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The AAPG/Datapages Combined Publications Database

GCAGS Transactions


Gulf Coast Association of Geological Societies Transactions
Vol. 50 (2000), Pages 321-330

Sensitivity Analysis of Petroleum Formation Modeling in the Northern Gulf Basin

Eric J. Nelson, Michael D. Lewan, Paul Weimer


The petroleum systems in the northern Gulf of Mexico Basin were examined to estimate the sensitivity of important modeling parameters in petroleum formation. A series of 1-D models were analyzed for three thermal history parameters (thermal conductivity, heat flow, and surface temperature) and various kinetics parameters for different kerogen types. Source intervals in the study area included Eocene, Turonian, and Oxfordian strata. The results indicate that varying each of these parameters can have a significant effect on the timing of petroleum generation.

Three thermal history parameters were varied by +/- 20% of their original values. Changes in thermal conductivity and heat flow were capable of altering the transformation ratios of the source intervals from 0.03-0.97. Modifying surface temperature affected the transformation ratios of the source intervals from 0.30-0.70.

Timing of oil generation can also be significantly affected by kinetics parameters, the values of which are influenced by the kerogen type and the pyrolysis method (Rock-Eval, hydrous) from which they were derived. Models of the three source intervals using different kinetics give varying results. The Turonian source interval is a marine shale Type II kerogen. The 1-D models indicate a similar petroleum formation history, irrespective of the kinetics used. The Eocene source interval has been modeled as both Type II and III kerogens. Significant variations exist between the timing and rates of petroleum formation in the models. The Oxfordian source interval in the deep Gulf of Mexico is a Type IIS, and all models indicate an early oil generation.

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