High-resolution Elastic FWI for Reservoir Characterization

The Vp/Vs ratio can often be a good lithology indicator for a variety of depositional environments. The Vp/Vs ratio for sands tends to be lower than Vp/Vs for shales, irrespective of fluid. Integration of Vp/Vs estimates with other seismic volumes can often reduce the risk associated with predicting reservoir presence. In several instances, Vp/Vs volumes can also be used as input for populating seismically constrained geologic models. In this study we demonstrate the feasibility of applying elastic Full Wavefield Inversion (FWI) to generate high-resolution estimates of the Vp/Vs ratio, using a 3D marine streamer data set. The field data results (not shown in the abstract; will be discussed in the presentation) are encouraging and demonstrate the robustness and efficiency of our elastic FWI workflow. The inversion results match the seismic and well data very well, and are in good agreement with geologic interpretation. The results also illustrate a couple of key benefits of the FWI approach: the ability to perform true-amplitude imaging and to test the fidelity of the estimated model parameters by comparing simulated and real data. These may prove significant for reducing interpretation risk for cases of variable illumination, or complex overburden.