Late Mesozoic and Cenozoic Deposystem Evolution in the Eastern Gulf of Mexico: Implications for Hydrocarbon Migration
Published:December 01, 2001
Richard H. Fillon, 2001. "Late Mesozoic and Cenozoic Deposystem Evolution in the Eastern Gulf of Mexico: Implications for Hydrocarbon Migration", Petroleum Systems of Deep-Water Basins–Global and Gulf of Mexico Experience, R.H. Fillon, N.C. Rosen, P. Weimer, A. Lowrie, H. Pettingill, R.L. Phair, H.H. Roberts, H.H. van Hoom
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A preliminary analysis of Mesozoic and Cenozoic deposystems in the eastern Gulf of Mexico, using published regional stratigraphic and depth to basement studies, reveals striking elements of deposystem history and petroleum system architecture. Integration of thirteen regional studies into a single chronostratigraphic framework provides a basis for assessing accumulation rates within eight provisional Late Mesozoic second-order depositional sequences and eight Cenozoic second-order depositional sequences spanning the interval 165 Ma to the present.
Interval accumulation rate mapping reveals that major deposystems shifted in response to the changing tectonic setting of the Gulf basin. The evolving deposystems reflect changes in sequence architecture corresponding to evolution from a dynamic environment of salt tectonics and hot mobile crust in the youthful Gulf basin to cool thermally stable modern crust where gravity driven depositional patterns dominate. Shifting depocenters throughout this period differentially loaded and compacted underlying sediments, thus modifying pressure gradients that influence the lateral migration pathways of hydrocarbons. Analysis of differential deposystem loading predicts that hydrocarbon migration paths locally converge within the original Federal lease sale 181 area, principally because Late Cretaceous strata in the area are relatively thin compared to adjacent areas. While perceived hydrocarbon risk is therefore diminished, low accumulation rates for most sequences suggest that reservoir risk in a given vertical section is high. The search for productive reservoir in the area should therefore focus on specific parts of the section immediately above or below a condensed Middle Cretaceous Sequence Boundary (MCSB) interval that exhibit accumulation rates higher than the regional average. Accordingly, the late Albian-early Cenomanian (Paluxy sequence) and the middle to late Miocene (upper Miocene sequence) are preferred candidates for exploration.