A robust surface-consistent residual phase correction method based on migrated gathers

Abstract

Conventional residual static corrections determine the residual statics (time shifts) using common mid-point (CMP) gathers to estimate and correct anomalies induced by the near-surface. These time shifts disregard the phase errors existing in the data, which will reduce the resolution of the stacked image. Further errors result when reflection events in CMP gathers do not exhibit hyperbolic moveout. In order to solve these problems, we propose a robust surface-consistent residual phase correction method that simultaneously resolves both time shifts and constant phase rotations based on migrated gathers. The surface-consistent residual statics and phase are obtained from the migrated gathers expressed in terms of shot and receiver locations. We modified the standard technique of estimating the time shift corrections to include a surface-consistent constant phase rotation term. The proposed dual parameter algorithm (time shift and constant phase rotation) proved on a synthetic example that it was superior to conventional residual statics for improving the coherence of trace gathers. The computational effort can be reduced by generating migrated gathers and estimating the dual parameters in a spatially varying time window. We applied the proposed method to both synthetic and real data, and improved results were obtained with both.