Seismic Techniques for imaging Complex Geology

W. P. Wilson and A. P. Longo

As exploration continues to search for new opportunities, many companies continue to investigate in regions with complex geology. How well does seismic image the earth in these areas? Those who are able to accurately image the subsurface will have an advantage. Many pitfalls may exist within seismic time records in these complex areas. True structure identification depends on the quality of the data, the technology used to process the data, and the ingenuity of the interpreter to integrate other data into the interpretation.

Acquisition is the critical step, where the design for signal resolution, energy penetration, and noise reduction must be optimized. Great care must be taken throughout the processing effort, but dynamic static solutions and accurate migration are most important. In complex areas, usually there are rapid near-surface changes that cause time pull-ups and push-downs that must be addressed in the processing effort. Because of complexity, post-stack time migration has little chance of placing diffractions and dipping events into their correct positions. Using super computers, pre-stack depth migration and forward modeling can be used to improve imaging for more reliable interpretations. With the development of pre-stack depth migration, we have improved success rate and are modifying some concepts of structural deformation. Forward modeling can be used to gauge the accuracy of interpretations in complex areas by comparing synthetic seismic sections of geologic models (developed from interpretations) to original seismic sections.

Even with these advances in seismic imaging technology, the interpreter

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California