Conventional Logging Characterization Method of Tight Sandstone Reservoir Fractures in Northeast Sichuan

The tight sandstone reservoir in northeastern Sichuan show the basic characteristics of ultra-low porosity and dense matrix as a whole. Fracture is very important to improve reservoir seepage capacity and promote reservoir high production. The previously studied method of evaluating fractures in tight sandstone reservoir using conventional logs has the defects of poor certainty and easy misjudgment, and cannot accurately evaluate the fracture development of reservoirs, which is influenced by many factors, such as fracture occurrence, saturation, mud invasion depth and so on. Based on the limited coring and electrical imaging logging data of the target interval in the study area, and the logging response law of reservoir fractures, a method for identifying fractured sections in tight sandstone reservoirs is proposed, which uses the optimal continuous fitting method to determine the base block rock resistivity, the base block interval transit time, and then integrates the difference characteristics of bilateral lateral resistivity to construct a fracture synthesis index to comprehensively identify fractures. Finally, a quantitative interpretation model of reservoir fracture porosity, fracture opening, fracture permeability, and fracture saturation was established, the quantitative characterization of fractures in dense sandstone reservoirs in northeast Sichuan using conventional logs was achieved. The results of the integrated evaluation of logs applying this method can be better matched with the results of core physical properties, electrical imaging logs and gas test results, it provides a basis for the rational and efficient development of tight sandstone gas reservoirs.