TOLMACHOFF, WAYNE, Dekalb Energy, Bakersfield, CA
The AVO (amplitude vs. offset) technique became an important exploration tool for Dekalb following our initial Sutter County gas discovery in 1981. This technique requires the acquisition of seismic data with close horizontal resolution and an adequate range of station offsets to identify Forbes gas sands. Many different ways to display the AVO information have been used and the only preference is having access to many analysis techniques. This work resulted in the discovery of Pierce Road gas field in 1987. Successive field developments has resulted in 11 completed wells out of 12 attempts, with the single failure showing excellent AVO out of noncommercial gas sand. This above-average probability of success is a result of incorporating other geologic information into the prospect des ription and by understanding the limitations of the AVO technique. The ability to predict the presence of productive sands is enhanced by the use of the personal computer and the incorporation of measured shear wave velocities.