Application of P-wave azimuthal anisotropy for fracture detection in a volcanic reservoir

Summary: We present a case study of fracture detection using a 3-D P-wave seismic dataset from the Xujiaweizi (XJWZ) fault depression in the northern Songliao Basin in China. With the discovery of more volcanic gas-bearing reservoirs in XJWZ fault depression, we have realized that the most critical uncertainty in optimizing reservoir production is the location and characterization of the natural fracture system. Traditionally, fracture information comes from well data, in particular, image log (FMI) and core. This paper describes how p-wave azimuthal anisotropy can extend the characterization of fractures in volcanic (and other) rocks to regions between the wells. A major aspect of this study is to compare and contrast on a common dataset the effectiveness of different seismic azimuthal attributes in characterizing fractures and quantify those differences. Results indicate this is an effective approach for fracture detection and characterization in volcanic rocks. The final fracture orientation and density maps calculated from the p-wave azimuthal anisotropy are consistent with FMI interpretation and coring data from drilled wells.