DISCHINGER, JR., JAMES B., G. E. KRONMAN, and J. S. GROSS, Amoco Production Company, Houston, TX

ABSTRACT: Exploration in a Mature trend: An Example from the Wilcox Formation of Texas

The following case history of Muy Grande Field demonstrates that detailed work in mature trends can still expose significant reserves.

The Muy Grande Field in western Duval County, Texas, was discovered in 1989 with the drilling of the Amoco #1 Peters Estate. The well was drilled within the "Fandango Fairway," which extends from East Seven Sisters Field (350 + BCF) in northern Duval County to Fandango Field (165 + BCF) in Zapata County. Muy Grande Field, a faulted anticline, is currently thought to contain at least 200 BCF within stacked sandstone reservoirs ranging from 13,000 to 17,000 feet in depth.

The Muy Grande structure was one of several anomalies in the expanded Upper Wilcox trend that was identified by Amoco and thought to have significant potential. A major concern, however, was that the Muy Grande reservoir sand had been unsuccessfully penetrated in apparent trapping position on the structure by four separate operators. A historical analysis of gas production and shows shallower on the feature suggested that untested economic quantities of gas might still exist in deeper traps. State-of-the-art geologic, petrophysical, and geophysical data acquisition, processing, and analysis techniques were utilized to evaluate the structure.Detailed log analysis, production/show data, and data from fields along trend was used to define the trap, critical sealing faults, migration path , and potential pay zones, leading to the successful discovery and exploitation of this new field.

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