WATKINS, JOEL S., CHRIS KULANDER, LEE WILLIAMS, TOM BLASINGAME, C. L. DECKER, and ROBERT BERG
Texas A & M University, College Station, TX

Abstract: Comparison of Estimated Fault-Bound Compartment Area with Calculated Drainage Area: A Tool for Predicting Sealing Capacity of Faults

Three producing intervals from Ship Shoal 274 were analyzed using amplitude extraction techniques to delineate reservoir-compartmentalizing faults. Two sets of linear features are evident on amplitude-magnitude maps of the sands. On seismic sections, northwest-dipping minor faults correspond to NE-SW striking lineaments; this set of lineaments parallels a large-displacement fault in the region. Position and orientation of some northwest-dipping faults is corroborated by dipmeter-log data where available. The second set of lineaments is interpreted as normal faults dipping southwest and striking parallel to the main boundary fault of the salt-withdrawal basin. Together, the two sets of faults form a checkerboard pattern of fault-bound compartments.

Compartment area was estimated from maps of each sand for several compartments, then compared with drainage area calculated from production data from wells perforating the sand within that compartment. For two thin sands, estimated compartment area was in good agreement with calculated drainage area, but for the thicker sand, calculated area generally exceeded estimated area. This is interpreted to indicate that faults did not seal compartments in the thicker sand. The extent of fluid communication across faults appears to be a function of sand permeability, effective permeability of sand+fault, and sand thickness relative to fault offset, with the dependence on fault offset being greater for southwest-dipping faults.

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