Shear‐wave birefringence: A new tool for evaluating fractured reservoirs

Propagation characteristics of shear waves make them particularly well suited to exploration for and definition of fractured reservoirs. The Department of Geophysics at Colorado School of Mines conducted a three‐component P- and S-wave seismic survey in order to determine whether shear‐wave polarization and splitting (birefringence) caused by fracture induced azimuthal anisotropy could be measured over a naturally fractured reservoir. Results indicate that surface seismic recordings of shear waves can be used to calculate azimuthal anisotropy and that seismic observation of azimuthal anisotropy can provide information about the location, orientation, and intensity of subsurface fractures. Data obtained from this investigation indicate that measurement of shear‐wave birefringence is a potentially powerful tool for predicting fracture orientation and permeability trends.