In 1974 Texaco Inc. initiated a detailed geological-engineering study of the reservoir in the Cogdell Canyon reef unit. The goal of this study was to improve production. The Cogdell Canyon reef unit is located in the Horseshoe Atoll of northern Scurry and southern Kent Counties, Texas.
Detailed lithologic, paleontologic, and depositional environmental analyses indicate the presence of nine vertical zones ranging from late Strawn to early Cisco time. Six zones are recognized by paleontologic criteria alone, with three additional zones defined by lithologic criteria.
Each zone exhibits multiple depositional environments. Each environment produced a different rock fabric. Porosity and permeability, partly controlled by the original rock content and fabric, change laterally within each vertical producing zone.
The geologic model consisting of vertical stratification and lateral change within the Cogdell Canyon unit is compatible with engineering data resulting from known production since 1949. This geologic model also is compatible with increased oil production resulting from infill well drilling and redirection of the waterflood.