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Integrating Burial and Thermal Models for Source Rocks With Regional Seismic Interpretations and Structural Models of East Texas


In support of recent assessments of the undiscovered, technically recoverable oil and gas resources of the onshore coastal plain and State waters of the U.S. Gulf Coast, the U.S. Geological Survey (USGS) is researching the variability in generation, migration, and accumulation of hydrocarbons across different parts of the basin. As part of this effort, the USGS has interpreted a network of 2D seismic lines that span eastern Texas and westernmost Louisiana. This network includes two regional composite lines that are each more than 275 miles long, and trend in a north-south direction from the vicinity of the Texas – Oklahoma border to the Texas coastline. Based on interpretations of these lines, structural restorations have been constructed that model the post-Middle Triassic sequential structural evolution of east Texas, including the highly productive East Texas salt basin and the Houston diapir province. Previous work by the USGS integrated these structural restorations with thermal models (incorporating kinetics and burial histories for four wells) of two of the region's primary source rocks: the Oxfordian Smackover Formation and the Cenomanian-Turonian Eagle Ford Shale. This resulted in a petroleum system model for the spatial and temporal variation in hydrocarbon generation across east Texas. Building upon this model, we have constructed burial history curves for an additional suite of wells that cover a broader portion of east Texas. Model results have been combined with restored structural horizons through time to create a series of horizontal 2D petroleum systems models for east Texas. In addition to showing hydrocarbon generation and migration from the Smackover Formation and the Eagle Ford Shale, the petroleum systems models highlight potential hydrocarbon sources within the Paleocene-Eocene Wilcox Group. The petroleum systems models illustrate key differences in the timing and depth of hydrocarbon generation for the three source rocks along the length of the composite seismic sections, and highlight differences in hydrocarbon generation and migration between the East Texas salt basin, the Houston diapir province, and the flanks of the Sabine uplift.