Imaging from topography with Fourier methods

Gary F. Margrave and Zhengsheng Yao

ABSTRACT

The method of wavefield extrapolation by nonstationary phase shift is extended to the case of data recorded on a topographic surface. Using the NSPS (nonstationary phase shift) algorithm, the space-domain input data is phase shifted to a horizontal datum beneath the lowest topographic point. The nonstationary phase shift simultaneously accounts for lateral velocity variations and the lateral variation of downward step size. The f-k spectrum of the downward continued data is synthesized at the datum. A much more computationally expensive pseudo-inverse technique is also formulated for comparison. Tests on simple synthetics show that the NSPS method works nearly as well as the pseudo-inverse technique.

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