Abstract

3-D geophysical data can be a powerful tool for identifying and characterizing oil and gas reservoirs. However, successful application of 3-D seismic technology in carbonate platform successions has lagged its use in clastic reservoirs. Here we present the results of an integrated study of outcrops, cores, wireline logs, and 3-D geophysical data in a Permian (Guadalupian) platform carbonate reservoir on the Central Basin Platform of the Permian Basin which demonstrate the use of 3-D seismic data both as a tool for identifying the structural controls on reservoir development and for defining the distribution of diagenetically developed reservoir porosity.

The South Cowden Grayburg reservoir resembles many Permian carbonate reservoirs in the Permian Basin of West Texas in being composed of cyclic, shallow-marine, platform carbonates. It differs from most, however, in that the most productive areas of the reservoir owe their high productivity to enhanced porosity and permeability development caused by anhydrite dissolution and diagenesis. Preliminary analysis of 3-D seismic data shows that even simple mapping of seismic amplitudes can greatly improve our understanding of the distribution of reservoir properties.

3-D seismic data also show that both the structural configuration of the field and the distribution of depositional facies are the result of accommodation patterns created by the deposition of a clastic-rich lowstand prograding wedge that built basinward from the terminal Clear Fork platform margin during late Leonardian (San Andres) sea level fall. Reconnaissance studies along the margin of the Central Basin Platform suggests that other Grayburg reservoirs may owe their development to lowstand wedges formed at this time.