High-resolution, integrated 3D Joint Migration Inversion of Surface and VSP Data

Abstract

Surface-related and internal multiples will enhance the illumination of the subsurface and enable us to image areas that are beyond the coverage of primary reflections, especially in the case of datasets with a sparse acquisition geometry like 3D Borehole-related seismic data. In addition, shadow zones and acquisition geometry footprints, like what we encounter in 3D surface seismic, can be overcome by including the multiple scattering in the imaging process. In conventional imaging, the input data is first linearized, by suppressing the multiples, to make it suitable for linear migration algorithms and the associated velocity models are updated accordingly. However, it has been demonstrated that the nonlinearity in the data adds extra sensitivity to erroneous propagation operators. This unique property puts additional constraints on the possible solutions for the velocity model and will help expediting and steering inversion algorithms toward more reliable estimates. Furthermore, nonlinear migration algorithms must have a closed-loop architecture to ensure consistency between the input data and the estimated model parameters. In this paper we propose to deploy both surface seismic and 3D VSP data simultaneously in one joint migration inversion process, such that-at least within an area around the well location-an optimum high-resolution image and a better background velocity model is obtained and the lateral continuity and consistency is guaranteed. Furthermore, by including all multiple scattering in the inversion process - as proposed by joint migration inversion- a smooth velocity model will be obtained along with a true amplitude reflectivity image with high resolution.