Abstract: Solving the Fault Shadow Problem in the Wilcox Trend of South Texas

Stuart W. Fagin

Imaging distortions in the footwall of faults in the Wilcox trend of South Texas are shown to be caused by velocity effects associated with the truncation of overlying high-velocity Queen City Sandstone and low-velocity Reklaw Shale. The thinning of these units across the fault gives rise to appreciable velocity sags and pullups. Moreover, this variability in the thickness of velocity bodies gives rise to non-hyperbolic reflections which create apparent disruptions in footwall reflections. The only imaging solution which is free of these artifacts is prestack depth migration. A synthetic example is used to demonstrate fault shadow imaging artifacts and their elimination by depth imaging. Identical artifacts are identified on a real data set, and the imaging improvements f om prestack depth imaging are demonstrated.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela