Pre-stack Anisotropy Fractures Detection Based on OVT Domain Gather Data and Its Application in Ultra-deep Burial Carbonate Rocks

There are abundant fracture cave reservoirs wrapped in Ordovician tight limestone in the Tarim Basin, with an average buried depth of 7000m. The connectivity analysis of fracture-porous systems and hydrocarbon-bearing analysis has essential roles in the deployment of high-efficiency wells of the Ordovician carbonate reservoirs in the Tazhong and Tabei areas of Tarim Basin, as they are the major targets for increasing production. However, in the previous researches, the pre-stack fractures’ prediction and the oil/gas detection results using conventional processing data were lack of accuracy, which failed to complete the need of high-precision exploration and development. Firstly, the paper systematically analyzes the characteristics of azimuthal anisotropy analysis using conventional processing seismic data. Then it explains the process of selecting data, which is capable to meticulous reflect anisotropy characteristics of the formation and contains uniformed coverage to improve convergent results of elliptical fitting. Finally, the paper focuses on the three steps of operating azimuthal anisotropic pre-stack fracture detection using common reflection angle gather and receiving a reliable result. Practice demonstrates that using common reflection angle gathers during research of fractures in carbonate rock has a distinctive effect, which can provide a decisive basis for the layout of high-efficiency well groups in the development block.