Deepwater Basin Model for the Permian: Delaware Basin Example

The Permian was an unusual time in the Earth’s past, a time of continental accretion, falling sea level, and of global cooling. Basins formed at this time hold some of the most prolific petroleum systems in the world, are well studied, yet still hold much mystery with respect to their relationship between tectonic evolution, sedimentary fill, thermal maturities, and remaining exploration potential. One such important Permian basin is that of the deep Delaware Basin of southeastern New Mexico and west Texas U.S.A. Tectonic subsidence analysis of 11 boreholes reveal best fit kinetic maturities which require one major tectonic extension event from ~268 Ma to ~251 Ma (betas ~1.25 to ~1.53) and shortening from 80Ma to 65Ma (beta ~0.855). Principal source rocks are the underlying Devonian Woodford, Carboniferous Barnett, Permian Wolfcamp, Bone Spring and Delaware Mountain Group (DMG) formations. Modeling shows that the DMG and Bone Spring Formations are presently within the oil window whereas the Woodford and Barnett formations are below the oil window. The DMG began entering early mature oil phase in late Permian. Woodford and Barnett formation began entering the early mature oil phase in the late Pennsylvanian. The Bell Canyon formation is within the main oil window in the deeper part of Delaware Basin (northeast and eastern part of Delaware Basin) whereas the Brushy Canyon formation is within the main oil window in the northern part of the Delaware Basin. Major migration pathways in the Delaware Basin are SE to NW and SW to NE. The critical moment for the accumulation of liquids in the DMG and Bone Spring is Late Permian, around 265Ma -261Ma. Knowledge of the thermal maturity evolution of the Delaware Basin provides important constraints upon determining optimal exploration programs for exploiting liquids and gases either conventionally or unconventionally in these Permian strata.