YU, Z., and * IAN LERCHE, University of South Carolina, Columbia, SC

ABSTRACT: Impacts of Various TOC Distributions on Hydrocarbon Generation

This study uses numerical basin modeling methods to examine how various total organic content (TOC) distributions in formations, with a fixed average TOC, impact the overall oil and gas generation potential. Different geological and geochemical conditions, such as the thickness and burial depth of the source formation, the thermal gradient, organic richness, degree of spread, and types of kerogen are all considered in this investigation.

The results show that there is a significant impact on the overall oil and gas generation potential, especially when the source rocks are in the peak generation windows. The varying magnitudes of oil and gas generation can be up to 5-10 times different as shown in some cases. The general rules are that the richer and more spread the variation of TOC, or the thicker the formation and the greater the thermal gradient, the larger the difference between the distributions which favor generation. This study indicates that not only the average TOC richness, but also the TOC distribution in a source formation must be considered when the petroleum potential of a basin is evaluated.

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