Integrated Study Of Fracture Characterization Using 3D P-Wave Seismic Data in Southwest China

Here, we present a case study of fracture detection using 3D P-wave seismic data from the Sichuan Basin in Southwest China. A major aspect of this study is the integration of outcrop, core and wireline logs with seismic data for reducing the uncertainties in the seismic results. The target is a gas reservoir buried at about 1700m in depth, and the reservoir rocks are tight sandstones with an average porosity about 2% only, and fractures are the main fluid pathways. Analysis of core and log data from 21 boreholes reveals that there are two major sets of fractures in the study area striking northeast and northwest, respectively, with an average linear fracture density about one fracture every two metres. We have processed and analyzed 50 square kilometres of 3D P-wave seismic data in order to evaluate the fracture characteristics between the boreholes. The seismic data is of average quality. Nevertheless with carefully-calibrated processing, the final fracture orientation and intensity maps estimated from the amplitude attributes compare reasonably well with the regional pattern in the area, and the seismic results at the well locations are consistent with the borehole results.