ZHAO, HANK, and BRAD CURTIS
Republic Energy, Dallas, TX

Abstract: 3D Seismic Characterization of the Bell Canyon Reservoir beneath the Massive Salt Dissolution Bed at the Geraldine Field, Delaware Basin, TX

This work is based on 3D data acquired by Conoco-DOE-BEG on the Geraldine field. In the field, the reservoir rock is the 30 feet thick Ramsey Sand near the top of the Bell Canyon Formation, and 35 feet below the massive Castile anhydrite. The dramatic velocity change at the anhydrite-clastic interface generates the strongest seismic reflection in the data set. Due to the proximity of the reservoir to the interface, the strong seismic reflection hides the depositional characteristics of the reservoir rock. Therefore, the previous interpretation based on this strong reflector was not successful in defining depositional pattern and productive trend.

To solve the problem and model the field, three techniques were employed: 1) isochron mapping from both the base and the middle of the BC to the Castile base, 2) interval amplitude summation, and 3) residual and dip mapping. The results show that both isochron and summary amplitude thickness mapping clearly defined the field outline. The most anomalous image corresponds with the central part of the channel facies of the reservoir, which is also the highest productive trend. Finally, a geological model is used to explain that the deposition of the thin reservoir rock is continuously influenced by the earlier depositional environments in the rock several hundred feet deeper. The method used is applicable to similar reservoirs beneath salt dissolution beds.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas