Abstract

Great progress has been made on VSP techniques in recent years, especially the improvement of downhole geophone manufacture and VSP data-processing methods. In XJWZ area of Daqing oil field, the reservoir is formed mainly by volcanics, and its distribution is complex because of many periods of volcanic overlap in the area. Early seismic surveys in the area had been mainly 2D and narrow-azimuth 3D, which are not suitable for anisotropy analysis and fracture identification. Therefore, a joint survey of 3D VSP and full-azimuth surface seismic was implemented. The project was an attempt to combine the advantages of VSP and surface seismic by 3D VSP and full-azimuth surface-seismic simultaneous survey. Q factor and anisotropy parameters estimated from VSP are applied to 3D seismic processing. Reservoir characterization and gas-saturation prediction with final images showed encouraging results. Suggested wells have been drilled and wet gas has been found, so the validity of this method has been proved.

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