Developments in Seismic Imaging in Complex Geology

Wayne P. Wilson, William J. Sercombe, Andrew P. Longo

Interpretation of seismic in complex geology is a difficult assignment because acquiring accurate images of structural geology are complicated processes of recording reflected energy from changes in rock properties in time and determining the true structure in depth. Images presented in time may not represent true geology, and two methods: pre-stack depth migration and forward modeling, are significant tools to help the interpreter determine true structure.

The ability of seismic to image geology is limited by acquisition parameters and processing techniques. 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 static solutions and migration are the most important steps. 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, time post-stack migration has little chance of placing diffractions into their correct positions. The development of pre-stack depth migration is bringing tremendous opportunities for interpreters to get more accurate images of the geology, and more complete nderstanding on structural deformation. Forward modeling is another process used to gauge the accuracy of interpretations in complex areas. In this process, geologic models are developed from interpretations, and synthetic seismic sections are generated from the models using finite difference modeling. The similarities of synthetic seismic sections and original seismic sections are compared.

Pre-stack depth migration and forward modeling have been successfully used in Wyoming, Oklahoma, Pakistan, Colombia, and Ecuador.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995