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Estimates of undiscovered oil and gas, Permian Basin of West Texas and Southeast New Mexico

1979; United States Department of the Interior; Linguagem: Inglês

10.3133/ofr79838

2332-4899

G.L. Dolton, A.B. Coury, Sherwood E. Frezon, Keith Robinson, K. L. Varnes, Jan Wunder, Robert W. Allen,

Atmospheric and Environmental Gas Dynamics

Tables 1-13.Permian basin: 1. Discovered oil and gas in-place, Permian basin (1921-1974) 2. Estimates of undiscovered hydrocarbons, Permian system 3. Estimates of mean depth of undiscovered hydrocarbons, Permian, system 4. Probability estimates of undiscovered pool sizes, Permian system 5. Estimates of undiscovered hydrocarbons, Carboniferous systems 6.Estimates of mean depth of undiscovered hydrocarbons, Carboniferous systems 7. Probability estimates of undiscovered pool sizes, Carboniferous systems 8. Estimates of undiscovered hydrocarbons, older Paleozoic systems 9. Estimates of mean depth of undiscovered hydrocarbons, older Paleozoic systems 10.Probability estimates of undiscovered pool sizes, older Paleozoic systems 11.Estimates of undiscovered hydrocarbons, total Paleozoic 12. Estimates of mean depth of undiscovered hydrocarbons, all Paleozoic systems 13.Probability estimates of probability distribution of undiscovered pool sizes, all Paleozoic systems, Permian basin, total 14.Original probability estimates of undiscovered 15.Original probability estimates of undiscovered non-associated gas in-place-C-3 16.Original probability estimates of the pool sizes of undiscovered oil in-place C-4 17. Original probability estimates of the pool sizes of undiscovered non-associated gas iii ABSTRACTApproximately 91.6 billion barrels of oil-in-place and about 106.2 trillion cu ft of dissolved/associated and non-associated gas-in-place have been discovered in the Permian basin of western Texas and northeastern New Mexico.The objectives of this study were to estimate the in-place quantities of undiscovered oil, dissolved/associated gas, and nonassociated gas in the basin and to estimate the size and number of pools in which the appraised amounts of oil and gas occur.All assessments were initially made by age-depth units; each unit consists of rocks of a specific geologic age within a specific depth interval.The age intervals used were 1) the Permian System, 2) the Carboniferous systems (Pennsylvanian and Mississippian), and 3) the older Paleozoic systems (Devonian, Silurian, Ordovician, and Cambrian); the depth intervals used were 0-10, 10-20, and 20-30 thousand feet below the surface.Assessments were made for each age-depth unit at the 5, 25, 75, and 95 percent probability levels.Statistical means for each unit were computed.By making the assessments in the small age-depth units and by utilizing Monte Carlo aggregation procedures, it was possible to determine total quantities of hydrocarbons in the entire basin at all probability levels, as well as total quantities by age and by depth.The following table summarizes our estimates for undiscovered hydrocarbons-in-place: Commodity Oil (billion bbls) Natural gas (trillion cu ft) Undiscovered in-place resources Probability 0.95 0.05 3.32 10.43 12.89 33.80 Mean 6.35 21.87Our estimate of undiscovered oil-in-place at the 95 percent and 5 percent probabilities is 4 and 11 percent, respectively, of the known and produced oil-in-place.Our estimate of the total gas-in-place at the 95 percent and 5 percent probabilities is 12 and 32 percent, respectively, of the total known and produced gas in-place.Our estimates of pool size distributions indicate that undiscovered pools in the basin will be, on the average, significantly smaller than those discovered to date.No totally satisfactory method has been developed to determine the numbers of pools to be found, and no estimates of these numbers are presented.'Twttwy ignvoiM rocfc» not shown 'Of subsurface u»ag* MODIFIED AFTER OALLEY.1968Figure 2Generalized stratigraphic and lithologic column .showing productive intervals.Reassessments will always produce changes because ideas change with time, and in many areas significant new data will come to light.Those new ideas and new data, however, will not necessarily always result in decreased assessments.It is not possible, therefore, to extrapolate a reduced expectation nationwide from this single-area reassessment.The Resource Appraisal Group reserves the right to alter any of the results in this report in the event that such modifications are considered necessary during the preparation of a manuscript for U.S.