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Modeling the Burial History and Maturity of the Haynesville Formation in East Texas and Northwest Louisiana


The study area located in East Texas, Northwest Louisiana and southern Arkansas has been and still is a region of extensive hydrocarbon exploration. A rift-margin basin developed in the Late Triassic to Middle Jurassic related to the opening of the Gulf of Mexico. Subsequent cooling of the crust resulted in gradual subsidence and deposition of more than 5 km Mesozoic and Cenozoic sediments. Structural styles within the area are mostly characterized by rift margin basin structures and salt tectonics such as widely spaced normal faults with small displacement and a variety of structures related to salt diapirism. The geological model is constructed from stratigraphic well-log picks obtained from the IHS data base that covered several thousand oil and gas exploration wells. Additional information is obtained from published profiles, maps and publications. Digitized isolines of the top of salt model from the East Texas Basin salt tectonic atlas provided essential assistance for the construction of the base of the model. The picks of 12 formation tops were used for the construction of the geological model with PETREL®. The formation tops were interpolated, automatically corrected for intersections and locally corrected manually. Patchy distribution of well picks, salt tectonics and not well documented tectonic displacement impeded horizon interpolation and model construction. The resulting geological model comprising the NE Texas Salt Basin, Sabine Uplift and small parts of the NW Louisiana Salt Basin provides the base to construct a basin model with PETROMOD®. The model incorporates facies dependent lithology variations to account for lithology dependent variations of thermal conductivities. Erosion events are reconstructed in particular in and around the Sabine Uplift. Effort is taken to incorporate salt migration and the resulting formation of diapirs in the. A simple rifting-derived heat-flow boundary condition was defined assuming a heat flow peak of 150 mW/m2 at 190 Ma declining to a present day heat flow of 67 mW/m2. Model calibration with measured vitrinite reflectance data from the top of Sabine Uplift is good. The modeled burial and maturation distribution shows overmature, deeply buried parts of the Haynesville in the East Texas Salt Basin while the Haynesville on and around Sabine Uplift is mainly in the dry gas window. This also puts the most favorable areas for shale-gas potential to be located on and around the area of the Sabine Uplift.