Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
AAPG Annual Convention, Houston, Texas, April 9–12, 2006
Oil-Play Analysis of the Permian Basin: A Tool for Increasing Recovery from a Mature Oil-Producing Province
The Permian Basin of west Texas and southeast New Mexico remains an important oil-producing province, accounting for 18% of U.S. production (320 MMbbl) in 2004. With this major resource base, better understanding of reservoir geology and expanded use of enhanced-recovery practices in the basin can have a substantial impact on U.S. oil production. Thirty-two oil plays were defined on the basis of reservoir stratigraphy, lithology, depositional environment, and structural and tectonic setting; 1,339 significant-sized reservoirs (cumulative production of >1 MMbbl of oil through 2000) were each assigned to a geologic play. Cumulative production from these reservoirs was 28.9 Bbbl, or 95% of the basin’s total. Geologic play classification will aid in transferring successful secondary and tertiary recovery techniques to analogous fields.
Recent reservoir-development approaches used in the Permian Basin include CO2 injection, horizontal drilling, drilling targeted by seismic-attribute analysis, gravity drainage assisted by nitrogen and CO2 injection, water coproduction, and steam injection. CO2 flooding has worked well in plays having reservoirs with clear target intervals, such as stacked grainstone-rich carbonate cycles or sandstones, and good top and lateral seals. CO2 flooding is less likely to be successful in plays having strongly fractured, bottom-water-drive reservoirs. Remaining reserves of the significant-sized oil reservoirs in the Permian Basin were estimated using decline-curve analysis of play production data from 1970 through 2000. Estimated remaining oil reserves through 2015 are 3.25 Bbbl. The Northwest Shelf San Andres Platform Carbonate and Leonard Restricted Platform Carbonate plays compose more than 41% of this total.