Joint Prospecting of a Volcanic Reservoir with VSP and Surface Seismic Data

Volcanic reservoir exploration is quite challenging due to its rapid inherent velocity variation. The paper presents a case study of a gas-bearing volcanic reservoir, where zero-offset VSP, Walkaway VSP with eight azimuths, simultaneous 3D VSP and full-azimuth surface seismic data were acquired. A VSP-driven surface seismic data processing workflow was introduced to obtain a better image of the reservoir. Rather than conventional way of using VSP data for geologic body delineation, this workflow utilized VSP data to estimate parameters for surface seismic processing. Based on this workflow, the surface seismic data were processed and then used to estimate Poisson's ratio cube and fracture maps amenable for prediction of gas distribution in the reservoir. We demonstrated that the newly-processed surface seismic data with VSP-driven workflow are more reliable than that without assistance of VSP data, which can also be applied to other gas-bearing unconventional reservoirs.