Introduction

Seismic data gathered on land is distorted by irregular acquisition topography. Most seismic imaging algorithms are applied to data which is shifted to a planar datum. In regions of mild topography a static shift is adequate to perform this transformation Jones and Jovanovich (1985), however as the necessary shift increases in magnitude, the static approximation becomes inadequate. In this situation a procedure based on wave-equation extrapolation is more appropriate than static shift Shtivelman and Canning (1988); Wiggins (1984). The procedure is similar to wave-equation datuming of marine data Berryhill (1986); Yilmaz and Lucas (1986). However for data to be continued through some media, the velocity structure of that media must be known. The process of continuing the data and finding the velocity structure at the same time makes the process of wave-equation extrapolation difficult for land data.

I propose a method based on wave-equation extrapolation to be applied to data gathered in regions with irregular acquisition topography and where the near-surface velocity structure is unknown. The method is intended as an alternative to large static shifts.