts given in the Appendix. The 

inferred reserves for most of the regions were 

calculated by applying these ratios to 1972 estimates of proved (measured) reserves for each 

region (using data from the latest American 

Petroleum Institute sources) and subtracting 

out the value for indicated reserves from the 

total inferred plus indicated reserves. 

A description and explanation of the procedures used to calculate the inferred plus indicated reserves for the United States is provided in theAppendix with complete documentation. The Resources Appraisal Group derived 

from these calculations ratios both for oil :and 

gas for the 15 regions appraised in this report. 

The wide variability in the data used to determine the growth curves of Hubbert (1974) plus 

the fact that the measured (API and AGA 

proved) reserves portion of that data represent estimates cause a significant degree of uncertainty in the calculated estimates of inferred 

plus indicated reserves. This uncertainty is 

compounded by the fact that these estimates 

. were derived from API State or regional data 

and the growth curves were determined using 

total United States data. 

PETROLEUM RESOURCES OF THE 

UNITED STATES 

SUMMARY OF RESULTS 

This report summarizes the estimates of undiscovered recoverable resources of oil, natural 

gas, and natural gas liquid resources of the 

United States as assessed by the U.S. Geological Survey's Resource Appraisal Group based 

on a geological evaluation of over 100 potential 

petroleum provinces for onshore Alaska and 

the conterminous Lower 48 States, and all offshore U.S. Continental Shelves to water depths 

of 200 metres. 

The- undiscovered oil and gas resource estimates made by the many contributors to this 

study are based on a series of procedures which 

led to subjective probability distributions; the 

common characteristic was that each procedure 

was based on a detailed geological evaluation 

of each respective province or region. 

New knowledge generated by exploration 

programs and expert criticism of presently 

a~ailable data will, in the coming years, change 

26 

these estimates either upward or downward. 

All information about future oil and gas resources of the United States, ·along- with information on past production and identified reserves, are summarized by four methods of 

presentation. These presentations, designed to 

report all resource estimates in perspective, 

are summarized and illustrated in the following 

pages by these four methods: 

1. Tables.-Detailed tabulations for oil and 

natural gas compiled to show by regions : 

cumulative production, identified reserves, estimated undiscovered recoverable resources reported as a range of 

values ( 95 percent to 5 percent) ·and as 

a statistical mean. 

2. M aps.-A series of pull-apart maps which 

show by regions for · the contenninous 

Lower 48 States, onshore ·r.nd offshore, 

and for Alaska, onshore and offshore, the 

cumulative production and demonstrated 

reserves and the ranges ar.d statistical 

mean of undiscovered rec1verable resources for oil and natural ~~as. 

3. Resource classification charts.-A diagrammatic representation of oil and gas resources as classified by the U.S. Geological Survey and U.S. Bur€'au of Mines. 

4. Probability distributions. - Probability 

functions, in graphic display, showing the 

amount of undiscovered oil and gas resources for each region, w~th subtotals 

and totals for the United States. 

RESULTS-UNDISCOVERED RECOVERABLE OIL AND 

NATURAL GAS RESOURCI:S 

Tables 4 and 5 show detailed tabulations of 

total recoverable oil resources and total recoverable gas resources for the United States. 

The cumulative production, identified reserves, 

and estimated undiscovered resources are reported by regions, onshore and offshore, with 

onshore and offshore subtotals, and U.S. totals. 

The estimated ranges as reported by regions, 

subtotals, and U.S. totals were derived by the 

Monte Carlo simulation techniqu~s discussed 

previously and illustrated later in this report. 

The 95 percent to 5 percent range represents a 

minimum value that is associated with a 19 in 

20 chance that there is at least this amount and 

a maximum value that is associated with a 1 in 

20 chance that there is at least t.hat amount. 

The statistical mean is mathem-atically derived 

from the Monte Carlo technique. ~:hese figures 

may be mathematically totaled. Totals for the 
minimum and maximum values are not obtained 

by arithmetic summation. 

The total U.S. cumulative oil production 

through 1974 is 106 billion barrels; measured 

and indicated reserves total 39 billion barrels ; 

estimated inferred reserves are 23 billion barrels; and the undiscovered recoverable oil resources range from 50 to 127 billion barrels, 

with a mean of 82 billion barrels. 

I 

Cumulative production and measured (API 

proved) reserves and indicated r·eserve figures 

were derived from reported API-AGA estimates. States and districts were assigned to 

their respective regions, and, where allocations 

were required, State production statistics provided a basis for alloc-ation of the API-AGA 

data. 

The total U.S. cumulative natural gas production through 197 4 is 481 trillion cubic feet; 

measured reserves total 237 trillion cubic feet; 

estimated inferred reserves are 202 trillion cubic feet; and the undiscovered recoverable gas 

resources range from 322 to 655 trillion cubic 

feet, with a mean of 484 trillion cubic feet .. 

The maps shown in figures 9 and 10 illustrate 

by regions the distribution of the cumulative 

production and demonstrated reserves of oil 

and natural gas for the United States, through 

197 4 onshore and offshore. Maps presented in 

figures 11 ·and 12 show the estimated range of 

values, at the 95 and 5 percent probability 

levels, and the statistical mean of the undiscovered 'l'ecoverable oil and natural gas resources 

for the same regions as determined by the 

Monte Oarlo simulation technique of aggregating the separate probability distributions for 

each province within a region. 

In the case of the Bering Sea .subregion in 

Alaska and the Atlantic coast offshore region, 

the probability of bhe presence of economically 

recoverable oil or gas, in the judgment of the 

authors, i~s less than 95 percent. The resource 

appraisal at the 95 percent probability level, 

therefore, is zero. In these totally unexplored 

frontier areas, how·ever, the lack of discovered 

indigenous or adjacent recovera:ble hydrocarbons renders uncertainty sufficiently great that 

probability judgments at either high or low 

levels are weakened. For some planning purposes, therefore, estim·ates at the 75 and 25 

percent levels are judged to be more applicable 

and are •so shown on the maps and tables. For 

purposes of comparison with other areas, valuest 

at the 95 and 5 percent probability levels are 

,shown in the footnote on page 33. 

In figures 13 and 14, diagrammatic representations show total oil and natural gas resources of the United States within th~ framework of the U.S. Geological Survey's and the 

U.S. Bureau of Mines' resource clasRification 

system. Cumulative oil and natural gar production data through 197 4 are recorded at the bottom of the charts. The economic recovery factor 

used was based on a current national average 

of approximately 32 percent for oil and 80 percent for natural gas (McCulloh, 1973). The subeconomic portion of the remaining reso·xrces for 

oil is estimated to be ·an additional 28 percent 

recoverable, for a total of 60 percent recovery 

(Geffen, 1975). Subeconomic identjfied resources of crude oil were calculated or. the following assumptions: (1) that on the average, 32 

percent of original oil-in-place is recoverable if 

there are no substantial changes in pre~~nt economic relationships and known production technology, and (2) that ultimately the recovery 

factor oould be as large as 60 percent. By definition, the sum of cumulative production to 

date, plus the current estimate of demonstrated 

reserves, will account for 32 percent of the original oil-in-place in known fields; an in~rease to 

60 percenrt will allow another 28 percent to be 

recovered. As indicated in figure 13, that 28 

percent, which is currently considerec1 subeconomic, amounts to about 120 billion barrels. The 

inferred reserves are made up partl'"·"' of revisions of current estimates and I f.l.rtly of 

"undis.covered" oil from future extenfions and 

new pools in known fields. Assuming that all the 

inferred is "undiscovered," the 23.1 biJlion barrels, economically recoverable at the 32 percent 

recovery factor, would have a subecono'llic component of about 20 billion barrels. T~--.us, the 

subeoonomic identified category was E:qtimated 

to be 120-140 billion barrels. Similarly, the subeconomic oomponent of undiscovered resources 

was ·estimated to include 44-111 billior barrels. 

It is extremely optimistic to assume that 60 

percent of the oil-in-place will eventually be 

rooovered. If it becomes a reality, it is likely to 

occur only through gradual development over 

an extended time period. The remaining 40 percent of oil-in-place is not included as it is considered to be nonrecoverable, in much the same 

sense .as coal which is too thin to mine is excluded from recoverable re.sources. 

Subeconomic identified and undiscovered resources of natural gas, shown in figure 14, were 

27 
~ 

00 

TABLE 4.-Production, reserves, and undiscovered recoverable oil resources for the· United States, December 31, 197.1, (billion barrels) 

Demonstrated Total Cumulative Undiscovered Recoverable Resources 

Regions Cumulative Reserves Production + Inferred 2 

Production 

Measured !Indicated 

Demonstrated Reserves 1 Statistical Estimated Range 

Reserves Mean (95%-5%) 

ONSHORE 

1. Alaska--------------------- 0.154 9.944 0.013 10.111 3 

6.1 12 6 - 19 

2. Pacific Coastal States----- 15.254 2.699 1.091 19.044 0.3 7 4 - 11 

3. Western Rocky Mountains---- 1.115 0.417 0.089 1.621 0.7 4 2 - 8 

4. Northern Rocky Mountains-- 6.021 1.461 0.256 7.738 1.2 7 5 - 11 

5. West Texas and Eastern 

New Mexico--------------- 21.385 7.060 1. 991 30.436 1.6 8 4 - 14 

4 

6. Western Gulf Basin-------- 31.345 7.082 0.587 39.014 8.6 8 5 - 12 

7. Mid-Continent------------- 17.203 1.805 0.211 19.219 1.3 6 3 - 12 

8. Michigan Basin------------- 0.645 0.082 0.008 0.735 0.2 1 0.3 - 2 

9. Eastern Interior----------- 4.346 0.283 0.009 4.638 0.3 1 0.6 - 2 

10. Appalachians--------------- 2.539 0.155 0.067 2.761 ~egl. 1 0.4 - 2 

11. Eastern Gulf and Atlantic 

Coastal Plain------------- 0.039 0.042 0.006 0.087 0.1 1 0.2 - 2 

Total Lower 48 Onshore---- 99.892 21.086 4.315 125.293 14.3 44 29 - 64 

Total Onshore 

United States----------- 100.046 31.030 4.328 135.404 20.4 56 37 - 81 
1:'1:) 

(0 

OFFSHORE (0-200 metres) 

5 3 lA. Alaska-------------------- 0.456 0.150 Negl. 0.606 0.1 15 3 - 31 

2A. Pacific Coastal States---- 1.499 0.858 0.258 2.615 0.2 3 2 - 5 

6A. Gulf of Mexico------------ 4.135 2.212 0.050 6.397 2.4 5 3 - 8 

llA. Atlantic Coastal States--- 0.000 o.ooo 0.000 0.000 0.0 3 6 2 - 4 

Total Lower 48 Offshore-- 5.634 3.070 0.303 9.012 2.6 11 5 - 18 

Total Offshore 

United States---------- 6.090 3.220 0.308 9.618 2.7 26 10 - 49 

Total Lower 48------- 105.526 24.156 4.623 134.305 16.9 55 36 - 81 

Total Alaska---~----- 0.610 10.094 0.013 10.717 6.2 27 12 - 49 

TOTAL UNITED STATES- 106.136 34.250 4.636 145.022 23.1 82 50 - 127 -------- - -- - -~----- --~----

Inferred reserves were derived for all regions based on historical data. (See Appendix). 

2 . 

4 

5 

The low value of the range is the quantity associated with a 95 percent probability (19 in 20 chance) that there is 

~~least this amount. The high value is the quantity with a 5 percent probability (1 in 20 chance) that there is at 

least this amount. Totals for the low and high values are not obtained by arithmetic summation; they are derived by 

statistical methods. ---

Inferred reserves based on national onshore average. 

Inferred reserves based on data in AAPG Memoir 15 (1971). 

Negligible--,less than 0.001 billion baxrels for indicated reserves; less than 0.1 billion baxrels for inferred reserves. 

6 Estimates reported at the 75 and 25 percent probability levels because, in this area, these levels are judged to be 

more applicable for some planning purposes. It can also be noted that in frontier areas, lacking discovered 

indigenous or adjacent recoverable hydrocarbons, uncertainty is sufficiently great as to weaken probability estimates 

at extreme ranges. For purposes of comparison with other recorded ranges, the 95-5 percent probability range in 

offshore Atlantic is 0-6 billion barrels of oil. 
co 

0 

TABLE 5.-Production, rese'rves, and undiscovered recoverable gas resmtrces for the United States, December 31, 1974 (trillion cubic feet) 

- Demonstrated Total Cumulative Undiscovered Recoverable Resources 

Regions Cumulative Reserves Production + Inferred 2 

Production Demonstrated Reserves-! Statistical Estimated Range 

Measured Reserves Mean (951-5%) --------~.- --------- --------------- --- --- --~ --- - --------------------

ONSHORE 

1. Alaska-------------------- 0.482 31.722 32.204 3 14.7 32 16 - 57 

2. Pacific Coastal States---- 25.455 4.732 30.187 4.0 13 8 - 20 

3. Western Rocky Mountains--- 10.728 9.081 19.809 2.9 14 6 - 25 

4. Northern Rocky Mountains-- 11.485 6. 754 18.240 5.3 29 18 - 47 

5. West Texas and Eastern 

New Mexico--------------- 58.686 24.624 83.310 23.3 70 35 - 101 

6. Western Gulf Basin-------- 197.899 81.903 279.802 58.7 133 85 - 196 

7. Mid-Continent------------- 107.700 34.150 141.850 20.6 72 50 - 101 

8. Michigan Basin------------ 0.558 1.458 2.016 0.8 1 0.8 - 2 

9. Eastern Interior---------- 2.797 0.766 3.563 0.5 2 0.7 - 4 

10. Appalachians-------------- 31.057 5.985 37.042 3.3 10 5 - 17 

11. Eastern Gulf and Atlantic 

Coastal Plain------------ 0.001 0.001 0.002 I.!Negl. 1 0.4 - 2 

Total Lower 48 Onshore--- 446.366 169.454 615.820 11Q.4 14'l 246 - 453 

Total Onshore 

United States---------- 446.848 201.176 648.024 134.1 377 264 - 506 
c,o 

1--L 

OFFSHORE (0-200 metres) 

!A. Alaska------------------- 0.423 0.145 0.568 

3 

0.1 44 8 

2A. Pacific Coastal States--- 1.415 0.463 1.878 0.4 3 2 

6A. Gulf of Mexico----------- 32.138 35.348 67.486 27.0 50 . 18 

llA. Atlantic Coastal States-- 0.000 0.000 0.000 0.0 10 55 

Total Lower 48 Offshore 33.553 35.811 69.364 27.4 63 26 

Total Offshore 

United States---------- 33.976 35.956 69.932 27.5 107 42 

Total Lower 48-------- 479.919 205.265 685.184 146.8 408 286 . 

2 

4 

Total Alaska---------- 0.905 31.867 32.772 14.8 76 29 

TOTAL UNITED STATEs-- 480.824 237.132 717.956 161.6 I 484 322 - -- -- I 

Inferred reserves were derived for all regions based on historical data (See Appendix). 

The low value of thP. range is the quantity associated with a 95 percent probability (19 in 20 chance) 

that there is at least this amount. The high value is the quantity with a 5 percent probability (1 in 

20 chance) tha~there is at least this amount. Totals for the low and high values are not obtained by 

arithmetic summation; they are derived by statistical methods. 

Inferred reserves based on national onshore average. 

Negligible--less than 0.001 trillion cubic feet. 

5 Estimates reported at the 75 and 25 percent probability levels because, in this area, these levels 

are judged to be more applicable for some planning purposes. It can also be noted that in frontier 

areas, lacking discovered indigenous or adjacent recoverable hydrocarbons, uncertainty is sufficiently 

great as to weaken probability estimates at extreme ranges. For purposes of comparison with other 

recorded ranges, the 95-5 percent probability range in offshore Atlantic is 0-22 trillion cubic feet 

of gas. 

- 80 

- 6 

- 91 

- 14 

- 111 

- 181 

- 529 

- 132 

- 655 
3 

l 

CUMULATIVE PRODUCTION AND DEMONSTRATED RESERVES 

OIL AND NATURAL GAS* 

(Conterminous U.S. Onshore and Offshore) 

8 : I 

. I I 

18 :------~ -----1 I 

_j ~-----· 

Total Oil 134 Billion Barrels 

Total Natural Gas <685 Trillion Cu Ft 

Data through December 197 4 

* For regional distribution of Inferred reserves, see tables 4 and 6 

FIGURE 9.-Cumulative production and demonstrated reserves of oil and natural gas by regions forth~ conterminous 

United States, onshore ·and offshore to 200 metres. 

CUMULATIVE PRODUCTION 

AND DEMONSTRATED RESERVES 

OIL AND NATURAL GAS* 

0 

(0) 

... , .... tJI!t4" 

Total on-11 BiUion Barrels 

Total Natural Gas·l 3 TriUion Cu Ft 

Data through December 197 4 

* For regional distribution of inferred reserves. see tables 4 and 15 

FIGURE 10.-Cumulative production and demonstrated reserves of oil and natural gas by regions for Alaska, 

onshore and offshore to 200 metres. 

32 

calculated by using the same general procedures 

described above for crude oil. However, it was 

assumed that the average recover.r factor for 

gas is currently 80 percent and that, ultimately, 

the recovery factor could be as large as 90 percent (A. M. Derrick, verbal commnn., El Paso 

Natural Gas Co., May 29, 1975). Tl1us, the subeconomic identified category was e:~timated to 

be 90-110 trillion cubic feet and the subeconomic component of undiscovered resources 

was estimated to be 40-82 trillion cubic feet. 

The user of these data should be aware that 

the forecasts recorded for measured, indicated, 

and inferred reserves are single-number pointestimates of these quantities, de:rived from 

API-AGA statistics. By contrast, undiscovered 

recoverable resources are treated here ·as uncertain quantities, the degree of uncertainty 

about each being expressed in the form of 

probabilities derived from calibr~ tion of expert opinion. Thus, for example, the judgmental 

probability that undi·scovered recoverable re-
ESTIMATED RANGE AND STATISTICAL MEAN OF UNDISCOVERED RECOVERABLE RESOURCES 

CRUDE OIL AND NATURAL GAS** 

(Conterminous U.S. Onshore and Offshore) 

Undiscovered Recoverable Oil 365581 Billion Barrels 

Undiscovered Recoverable Gas 1,§~"'~1,~ Trillion Cu Ft 40i" 

Marginal Probabthty A->llhed 

For regoonal distributto"l of tnferred 

reserves. see tables 4 and 5. 

FIGURE H.-Undiscovered recoverable resources of crude oil and natural gas for the conterminous United States, onshore ard offshore tO 

200 metres. (Ranges of va-lues were derived by Monte Carlo methods from estimates made by the Resource Appraisal Group and 

reported at 95-5 percent probability levels in billions of barrels for oil and trillions of cubic feet for gas.) 

sources of crude oil lie between 50 billion barrels and 127 billion barrels is 90%, and the 

judgmental probability that undiscovered recoverable resources of natural gas lie between 

322 trillion cubic feet and 655 trillion cubic 

feet is also 90%. 

For planning purposes, it is desirable to report probabilities of events for total recoverable resources; e.g., the probability that total 

recoverable resources are less than a given 

number or between two numbers. In order 

to do this in a logical fashion, measured, 

indicated, and inferred reserves would each 

have to be treated as uncertain quantities, 

and probabilities for each would have to be 

assessed as was done for undiscovered recoverable resources. All four categories could then 

be combined by the same computational methods used to aggregate probability assessments 

for individual provinces into probability assessments for regions or for the United States 

as a whole. 

1 Estimates reported at the 75 and 25 percent probability levelsbecause, in these areas, these levels are judged to be more applicable 

for some planning purposes. It can also be noted that in frontier areas, lacking discovered indigenous or adjacent recoverable hydrocarbons, uncertainty is sufficiently great as to weaken probability 

estimates at extreme ranges. For purposes of comparison with other 

recorded ranges, the 95-5 percent probability range in offshore 

Atlantic is 0-6 billion barrels of oil and o--22 trillion cubic feet of 

gas (fig. 11); in the Bering Sea it is 0-8 biHion barrels of oil and 

_0-18 trillion cubic feet of gas (fig. 12). 

ESTIMATED RANGE AND STATISTICAL MEAN OF 

UNDISCOVERED RECOVERABLE RESOURCES 

CRUDE OIL AND NATURAL GAS** 

(Alaska Onshore and Offshore) 

* 2w19 

* ~295@ 

5w16 

.. ~9) 

1z;6 

• liJl7 

... "'" ee•t~J14l• Undiscovered Recoverable Oil 12 z1

4 9 Billion Ba1·rels 

Undiscovered Recoverable Gas 1, 9J ,~ Jl3l Trillion Cu Ft 

* Marginal Probability Applied * * For regoonal dostribution of onferred reserves. see tables 4 and 5. 

FIGURE 12.-Undiscovered recoverable resources of crude oil and 

natural gas for Alaska onshore and offshore to 200 metres. 

(Ranges of values were derived by Monte Carlo methods from 

estimates made by the Resource Appraili!al Group and reported 

at 95-5 percent probability levels in billions of barrE'ls for oil and 

trillions of cubic feet for gas.) 

33 
CRUDE OIL RESOURCES OF THE UNITED Sl,ATES 

(BILLION BARRELS) 

ECONOMIC 

SUBECONOMIC 

IDENllFED 

Demonstrated 1 UNDISCOVEFED 

Inferred 

5

. · · o· :-:: :1· :2· ·:7· ·:• .-. • • 0 

... . . . ................. t ~~~-~ 

120-140 44-111 

0 

! 

·i ~--~------------~--------~~ 

Total U.S. Cumulative Oil Production 106 Billion Barrels 

12/31/74 

NATURAL GAS RESOURCES OF THE UNITED Sl-ATES 

(TRILLION CUBIC FEET) 

Inferred 

Demonstrated I lNlSCOVEFED 

Measured 

ro easi ~ ~ d geological assurance 

Total U.S. Cumulative Gas Production~~ 11. Trillion 

Cu Ft 12/31/7 4 

34 
• FIGURE 13.-Diagrammatic representation of estimated crude oil resources using the U.S. Geological Survey's resource classification system (modified from McKelvey, 1973). Cumulative 

oil production is cited below the figure. 

An intuitively plausible approximation, 

given that only single-number .point-estimates 

for measured, indicated, and inferred reserves 

are available, is to ·add these point-estimates to 

the end points of an interval of values of un- · 

di•scovered recoverable resources and then assert that the probability assigned to this interval for undiscovered recoverable resources 

is equal to the probability that total recoverable resources lie in the interval so translated. 

This is correct only under a very special assumption; namely, that measured, indicated, 

and inferred reserves are known with certainty 

and have values equal to the point-esUmates 

cited. Given this assumption, the probability 

that remaining recoverable resources of crude 

oil lie between 112 •billion barrels and 189 billion 1

barrels is 90% [to compute the interval, 

add 62 billion barrels (the !SUm of point-estimates for measured, indicated, and inferred 

reserves) to the end points (50 billion ·and 127 

billion ~barrels) of the 90J'o.probability interval 

for undiscovered recovemble resources]. Doing 

a similar computation using 237 trillion cubic 

feet •and 202 trillion cubic feet as point-estimates of measured reserves of natural gas ·and 

of inferred reserves of natural gas, respectively, 

the probability that total resources of natural 

gas lie in the interval 761 trillion cubic feet to 

1,094 trillion cubic feet is also 90%. 

With respect to crude oil, and taking into 

account that in fact there is uncertainty about 

measured, indic·ated, and inferred reserves, it 

i•s reasonable, without detailed calculations, to 

assert that the probability that total resources 

of crude oil lie in the intennal 112 to 189 billion 

barrels is 90% or smaller. With respect to natural gas, and taking into account that in fact 

there is uneertainty •about measured and inferred reserves, it is reasonable, without detailed calculations, to ·assert that the p'roba-

'bility that total resources of natural gas lie 

in the interval 761 to 1,091, trillion cubic feet 

i·s 90% or smaller. 

A slightly weaker assumption tha:n asserting 

that measured, indicated, and inferr·~d reserves 

are known with certainty and are e1ual to the 

point-estimates given them, is that each pointestimate equal•s the mean value of the uncertain quantities so estimated. Then the sum of 

point-estimates of measured, indicated, and 

inferred reserves plus the mean value of undiscovered recoverable resources ~-:n be interpreted a.s the mean value of total recoverable 

resources. 

Probability di·stribution eurves (from computer ·giraphic display), showing the ~total 

amounts for undiscovered recoverable oil and 

gas resources (derived by the MontP.J Carlo aggregating technique for each of .the 15 regions 

and for U.S. ·subtotals and totals), ar~ shown in 

the following figures: 

Undiscovered recoverable oil resourc,~s Figure 

Onshore Regions 1 through 11 ------------ 15 to 20 

Offshore Regions 1A through 11A -------- 21 and 22 

Total Lower 48 onshore and total Lower 48 

offshore ------------------------------ 31 

Total onshore United States and total o4fshore United States ------------------- 32 

Total United States ---------------------- 33 

Undiscovered reclYVerable gas resourc?st 

Onshore Regions 1 through 11 _________ --- 23 to 28 

Offshore Regions 1A through llA --------- 29 and 30 

Total Lower 48 onshore and total Lower 48 

offshore ------------------------------ 84 

Total onshore United States and total o .. -

shore United States -------------------- 35 

Total United States ---------------------- 36 

The reported range of undi.acover(~ resource 

estimates does not include the occurrence of 

VlOlumes which may fall either abov~ or below 

the 5 pereent and 95 percent p¥()babiUties 

shown. Inspection of the regional probability 

curves included with this report ·Shovrs the magnitude of estimates whierh could oo made for 

any ·selected range. The total prob<:l.bili:ty distribution ranges of 0 to 100 percent can be read 

directly from the cuTVes. 

• FIGURE 14.-Diagrammatic representation of estimated natural gas resources using the U.S. 

Geological Survey's resource classification system (modified from McKelvey, 1973). Cumulative gas production is cited below the figure. 

35 
ALASKA ONSHORE 

\,. 

~9.7$ 

~ 

__J 

~ 

COe.s 

<( 

ca 

0 

0::::: 

a_0.2 

~.e 

z.s 

~ 

1\ 

\ 

\ 

~ 

" 1--- 7,1,; 12.5 17.5 

BILLION BARRELS 

PACIFIC COASTAL STATES ONSHORE 

l. 

~0. 

~ 

__J 

~ 

co C!, 

<( 

co 

0 

0::::: 

a.. o. 

- t75 

5 

2 

e. 0 

z.o 

......... 

~ 

\ 

_\ ~ r--- 4.0 6.0 8.0 10.0 12.0 

BILLION BARRELS 

~.s 2?.s 

14.0 16.9 

FIGURE 15.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resources for onshore: 

Region 1. Alaska. 

Region 2. Pacific Coastal States. 

\lESTERN 'ROCKY MOUNTAINS ONSHORE 1.00 

~0.75 

~ 

__J 

~ 

CO e.se <( 

ca 

0 

0::::: 

a_0.Z 

0.0 

'5 

0 

e.e 

\ 

~ 

\ 

I~ ,___ 

2.j 5.9 7.5 10.0 

BILLION BARRELS 

NORTHERN ROCKY MOUNTAINS ONSHORE 1,6 

~8.7 

~ 

__J 

~ 

5 

co e.se <( 

ca 

0 

0::::: 

a.. 9.2 5 

0.0 0 

2.0 

~ 1\ \ 1'\. 

""' I'--~ 

4.0 6,9 9.0 19.0 t'Z.B 

BILLION BARRELS 

12.5 If. 0 

14.8 u.ra 

FIGURE 16.-Lognormal probability distrib•1tions of the 

Undiscovered Recoverable Oil Resourcer for onshore: 

36 

Region 3. Western Rocky Mountains. 

Region 4. Northern Rocky Mountains. 
WEST TEXAS AND EASTERN NEW MEXICO ONSHORE 

1. 

~e. 

........ 

_J 

........ 

o::l e. c::( 

o::l 

0 

0:::: 

a.. e. 

e. 

~ 

75 

50 

z 

e 

e.e 

\ 

f\ 

\ 

\ 

~ t---. 

5.e 10.e 15.e ze.e zs.e 

BILLION BARRELS 

WESTEfN GULF BASIN ONSHORE .00 '[\ ~e 

.50 

........ 

_J 

........ 

o::le 

c::( 

o::l 

0 

0:::: 

a.. e. 25 

e. 00 

e.o 2.5 

\ 

1\ 

\ \ 

"'--~ 

5.0 7.5 10.8 1Z.S ·15.0 

BILLION BARRELS 

30.0. 

17.5 

FIGURE 17.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resources for onshore: 

Region 5. West Texas and Eastern New Mexico. 

Region 6. Western Gulf Basin. 

MID-CONTINENT ONSHORE 1. 

>- o. t-

.... 

75 \ 

l 

1\ ....... 

_J 

........ 

o::l Cl. 

<( 

o::l 

0 

g: B. 

5 

25 \ 

"' I'-- e. ee 

e.e s.e 11!.8 15.6 

BILLION BARRELS 

MICHIGAN BASIN ONSHORE 

1.0 f) 

>- 0.7 

t- 5 \ ....... 

_J 

........ 

o::l fl. 5 

c::( 

o::l 

0 

0:::: 0... B.2 

e 

5 

e.e e.ae 

\ 

\ 

1\ 

~ t---

1.08 2.00 3.00 

BILLION BARRELS 

20.0 25.8 

'1.00 s.ee 

FIGURE 18.-Lognormal probability distributio"1s of the 

Undiscovered Recoverable Oil Resources for onshore: 

Region 7. Mid-continent. 

Region 8. Michigan Basin. 

37 
EASTERN INTERIOR ONSHORE l.O 0 

i= 0.7 5 

-

_J 

-~0.5 0 

CXl 

0 

0:::: 

a.. 8.2 s 

8,0 B 0.ee 

\ 

\ 

~ 

\ 

" 1'---- 1.80 2.00 3.00 

BILLION BARRELS 

APPALACHIANS ONSHORE .& 

5 

0, 0 

o.oo 

'\ 

r\ 

\ 

\ 

I~ r--- 0.50 1.ee 1.50 a.ee 

BILLION BARRELS 

4,00 5.08 

2,50 3.00 

FIGURE 19.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resources for onshore: 

Region 9. Eastern Interior. 

Region 10. Appalachians. 

EASTERN GULF AND ATLANTIC COASTAL PLAIN ONSHORE 

,l..O 

i= 0."7 

-

_J 

-

CXl e.s c::( 

CXl 

0 

0:::: 

a.. 111.2 

s 

(11.0 

o.oo 

" 1\ 

\ 

'\ 

"' "' ~ t--

0.50 a.oo 

BILLION BARRELS z.se 3.00 

FIGURE 20.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resources for onshore: 

Region 11. Eastern Gulf and Atlantic Coastal Plain. 

ALASKA OFFSHORE 

1. 

·:~ i= e. 

-

_J 

-

CXl e. c::( 

CXl 

0 

0:::: 

a.. e. 

.. 

7 

s~ 

2 

0 

o.e 

' 1\ 

"\ 

~ t--

10.0 

BILLION BARREL~ 

PACIFIC COASTAL STATES Oli'SHORE 

1.00 

i=0.7S 

-

_J 

-

CXl 9.50 

c::( 

co 

0 

0:::: 

a.. 0,2 5 

0 

"" r\ 

\ 

"" " ~ 1--- 0,0 

l.BB 2.08 3.00 4.EI9 5.89 

BILLION BARREL: 

40.0 se.e 

7.99 8.08 

FIGURE 21.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resourc~s for offshore: 

Region 1A. Alaska ( 0-200 m). 

Region 2A. Pacific Coastal States (0-200 m). 

38 
GULF OF MEXICO OFFSHORE 

I, 0 

>- 1-0 . ·= ........ 

_J 

........ 

~e. 

cc 

0 

0:: 

c.. e. 

s 

2 

~ 

1\ 

\ 

\ 

~ 

o. e 3.0 s.e 

~ 

7.0 

~ 

BILLION BARRELS 

ATLANTIC COASTAL STATES OFFSHORE 1 .... 

~ o. 

........ 

_J 

........ 

~e. 

cc 

0 

0:: 

c.. o. 

7 

5 

It 

~ '\ 

"' "\ ~ t---- 2.6 4,0 6.0 

BILLION BARRELS 

9.0 

s.e 

11,0 

10.0 

FIGURE 22.-Lognorm.al probability ·distributions of the 

Undiscovered Recoverable Oil Resources for offshore: 

Region 6A. Gulf of Mexico (0-200 m). 

Region llA. Atlantic Coastal States (0-200 m). 

ALASKA ONSHORE 

J.,O 

>- 1- o.7 ~ 

........ 

_J 

........ 

cc c:c o.s 

cc 

0 

0:: 

e 

c.. 0.2 

e.e • IG 

" 1\ 

\ 

\ ~ r--. 1-:-:-:-.- ·-

TRILLION CUBIC FEET 

PACIFIC COASTAL STATES ONSHORE 

1 • ... 

>- 1- •. ........ 

_J 

........ 

~o. 

cc 

0 

0:: 

c.. 0. 

e. 

75 

"' 

t 

0 

6.11 

''\ 

\ 

\ 

K I--. 

10·· 1S.O 20.0 es.0 

TRILLION CUBIC FEET 

FIGURE 23.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas ResOl,t'Ces for onshore: 

Region 1. Alaska. 

Region 2. Pacific Coastal States. 

39 
WESTERN ROCKY MOUNTAINS ONSHORE loO 

~O,?S 

......... 

....J 

......... 

a:l o.S 

o;:( 

ca 

0 

ex: 0.. o.a 

0 

\ 

\ 

\ 

~ :--_ 

e.e Z.5" 10.~ 17.5 32.5 ~7. s 

TRILLION CUBIC FEET 

NORTHERN ROCKY MOUNTAINS ONSHORE 

l· 

~o. 

......... 

....J 

......... 

ca o. c::( 

a:l 

0 

0:::: 

0.. o. 

o. 

75 

5 

~· 

0 

"""' \ 

\ 

' " ' 1'--- 10.0 20,0 30.0 ~e.e se.e - 60.0 ?e.e 

TRILLION CUBIC FEET 

FIGURE 24.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas Resources for onshore: 

Region 3. Western Rocky Mountains. 

Region 4. Northern Rocky Mountains. 

40 

WEST TEXAS AND EASTERN NEW MEXICO ONSHORE t. 

~o. 

......... 

....J 

......... 

a:l e. c::( 

a:l 

0 

0:::: 

0.. o. 

,, 

s 

26 

.oo 

\ 

\ 

\ 

~ r--- .. 0 

TRILLION CUBIC FEET 

WESTERN GULF BASIN ONSHORE 

1. "" 

>-e 

1--

......... 

.7 

....J 

......... 

aJO 

c::( 

a:l 

0 g:o 

0 

,6 

. .. ~ 

.o 0 

' r\ 

\ 

\ 

"" t-:-.. 

so 1S0 

TRILLION CUBIC FEET 

175 

FIGURE 25.-Lognormal probability distri'·~1tions of the 

Undiscovered Recoverable Gas Reso·,rces for onshore: 

Region 5. West Texas and Eastern Ne..,., Mexico. 

Region 6. Western Gulf Basin. 
MID-CONTINENT ONSHORE 

.. 

~·· ....... 

...J 

....... 

~ o. 

a:l 

0 

a:: 

0.. o. 

., 

i 

as 

0 ,0 

\ 

~ \ 

""' ~ 

0 

TRILLION CUBIC FEET 

MICHIGAN BASIN ONSHORE 

.. 

>- •. 

1-

....... 

...J 

....... 

a:l o. c::( 

a:l 

0 

g: o. 

'15 

5 

25 

o. oo 

o.oo o.so 

\ I\ 

\ 

\ 

__.... I"' r-:-:-... ....L 

1.ee s.ose a.ee a.se 

TRILLION CUBIC FEET 

3.ee 3.50 

FIGURE 26.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas Resources for onshore: 

Region 7. Mid-continent. 

Region 8. Michigan Basin. 

41 

EASTERN INTERIOR ONSHORE L0 

~ 0.1 ' ....... 

...J 

....... 

a:l 0.5 c::( 

a:l 

0 

ex: 

0.. 0.2 

e • 0 

o.o 

\ 

\ 

\ 

1\ 

"' t----

a.o 4.0 6.0 e.e 

TRILLION CUBIC FEET 

APPALACHIANS ONSHORE .. ~ --1\ • 7'5 

.5 ~ ' .as \ 

" .o ... s.o 10.0 u;.e 

~ 

ae.e a5.e 3e.e 

TRILLION CUBIC FEET 

10·· 

:ss.e 

FIGURE 27.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas Resource.s for onshore: 

Region 9. Eastern Interior. 

Region 10. Appalachians. 
EASTFF&J :roLF AND ATLANTIC COASTAL P I.ATlil ONSBlRE 

~ 0,7 5 

--l 

-

co 0,5 11 c::( 

co 

0 

c::: 

a.. e.z 

e,ea O.B9 

\ 

~ 

\ 

~ t--- e.SB 1.1!18 1.56 z.eo 

TRILLION CUBIC FEET '3.00 

FIGURE 28.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas Resources for onshore: 

Region 11. Eastern Gulf and Atlantic Coastal Plain. 

ALASKA OFFSHORE 

t. 

~0. 

--l 

-

CO e. c::( 

co 

0 

c::: 

0... o. 

e. 

-~"' 75 

5 

z 

0 

\ 

' 

~ 

' ~ 1'--

0 zo 80 100 

TRILLION CUBIC FEET 

PACIFIC COASTAL STATES OFFSHORE 

'l. 00 

~e. 

--l 

-

co e. c::( 

co 

0 

c::: 

a.. e. 

o. 

-

25 

e 

.l,G 

'""" 1\ 

\ 

1\ 

\ 

""' 1'---. t---. 

J.O 5.0 7.9 

TRILLION CUBIC FEET 

140 

9.8 

FIGURE 29.-Lognormal probability distributions of the 

Undiscovered Recoverable Oas Resources for offshore: 

Region lA. Alaska (0-200 m). 

Region 2A. Pacific Coastal States ( 0-200 m) . 

GULF OF MEXICO OFFSHORE 

.v 

~0 .75 

-l 

-

-

~e 

co 

0 

c::: 

O...e 

.50 

.2 

\ 

r\ 

\ 

\I 

f\. 

" I'-- 0 ..... e. 25. 58. 75. 108. 12'5. 158 

TRILLION CUBIC FE[T 

ATLANTIC COASTAL STATES OFFSHORE 

.. 

~·· --l 

-

coo. 

c::( 

co 

0 

., 

~~ 

5 

g:e .2 ""' "\ 

"" '~ r----

175. 

e. ee 

e.e s.e lO.e 1S.o a.o 2s.e Jlll.e 35.8 

TRILLION CUBIC FEET 

FIGURE 30.-Lognormal probability distril)utions of the 

Undiscovered Recoverable Gas Resources for offshore: 

Region 6A. Gulf of Mexico (0-200 m). 

Region llA. Atlantic Coastal States (0-200 m). 

42 
TOTAL LOWER 48 ONSHORE 

,v 

>- t-• 

1---4 

...J 

1---4 

ca. 

c:( 

ca 

0 

0:::: 

0... e. 

,& 

,.,. 

0 ... 

20.0 

.......... 

"' \ 

i\. 

\ 

' I'-- Je,O -40,8 '58.8 &e,e ?e.8 

BILLION BARRELS 

TOTAL LOWER 48 OFFSHORE 

'·" .. 

~~~-75 

1---4 

...J 

1---4 

ca e.s c:( 

ca 

0 

0:::: 0... o.z 

0.G z •. '!i 

~ 

\ 

\ 

~ r-- T.S 1i!,S 17,5 

BILLION BARRELS 

80,8 

aa.s i!7, s 

FIGURE 31.-Lognormal probability distribution of the 

Undiscovered Recoverable Oil Resources for onshore and offshore: Total Lower 48 onshore and 

total Lower 48 offshore (0-200 m). 

TOTAL U. S. ONSHORE (LOWER 48 AND ALASKA) 

1. v ' r'\. ,7 

~ 

\ 2S \. ~ 

e. • . '5'J ?e 

"'---as. 1ee 11'5 

BILLION BARRELS 

TOTAL U. S. OFFSHORE (LOWER 48 AND ALASKA) 

1 .o ............ 

1\ .7'i \ 

.6 ~ 

25 

\~ 

" "'-t--

·- 20 40 6e 

BILLION BARRELS 

FIGURE 32.-Lognormal probability distributhns of the 

Undiscovered Recoverable Oil Resources for onshore 

and offshore: Total onshore United States (Lower 

48 and Alaska) and total offshore United States 

(Lower 48 and Alaska, 0-200 m). 

43 
TOTAL U, S. ONSHORE AND OFFSHORE 

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

"' ,? \ ~ _.,. 

... ~ ~~ 1---- .. -;5 ... 125. 158 

·~ BILLION BARRELS 

FIGURE 33.-Lognormal probability distributions of the 

Undiscovered Recoverable Oil Resources for total 

United States, onshore and offshore (0-200 m). 

TOTAL LOWER 48 ONSHORE 

1. ... 

'5 

"' 

o. 0 

200 

---. 

~ 

1\ 

"\ 

~ 

. " ~ . ~ 

- TRILLION CUBIC FEET 

l'OTAL LOWER 48 OFFSHORE 

l • ... 

~0 ,?5 

....... 

_J 

....... 

ca e. c( 

ca 

0 

g: 0. 

e. 

s 

2 

-

'[\ 

\ 

\ 

"'-1--- 0 100 l:SO. 

TRILLION CUBIC FEET 

sso 

288. 

FIGURE 34.-Lognormal probability distributions of the 

Undiscovered Recoverable Gas Resources for total 

Lower 48 onshore and total Lower 48 offshore 

(0-200 m). 

TOTAL U .. S ONSHORE (LOWER 48 AND ALASKA) 

1. 

~· ....... 

_J 

- --..... 

·' 

~ 

\ ....... 

C:Oe 

c( 

C:O 

0 

0:::: 

r\ 

,$ 

c..• ,2 ~ ~~ ...._ . . 0 • o 

zoo 

TRILLION CUBIC FEET 

TOTAL U.S. OFFSHORE (LOWER 48 AND ALASKA) 

1 • "" 

~e .75 

....... 

__J 

....... 

C:Oe 

c( 

C:O 

0 

0:::: 

c.. a 

... 

,2 

""' \ 

\ 

\ 

I' "' ~'----~ 

S?S 

0 ..... e. se. tea. tso. 200. Z'SG. !Qe • 

FIGURE 35.-Lognormal probability distribt,tions of the 

Undiscovered Recoverable Gas Resources for total 

onshore United States (Lower 48 and Alaska) and 

the total offshore United States (Lower 48 and 

Alaska, 0-200 m). 

44 

TOTAL U.S. ONSHORE AND OFFSHORE 

.. ... 

~ .. ....... 

_J 

....... 

co •. 

c( 

co 

0 

g: •. 

o . 

.. 

i! 

.. 

aose 

~ 

~ 

\ 

I"' ~~ r-- .... 3Se. 

TRILLION CUBIC FEET 758. sse 

FIGURE 36.-Lognormal probability distrib•ltions of the 

Undiscovered Recoverable Gas Resour~es for total 

United States, onshore and offshore (0-200 m). 
RESULTS--UNDISCOVERED RECOVERABLE NATURAL 

GAS LIQUIDS RESOURCES 

Table. 6 summarizes the resu1ts for undiscovered recoverable resource estimates of 

natural gas liquids in the United States derived 

from historical ratios based upon natural gas. 

cumulative production. 

The total undiscovered recoverable resources 

of NGL, calculated by applying different regional factors to the statistical mean estimates for 

ga:s,are 15.8 billion barrels. If the national average (33 barrels NGL per million cubic feet of 

gas) is applied, the resources are cal·culated to 

be 16.0 billion barrels. 

Total U.S. NGL cumulative production to the 

end of 1974 was 15.73 billion barrels; measured 

reserves were 6.35 billion barrels; inferred reserves, estimated at 6 billion barrels; and the 

range for undiscovered recoverable resources, 

based on the calculated NGL/natural gas ratio 

is 11 to 22 billion barrels (Table 1, p. 4). 

COMPARISON OF HYDROCARBON RESOURCE 

ESTIMATES IN THE UNITED STATE.~ 

There have been many past estimates· of U.S. 

oil and gas resources. The many possible parameters which affect resource figures have not 

always been taken into consideration when different estimates were compared. Tenninology 

has often been inadequately defined, and figures 

have been compared without asce':'taining 

whether they were comparable. Some examples 

are: inclusion or deletion of important regions 

such as Alaska; varying offshore boundaries as 

determined by different water depths; inclusion 

or exclusion of natural gas liquids; an1 inclusion or exclusion of inferred (pr')bable) 

reserves. 

Figures 37 and 38 summarize and eompare 

some of these estimates. 

The first group of estimates in figur~~ 37 depicts only those that specifically inclu1e total 

undiscovered recoverable liquid hydrc<>..arbons 

TABLE 6.-Estimates of undiscovered recoverable resources for natural gas liquids in the United States 

Region 

1. Alaska -------------------- 2 33 

2. Pacific Coastal States----- 41 

3. Western Rocky Mountains 1---

l 26 4. Northern Rocky Mountains--

5. West Texas and 

Eastern New Mexico ------- ~0 

6. Western Gulf Basin--------- 33 

7. Mid-Continent-------------- :n 

8. Michigan Basin ------------ 27 

9. Eastern Interior----------- 33 

10. Appalachians -------------- 8 

11. Eastern Gulf and 

Atlantic Coastal Plain --- 33 

Total Lower 48 Onshore --

Total Onshore 

United States ----------

lA. Alaska-------------------- 25 

2A. Pacific Coastal States ---- 41 

6A. Gulf of Mexico ------------ 25 

llA. Atlantic Coastal States --- 3 25 

Total Lower 48 Offshore--

Total Offshore 

United States ------------

Total United States ----- 33 

Undiscovered Recoverable 

Natural Gas-Statistical Mea 

(in trillions of cu ft) 

ONSHORE 

32 

13 

43 

70 

133 

72 

1 

10 

1 

345 

377 

OFFSHORE (0-200 metres) 

44 

50 

10 

63 

107 

484 

1 Regions 3 and 4 were treated together because of data availal,ility. 2 Ratio assumed to be national average. 

3 Ratio assumed to be offshore average. 

45 

Undiscovered 

Recoverable r!GL 

(in billions of bbls) 

1.1 

0.5 

1.1 

3.5 

4.4 

2.2 

0.1 

0.1 

11.9 

13.0 

1.1 

0.1 

1.3 

0.3 

1.7 

2.8 

15.8 
~ 

0) 

(/) 

...J 

w 

a: 

a: 

<( 

m 

z 

0 

~ 

...J 

as 

~ 

(/) 

a 

5 

0 

~ 

U.S. UNDISCOVERED RECOVERABLE RESOURCES OF LIQUID HYDROCARBONS 

ONSHORE AND OFFSHORE 

Max 

264 

113 

ALASKA 

Offshore~ 

Onshore. 

LOWER 48 

Offshore a .,.,_.,....., 

Onshore ~.,' .'·~i'' 

OffshoreOnshore 

Combined 

Offshoreg~~~~~~d 

A LASKA AND LOWER 48 

D 

.,..._ __ UNDISCOVERED OIL AND N.G. l.--------

232 

Range 

50-127 

255 

NPC 

1970 

(9) 

UNDISCOVERED OIL-+11.-- UNDISCOVERED AND--. 

INFERRED (PROBABLE) OIL 

(1) Theobald and others, U.S. Geol. Survey Circ 650, 1972. Includes water depth to 2,500 m (8,200 ft). 

(2) U.S. Geol. Survey News Release, March 26, 1974. Includes water depth to 200m (660ft). 

(3) Hendricks, U.S. Geol. Survey Circ. 522, 1965. Adjusted through 1974. Includes water depth to 200m (660ft). 

(4) Nat'l. Academy of Sciences, "Mineral Resources and the Environment," 1975. (See National Research Council). 

Water depth not indicated. 

__1._50 

___9;,00 

__1.50 

_lOO 

_1.50 

__2_00 

_1_50 

00 

(5) U.S. Geol. Survey "Mean", Oil and Gas Branch Resource Appraisal Group, 1975. Includes water depth to 200m (660ft). 

(6) Mobil Oil Corp., Expected Value: Science, 12 July 1974. (See Gillette). Includes water depth to 1,830 m (6,000 ft). 

(7) Weeks, L.G., Geotimes, July-Aug., 1960. Adjusted through 1974. Water depth not indicated. 

(8) Hubbert, Senate Committee Report, 1974. Includes water depth to 200m (660ft). 

(9) Am. Assoc. Petroleum Geologists Mem. 15. 1971. Also National Petroleum Council, "Future petrolP.ttm prnvincP.s nf 

the United States," 1970. Some areas are excluded from this estimate. Includes water depth to 2,500 m (8,200 ft). 

(10)National Petroleum Council, "U.S. Energy outlook-- oil and gas availability," 1973. Includes water depth 

to 2,500 m (8,200 ft). 

FIGURE 37.-Comparative estimates of oil resources in the United States. 
Iw 

w 

u.. 

() 

iD 

::J 

() 

z 

0 

:::i 

...J 

a: 

I-

~ 

f/) 

<( 

(!) 

20 

12 

7 

5 

U.S. UNDISCOVERED RECOVERABLE RESOURCES OF NATURAL GA~ 

2100 

1972 

(1) 

Max 

1974 

(2) 

1965 

(3) 

ONSHORE AND OFFSHORE 

ALASKA 

Ofhho"~ OffshoreOnshore 

Combined Onshore 

LOWER 48 

Ofhhocld 

On shore . · 

ALASKA AND LOWER 48 

Range 

322-655 

1973 1975 1975 

(4) (S) (6) 

D 

1974 

( 7) 

1974 

(8) 

NP 

1965 1971 1973 1973 1975 NPC (3) 1970 (10) (4) (6) 

--------UNDISCOVERED GAS-----

( 9} 

-UNDISCOVERED AND--+ 

INFERRED (PROBABLE) GAS 

(1) Theobald and others, U.S. Geol. Survey Circ. 650, 1972. Includes water depth to 2,500 m (8,2.00 ft). 

(2) U.S. Geol. Survey News Release, March 26, 1974. Include8 water depth to 200m (660 ft). 

(3) Hendricks, U.S. Geol. Survey Circ. 522, 1965. Adjusted through 1974. Includes water depth to 

200m (660ft). 

(4) Potential Gas Committee, "Potential supply of natural gas in the United States," 1973. Includes 

water depth to 460 m (1,500 ft). 

(5) Nat'l. Academy of Sciences, "Mineral Resources and the Environment," 1975. (See National Rese.arch 

Council). Water depth not indicated. 

(6) U.S. Geol. Survey "Mean", Oil and Gas Branch Resource Appraisal Group, 1975. Includes water depth 

to 200m (660 ft). 

(7) Mobil Oil Corp., Expected Value: Science, 12 July 1974. (See Gillette). Includes water deptt to 

1,830 m (6,000 ft). 

(8) Hubbert, Senate Committee Report, 1974. Includes water depth to 200m (660ft). 

(9) Am. Assoc. Petroleum Geologists Mem. 15, 1971. Also National Petroleum Council, "Future petroleum 

provinces of the United States," 1970. Some areas are excluded from this estimate. Includes water 

depth to 2,500 m (8,200 ft). 

(lO)National Petroleum Council, "U.S. energy outlook -- oil and gas availability," 1973. Include.s water 

depth to 2,500 m (8,200 ft). 

FIGURE 38.-Comparative estimates of natural gas resources in the United States. 

(crude oil plus nwtural gas liquids) ; the second 

group includes estimates for crude oil only; the 

third group depiots undiscovered recoverable 

resources of crude oil plus inferred (probable) 

reserves of crude oil. 

metres water depth. Some estimates inc1ude offshore areas beyond 200 metres, as indic f-lted. 

Where possible, an attempt was mado to subdivide the estimates into oonJterminous States 

(Lower 48) and Alaska, with a furthe':' breakFigure 38 shows the first gr:oup of estimates down into onshore and off·shore. 

for undiscovered recoverable natural gas only; 

the second group includes inferred (probable) 

reserves. 

All the estimates shown in figures 37 and 38 

include at least the Continental Shelves to 200 

Because the estimators reported thE';r numbers with ·such a variability of paramet~rs, the 

following explanations are provided for comparing the various calculated estimates: 

Hubbert, M. King, 1974.-The undiscovered 

47 
oil and gas resources for the conterminous 

United States (29 billion barrels of oil and 281 

trillion cubic feet of gas) are shown in the text 

and graphs as of 1972 (Hubbert, p. 123, 125, 

145, 146). The figures for Alaska were derived 

by applying Hubbert's factor (40 percent) for 

the degree of advancement of petroleum and 

natural gas discovery in Alaska to the ultimate 

amount to be produced (43 billion barrels oil 

and 134 trillion cubic feet; p. 153, 154), yielding 26 billion barrels oil and 80 trillion cubic 

feet of gas. NGL's were derived by application 

of the factor of 30,000 cubic feet gas/barrel of 

NGL (Hubbert, p. 151, 154) to undiscovered 

gas, yielding 9 billion barrels NGL for the conterminous United States and 3 billion barrels 

NGL for Alaska. 

Hendricks, T. A., U.S. Geological Survey, 

1965.-Cumulative production, proved remaining reserves, indicated reserves, and calculrated 

inferred reserves,as of the end of 1974, were 

subtracted from H·endricks' total economically 

recoverable oil, natural gas, and natuval gas 

liquids. 

National Petroleum Council, 1970; American 

Association of Petroleum Geologists, 1971.-

The total undiscovered recoverable oil resources 

reported (table 3, p. 24, Memoir 15) are the sum 

of the "possible" and "probable" for all regions 

and the "speculative" only for region 11 (Ears.tern Gulf and Atlantic Coast Plain, onshore and 

offshore). The total undiscovered recoverable 

gas resources are the sum of "possible," "probable," and "speculative" for all regions. The 

figures do not represent the estimated potential 

of the entire United States. Some of the areas 

excluded from the studies were the offshore of 

Alaska outside· of Cook Inlet and Bristol Bay, 

the onshore and offshore of Washington and 

Oregon, and the offshore of central and northern California. Therefore these estimates may 

be understated in comparison with other estimates for the entire United States. 

National Petroleum Council, 1973.-Remaining disco:verable oil-in-place was reported. The 

amounts of undiscovered recoverable oil shown 

here were derived by applying primary recovery 

factors, as reported by the National Petroleum 

Council for each region, to their remaining discoverable oil-in-place numbers. The National 

Petroleum Council reports as remaining discoverable oil-in-place, the sum of probable, possible, and half of the speculative categories. 

Weeks, L. G., 1960.-Cumulative: production, 

proved remaining reserves, indicated reserves, 

and calculated inferred reserves at the end of 

197 4 were subtracted from Weeks' ultimate resou~ces of liquid petroleum. 

CONCLUSIONS 

The oil and gas resource asseE·sments presented in this report are the produ(>.t of a careful analysis of a large quantity of fundamental 

data by many highly qualified geologists. The 

"new approach" used is in reality ·a combination 

of many individual approaches thr.t have been 

u~ed by previous estimators, standardized, and 

documented for public inspectio:'l. Sufficient 

data have been collected and anal.'"Zed to provide a well-founded, balanced appr<:\.i:sal of U.S. 

oil and natural gas resources; the r~~sults should 

be regarded as a first attempt to apply new 

methods to available informatior. These resource estimates are .subject to revision as 

methodology improves, better data are acquired, technology changes, changing economic 

conditions are taken into account, rand as deepwater ·areas are incorporated into the appraisal. 

The primary purpose of this study was to estimate the ·amount of oil and gas available for 

discovery and recovery under conditions representing ·a continuation of historic·al trends of 

technology .and economics; no atte1npt has been 

made to predict how much wiH b~ discovered, 

nor when discoveries will be made:·. The uncertainties involved are emphasized by reporting 

undiscovered recoverable resource estimates in 

terms of ranges of values, representing on the 

one hand a 19 in 20 chan.ce that there is more 

than the low value and on the other hand, a 1 in 

20 ·chance that there is at least as much as the 

high value. Thus, the current appraisals indicate that the estimated statisical mean of undiscovered recoverable resources o-!. crude oil in 

the United States, onshore and offshore, 

amounts to 82 billion barrels, but this value lies 

within a range of 50 to 127 billion barrels. The 

corresponding figures for gas are: a statistic:aJ. 

mean of 484 trillion cubic feet, wit:h in a range of 

48 
322 to 655 trillion cubic feet. In each case the 

mean value of the undiscovered recoverable 

quantity is on the order of one-half the amount 

which has been identified and produced to date 

(tables 4 and 5). The results also suggest that 

nearly one-half of the undiscovered recoverable 

oil resources and more than one-quarter of the 

undiscovered recoverable gas resources may 

occur in off.shore regions of the United States 

and in the onshore frontier provinces of the 

State of Alaska. It is important to note that 

these resources are located in regions of difficult and costly operations-particularly in the 

hostile physical environment of the Arcticand require long lead times for exploration and 

development. 

The Resource Appraisal Group plans to continue development of an oil and gas resource 

appraisal system within the U.S. Geological 

Survey. A great quantity of geological andrelated data is available which still needs to be 

analyzed and integrated into the system. It is 

anticipated that activities will be focused on updating and adding critical information not only 

through our own efforts but by coordination 

with other interested groups. Special projects 

planned include such items as field size distribution studies, petroleum zone studies, develoPment of penetration maps and cross sections to 

show locations and results of wells drilled, ap.-

praisal of deep-water potential, and acquisition 

and development of data banks and data systems. Economic studies also are needed and can 

be integrated into the system. As new data, 

new interpretations, and new procedures become available, the current estimates will be 

refined and revised. 

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of Alaska: Am. Assoc. Petroleum Geologists Pacific 

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American Association of Petroleum Geologists, 1969, 

Circum-Gulf of Mexico issue: Am. Assoc. Petroleum 

Geologists Bull., v. 53, no. 12, pt. 2, p. 2397-2709. 

--- 1974, [North American developments for 1973 

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American Geological Institute, 197 4, Dictionary of geological terms: Garden City, N.Y., Anchor Books, 

545 p. 

49 

American Petroleum Institute, 1971, Petrole•,m facts 

and figures: Washington, D.C., Am. Petrol(''lln Inst., 

604 p. 

American Petroleum Institute, American Gas Association, and Canadian Petroleum Associatkn, 1966-

1974, Reports on proved reserves of crud~ oil, natural gas liquids, and natural gas in tre United 

States and Canada [annual volumes for the years 

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Beebe, B. W., and Curtis, B. F., eds., 1968, Natural 

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gases in rocks of Mesozoic age, Pt. 2, V. 1; and 

Natural gases in rocks of Paleozoic age, Pt. 3, V. 2; 

Papers of general scope, Pt. 4, V. 2, of Natural 

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v. 1, p. 1-1226; v. 2, p. 1227-2493. 

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Cram, I. H., ed., 1971, Future petroleum provinces of 

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Assoc Petroleum Geologists Mem. 15, v. 1, p. 1-803, 

v. 2, p. 805-1496. 

Crow, E. L., Davis, F. A., and Maxfield, M. W., 1960, 

Statistics manual: New York, Dover Pub. Inc., 

288 p. 

Eardley, A. J., 1962, Structural geology of North 

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Emmerich, H. H., ed., 1974, Selected papers f~om East 

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58, no. 6, pt. 2 of 2, Spec. Issue, p. 1055-1239. 

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Gary, Margaret, McAfee, Robert, Jr., and W(Jlf, C. L., 

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Gillette, R., 1974, Oil and gas resources-did U.S.G.S. 

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130. 

Grantz, A. A., Holmes, M. L., and Kososki, B. A., 1975, 

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Survey open-file rept. 75-124, 49 p. 

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framework of petrolifero us rocks in Alar ka: Am. 

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Am. Assoc. Petroleum Geologists Mem. 14, 575 p. 

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natural-gas liquids in the United States and the 

world: U.S. Geol. Survey Circ. 522, 20 p. 

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the Committee on natural resources of the National 

Academy of Sciences-National Research Council: 
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Geologists Bull., v. 51, no. 11, p. 2207-2227. 

--- 1974, U.S. energy resources, a review as of 1972, 

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Kaufman, G. M., 1962, Statistical decision and related 

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America: U.S. Geol. Survey, scale 1:5,000,000, 2 

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K. M., 1974, Energy and mineral resources of 

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A. M., ed., Mesozoic-Cenozoic orogenic belts: Geol. 

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McCulloh, T. H., 1973, Oil and gas, in Brobst, D. A., 

and Pratt, W. P., eds., United States mineral resources: U.S. Geol. Survey Prof. Paper 820, p. 

477-496. 

McKelvey, V. E., 1973, Mineral resource estimates and 

public policy, in Brobst, D. A., and Pratt, W. P., 

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--- 1974a, USGS releases revised U.S. oil and gas 

estimates: U.S. Dept. Interior News Release, 4 p., 

1 table, March 26. 

--- 197 4b, Hydrocarbon reserves and resources of 

the United States: Testimony before Special Subcommittee on integrated oil operations of Senate 

Committee on Interior and Insular Affairs, Feb. 

20, 1974. 

Maher, J. C., and Applin, E. R., 1971, Geologic framework and petroleum potential of the Atlantic coastal 

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Martin, R. G., and Case, J. E., 1975, Geophysical studies in the Gulf of Mexico, in Ocean basins and 

50 

margins, V. 3, of The Gulf of Mexico and Caribbean 

Sea: New York, Plenum Press [in press]. 

Megill, R. E., 1971, Exploration economics: Tulsa, Okla., 

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Meyerhoff, A. A., 1967, Future hydroca1·hon provinces 

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Schlee, J., Behrendt, J. C., Mattick, R. E., and Taylor, 

P. T., 1975, Structure of continental margin off 

mid-Atlantic States (Baltimore Can:Ton Trough) : 

U.S. Geol. Survey open-file rept. 75-60, 45 p. 

Smith, M. B., 1964, Map showing distribution and configuration of basement rocks of California: U.S. 
Geol. Survey Oil and Gas Inv. Map. OM-215, scale 

1:5,000,000. 

State of Alaska, 1973, Statistical report: Alaska Div. 

Oil and Gas, 209 p. 

State of California, 1971, The offshore petroleum resources: California Resources Agency, Dept. Conserv., 192 p. 

--- 1973, Energy in California: California Resources 

Agency, Rept. TR07, 69 p. 

--- 1973, Oil and gas and geothermal production 

statistics: California Div. Oil and Gas. Summ. Operations, v. 59, no. 2, 187 p. 

Spurr, W. A., and Bonini, C. P., 1973, Statistical 

analysis for business decisions: Homewood, Til., 

Richard D. Irwin, Inc., p. 97-98, 114, 376, 378. 

Stose, G. W., and Ljungstedt, 0. A., compilers, 1932, 

Geologic map of the United States: U.S. Geol. Survey, scale 1: 2,500,000. 

Theobald, P. K., Schweinfurth, S. P., and Duncan, 

D. C., 1972, Energy resources of the United States: 

U.S. Geol. Survey Circ. 650, 27 p. 

U.S. Bureau of Mines, 1967, Heavy crude oil-resource, 

reserve, and potential production in the United 

States: Petroleum Staff, Mineral Resources Office, 

76 p. 

U.S. Department of the Interior, 1968, United States 

petroleum through 1980; U.S. Dept. Interior, 92 p. 

--- 1969, Petroleum and sulfur on the continental 

shelf-a summary of activity in exploration and 

production of oil, gas, and sulfur 1953-1963: U.S. 

Dept. Interior, 61 p. 

51 

--- 1970, National atlas base map of AlaRka: U.S. 

Geol. Survey, scale 1:2,000,000. 

--- 1973, Federal and Indian lands-oil and gas 

production, royalty income and related statistics for 

calendar year 1973: U.S. Geol. Survey Conserv. 

Div., 326 p. 

--- 197 4, Outer continental shelf statistics, 1953 

through 1973: U.S. Geol. Survey Consr~rv. Div., 

83 p. 

--- 1974, New mineral resource terminology adopted: 

U.S. Dept. Interior News Release, April. 

U.S. Geological Survey, 1975, Sediments, structural 

framework, petroleum potential, environm~ntal conditions, and operational considerations of the MidAtlantic area: U.S. Geol. Survey open-file rept. 

75-61, 143 p. 

Vlissides, S. D., and Quirin, B. A., 1964, Oil and gas 

fields of the United States exclusive of Alaska and 

Hawaii: U.S. Geol. Survey scale 1: 2,50'1 ,000. 

Webster's Third New International Dictionary of the 

English Language Unabridged, 1971: S"'"'.'ing:field, 

Mass., G. C. Merriam Co., 2662 p. 

Weeks, L. G., 1950, Concerning estimates of potential 

petroleum reserves: Am. Assoc. Petrole:um Geologists Bull., v. 34, p. 1947-1953. 

--- 1960, The Next Hundred Years~ Energ:r Demand 

and Source of Supply: Geotimes, v. 5, no. 1, p. 

18-21 and 51-55. 

West, J., 1974, U.S. oil-policy riddle-how much left 

to find?: Oil and Gas Jour., v. 72, no. 37, p. 25-28. 

Zapp, A. D., 1962, Future petroleum producing capacity in the United States: U.S. Geol. Survey Bull. 

1142-H, 36 p. 

APPENDIX 
RAG Pr >vi nee Nt,~mber -----------

~ptR\Mt.N1A~x:~·:·'w ~ - i. • ~ o ". ; ' ' ' ·- ... I o' ·'\ q •• •--~ ll .. u J '--~~ ~ 

AAPG Region Number _.:;1C.:__.:::I _______ _ 

Completion Date .OEC. 18, l't7tf 

REVISED SHORT FORM FOR RESOURCE APPRAISAL AND EVALUATION BY GEOLOGIC PROVINCES 

*I. IDENTITY AND LOCATION OF GEOLOGIC PROVINCE 

*A. Name of Province or Basin(s): _....:.M...JJ..:IC.=.M::.:.:.:16=A.;;;I\I:.....:eA~.::$~1:.::N:_ __________________ =------------------

B. Geographic Location: 

1. Country: 1J. S.; ALL OF STATE 01' MI~NIGAN; PAA1"$ olf' WISCONSIAI, N. .111/D.III.IIIA .liND IIIW OH.IO ,· /1/F I.UI/1101$ 

2. Location: 

~ Latitude between parallels N or ,:; -.!!.. • 

and N or S _ft.. 

Longitude between meridians E or W ~ 

Offshore: ~ and E or W w 

Onshore: 

C. Name of the author(s) of the form: ..=IJ~~:.·:...N'-A..c:/'t!..;LU"II.IIL~:.~I-~.~:A':a.... ___________________ _ 

D. Date of completion of the form: OIC. I 1$ 1.....;..19.:..7-::-.'<~.:...-____ _ 

-1-

*ltem.:i pr<:c,·l~d by an asterisk are explained fn instruction sheets. December 4, 1974 
>':E. Indicate the level or degree of knowledge concerning this province as a whole: 

Yes 

1. Surface geologtc studies l1 

2. Drilling stages: 

a. No drilling (no seismic) 

b. No drilling (w/seismic) 

c. Early stage (immaturely explored) X 

d. Intermediate stage (fairly well explored) l( 

Q1 

Ql e. Late stage (maturely explored) " 3. Province well-explored to basement depths: 

a. Drilling only i /"'~A/0/1 

b. Drilling and seismic MINOif 

I'AOLJA6l.E• 

c. Seismic only j.eur UNitN6tNN 

*II. BASIC GEOLOGY BY PROVINCE 

,.,A. Province geometry: 

*1. Configuration of province: F'AIRLY EQult:}IM6N310NAL (t: /) 

-2-

No 

I 

I (J.JtT.F SIJ.IJRIA/1 AND OJPOOVICIAN) 

( M1Doi.E lfNJ:J 1.ow1A .0111. -tMO uJIIIIOFA su .. ) 

(P.FN/o/SYL Wllt/14/111 MISSIS~II'PIAA11 AAIO) 

t,JPNit .()11/tM,A# 
Ol 

0) 

*2. ~ of province: 

Area(square mile) Percent explored Percent productive 

Total Area of Sedimentary Rock Province: /2 2,000 tOS% .:::2s-as% 

Area with maximum depths to basement of: 

a. less than 5,000 feet -::;; 7.3_1_200 - 20 '% - s-~,o% 

b. 5,000 to 10,000 feet = 3'-, '-00 =:::. -t.s% a2o-2s% 

c. 10,000 to 15,000 feet ~ 1a, aoo ~ '" 0 

d. 15,000 to 20,000 feet 

e. 20,000 to 30,000 feet 

f. greater than 30,000 feet 

ro-rAI. ( 122)000) 

!Q!!: a through f should not exceed total area of province 

*3. Thickness of sedimentary rock to basement: 

i Minimum thickness Average thickness Maxim11m thickness 

Total province: l 0 

{ OUTCJ'ioP $ AL 0/1/t. FJ.ANNS 

OF .IMS/11 ) 

-3-

-It:. 74 , ,.,,ooo- IS,ooo 

% Area Underwater 

~ IS- 20 °/. 

100% e.w r1111 .. R~ 

-::::::.. VN.Lll~ WATI'If ''"' 
01 

-;:J 

*4. Estimated volume of sedimentary rock in total province: /OB 000 cubic miles. 

a. Estimate percent of rock volume in province that is: 

(1) Ddlled: ~ (;aO X 1. 

(2) Explored. (by seismic, etc.): > 75 % '7. 

*B. Geologic Age Relationships: 

1. Give the range in age (by geologic periods) of the preserved sedimentary rock section: 

C ~~ 

a. From AMIJAIAN "'"' cJu8ASSIC + PJ.E'ISTOCENI ( PAFI:JO/'tll/tiANTLY PAU"OifOIC ) 

b. Missing sections: TAJASSIC:: TNAU LOWI8 eJ,I'ISTOC€1111' 

c. Age of basement: PACCAM4.qiAN' ; Lithology: IGNFOCIS ANQ METAMOifPHICS 

2. Age of major tectonic episodes or orogenies •ffectlng the sedimentary basin: 

a. ll. SIL tJAIAitl 

b. DE'VOIWAN - 2 ro .3 J01AIOLJS THIPt/ 01.1., 

c. l.owi'A AND MI.ODJ£ O~DtJ'hCIAN 

d.~~~~=:----- e. Is there evidence of recurrent structural growth? II" Yes No 

-4-
at 

00 

3. Age and type of major faulting: 

Ind" heth ------ - ------

1 .. - d - - Age Type of faulting Production Prospective Production Not Related 

a. I()FVONIAN NM.MII~ ro 411SEI'11Nr NOT XNDWAI TO /U' 

0AIJOVIC/.4N ( ?) GA .. IJEN- ,., .. ~lfOW I~ b. AIVD J.aN& ( $11i'FA .. l I'II'U>. ~ 

c. -- - - -

*4. Ag~, maximum gross thickness and lithology of sedimentary rock of major producing horizons and/or prospective horizons: 

EsT. VO, 

A_ge Maximum Gross Thickness I Lithology Productive or Prospective 

.()FVON/AAI ':!! 3"SS 

Cu.,.,:,. 

-- a. 7. 300 CAA!IJON .. TE 

b. OA~OVICIAN a ':J'-o 5 000 CAA40IIIAT'6 

-- c. S11.~lfllll't/ ~ -#130 8 500 CAAIJONArl 

--- d. M/SSISSIJI'PIIfltl Gira7"0 .3513 SA.vasrONI ........-

e. ()AO.- CN"'MIAN ~2!.00 /~000 SA/IID$T'ONF ---- f • 

.&· 

5. Time of hydrocarbon generation: I'AoiJAIIJ. Y Oll.OOVIC/AN 'TI/Atl .OIVON/AAI a PoSS18L Y /Nro TNr M/SS/S.Sh~.IIMAI 

*C. Stratigraphy and Lithology: 

*1. Host abundant lithologies in the province and estimated percentage by volume of the total province. 

Lithology Marine or non-marine Per:ent Volume 

a. CAIIIJONJIITI 11AAIAIE' 4'1% 

SANO STOII/I 

I'AIHAAILV /llllfiiiNI • 

.2a % b. ~~ NMI·H.IIAI/1/1 

£.: SNAL£ Jt"AA 1/IIE II~ 

!:.. EVAJOoAiriS /"'AAI/11# /Z ~ 

-5-
~ 

~ 

2. Ratio of marine to non-marine sedimentary rocks in the basin (by yolume): S& ~o: I 

-------~-------------------------------------

*3. Major regional unconformities: Number ____ ~SI~-'2---------------------------------------------------------------------------

Age Magnitude 

a.Jif!S\ISS/AII/-·JOINN'SXCVAN.I...... (t;;4) WlrHIN ANO ~r"WIE'III JOI,./0-t:JS 

I.ATI SILl/AlAN AN.O 

b. IAifLY DIVOJV.I,IMI I 3 WI'TIIIN AN() tJN¥ 4E'TWFIIII /OIA/O.OS 

c. IOIVO/ti/AN 2 OA J WITHIN .PE"A/0.0 

d. CII/"'AJiflltll- OJI.()OIIIt!IIIA/ :::: 3 WITHIN A#IJ ONE" OE'TWE'EN J0EAIODS 

l.A'TI' JOIAHIIIIt/ T"AtJAICA'TI"S MOAI' -rNA/11 OAII EllA. 

4. Presence of exceptional geologic features; depositional or structural (such as reefs, deltas, sa~t domes or diapirs, strat 

pinchouts, etc.) 

Types Geolodc Ae:e Associated Lithologies 

a. RIE.r.s SILURIAN 11111.0 .OIIIo~NAAI CAlf IlONA 'TIS 

b. SIU T AINCIIOU"''S IIN.O IVAI':. SII.UAIII/11 EVAPOAITES - RGI.If'TI.O 'T'O ClfA4o.VA -r~s 

c. lJoLOHI'rl'e.I'.O "'ONIS $11.11111111111 AN.D ..OIIIIJAINIAI C.IIAIJONAr.FS (~rl'll.lfCEifi'NT DOI.OHIYIS WITH/AI LIHI"I,-0/l/E.S) 

d. 

e. 

*5. The presence of known or potential stratigraphic traps: 

Indi ---- h ··-------- --------- -

Trap Type Geologic Age Productive Non-productive Prospective 

a./)oAOH/T'I.EO Clllt1Jt»'A1 "s f .0..VON.IAN' , SOHr AAE 

--- b. 

( 0111001/lt:ll'l/1 

SU.U#/11'1111 

c. SAND 19~11 ours /"''ISS/SSIPPIA/11 .,...,- ..,-- (!'11JS'f"I.Y GIIS ,-A6.ctJ 

('TAAT. •) d. ,9EFFS ST"#Ut!r. SII.VIti/M' liND .DI&IMNII. v ~ v 

e. -- --

-bCT.IOAI) 
0') 

0 

*6. The presence of known or potential structural traps: 

Indicate wheth er currentl : 

Trap Type Geologic Age of Origin Productive Non-productive Prospective 

a. All"riCI.INI'IL .OIVO/I/111/11 ,.......... / 

b. GAJI/IJI"AI FAfllTIN& ") OADOVICIIIAI ~ -- (SEV~Itlfl Fll'l.b!l - I ,s l.lfiC ~$'1" IN 8111SIN) 

ANI) 

c. JlllTIAID CAI!MWIITII ~5 SllliAIIIAI 

d. 

e. --·---

7. Evaporites and their relationships to major reservoirs: 

Present Act as seals to major reservoirs 

(Check one) Yes No 

a. No evaporites in section 

b. Evaporites above potential reservoirs 

e. Evaporites below potential reservoirs 

d. Evaporites above, below and within potential sections .........- v"(IAI HINIJ.f Cll$1$) HAJOAIT'i' 

*D. Structural aspects: 

*1. Type of basin (or basins) included within province (use Basin Classification in instructions): ________________________________ __ 

J/IITE"A/011 IJA$1111 ;. C.AA'TOII CFit/T8A 

-7-
C) 

.... 

2. Structural basin geometry: 

(Check one) 

a. As}'llllletdcal 

b. S}'llllletrical--gentle slopes / (NFIIAL)I So) 

c. Symmetrical--steep slopes 

d. Information unavailable 

3. Presence of regional structural or erosional highs: 

Yes No Estimated Number 

a. Known highs .,..,.- MNVY 

.,- HAJ'4r AIJ.ArE.O 7"0 

b. Suspected big~ ____ ~---- 4-'ISEMEN'r 

Characteristics of known 

c. reafenal biiJla: 

Probable Estimated Magnitude 

Natur~~i in General Geometr (in feet)(i.e. closure, relief) 

AlllriCLIAIAL_ N~AALY SYI!NITAit.ft ~~-so~ 

-8-
*E. Presence of Regional Producing Trends: 

1. Number and gross area of major producing trends: 

Number Roll&ll ISTIHII"riS Typ_e o f 

Oil Gas Combined Oil and Gas Gross Area (square miles) Age of ma1or reservoirs Structural Strat Combination 

a. ~ 21, 3 't) S.Q. ""'· CFVON/,fN --- ......- / (.(I£1F' 

b. .., 4270 SQ. HI. HISS. ANIJ JII'INN. / 

c. ,...- "~05 !Q.HI. Sll. UAIII/11 / 

d. .,..,.- G.fOO SQ. HI. OAIIO V1e111~ / 

F. Presence of current non-producible hydrocarbons in the province: 

1. Presence of natural oil and gas seeps: 

Extent 

None Minor Si2nificant Abundant 

~ a. Oil ..,.--

b. Gas ~ ------ --

c. NGL 

d. Combinations of above 

2. Indicate whether the following are known to occur within the province: 

Yes No Unknown 

a. Heavy oils (API gravity less than 12) ,._--

b. Tar sands ,-

c. Oil shales ,...-

d. Tight gas sands ? {PAOIIIfl. i.IJLE) 

e. Other bitumen or solid hydrocarbons ,-

f. Significant oil and gas shows 

,.,.. -0., 
0) 

co 

*III. FIELD AND RESERVOIR INFORMATION BY PROVINCE 

*A. Producing reservoirs in order of importance of gross ~ potentials and/or prospective reservoirs: 

rHALI 1f#7 

Order Geologie Principal horizon Lithology Maximum thickness Areal extent Indicate Cumulative Measured and/or 

Age or pay zone of reservoir within pTovince Productive or Production Indicated Reserves liT. 'riiiCitNIII • VOL, % or square miles Prospective (BBLS) (BBLS) 

1 t.U.HI. 

orv. OvN411-IIo &rls Cm- ~401</A~I :::::: 201 

/000 2! /0" .P.to,ouc TIVI .125 "''" 

2 Dlt/. TAIIVE~SE C~•#lfT'I ~12S' .2ooo - 20~ J011610ucr1111 '5 '""' 

3 Oil D. TII'II/'TIW-,eJ.Mit J&1164 CAAIJ•IIIIf7"1 ;;;;;: ~01 sooo - G,% JOitOIOUC. 'riVE = 77 '"'" 

4 DEll. DITilo,.r ~/VIA C/11114oNiff'l ~21o' 4306 == ·~ JO~tJC.TitiE 43 '""' 

5 6/L. &AuNA• NIAtJ,AIIIfN t!M40111ATI so-t.o' 5500 - 5% JI'A010ucr1vE B mm 

6 HI$~. 8£RE"A- S/f.N() SroiiiE' =:3z' f = 3% PAOIOI.JCTIIIE 2 '"'" 

7 ,.,,.,, HMSH~LL CAMD.sT~ 9£. 77' ., = 3~ J0A6011C. TIt/~ • a73 ,., 

8 Oil D. SilO. - "rlli'NYOIII CAAIJONATI ''-,000 ? ~OSI"It.TIIIE -- *B. Producing reservoirs in order of importance of gross ~ and NATURAL GAS LIQUID potentials and/or pTospeetive reservoirs: /'/0 .DATA Oltl NGL 

Order Geologie Principal horizon Lithology Maximum thickness Areal extent Indicate Cumulative Measured and/or Cumulative Measured and/ 

Age or pay zone of reservoiT within province Productive or Production Indicated Reserves Production or Indicated 

% or square miles Prospective GAS NGL Reserves 

1 MISS. STIAY- HMSNIIJ.J. SAA/D.S7'6411 == 

GJo' =:3X JOAUJUCTIVF 21-f bet 

2 &IL. Slti.JNA• /1/IAMIIIfN l:MSO/t/11.,.1' - (QO' as~ PAODUC.T/VI I~~~ 

3 ~(). 'rTA61t/TOifi-IJLMII AN~ ... »' ~ c.o' :::::: t.% PllOCtiCT'Itll ,,. «.1 

4 o•v. !JI,JA/J:JII•AII4 CIT'I' CA.fiJDNitTE - 20 1 .(. /0 ~ J0A6<lfJC. T 1111' '~' bel 

5 O.fl. I:JITifOIT lfltllll CM40H473f = 21o' -::::::. 1% J0Ao101Jt.T/V~ off. hcf 

6 it'fl$5. 81AIA S.WDS1'Aifltl lt.' ...... 

= 3•A ,O,fO.OfJt. Tllll Jo bel 

7 Dllf. TAA'IIE~s• CIIIIJOAIII~I 12$ 1 

- 20 ~ JO,fJJ_DCJC T/118 ' = be( 

8 I> IV. hlrltiH S.M4LI SIIAL# ....... 4' ? ,O~C'I'I'IIE 3of5 MC' 

• C..,101C Qj.ACIAl .oAI'T Tl~l .c. I' ? PlfOCtJCTIIIG I HC~ 

sJWOs~"466'- s-oo' -10- ,, C:.MIIIIIIIIAI ~ 

-~ItO SJOE'C.,.IVI - ' ___, 
*C. Characterization of probable source beds: 

Order Geologic Gross Maximum Gross MaKimum Lithology Estimated Number Marine Non-marine ReasoQable Proximity 

Age Thickness Volume of beds of Reservoir Beds 

1$7: 11 lt/IIOW/11 " Cu.,.,, Yes I No 

1 iJ"AM• CA.f.S~ VIS 

Drv. 2ooo'- 3ooo' >5200 IHINI.t• $1/AUJ 3•-f lf'UHA't'IIAI$ -- ,.,.--

2 aooo' >sooo CAA.S. • 56 ,.,- ...--I SIJ.. SHIII.F- 56 S F•AHAriONS 

3 OIID. IS001 > S-400 SIIIILI" • •• 

C:.Jfll!lll • • 40 3 ,roAHIIr'ION.S ,_-

4 --- 5 HAr111 AD. OITA/1/A.t SIJIJ6U IJIIJS .IAI Till .I f/SS, Alllb - ··~~ ''· .... ·' rNA7:_ _.tf!/ (_NOT 1.1 f7"1.0 HFAI' - J. t.IT~/1/Fo ;V( IT AVAIJ.A. '4J.6. 

6 

1 

~ 'r.TAI. P. ~o«s .. .~ 1.1' > 151 ~00 ~.,.,,: 

*D. Characterization of major seals in the stratigraphic section: 

Order Geologic Lithology Significant Seals 

Age Hydrodynamic conditions Continuous--Discontinuous 

Yes No 

l DIV. A. AT I' PAC 8A8LY IJO rN (oviA ~Jt'.AJ. '1/f'/CANT Alli'AS) 

2 "'"" 1'11/110~ SJIAI.I'S .P~ .8A8.LY .l3t rH 

3 S/Lo C.M4tMIAT £' l'tft. Al~BLY <10 TN 

4 SIL. E'VAP61flriS p~ 1

6A8LY 60 rrN 

5 OAIJ. SHIUE PAo ~A8.LY .eo -rll 

6 OAD. CMIJ. 

---;--) 

iO.Ilo GA8LY 8C Til 

--

8 I 

--· -ll-
0') 

01 

*E. Field size distributions by proven acres or areal extent in square miles; 

1. 

2. 

*3. 

*4. 

5. 

p 

_ roven area 

Oil field sizes in the province: Square miles Acres 

a. Average I. /'1 721 

b. Most reasonable minimum . 02 IO 

c. Most reasonable maximum _____ll._.J II. Zoo 

Gas field sizes in the province: 

Size in 

Recoverabl 

-.- . --- , 

:::::::. 5 mdl. AA/$. 

< I ,.,,-t/. hbls . 

>_ISO,;!!_._~~$. 

Size in 

Proven area Recoveraole 

Square mile Acres Reserves (cuft) 

7.J ~5000 ....... a. Average ..... 30 I:J~( 

b. Most reasonable minimum 3., ~2500 < '.Oct 

c. Most reasonable maximum '~·" >1o,oo~~2oo hcf 

Total number of oil and combined oil and gas fields discovered to date: ) 

HICH. :CNOIA/1/A (Oil ONLY) (JIIId (OIL ONI. )" 

a. fields 3'1~ (J/111. '/7.s) 2<. FI#LD$ --/I ~11'~1)$ 

~ b. pools 4./ 'i (JAN. '/73) ? 

Total number of gas fields discovered 

HICII. to date: 

a. fields l (,' (cJAII. 'h.s) 

INONMIA 

? 

b. pools I B' (JAN. V,.s) 

Recovery factor for crude oil in province: 

a. Average recovery factor: 31.8 % 

b. Most reasonable minimum recovery factor: 'S: /0 

c. Most reasonable maximum recoveT}' factor: ...... '15 

'7. 

'7. 

-12-

~ 

"7FIEl.OS 

? 

-
0') 

0') 

F. Indicate whether hydrodynamic conditions within the province are related to hydrocarbon occurrence: Yes ~J'Jt~A4tY}No ------------

G. Indicate whether the timing of hydrocarbon migration versus trapping is a major factor to the probable occurrence of oil and gas fields in the province: Yes No,......... ...Ottt4A&Y .M»r. 

Comments: .NO .OrrAILE'D IN,-6RHA'T/•N AVIIIJ.AIJJ.r. 

*IV. PRODUCTION, RESERVE i~D R~SOURCE INFORMATr~N BY PROVINCE 

*A. Cumulative oil and gas production, reserves and resources: 

Crude Oil Natural Ga& Liquids Natural Gas } 

(As soc iated.f Non-As soc ia ted 

1. Total production Gt24 I 13GI ooo '1:34 • ., 17~ NI.I.UIJAI CU 'FT 

2. Measured reserves 8/i02t 000 ,, 2. '" , w.s HIJ..t.l4# Ci) ,,.,. 

3. Indicated reserves 

4. Inferred reserves 

s. Undiscovered recoverable resources 

6. Estimated original oil-in-place ~Jr 2..119 27,,000 

B. Exploration and development information: 

1. Date of first producing well: 

a. Oil 192S (''*'T SIGN/FICfWT WI'I..L) Fllt6T ~11'1.0 DIS. 1•14 AND A4.0. 

b. Gas /OJ27 

2. D4!.te of first producing major field discovery: (J.AIGE~ rNAN 100 MJA.L • .CS4LS.) 

•. Clil ''57\ COHI!JAIITION ; 

b. Gas J'S? 

-13-
0) 

-1 

3. Date of first well drilled within the province: LAT'G' 1880's 

4. Number of exploratory wells within the province at time off!!!! discovery (either oil or gas): • ? 

5. Number of exploratory wells within the province at time of first ma1or discovery (either oil or gas): ?. 

JAN. '/.,3 

Te-rAL WI'JlS 6. 

7. 

8. 

9. 

10. 

Total number of exploratory wells drilled to date: 13. IIJO (date): I I I I 7.3 

Total number of development wells drilled to date: --~"~~~·~3~4~~-----------­ (date): I I I I 73 

Well density per square mile in province=----------~·~2~2~3~----------------------------------------------------

Oldest beds penetrated in basin to date: 

a. CAM41111N(,o#ICAH.t:JA'IAN lJASI'MINT) (geologic age). 

Deepest beds penetrated in basin to date: 

b • .ORII.liD ,~, ''"' (JlW '/z.tl 

EST: M.qN, DFPTII l"f, 000- I.S, CIOO 

a. (geologic age) b. __________________________________ __ 

(depth in feet) 

(depth in feet) 

ALL 'rl~l: 

oii --;;:;-;; 

GAS 2.051 

DAY IJ1 160 

i"7,'i.t; 

V. QESOURCE ESTIMATES BY PROVINCE 

A, Resource estimates that have been cited in the literature and other sources, relating to total hydrocarbons in the province. 

Sources of reference or data Estimated amounts 

(bbls or cuft) 

Indicate the units 

reoorted 

1. /"''iM. IS - A APt; : (c)) I I. a IJII.I... S.tll s. I.M£TH60: VO.L AND >'ll.tD OF $Q. 000 ""'%,. •l. 

2. 81U.. 81JI.S. 5 .HI. U' Pllo~EIJ ,PAUJIIC'11VEACIIA" 

3. /111..1... 4/JlS. SQ • .HI. OF nJt.OIGUJ.qri.L,., .. IXI'UREQ 

riA~I'rOill', 

B. The evaluator's 4·-----------:-~;::::::---;::-::~~~-- estimate of the resources within the province if different from the above values in A. 

lt/IAA EA TO I. 0 <GILl. • 8/JI..$. 

1. Qualitative Rating (zero, poor, fair, good,etc.): --~~-:~~euf~~~~O=-~~~"~'~A~-----------------------------------------------­

·14-
0') 

00 

C. The evaluator's opinion as to the most similar producing (or non-producing) analog basin(s); and/or analog basins or provinces 

cited in the literature or other sources: 

lnicate wheth -- -- -- ----.. ·-- Name of Province or basin , Location Producing Non-producing Pros_l)ec t i ve Source of Refe~ 

1. W. AJ IJriiTA ~lM'A1'A1~ ~ ACJT/(OA - 4. Hll.l.l~ 

2. ~8QN' .4tY tJM/111 

t:IN1'AIU 

UAIA.tU / 4f"AIR TO POOR) AvrHolf - 8. 1'111.1. TAl 

( JOoA-,,..VS •') 3. ll.l./1101.$ 4/ISIK rN/S 4A31N ll.l.INGI.S ~ _______ ____j ~"~~~· _ __! S /.4 A!!_ G ---

-15-
FORM /13 

PROVINCE SUMMARY SHEET 

Region RAG No. --~~~--------------------­

PROVINCE --~M~IC~H~I~G~A~N~B~A~SI~N~--------------------------------------------

*Stage of2Exploration: Early S!b t ORo Intennediate o~v. t U.SIL. Late PENN .• Mils. I U.D£1t 

*Area (Mi )-----Total Sed. Province: 12 2, ooo 7. Productive-== 25 -~s·@ 

Areas by Depth Units: 5000 1 = 731 200 5000-10,000 1 := 36, 600 

10,000 1-15,000 1 ~ 12.200 15,000-20,000 1 

20 0 000 I-30 0 000 I 30,000 I ------------

*Thickness of sediments (Ft.): Avg. 4 "74 Max. 14,000- 15,000 

*Volume of sediments (Mi. 3) 10~,ooo 

Total Province: 

7. Drilled eo: 60 % 

7. Explored > 75% 

Stratigraphic Age Range: From CAM§RIAN Through lo!URASSIC t P!:EISTOCEN£ 

*Producing and/or Prospective Horizons ------------------~------------------------ Age: a. SILURIAN b. DEVONIAN c.Qcn10.e.-CAM d • ..:.M..:.I:.:s .... s. __ __ Gross Thickness: !!!!:4.130 3 1 655 3 1

pp0 7PD Total: ~ 

*Dominant Lithology (Total Province) Type CARBONATE 

1 

SANDSTONE, S HA_L_E_,--::::E:-v.-~-:P:-0-R-I_T_£_5 ______________ _ 

7. of Volume 47% 23% 181 12' Ratio, Marine/non-marine ---==..:I..::O:...;:;_f!...-_____________________________________ _ 

Types Stratigraphic of Traps ~-----------~~--------~~--~------------------------------ DoLOMITIZ£0 CARBONATES, SAND P1NCHOVTS, R££F"S 

Structural ANTICLINAL. GBAIKN FAULTING ANO ALTERED CARBONATCS 

*Structural Aspects ------=------=------~~------------------------------------­ Type Basin INTERIOR BASIN, CRATON C6NTER 

Geometry SyMMETRICAL -- GENTLE SLOPES (NEARLV so) 

Indications of Hydrocarbons ----------------------------------------------------- Producing Trends Mess. t peNN.- GAA i p1y ro Osp- c 0M,,,,o OIL 4 Gas· Tv G1pss A1

11fA"a 31455 M.2 

Seeps, Tar Sands, etc. OIL 4 Ga;, 5nPS- M1NO!! ExTENT 

Probable Source Beds (Age and Litho logy) 0£¥ :;:tO:: sMy& I S!L.l'JAt£: io J ORR ~~'if: ;g 

Major Seals (Age and Lithology) OEv. TWROUGH ORo., CARtoHATE. £.VAPORIT£5, t $HALE 

Field Size Distribution: Avg. R.Min. 

Oil (mill. bbls): -==s <I 

Gas (bcf): -==~o <fo >200 

Nature of Hydrocarbons: Avg. R.Min. R. Max. 

API Gravity 

Sulfur Content 

*Recovery Factor :,!. ' =Jo J= 45 

*Production, Reserves, & Resources: Crude Oil NGL Nat. Gas 

Cum. Production (bill.b~ls.;tcf)~p~2~4~13~"~·0~00~~Mw•4*.~-------------4~3~4~4~7~~~M&~L~-~C~u~FT~.--­

Measured Reserves --~8~1~,o~2~!~0~0..::0~Ma•~L~L-----------4'r~2~9~b~~8~15~M~•~q~.~C~u~F~T.--­

Indicated Reserves 

Inferred Reserves 

*Wells Drilled to Date: -~2~7u..:.l.-.. :..~i~~~......--- Date: _1_/ ___ 1 _/~ Exploratory Wells --~'~3~lw0w0;...]~1~/~l~/~7~3~) ______________________________________ __ 

Development Wells ____ 1~3~3~4~9~(~1/~r/~7~3~) ______________________________________ __ 

*Resource Estimates (Undiscovered--In Billion BBLS or Trillion Cu.Ft.) 

Recoverable In Place 

Outside Sources (MEM IS) .,73 l2"23 !tLL. B1$L$. 1 REcow•A•u UNOI!cov,.uo /Us. 

U.S.G.S. Evaluator c::: I 6tl.!,. 8~&. I RECg_vFfl.AeLE ~VJ!!'P B.~"L 

Analogs w ALBi'ATA HunMN iAY j,iA,... JLu;qt; 8A&IN{ p;;;;o;a o;;H'' 8AStN) 

RAG Estimate -----------------------------------------------------------------

*Province Qua li ta ti ve Rating: Oil __ _,.G:.;:O::.:O::.:Po:.-------- Gas _....:.F..!.A::.:I.:.;R:.._ _______________ _ 

Posted by: KuRT CARLSON Date 2- 1~- 75 Approved ;l.hz//4,._ Date~ 

* Data most pertinent to resource appraisals. 2/4/75 

69 
-::1 

0 

FORM I 4-A R£GJON 8 Region *a t)ICHI~~N aASIN AR£A RAG No. .I Province ljJCtfi!!AN ~ASIN ARrA 

RESOURCE APPRAISAL --PROVINCE ESTIMATE 

Province Area 122.000 (mi2) Province Volume: IO!l 1 000 (mi 3) 

OIL NGL GAS 

PRODUCTION AND RESERVES (Bill. BBLS) (Bill. BBLS) (TCF) Cumulative Production: 12 r/73 AP~-- ~27 .Oil -_AEZ_ _/2/72 - .4''35 12l_7_z. Identified Reserves! 

Measured Reserves .072 .OZS" 1.549 

Indicated Reserves 

Inferred Reserves (.Ifp:. ;3.19) = • 2 2.9 ..... .00') 2:. .802 _{"Zjp •.518) I 

Total (Cumulative & Identifiedl_: .92_8 .015 2.786 

OIL NGL £ST. GAS 

UNDISCOVERED RESOURCES (Billion Barrels) (Billion Barrels_l (Trillion Cubic Feet) 

Resource Appraisal Methods Total 1 una1scovered Total Undiscovered Total Undiscovered Lln~e lRe_c_ Resource IRec ResourcE In-Place Rec. Resource Rec. ResourcE In-Place Rec. Resource Rec. Resource MBTHeD I--VOLUMETRIC-ANALOG 

Analog 1: Analog 2: 

Yield Factors: MICHIGAN Ba&IN lLLINOI& 84t.IN 

.0864 44 Oil: IGt.OOO 3-4.000 1 5.-400 /.728 .800 ./08 .0414 4.455 ~.564 .778 

Gas: 2.5MM 20.MM 

Rec. Factors: "32/So I so 2 II. 475 ~672. ..z. 744 .086 .0""*"* .024/ 2 70 2. /fo TOO LOW 

METHOD IV: HENDRICKS' CATEGORIES 

Dis.-Rec. Factors: Categocy 1: 4 /2.200 "3.05 2./22 l2.20 .610 .S65 I ?;O.s 15.25" 12. fl,_4 _l 

( 25/50/50) II _l 

Cat~~l: ~ ~0..5.00 7.....6..2..5_ _6 .. _lz'J7 2.440 lZ'J.O 1.175 1."-1.0 ...3.0~ ~7. 714 I 

-- ..AU. ....GAS....£. t;lUR£5 TOO....H.IGII. ~Too Low 

METHOD: l.m PRODUCTIVE • AIECOVERY_l PROCEOUAr. I...!J 

Yield Factors: Oil: 2:~MM~a Gas: -4MM/M,a 4. 294 /.379 .451 .10' . 087 . 042 ~ 2.T~O Too Low 

Prod.Area/Unexpl.Area: 22' 11,• /7.52.7H,a 5.{.<f4 /.'14 9....8..6_ .15/ ./2/ .076 4.733 ~78" /.000 

DOCUMENTED RESOURCE ~ Ll'U\L£.~: l..(UNDlU 

AAPG~ Memoir 15. 1971 ~ ._150 zu .L 1.1"'(!1_ 

~L HYDROCARBONS ~ .680 L"?t0..6.~ 

National Petroleum Council Estimates,l973 lcZ'O UNO S,-.LNPI..M;L- .41~ 4.8 

ANOGRE Estimates 6. 00 IN- PLI4CE !__ 

OTHER ..11 ....5..00?>- /,1,_01_- .673-

METHOD .II 6.722 2.15/ I.Z2~ .U 

4J l-IYDR0cAR&ON5 - BUI MOl:IILY 01 

.J>r Date 2-2.0--75 I-? Jz<~6 Date /;}..L.;1.1Lz~ ; ; 
....:J 

1-l 

METHOD I 

Volumetric - Analo 

DOCUMENTATION FOR RESOURCE APPRAISAL METHODS USED ON FORM 4-A 

METHOD 11 METHOD III 

Exolored Area - Recovery Pvocedures Productive Area - Recovery Procedure 

METHOD IV 

Hendricks' Cate2ories 

Analog I Areas Category 1 ___ 4..._ ________ _ 

1._...:..;,-~~--~~-=----- 2. 

3.----~._~~~~--~~--A-C-K~R-IV~E~R----il Discovery-Re~ove~ Factors: _____ _ .25/.50 1.50 

Modifications :._.l.lN~Ou.:Nu.E...._ _____ _ 

Recovery factors used: ,._, 9 " 'R¥ • 

Analog 11 

A~~as Une~1o~r~:~ . en~~ _ prv I ~: 5i¥i!2 fu: i.?i.·aCategory *---------

Yield·· • ~ · · • ·• Discovery-Recovery Factors: ______ __ 

Basin or Province Name: ILLINOIS 

SIN 

Yief~factors used: 

OIL~GAS~ NGL :nvr'-'D"'"'l 1 Recovery factors used: .-. -- 1--

(A-~ EXCLUDED) 

588, 79", 0'38 8~l5. /Mi.z. fA- S II'ICLU0£0) 

1. .. _,_, ~~ , e:;~~ ~~- r - ~ I ~: tOJ9,9J~ iii: J94 :£i mz;-:: a 

.!J &EE FOOl NOTE - ~- .C- A 

Rt.c. :32/80 /80 

AAPG, Memoir 15, 1971: Tables: /0 Pages: __ ........ ..w~~"--------------- NPC Estimates, 1973: Tables: 29; 222. Pages: _ _.l_.7 .... 1_._3~!po&,j7.__ __________ _ 

Other ANOGRE Published Eetimates: S~o-u-rc_e_s_:-~D~a~t-e_: __________________ ~P~a-g_e_s_: ____________________ _ 

Other Procedures: ________________________________________________________ _ 

DEFINITIONS FOR RESOURCE APPRAISAL METHODS USED ON FORM 4-B 

REASONABLE MINIMUM -- That quantity which the estimator associates with a 95% probability that there is at least this amount. 

.25 l.~o!. so 

Modifications:_.l.lNi.lljO:.:,;N:u;E...._ _____ _ 

MOST LIKELY -- That quantity which the estimator associates with the highest probability (of occurrenc~ that there will be this amount. 

REASONABLE MAXIMUM -- That quantity which the estimator associates with a 5% probability that there is at least this amount. 

EXPECTATION --Also called "EXPECTED VALUE" or "BEST ESTIMATE" -- A mathematical term. It is the only value we ·are entitled to add if we combine estimates 

of similar quantities in other provinces. 

E = R. Min. + M. L. + R. Max. = 50 + 300 + 850 = 400 3 3 

MABGINAL PRQBA8ILITY -- That probability which the estimator would assign to his basic assumptions that oil and gas accumulations are actually present in 

the province to be evaluated. 

2/27/75 
-::! 

~ 

FORM If 4-B 

RESOURCE APPRAISAL --PROVINCE ESTIMATE 

PRODUCTION AND RESERVES 

Total (Cumulative & Identified2 

REGIONAL REPRESENTATIVE 

Resource ~eraisal 

a. Reasonable Min. _(95'7. "at least ) 

b. Reasonable Max. (5'7. 'at least") 

c. Ma~t Liki!!lv 

d. EXpectation: {a± b +c) 

3 

Meth~: 

___ Rec.--Yield Factors.: 

Classify: H_y~othetical Speculative 

OIL 

(Bill. BBLS) 

,,28 

OIL 

(Billion Barrels) 

Total Undiscovered 

In-Place Rec. Resource Rec. Resource 

~681 /.178 ._2_50 ANA/.. 

•us _z. '.1.8 _2,®0_ ~~~ 

_5_.40 /.7Z_B ....8._00 ANAL. 

_6_,_o_75_ .J.,'1H 1.01~ 

Posted by ?:'3. ?ny+>=-= Date Z- 28-75 

RESOURCE APPRAISAL GROUP 

Reconmended Appraisal: 

a. Reasonable Min. (95% "at least") s x.s:- /, .;t.3 n 3oo 

b. Reasonable Max. ( 5'7. at least") .,, /t:. .;l.9~"ii' ::J, 0/JtJ 

c. Most Likely r:'//J / .. ~ .30 L7 7t:?(} 

d. Expectation: (a + b + c) 

3 /. .O_'i I, f-2-"i' /,. tnrQ 

Method: 

Rec.--Yield Factors: ~ginal Probability: 

Region "'8 MICHIGAN BASIN RAG No. 

Province 2 

Province Area 122.000 (mi 3 ) 

Province Volume: 108. 000 (mi ) 

NGL 

(Bill. BBLS) 

.04S 

NGL 

GAS 

(TCF) 

2.786 

GAS 

(Billion Barrels) (Trillion Cubic Feet) 

Total Undiscovered Total Undiscovered 

I 

I 

In-Place Rec. Resource Rec. Resource In-Place Rec •. R~source Rec. Resource 

.ll?> 090 .045 L4..A.l2S ~_5'_8~ 800 .681 .54S .500 5.9_13_ ~ 71~ 2.000 j .181 I 1"15 .100 _4_.__HB_ ~ 88~ 1.100 ' 

.325 .260 . 2/!i _5:./0...B_ ~ /.300 ' 

.y, i)(r :J... 3 S'1j',; i"J.I.-,, 

-~9f'..:r.. ~7-r.'C ~...DVrL 

.V..Y..r? 3.ri!C /, /017 

-~ /U"? -~ IJY£ /, .3P"'() 

£-·,st<:d by :J3, /!J..:t/=<(.6--: .c~.;-~ Date hzMr./t pc Approved Date:...·-----------

/?#Cc.-~---=-. 
ESTIMATES OF INFERRED + INDICATED RESERVES FOR THE UNITED STATES BY STATES 

By R. F. Mast and Janet Dingler 

The best source of reserve data currently 

available is that published by the American Gas 

Association, the American Petroleum Institute, 

and the Canadian Petroleum Association (AGA, 

API, CPA, 1973). Figure 39 shows the assumed 

correlation between the AGA, API, CPA (1973) 

terminology and ·the modified U.S. GeologiG'31 

Survey mineral-resources teTininology used in 

this report. 

At any time after discovery, the estimated 

total amount of oil and gas reported by APIAGA to be recoverable from a field, or fro.m a 

group of fields, is equal· to the cumulative production + the estimated amount of proved 

(measured) reserves. This quantity is equivalent to current estimates of ultimate recovery 

made annually by the AGA-API (1973). 

A'S fields are developed and produced, this estiModified from 

mated API-AGA ultimate recovery tende- to increase. Experience has shown that in the early 

years after di.soovery, revisions ·and exte-nsions 

·added to the API-AGA estimates of ultimate recovery tend to be large, wherf'~, in 

later years, as the fields reach full development, 

the revisions and extensions added tend to be 

smaller (Hubbert, 1967). With time tho. es~timated API-AGA ultimate recovery appr"laches 

as a limit the actual amount of oil and g2q that 

will eventually be p~oduced. Increases in estim,ates of API-AGA ultimate recovery result 

primarily because: 

1. Fields are continuously developed ann new 

drilling proves additional resen~~.s in 

known reservoirs, either within the old 

reservoir limits or in extensions to the 

field, and/ or reservoir limits ; 

Modified from 

lhlbbert ( 196 7) AGA, API, CPA (1973) U.S. Department of Interior 

terminology terminology (1974) mineral resource 

classification 

Cumulative Cumulative 

Ultimate Ultimate production Ultimate production 

production recovery recovery (not considered 

from from from part of resources) 

known known known 

fields fields fields 

Proved Measured 

reserves reserves 

I 

Indicated Indicated D 

additional reserves E 

Future reserves N 

recovery T 

growth I 

from F 

known Inferred I 

fields E reserves D 

FIGURE 39.-Correlation of production and reserve terminology. 

73 
~ 

TABLE 7.-Estimated Inferred + Indicated Reserves of crude oil for the United States through December 31, 1972 

[In thousands of barrels: derived by application of Hubbert's Correction Factors to API Ultimate Recovery for each State; *includes 

offshore] 

State Estimated ultimate 

production 

from known fieldsll 

API 

cumulative 

productionll 

API 

proved 

reserves 

Estimated inferred 

+ indicated 

reserves 

Inferred+indicated/ 

proved reserves 

Alabama----------------

Arkansas---------------

California 

Coastal-------------

Los Angeles basin---

San Joaquin basin---

Colorado---------------

Florida----------------

Illinois---------------

Indiana----------------

Kansas-----------------

Kentucky---------------

Louisiana 

North---------------

South------------~--

Michigan---------------

Mississippi------------

Montana----------------

Nebraska---------------

New Mexico 

Northwest-----------

Southeast-----------

New York---------------

North Dakota-----------

Ohio-------------------

Oklahoma---------------

Pennsylvania-----------

Texas Districts 

RR1-----------------

RR2-------~--------­ RR3----------------- RR4----------------- RR5----------------- RR6----------------- RR7B---------------- RR7C---------------- RR8----------------- RR8A----------------

285,166 

1,616,003 

3,783,671 * 

8,191,663 * 

9,108,253 

1,660,282 

789,637 

3,316,788 

511,520 

5,486,464 

710,784 

2,326,706 

19,920,425 * 

872,705 

2,361,968 

1,421,936 

507,831 

245,392 

3,971,715 

233,252 

754,041 

1,030,213 

12,834,742 

1,315,152 

917,327 

2,702,044 

7,938,132 * 

3.431.894 * 

973,101 

8,520,563 

2,025,414 

1,782,673 

12,146,873 

7,909,331 

132,527 

1,339,464 

2,737,721 * 

6,463,271 * 

6,893,901 

1,006,325 

40,702 

2,939,632 

435,120 

4,432,865 

602,563 

1,785,824 

10,717,878 * 

612,915 

1,362,197 

790,344 

333,948 

145,575 

2,720,692 

223,842 

395,034 

785,383 

10,665,828 

1,276,630 

661,154 

1,784,150 

5,874,257 * 

2,720,069 * 

816,904 

5,732,185 

1,460,949 

1,259,396 

8,277,228 

3,388·,530 

56,734 

113,100 

338,322 2 

522,048 4 

1,758,365 

326,411 

208,149 

174,883 

29,383 

453,394 

48,193 

281,451 

2,351,243 6 

62,002 

312,458 

241,248 

30,553 

24,246 

558,347 

9,246 

166,033 

127,385 

1,303,004 

37,345 

147,324 

636,768 

1,423,426 8 

286,674 lO 

98,963 

2,208,438 

235,962 

239,270 

3,402,358 

2,793,503 

95,905 

163,439 

351,046 l 

181,750 3 

455,987 

327,546 

540,786 

202,273 

47,017 

600,205 

60,028 

259,431 

1,257,971 5 

197,788 

687,313 

390,344 

143,330 

75,571 

69~,676 

164 

192,974 

117,445 

865,910 

1,177 

108,849 

281,126 

376,631 7 

~Ql,~Q~ 9 

57,234 

579,940 

328,503 

284,007 

467,287 

1,727,298 

1.69 

1.44 

1.04 

0.35 

0.26 

1.00 

2.60 

1.16 

1.60 

1. 32 

1.24 

0.92 

0.53 

3.19 

2.20 

1.62 

4.69 

3.12 

1.24 

0.02 

1.16 

0.92 

0.66 

0.03 

0.74 

0.44 

0.26 

1. ()~ 

0.57 

0.26 

1.39 

1.19 

0.14 

0.62 
-:] 

en 

RR9----------------- 3,270,728 2,623,006 324,018 323,70~ 1.00 

RRlQ---------------- 1,717,741 1,419,173 177,275 121,293 0.68 

U tab------------- ------- 1,126,984 439,486 244,397 443,101 1.81 

West Virgi~ia---------- 545,217 504,975 34,040 6,202 0.18 

Wyoming---------------- 5,385,481 3,621,094 949,779 814,608 0.86 

Miscellaneous---------- 58,348 23,533 61526 - 28.289 ~ 

Total U.S. (onshore 48)- 22,742,264 14,148,040 0.62 

Alaska *--------------- 26,325,848 467,372 10,096,282 15,762,194 1.56 

Gulf of Mexico--------- 9,380,815 3,390,408 2,565,862 3,424,545 1.33 

2 

3 

4 

5 

6 

7 

8 

9 

10 

Includes onshore inferred + indicated reserves only (offshore inferred + indicated reserves, 181,582 MBBL were 

estimated froM onshore + offshore inferred + indicated reserves in the same proportion as offshore proved reserves 

to onshore+ offshore proved reserves, and subtracted). 

Offshore proved reserves, 175,000 MBBL (Energy in California, January 1973), have been subtracted. 

Includes onshore inferred + indicated reserves only. (offshore inferred + indicated reserves, 264,593 MBBL were 

estimated from onshore + offshore inferred + indicated reserves in the same proportion as offshore proved reserves 

to onshore+ offshore proved reserves, and subtracted). 

Offshore proved reserves, 760,000 MBBL (Energy in California, January 1973), have been subtracted. 

Includes onshore inferred+ indicated reserves only (offshore inferred+ indicated reserves, 3,197,549 MBBL were 

estimated from the Gulf of Mexico inferred + indicated reserves in the same ratio as offshore Louisiana (south) 

proved reserves to Gulf of Mexico proved reserves, and subtracted). 

Offshore proved reserves, 2,395,784 MBBL have been subtracted. Estimated Louisiana offshore portion of Gulf of 

Mexico total. 

Includes onshore inferred + indicated reserves only. (offshore inferred + indicated reserves, 150,817 MBBL, were 

estimated from the Gulf of Mexico proved reserves, and subtracted). 

Offshore proved reserves, 113,000 MBBL, have been subtracted. Estimated Texas RR#3 offshore portion of Gulf of 

Mexico total. 

Includes onshore inferred + indicated reserves only. (offshore inferred + indicated reserves, 76,180 MBBL, were 

estimated from the Gulf of Mexico inferred + indicated reserves in the same ratio as offshore Texas RR#4 proved 

~ese~"Ves t~ Culf of Me~i~D proved ~2s2rves, and subtracted). 

Offshore proved reserves, 57,000 MBBL, have been subtracted. Estimated Texas RR#4 offshore portion of Gulf of 

Mexico total. 

11 Estimates of cumulative production and proved reserves are those reported by API as of December 31, 1972. 
TABLE B.-Estimated Inferred + Indicated Reserves of natural gas for the United States through December 31, 1972 

[In millions of cubic feet; derived QY application of Hubbert's Correction Factors to AGA Ultimate Recovery for each State; *includes 

offsborej 

Estimated ultimate AGA AGA State Estimated inferred Inferred+indicated/ production cumulative proved 

productionS + indicated proved reserves from known fields8 reserves reserves 

Alabama---------------- 711,575 32,450 245,714 433,411 1. 76 

Arkansas--------------- 6,828,805 2,648,096 2' 455 '877 1,724,832 0.70 

California 

Coastal------------- 6,003,609 * 4,582,833 * 761,580 * 659,196 * 0.87 * 

Los Angeles basin--- 7' 779,581 * 6,763,260 * 493,340 * 522,981 "It 1.06 * 

San Joaquin basin--- 22,153,206 14,688,996 4,073,942 3,390,268 0.83 

Colorado--------------- 5,232,405 2,232,981 1,655,200 1,344,224 0.81 

Florida---------------- 535,276 18,637 180,629 336,010 1.86 

Illinois--------------- 1,362,354 1,449,540 545,361 0 o.o 

Indiana---------------- 203,166 169,129 87,324 0 0.0 

Kansas----------------- 34,656,662 19,989,737 11,938,716 2,728,209 0.23 

Kentucky--------------- 4,615,028 3,016,192 938,082 660,754 o. 70 

Louisiana 

-=1 North--------------- 27,641,650 20,541,151 3,320,328 3,780,171 1.14 

0') South--------------- 208,363,462 * 79,933,750 * 52,258,173 2 41,478,706 1 0.79 

Michigan--------------- 2,404,169 435,268 1,296,815 672,086 0.57 

Mississippi------------ 7,490,832 4,732,872 1,104,336 1,653,624 1.50 

Montana---------------- 3,012,174 1,371,489 1,064,036 576,649 0.54 

Nebraska--------------- 393,240 282,452 50,260 60,528 1.20 

New Mexico 

Northwest----------- 18,258,544 8,002,925 8,160,874 2,094,745 0.26 

Southeast----------- 23,574,328 15,130,778 4,174, 773 4,268,777 1.02 

New York--------------- 625,744 517,541 139,184 0 0.0 

North Dakota----------- 1,467,298 657,972 441,625 367,701 0.83 

Ohio------------------- 6,780,545 4,923,164 1,146,677 710,704 0.62 

Oklahoma--------------- 67,867,548 39,101,016 14,492,030 14,274,502 0.98 

Pennsylvania----------- 10,690,352 8,677,438 1,406,948 605,966 0.43 

Texas Districts 

~1----------------- 5,028,395 2,174,549 1,620,405 1,233,441 0.76 

RR2----------------- 31,168,539 16,531,304 9,496,136 5,141,099 0.154 

RR3----------------- 64,345,153 * 31,243,379 * 11,000,458 4 5,830,303 3 0.53 

1&4----------------- 67,502,443 * 29,444,933 * 14,637,694 4 8,371,274 5 0.57 

RR5----------------- 4,620,996 2,068,519 1,171,395 1,381,082 1.18 

RR6----------------- 24,841,388 15,702,124 5,710,441 3,428,823 0.60 

RR7B---------------- 5,844,960 4,220,331 663,560 961,069 1.45 

RR7C---------------- 9,493,641 4,330,537 2,581,980 2,581,124 1.00 

RR8----------------- 51,013,171 20,372' 613 15,481,337 15,159,221 0.98 
RR8A----------------

RR9-----------------

RR10----------------

Utah-------------------

Virginia---------------

West Virginia----------

Wyoming----------------

Miscellaneous----------

Total U.S. (onshore 48)· 

Alaska *---------------

Gulf of Mexico---------

7,722,983 

6,547,247 

54,500,086 

2,876,527 

139,064 

17,898,003 

13,796,520 

116,163 

68,476,312 

4,314,806 

3,571,066 

40,844,936 

978,864 

57,449 

14,140,583 

6,296,109 

78,423 

629,864 

2,366,951 

1,559,594 

9,359,260 

1,022,110 

35,921 

2,345,957 

4,088,728 

269,987 

195,843,738 

31,455,443 

38,785,667 7 

1,041,226 0.44 

1,416,587 0.91 

4,295,890 0.46 

875,553 0.85 

45,694 1.27 

1,411,463 0.60 

3,411,683 0.83 

0 0.0 

138,929,576 o. 71 

36,391,005 1.16 

27,226,723 6 0.70 

Includes onshore inferred + indicated reserves only (offshore inferred + indicated reserves, 15,300,000 MMCF were 

estimated from onshore + offshorP. inferred + indicated reserves in the same proportion as offshore proved reserves 

to onshore+ offshore proved reserves, and subtracted). 

2 

Offshore proved reserves, 19,392,833 MMCF, were estimated as 50 percent of the Gulf of Mexico proved reserves, and 

~ subtracted. ~ 

Includes onshore inferred+ indicated reserves only (offshore inferred+ indicated reserves, 6,574,597 MCCF, were 

estimated from onshore + offshore inferred + indicated reserves in the same proportion as offshore proved reserves 

to onshore+ offshore proved reserves, and subtracted). 

4 

Offshore proved reserves, 9,696,416 MMCF were estimated as 25 percent of the Gulf of Mexico proved reserves, and 

subtracted. 

5 

Includes onshore inferred + indicated reserves only (offshore inferred + indicated reserves, 5,352,126 MMCF were 

estimated from onshore + offshore inferred + indicated reserves in the same proportion as offshore proved reserves to onshore + offshore proved reserves, and subtracted. 

6 

Sum of estimated Louisiana (south), Texas RR3 and RR4 offshore inferred+ indicated reserves. 

7 AGA, API, CPA (1973), p. 114. 

8 Estimates of cumulative production and proved reserves are those reported by AGA as of 

December 31, 1972. 
2. New drilling finds new reservoirs within the 

field limits; and 

3. Recovery of oil and gas is found to be greater than anticip3ited and/ or new recovery 1 

processes are applied to reservoirs to recover quantities of oil and gas that were 

previously considered nonrecoverable. 

Many authors have discussed the growth of 

API-AGA ultimate recovery with time from 

known fields; Hubbert (1967, 1974) has presented a method for making estimates of the 

future growth of API-AGA ultimate recovery. 

His method is based on average growth curves 

derived from past changes in estimates of APIAGA ultimate oil and gas recovery with time 

since the fields were discovered. 

As shown in figure 39, Hubbert's (1967, 1974) 

future recovery growth in known fields is correlated with the indicated + inferred reserves in 

this report. Indicated and inferred reserves 

are limited to areas immediately adjacent to or 

within the limits of known oil and gas fields. 

Estimates of these reserves assume a future 

economic climate including the economic impact of future technological advancement, 

which must be at least equivalent to the historical economic climate including the historical economic impact of technological deve]opments. 

Indicated + inferred reserves for the United 

States were estimated by applying the a correction factor (Hubbert, 1974) to the December 

31, 1972 ultimate recovery dat,a for each State 

published by AGA, API, CPA (1973). Tables 

III and XVII of AGA, API, CPA (1973) list 

crude oil and natural gas ultimate recovery 

data respectively by State, and within States, 

according to the year in which the fields were 

discovered. Hubbert's (1974) equations for 

these growth curves are expressed as: 

Y00 = Y.,.a 

where Y oo is the estimated oil (or gas) ultimate production (see fig. 39), a=1/[1-e-0·

016 

(T+l.503)] for oil, a=1/[1-e-0.063(T+4.343)] for 

gas, r is the elapsed time from the beginning of 

the year of discovery of the fields, and Y.,. is 

the past production plus the current estimate of 

proved reserves for those fields. Hubbert's ulti78 

mate production refers to the sum of cumulative past production, current estimates of 

proved reserves, and the amount of recoverable 

oil or gas in k:Qown fields to be ac"1ed by future 

developments and additions to re;--erves. 

Using the AGA, API, CPA (1973) data from 

their table Ill, the estimated ultimate production of oil, Y oo , from fields disc<J vered . in each 

year back to 1920, was calculr.ted for each 

State, and API-AGA district, yrhere r=1973 

-year of discovery. This proce-lure assumes 

that Hubbert's curves, which were derived 

from data for the entire United States, could 

be used to approxim·ate ultimate production in 

individual States or districts. F01· all fields discovered prior to 1920 a=1.0 ·was used. The 

same procedures were used to estimate ultimate production for natural gas (associated+ 

dissolved) using the December ~1, 1972, ultimate recovery data from table YVII of AGA, 

API, CPA (1973). 

Inferred + indicated reserves as of December 31, 1972, for each State were then calculated 

as: 

Inferred + Indicated Reserves = Estimated 

Ultimate Production - Cumulative 

Production - Proved Reserves. 

The State cumulative production and proved 

reserves ~ata for oil were obtain~d from table 

III (AGA, API, CPA, 1973), columns 2 and 3. 

The State proved reserves data and cumulative 

production for natural gas were obtained from 

tables XIII and XVIII (AGA. API, CPA, 

1973), respectively. 

The AGA, API, CPA data, and consequently, 

the calculated inferred + indic.q.ted reserves 

figures, contain both onshore .and offshore data 

for Alaska, California (coastal an~ Los Angeles 

Basin), Louisiana (south), and Texas Railroad 

Districts 3 ·and 4. All other States have onshore 

data only. 

The inferred reserves + indicated reserves 

and the data used for the calculations for each 

State are given here in tables 7 ~nd 8. Adjustment to the data to account for offshore areas 

are specified in footnotes to thor~ tables. The 

calculated ratios of inferred + indicated to 

proved reserves are also given in the tables. 

~U.S. Government Printing Office: 1917-240-961/107