490 



UNITED STATES MINERAL RESOURCES 



earth, which had yielded or appeared likely to yield 

 oil" (Pratt, 1951, p. 9). De Golyer (1951, p. 9) 

 criticized the Stebinger-Weeks-Pratt methods and 

 assumptions in the following terms, "any hypothesis 

 of equal expectation of minable oil by volume or 

 area of sediments over large areas presupposes that 

 the effects of all these processes will average about 

 the same or, in case of inequalities that they will 

 compensate." Of the figures themselves, De Golyer 

 wrote, "They may be too high. They may be too low. 

 I do not know. I am inclined to think that Pratt's 

 original estimate of 100 billion bbl for the United 

 States may be too low even if we add 13 billion bbl 

 for the continental shelves . . . ." Inasmuch as cumu- 

 lative production for the United States is today 

 above 97 billion barrels, with 38 billion barrels more 

 already categorized as "proved reserves" capable of 

 economic extraction under current technology, the 

 Stebinger-Weeks-Pratt estimation of 1942 was ob- 

 viously an underestimation. The comparative suc- 

 cess of a subsequent basically similar partial pro- 

 jection (Hopkins, 1950) leads one to ask, can we 

 tell at this time that Hendrick's 1965 estimation of 

 400 billion barrels is an overestimationi 



Although Hubbert's predictive (or projective) 

 analytical procedure and results are perhaps more 

 widely publicized than others, he is by no means 

 the only scientist to have applied this method. Arps, 

 Mortada, and Smith (1970) and Moore (1970a, b), 

 provide examples of predictions made recently using 

 similar mathematical analytical techniques which 

 give somewhat divergent results; 165 billion bar- 

 rels of "proved ultimate recovery discovered" 

 (Arps and others, 1970, fig. 4) or 353 billion barrels 

 (or 60 percent recoverable of 587 billion barrels of 

 oil originally in place in the United States are pre- 

 dicted as discoverable ; Moore, 1970a, fig. F-l) Does 

 Moore know something that Hubbert does not to 

 cause his projection to be so much higher (353 

 billion versus 200 billion barrels; or versus 165 

 billion in the case of Arps) ? I think not. The pro- 

 jective techniques employed are all probably equally 

 sound and the same basic data were entered into 

 each projection. There is simply enough latitude in 

 the method that such divergent results all lie within 

 the range of valid results. More importantly, these 

 divergences are a measure of the adequacy of the 

 projective baseline, which is no doubt subject to 

 further evolutionary change as economic incentives 

 enlarge, as competitive pressures force improve- 

 ments in conservative efficiency, and as technologic 

 advances permit improved and expanded explora- 

 tion (greater ability to discover smaller and less 

 conspicuous traps and to exploit a larger part of 



the resource base and a larger part of the prospec- 

 tive rocks). Speaking of the annual world oil dis- 

 covery rate in a similar context, Warmen (1971, p. 

 97) wrote, "for a curve with such violent fluctua- 

 tions, it is not possible to carry out meaningful 

 mathematical analysis." Needless to say, future 

 changes in the baseline will inevitably be enlarge- 

 ments. 



For the sake of easy comparison at a glance, all 

 of the more authoritative estimates of future and 

 ultimately producible petroleum for the United 

 States have been brought together in figure 60 and 

 plotted as a function of their date of publication. 

 Plotted also is the gross curve of production plus 

 cumulative discoveries. The reader will note that 

 the many more or less independent projections 

 show a great deal of scatter (divergences such as 

 those among the projections of Arps, Hubbert, and 

 Moore) , and that they tend to grow with the passage 

 of time in a fashion that more-or-less parallels the 

 growth of the curve of cumulative production plus 

 reserves. Both the scatter and the tendency to grow 

 are meaningful. They reflect the fact that the area 

 under consideration has not remained constant 

 through time — new producing regions and areas 

 have been brought into the picture through com- 

 binations of business enterprise, economic pressures 

 of many sorts, technologic advances, and exploita- 

 tion eff'ectiveness. There is considerable room for 

 continuation of this evolutionary advancement — in 

 all respects. Much of the United States continental 

 shelf is unexplored. Who can say at this time that 

 another "Los Angeles Basin" doesn't wait for dis- 

 covery and exploitation beneath the waters of the 

 Southern California Borderland (Emery, 1960) ? 

 Who knows that there is not another "Middle East," 

 for example, beneath the continental margin off the 

 southern Atlantic coast of the United States, with 

 another "Ghawar" accumulation (the largest single 

 oilfield yet discovered in the world) containing an- 

 other "75 billion barrels of producible reserves" 

 (Arabian American Oil Company, 1959; Halbouty 

 and others, 1970) ? The onshore-offshore region 

 south of Cape Hatteras has much in common geo- 

 logically with the onshore-offshore region of Saudi 

 Arabia, including a very thick section of structur- 

 ally simple sedimentary rocks of the same ages and 

 similar lithologies beneath a very large area. Prior 

 to discovery by the drill and subsequent develop- 

 ment, Ghawar field was not a particularly conspicu- 

 ous prospect or structure, either from surface 

 geologic mapping or geophysical interpretation 

 (Arabian American Oil Company, 1959, especially 

 p. 437 and p. 440-443). Does anyone know that 



