Residual statics analysis using prestack equivalent offset migration
The equivalent offset mapping (EOMAP) method of residual statics analysis uses the concepts of equivalent offset and common scatterpoint gathering, which were introduced for prestack time migration. Static reference traces are formed at each input trace location by the forward and inverse EOMAP's. Conventional cross-correlation and decomposition combine to produce the surface consistent source and receiver statics. The prestack migration and de-migration processes involved allow the statics analysis to be performed before NMO correction without either offset or structure dependence. The offset and structure independence allows the cross-correlation between the summation traces of each source or receiver gather to directly estimate the statics with more stability.
The EOMAP processes do not involve any time shift. By using the asymptotic equivalent offset concepts, they can be totally velocity independent.