ABSTRACT

Hydrocarbon maturation and migration analysis employing parameters dealing with original depositional environments, lithic stratigraphic thickness patterns, post-depositional changes, and time-depth thermal history provide quantitative hydrocarbon expulsion estimates for north Louisiana's hydrocarbon system. Since the early Cretaceous, oil emanating from kerogen rich late Jurassic post-Louann source rocks has been available for migration into the system's Jurassic, Cretaceous, and Tertiary reservoirs.

Data from a stratigraphic framework of sea-level referenced geologic time-depth profiles provide the basis for illustrating the results of numerical simulations of the changes that occurred during the evolutionary development of the hydrocarbon system. Palinspastic reconstructions show the sequential depositional and post-depositional stratigraphic and structural changes that occurred across a grid of representative vertical profiles. Results of the analysis permit estimates to be made of zone-specific, time-oriented volumetric oil contributions potentially available to the system. This enables sequential stratigraphic mapping of the geologic history and the inferred linkage of present reservoir contents with hydrocarbon expulsion from specific source rocks.

The sedimentary section in north Louisiana is estimated to have been capable of generating between 2000 to 2500 billion barrels of oil during approximately 150 million years of geologic time. The major portion of the oil was generated in Upper Jurassic and Lower Cretaceous source rocks with a significantly decreasing amount coming from the Upper Cretaceous and Paleocene. Maximum potential expulsion of hydrocarbons was reached during the Paleocene-Eocene, when approximately two-fifths of the total oil is estimated to have been generated.