Logging identification and evaluation of fractures in volcanic reservoir in Xushen gas field of Songliao basin

At present, most of the methods to study fractures almost adopt a single method, which has some limitations on the macro-prediction and micro-characterization of fractures. By using core descriptions, CT image analysis, conventional logging, logging and other special integrated methods, the fracture development features of volcanic reservoirs in Yingcheng formation of Xushen gas field were described, which included qualitative and quantitative identification of cracks, calculated fracture porosity, fracture density and other parameters, determination the crack direction, and then the effective reservoir fracture evaluation criteria were established. The fractures of type I volcanic reservoir are high-angle fracture with good validation, and fractures of type Ⅱ reservoir are mainly of micro cracks with good validation.The fracture direction is mainly north-north-west, north-east direction, with multi-phase and banding. The volcanic rock reservoir is mainly fracture-pore type, followed by porosity type, with the least pore-fracture type and no development of large-slot and large-hole type.