Application of Anisotropic Rock Physics Modeling in Integrated Interpretation of Seismic and CSEM Data

Elastic and electrical anisotropy in rocks exists on a large range of length-scales. It is important to understand elastic anisotropy to avoid: misplacing seismic reflectors; incorrect well-ties; inaccurate AVO interpretation; and inaccurate seismic inversion. Similar is true for electrical anisotropy when: interpreting CSEM and well-log data; quantifying resistivity anisotropy; using log data to ground truth CSEM inversion data; estimating hydrocarbon saturations, and using log data to build realistic starting models for CSEM inversion. In this study a workflow is presented combining rock physics modelling, upscaling, and feasibility studies to jointly interpret co-located elastic and electric properties at a given site. Rock physics models are developed which calculate elastic and electrical anisotropy from the volumetric fractions of solids and fluids in the rock, and the microstructural information within the rock. To upscale the geophysical properties the subsurface strata is treated as a stack of fine isotropic and/or transverse isotropic layers, each with its symmetry axis normal to the bedding plane. Seismic feasibility is accomplished using synthetic seismograms and CSEM feasibility is achieved by calculating the synthetic amplitudes. Case studies are presented using the workflow.