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Delaware Basin Evolution: Preliminary 3-D Basin Model for Petroleum System Analysis

Abstract

Basin modeling of the polyhistory Delaware Basin incorporating 126 oil and gas exploration wells provides critical insight into its petroleum system evolution. One dimensional basin models reveal five significant tectonic subsidence episodes: 1. The Tobosa Basin Rift and Rapid Subsidence Phase (488 – 435 Ma), 2. The Tobosa Basin Thermal Decay and Stable Platform Phase (435-320 Ma), 3. The Foreland Permian Basin Rapid Subsidence Phase (320-250 Ma), 4. The Mesozoic Delaware Basin Stable Platform Phase (250-80 Ma) and 5. The Delaware Basin Cenozoic Tectonic Uplift Phase (80-0 Ma). Fitting calculated kinetic maturities which incorporate borehole temperature derived heat flows to observed vitrinite reflectance values reveal that the latter three tectonic phases were relatively thermally invariant and can best be explained not by classic models of fault mechanical subsidence and subsequent thermal cooling but instead by an overprint of lithospheric flexure. Two dimensional basin modeling of regional North-South and East-West cross sections reveal lateral variations in sediment geometries, thicknesses, and lithologies associated with the tectonic phases and have important implications concerning episodes of basin opening, stagnation, and closing with respect to the Panthalassa Ocean and to predictions of reservoir, source, and seal quality. Three-dimensional modeling of the Delaware Basin's developing asymmetry display gas and oil migration pathways from evolving basin Simpson, Woodford, Barnett, Wolfcamp, and Bone Spring depocenter source pods to developing intrabasinal structural highs and extrabasinal margins. These pathway vectors predict large magnitudes of hydrocarbons to have migrated within major carrier beds toward the surrounding shelves. These preliminary regional basin model observations of evolving tectonics, thermal histories, sediment geometries, organic maturities and hydrocarbon migration pathways can provide the basis for testing new hydrocarbon play concepts within the Delaware Basin.