Abstract: Limitation Of Reflection Seismic Technology In Imaging Complex Structural Terrain As Defined By Synthetic Seismic Modeling

ERDLAC, RICHARD J., JR., DOUGLAS B. SWIFT, and JAMES J. REEVES, West Texas Earth Resources Institute, Midland, TX

Modern PC computer technology has spurred the development of numerous geologic software packages for assisting the interpreter. WTERI used GMAplus Structural Modeling software to generate synthetic seismic profiles of three different structural types. These include monocline formation, thrust fault development with varying syntectonic sedimentation rates, and thrust fault development at constant sedimentation but with higher strain.

Synthetic seismic profiles were generated and compared for each of these structural terrains using four ray tracing techniques. Strikingly different variations in interpretation from the actual geologic cross section were often possible. For example, as a monocline develops, early images of folding are replaced by a discontinuous zone interpreted as faulting. Footwall reversal provides evidence that folding is accommodating deformation rather than faulting. Thrust faulted terrain displays variations on synthetics which are due to variations in amount of syntectonic sedimentation. At constant sedimentation, increased strain in thrust fault development produces images that are strongly dissimilar to each other in the four ray tracing procedures. On synthetic seismic sections, thrust faulted terrain can resemble the western boundary of the Central Basin Platform of the Permian Basin or it can resemble relatively flat strata. This suggests that although undeformed strata cannot mimic complex structural terrain on seismic, it is possible for complex structure to be imaged as undeformed geologic strata.

AAPG Search and Discovery Article #90936©1998 AAPG Southwest Section Meeting, Wichita Falls, Texas