Plane-wave migration in tilted coordinates

Guojian Shan and Biondo Biondi

shan@sep.stanford.edu, biondo@sep.stanford.edu

ABSTRACT

Plane-wave migration in tilted coordinates is powerful to image steeply dipping reflectors, although the one-way wave-equation operator is used. In plane-wave migration, the recorded surface data are transferred to plane-wave data by slant-stack processing. Both the source plane-wave and the corresponding slant-stacking data are extrapolated into the subsurface, and images are generated by cross-correlating these two wavefields. For each plane-wave source, we assign tilted coordinates whose direction depends on the propagation direction of the plane-wave. For isotropic media, the one-way wave-equation operator does not change. For vertical transversely isotropic (VTI) media, one-way wave-equation operators for tilted transversely isotropic (TI) media are required because of the rotation of the coordinates. I apply this method to the BP 2004 velocity benchmark, to a synthetic dataset for VTI media, and to a real anisotropic dataset. The numerical examples show that plane-wave migration in tilted coordinates can image steeply dipping reflectors and overturned waves, and it is a good tool for salt delineation.