Edwards 1980: The Upper Wilcox Rosita delta system of South Texas. Corpus Christi Geol. Soc. Bull. February, 1980, 5-11.

INTRODUCTION

This study of the upper Wilcox of South Texas was conducted to locate sandstone reservoirs suitable for the production of geopressured geothermal energy. Such reservoirs ideally have high permeabilities of at least 20 md and should be capable of producing 40,000 barrels per day of hot, pressured methane-saturated water (Bebout et al., 1978). The potential reservoirs outlined by this study, and for which permeability data were available, have permeabilities that are too low for sufficiently high rates of water production.

This investigation is based largely on the detailed correlation of approximately 500 well logs and a commercially available structure map on the top of the Wilcox.

A depositional framework of Wilcox Group was first proposed by Fisher and McGowen (1967) and Fisher (1969). These authors considered the important Wilcox sandstone reservoirs stretching between Zapata and Bee Counties to represent lower Wilcox shelf edge sands reworked along strike from the Rockdale Delta System located to the northeast. In the present study, the major sandstones of the South Texas deep Wilcox trend have been interpreted as belonging to the upper Wilcox, and to having been deposited in large growth-faulted delta complexes that prograded out to the shelf edge. These conclusions conflict with previous studies which have suggested that 1) the upper Wilcox formed in high-destructive deltas which did not undergo extensive growth faulting (Fisher, 1969), and 2) the deep upper Wilcox was deposited in deep water by turbidity currents (Berg and Tedford, 1977).

Back To Gulf Of Mexico Publications

Back To Top

©by Marc B. Edwards
Consulting Geologists, Inc