固物研究生论坛 - Microseismic event location with the cross double-difference method

Determining anisotropic medium parameters and event locations should help to provide a better understanding of the subsurface structures and hydraulic fracturing. The double-difference (DD) tomography method has been applied to simultaneously locate the seismic events and determine the velocity model. We propose the cross double-difference (CDD) method to simultaneously invert the elastic moduli (Cij) and event locations in vertically layered transversely isotropic (VTI) media with the arrival times. A horizontal slowness shooting algorithm is applied for anisotropic ray tracing that calculates travel times and ray paths of direct waves. It employs Snell’s law implicitly and this makes the algorithm easily implement without any interface treatments. The results show that when the noise is small, the accuracy of the event locations determined by the DD method is a little bit better than CDD, however, when the noise is large, the event locations determined by the CDD method are more accurate than DD.