Building Anisotropic Velocity Model Using Rock Physics and Local Tomography – A North Sea Case Study

Abstract

Anisotropic velocity models are poorly constrained by surface seismic data alone. Rock physics anisotropic modelling of shale compaction and digenesis provides information which can be used to constrain anisotropic velocity model building. We demonstrate this new anisotropic model building methodology which incorporates shale compaction model, check shot data and tomography to build a 3D spatially varying anisotropic velocity model in the North Sea. The initial rock model is built by analysing well log data, temperature gradient and additional geologic information. Tomography with checkshots (local tomography) which takes into account both residual moveout of surface seismic data and vertical traveltime from checkshot data was used to calibrate rock model to predict a similar anisotropy profile. After calibration a 3D anisotropic model is built to produce spatially varying anisotropic parameters consistent with both rock model and checkshot data.