Elastic common-receiver Gaussian beam migration of 4C ocean-bottom node data

Abstract

Four-component (4C) ocean-bottom node (OBN) surveys provide an opportunity to image subsurface elastic properties for oil and gas exploration in deep water environments. However, sparse acquisition sampling is challenging for high-quality imaging of OBN data. To alleviate this problem, we present a common-receiver domain 4C elastic Gaussian beam migration method based on an elastic reciprocity transformation that considers the monopole/dipole characters of both sources and receivers. Common-receiver migration is also computationally efficient in the OBN survey which has the number of shots usually larger than the number of geophones. We accomplish P/S and upgoing/downgoing wavefield decompositions at the “source-side” during migration. A decomposition matrix and a wavefield continuation formula are derived from the elastic Kirchhoff-Helmholtz integral with the representation of Green’s function as a superposition of Gaussian beams. The local slant stack is performed on the better-sampled common-receiver recordings, which is less sensitive to aliasing. We validate the performance of the method on synthetic data using the case of coarse sampling of OBNs in both deep and ultra-deep water environment.