Inline Delayed-shot Migration in Tilted Elliptical-cylindrical Coordinates

Summary

Riemannian wavefield extrapolation, a wave-equation imaging method for efficient one-way propagation of 3D wavefields, is extended to 3D seismic surveys. I formulate an inline delayed-shot migration procedure in 3D tilted elliptical-cylindrical (TEC) coordinate systems. When inline coordinate tilt angles are well matched to the inline source ray parameters, the TEC coordinate extension affords accurate propagation of both steep-dip and turning-wave components important for successfully imaging complex geologic structure. I show that wavefield extrapolation in TEC coordinates is no more complicated than propagation in elliptically anisotropic media, which is easily handled by current finitedifference practice. I apply this approach to a realistic 3D wide-azimuth synthetic derived from a field Gulf of Mexico data set. The resulting images demonstrate the imaging advantages made possible through 3D RWE implementations, including the improved imaging of steeply dipping salt flanks, at reduced computational cost.