A Study On The Application Of Converted Wave Static Correction

The processing of converted-wave seismic data is quite different with conventional P-wave seismic data.As one of the crucial step of converted-wave imagining,converted-wave static correction is the most problematic step.The converted-wave propagation path is asymmetrical,the converted S-wave will generated when down-going P-wave encounter the interface between weathering and the high velocity layer.Moreover,S-wave velocity is much slower than P-wave and change dramatically on the horizontal direction in weathering.Hence,Converted-wave receiver statics commonly two to ten times greater than P-wave statics for the same location.The P-wave statics solution are largely unrelated to converted-wave statics,so it is generally not feasible to approximate the S-wave statics by simply scaling the known P-wave statics value.We need to carry on a special study on the application of converted-wave static correction.This paper commerce with the basic concept of converted-wave static,introduce the overseas and domestic research status of converted-wave static correction methods.The trace-to-trace coherence of the common receiver point stack method and the method using P-wave as a structural reference to compute initial receiver statics are broadly used by the industry.The first mentioned of two is used to calculate the short-wavelength statics component and the latter is used to calculate the long-wavelength statics component.The optimized delay time converted-wave static method used the cross correlation results of X and Z component first break in common receiver point stack and pick the peak of stacked results,this method can obtained long and short wave-length statics at the same time.Because the P-SV wave receiver statics is very large,we should use combined static correction method to eliminate statics step by step.Processing the practical seismic data of Sulige area,proving delay time method combined with optimizing the trace-to-trace coherence of the common receiver point stack in thick weathering area can give a good result.According to the actual situation of the M work area,the weathering statics problem is particularly severe due to the irregular thickness of glacial sediments.We use 3D refraction static method and cross-correlation residual static method to eliminate the P-wave statics,then apply the P-wave source static to P-SV wave,using P-wave as a structure reference to compute receiver long-wavelength statics and computing receiver short-length statics by optimizing the trace-to-trace coherence of the common-receiver-point stack.The processing result of practical seismic date demonstrate that combined static correction method can preferably solve converted-wave static and have practical value.