WENGER, LLOYD M., EXXON Production Research Company, Houston, TX; and THERESA F. SCHWARZER, EXXON Exploration Company, Houston, TX

ABSTRACT: Secondary Migration Evaluation of Tertiary-Reservoired Hydrocarbons in South Louisiana: An Application of Oil-Source Correlation Techniques

Oil-source rock correlations, along with regional mapping of oil families, source organic facies, and maturity level have provided vital input for reconstructing maturation/migration timing and migration pathways from source to trap in the Tertiary of south Louisiana basin models of hydrocarbon generation and migration (e.g., TEMISPACK) support observed geochemical evidence for both short and long distance strata-parallel, and cross-stratal migration, including vertical migration of Tertiary hydrocarbons up listric growth faults.

Four onshore oil subfamilies have been identified through geochemical characterization of produced hydrocarbons from Tertiary reservoirs ranging from Paleocene to Pliocene age. These subfamilies are genetically related to Lower Tertiary Wilcox and Sparta shale source rocks which contain mixtures of varying amounts of marine algal and terrestrially-derived higher plant organic matter. The terrestrial versus marine-sourced proportions of the oil subfamilies are consistent with the regional distribution of facies within (or distal to) the Eocene Holly Springs delta system.

Strong evidence for the correlation of Tertiary-reservoired oils with Eocene Wilcox and Sparta shales were drawn from similar molecular distributions between oils and source rock extracts. Positive oil to source rock correlations have been made for the terrestrial and intermediate (mixed marine and terrestrial) oil subfamilies. Where deep penetrations of the Cretaceous were encountered in southern Louisiana, all were post-mature with respect to oil generation making the Cretaceous an unlikely source of the moderately mature Tertiary-reservoired hydrocarbons. In addition, there is no indication of source potential in Oligocene and younger intervals.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.