How a Texas heavy oil prospect was evaluated

In December 1979, a 6,500-acre farm-in prospect was offered to Shell Oil as a candidate for primary heavy-oil production using steam injection. This work describes the petrophysical, geologic, and economic considerations which entered into the prospect evaluation. The prospect was the shallow (2,000 ft) San Miguel sand in southwest Texas. Preliminary evaluation of the prospect was made using a limited data base provided by the lessor. This evaluation was uncertain due to the lack of accurate knowledge of formation oil saturations and properties. To obtain the needed data, it was recommended that a test well be drilled, cored, and logged. The test well was drilled in April 1980, and a full suite of conventional logs was obtained over the San Miguel sand. In addition, the Schlumberger nuclear magnetism log (NML) and electromagnetic propagation tool (EPT) were logged over the sand. 14 refs.