Tapering in the wavefield extrapolation
Kun Liu, Hugh D. Geiger, John C. Bancroft
Recursive Kirchhoff extrapolation has attractive merits that make it an ideal candidate for implementation in pre-stack depth migrations. However, the artifacts resulting from data and operator aperture truncations may cause instability and inaccuracy. Tapering is widely recognized as an effective tool to deal with truncation problems. In wavefield extrapolation, the conventional method is to apply a taper to the data edges and then extrapolate the tapered data with a tapered extrapolator. However, as we show in this paper, this method may result in a loss of accuracy, especially for the first-step of wavefield extrapolation where the input surface data are usually zero-padded to the extent of the migration aperture. We introduce an adaptive tapering scheme that varies with output locations and handles both truncations dynamically. Synthetic examples show that the extrapolation with adaptive tapering achieves a better accuracy than conventional separate application of data tapering and operator tapering.