Pre-stack VSP Elastic Inversion for Lithology Delineation in an Offshore Field of the Arabian Gulf, Saudi Arabia

We present the results of a feasibility study on the application of pre-stack VSP elastic inversion to characterize the distribution of sand stringers in an offshore field of the Arabian Gulf of Saudi Arabia. Using amplitude preserving wavefield extrapolation techniques, the VSP data was converted into a pseudo surface seismic volume from which VSP common-midpoint (VSP-CMP) gathers were generated for the inversion analysis. AVO inversion was carried out using a standard surface seismic simultaneous AVO/AVA inversion workflow. Comparison with the surface seismic inversion showed that the VSP elastic inversion results were higher in resolution and showed a slightly better correlation with the well logs. Standard rock property analysis, cross-plots and body checking using multiple volumes can be carried out on the inverted VSP-CMP results. Overall, these preliminary results are very encouraging.