Requirements and Boundary Conditions for Near Surface Seismic Inversion

Summary Marine reflection seismic data acquisition for inversion of near surface targets, which is restricted to the first 30–100m of the earth’s surface, is both a challenging and important task. Nevertheless, there are no comprehensive acquisition and quality control guidelines for this type of data set. In order to determine the requirements and boundary conditions for near surface seismic inversion, the soil property ranges of sediments in the North Sea and Baltic Sea have been established as a first step. Then the typically used seismic source signals have been analyzed. A range of synthetic models was generated and analyzed to develop optimum acquisition parameters. Source, receiver, positioning and recording parameters have been found to be most relevant. So, very exact corrections e.g. in terms of gun delay, positioning errors or source and receiver directivity have been identified to be substantial. Also, offsets greater than about three times the target depth and a channel spacing smaller than 2 m to avoid aliasing for high resolution signals have been found to be necessary. Further establishment of near surface seismic inversion in industrial and academic work flows has the great potential to reduce cost and enhance knowledge.