Study on acoustic logging response of fractured reservoirs using a novel equivalent medium model

Acoustic logging is one of the most effective methods for fractured reservoirs exploration. To understand the measurement characteristics of fractured reservoirs is the key procedure to evaluate the reservoir using acoustic logging data. By combing the Hudson equivalent theory and the Schoenberg’s theory, a novel acoustic equivalent medium theory of fracture reservoir was constructed. Bond transformation is introduced to model fractures with arbitrary azimuth and polarizing angle. The response of fractured reservoir measured by acoustic logging tool is simulated using a finite difference code. The influences and acoustic responses from crack density, width, angle and filling material on compressional and shear wave slowness of acoustic waves are analyzed and summarized. The analysis results can provide a theoretical foundation for evaluations of fractured formations with acoustic logging data.