Increasing reflection coherency through improved static corrections: An iterative tomographic approach

Computation and application of statics corrections have always been problematic on CMP reflection data, especially in highly weathered and structurally altered environments. Tomographic estimation of the velocity field is a severely underdetermined problem, only to be exacerbated by the lack of a priori information of the survey site. Statistically driven static techniques are sometimes considered unplausible for specific subsurface conditions rendering them only aesthetically useful to the final stacked section. Using turning-ray tomography to make static corrections (tomostatics) and iteratively developing the best tomographic model will ultimately optimize the static correction for each source and receiver station. Cross-correlation statics routines guided the selection of the best initial model, monitoring changes in specific near-surface reflections during iterative application of tomostatics. Combining statistical techniques with geologically based models of the subsurface increases the total reflection coherency and accuracy of the final stacked section.