Interactive Static Corrections to Avoid Mis-interpretation of Seismic Data Due to Near-surface Velocity Changes

Abstract

Static correction computation is an important step in the seismic processing of land and transition zone data. Complex near-surface overburden velocity changes do hamper proper imaging. Geological and physical features (like: permafrost, pinch outs, swamps, sand dunes etc) may introduce irregular travel time delays. Automatic residual static algorithms sometimes fail to resolve these static corrections and thus may give rise to serious mis-interpretation of the subsurface structuration. Costly dry holes have been drilled based on false tectonic structures visible on non-optimal processed seismic data. These errors can be overcome by introducing an interpretation / modeling phase in the determination of the static corrections, using receiver and shot partial-offset stacks. The Interactive Static computation method uses diagnostic partial stacks in various domains to distinguish anomalies caused by drastic lateral velocity change in the shallow subsurface. Case studies illustrate the benefit of such a static correction method.