Offset dependent static corrections on a continental shelf edge 3D seismic survey

Abstract

In seismic data processing the problems associated with rapidly varying sea floor topography are well documented. Numerous two-dimensional procedures are available for solving these problems, ranging in complexity from simple replacement statics to full wave equation datuming. In view of the size of 3D data sets it is imperative that these procedures be cost effective. Our search for such a procedure has resulted in the development of Modelled Offset Dependent Statics (MODS), which gives good results at relatively low cost. Simple replacement statics based on vertical raypaths are theoretically only correct for flat reflectors at infinite depth. In the MODS method water replacement static corrections are calculated for every individual offset trace by ray tracing to one target horizon only, using a three dimensional depth model of the sea floor and the horizon of interest. MODS has been successfully applied to a continental shelf edge 3D seismic survey. The data quality improvement demonstrates the appropriateness and the value of the technique.