UNITED STATES MINERAL RESOURCES 



OIL AND GAS 



By T. H. McCuLLOH 



CONTENTS 



Page 



Abstract 477 



Introduction 477 



The problem 477 



Geologic setting 478 



Producible hydrocarbon assessment 480 



Fluid hydrocarbons from sedimentary organic 



detritus 484 



Petroleum migration and entrapment 485 



Petroleum and natural gas resources 487 



Selected references 493 



FIGURES 



57. 



58. 



59. 



Page 



Graph showing age-dependent variations in the 

 average content of organic carbon in sedi- 

 mentary rocks from the Russian Platform and 

 the United States 479 



Graph showing age-dependent variations in pro- 

 duced and proven reserves of oil and gas for 

 the United States and the world 482 



Diagram showdng selected diagnostic and critical 

 steps in the genesis and migration of petroleum 

 and natural gas from sedimentary organic 

 matter 488 



Graph showing estimates of ultimate producible 

 oil resources (and ultimate oil in place) of the 

 United States, in relation to records of cumula- 

 tive production plus proved reserves from 1900 

 through 1972 491 



Graph showing United States and world crude 

 oil production and proved reserves in relation 

 to selected important developments in petro- 

 leum exploration technology 492 



ABSTRACT 



Thermal "cracking" of part of the biogenic organic de- 

 tritus interred in fine-grained subaqueous sediment releases 

 hydrocarbon compounds that form petroleum and natural gas. 



Rapid nearshore marine deposition favors accumulation and 

 preservation of such sedimentary organic matter. Tempera- 

 tures high enough for cracking to begin and compactional 



pressures great enough to actuate mechanisms of hydro- 

 carbon expulsion and migration require basinal burial to 

 depths of 1,500 feet or more. Wherever fluid hydrocarbons 

 migrating toward the surface are interrupted and trapped, 

 oil and gas reservoirs occur. 



Organic carbon, hydrocarbons, and producible hydrocarbon 

 accumulations are distributed extremely unevenly in the 

 United States and the world. They are practically restricted 

 to sedimentary rocks and are much more abundant in geologi- 

 cally young strata than in old. Producible hydrocarbons oc- 

 cur with greatest frequency and in greatest volume at depths 

 shallower than 10,000 feet, and a very small percentage of 

 all known accumulations contains a very large percentage 

 of all proved reserves. A few regions (notably the Middle 

 East) contain a disproportionate share of the world re- 

 serves. 



All estimates of petroleum and natural gas resources de- 

 pend upon prior exploration results and are unreliable. 

 Changing economic incentives, technologic advances, en- 

 larged prospecting areas, and creative thinking all increase 

 exploration effectiveness. 



INTRODUCTION 



THE PROBLEM 



What are the ultimate potential United States and 

 world resources of petroleum and natural gas, both 

 those discovered and those waiting to be found? 

 Where are they? What part of them can be found 

 and exploited economically? What fraction of the 

 total was originally within the territorial limits of 

 the United States? How much of that fraction lies 

 beneath the continental shelves — and where? To 

 what extent will the United States be dependent in 

 the future on imported petroleum, and how can we 

 be assured of an economical supply? What should 

 be the national goal and policy toward encouraging 

 domestic exploration on land and beneath the 

 continental shelves? What part of our national 

 research and investment capability should be devoted 

 to programs aimed at utilizing coal resources or 

 nuclear "fuels" more fully in the future in place of 

 petroleum and natural gas? Should special incen- 

 tives be provided to support conservative but eco- 



U.S. GEOL. SURVEY PROF. PAPER 820 



477 



