ABSTRACT

This paper is a statistical study of the down-dip South Texas Wilcox-Eocene producing trend from an engineering and geological viewpoint. The trend includes 193 fields which produce from Wilcox reservoirs, and it extends area-wise from northern Duval County to Lavaca County, Texas. Approximately 70 percent of the fields are gas and condensate productive, so the trend is considered primarily natural gas trend.

The reservoir characteristics of the Wilcox sands create some definite engineering problems. The recognition and solution of these problems represents the difference between a sound operating program with a good return on invested capital and a marginal or subeconomic operation. This paper points out the geologic and reservoir conditions that create these problems and indicates some drilling, development, and completion procedures that will help minimize their effects in the future.

Discovery and development rates are studied and compared to costs, reserves, and margin of profit. Increasing prices for gas, oil, and condensate coupled with increasing market facilities along the trend give a firm basis for the prediction of future activity. Discovery rates and return on invested capital are sufficient to attract drilling and development programs in the future. Prudent operators, with reliable engineering and geologic studies, can expect a fair return on their money.