--> ABSTRACT: Origin of Hydrocarbons in Gulf of Mexico Basin: A Reappraisal, by K. K. Bissada, B. J. Katz, S. C. Barnicle, and D. J. Schunk; #91030 (2010)

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Origin of Hydrocarbons in Gulf of Mexico Basin: A Reappraisal

K. K. Bissada, B. J. Katz, S. C. Barnicle, D. J. Schunk

The origin of hydrocarbons in the Gulf of Mexico basin has been a subject of controversy for many years. One argument invokes source rocks of average organic enrichment, pervasively distributed throughout the Tertiary sequence and closely associated with the reservoir system. Another argument invokes exceptionally rich, discrete source rocks not in contact with the reservoirs, possibly in pre-Tertiary sequences. Continued exploration success in the basin hinges on the resolution of this controversy because of implications on patterns of hydrocarbon migration within the basin and the timing of petroleum generation relative to reservoir and trap development.

Geochemical analyses of hundreds of crude oils, natural gases, and nonreservoir rocks from the Mesozoic and Cenozoic trends along the northern Gulf of Mexico basin indicate the general inadequacy of the Tertiary section to source the huge oil accumulations within Cenozoic reservoirs. Furthermore, other than the biogenic gas, isotopic data indicate that the majority of nonassociated gases found in Cenozoic accumulations have been thermogenically derived from much greater depths where maturation is consistent with dry gas generation.

Geochemical data from several Mesozoic units in the basin, but outside the Cenozoic trend proper, indicate the existence of excellent Mesozoic source rocks. It is proposed that such units extend below the Cenozoic producing trends and are drained by deep-seated faults and piercement salt structures. Maturation history, structural style, and patterns of migration and remigration control the variable productivity along the various trends.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.