(OTC 21759)Application of High Resolution Zero-offset and Walkaway VSP in Fine Delineation of Reservoir

摘要

To more finely delineate reservoirs and estimate more reliable oil and gas reserves, we have carried out onehigh-resolution zero-offset VSP(ZVSP) survey and two 2-D cross walkaway VSP (WVSP) surveys, based on availablewell log and 3-D surface seismic data, in L oil field. For each shot of VSP data acquisition, the depth of seismic sourcewas selected carefully and the source was exploded with a small charge of dynamites in a single source well. Seismicsignals were recorded in a denser 2.5m receiver spacing by eleven-level borehole geophones with clamping devices. Thefrequency bandwidth of recorded data is 8~120Hz. High resolution VSP data processing mainly consists of a firstconsistency processing, a subsequent estimate of absorption and attenuation coefficient Q from VSP and then the use ofthe Q value to increase the resolution of 3-D surface seismic data. The high-resolution-improved VSP data modify thedepths of tops of three dominant reservoirs inferred from well log and add a new reservoir by a comparison of seismicevents and geological layers. Finely delineating reserves by a joint use of WVSP images and thehigh-resolution-improved 3-D surface seismic data enhance the reliability of reservoir estimate of L oil field.