Geochemical Characteristics of Upper Tertiary Shales, Offshore Texas

Wallace G. Dow, M. Arif Yukler

Organic geochemical characteristics of upper Tertiary shales are defined in two offshore Texas wells. Organic facies data can be related to depositional environments including water depth, sedimentation rate, and redox potential at the water-sediment interface. Kerogen type and maturity define the oil and gas-generating capability of typical Gulf Coast Tertiary shales. These data are used to establish reaction kinetics and hydrocarbon yields for Gulf Coast kerogens. One-dimensional quantitative basin analysis models of the subject wells relate geochemical data to hydrocarbon generation and demonstrate the effect of high heating rates on controlling the type of petroleum formed. Rapid generation and expulsion can result in more liquid petroleum from poor-quality source rocks than would be expected under average burial conditions. This study has defined the petroleum-generating capability of Gulf Coast Tertiary sediments and the type of hydrocarbons they will generate and expel.

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