ABSTRACT

Lying virtually unexplored, a large area of stratigraphic promise covers more than 5,000 square miles over the updip Lower Cretaceous rocks southeast of the Llano Uplift of South Texas. Tectonic instability of the region has fostered structural anomalies which have created conditions favorable for the accumulation of hydrocarbons in the resulting stratigraphic traps. Residual pre-Cretaceous topographic features form the structural framework upon which the stratigraphic traps were formed.

Geological evidence points to reef development, beach rock in high energy zones, basal onlap, inter-formation wedge-out, and intra-formation facies changes as the types of stratigraphic traps which exist. Potential reservoir rocks are carbonate, with the exception of one formation which is clastic. Hydrocarbons have been detected in non-commercial amounts in all of the reservoir rocks. Petroliferous shales separate the carbonates.