Abstract:In Ordovician carbonate reservoir in the north of Tarim Basin, karst caves and fractures developed along faults are important reservoir spaces. The key to seismic identification of fracture-cavity reservoir lies in the description of faults, fractures and karst caves. Because of the diversity, multi-scale and irregularity of reservoir space, such as karst caves and fractures, the seismic response usually shows complex characteristics of diffracted wave. The identification method based on diffracted wave can remove reflected wave from seismic data and only use diffracted information in seismic wave field for analysis. Therefore, based on plane wave destructive filtering and mean filtering, diffracted wave data are separated from conventional reflected wave data. Then, the ability of the diffracted wave data to describe the cave is compared. The fault recognition ability of diffracted wave data is compared and analyzed by combining the coherence attribute and likelihood attribute. Based on the actual diffracted wave data, the recognition ability of coherence and likelihood to faults and fractures is compared. The application of actual data shows that diffracted wave information can effectively identify geological bodies such as karst caves, small-scale faults and fractures, which is of great significance for the study of fracture-cavity carbonate reservoirs.