Pitfalls of microseismic data inversion in the case of strong anisotropy

In downhole microseismic monitoring, anisotropic models are presently useful for obtaining the locations of events and give realistic description of the media. In anisotropic media, the wavefield structure is complex because of shear-wave splitting and singularities. We show the results of conventional processing and kinematic inversion using velocity model calibrations for strongly anisotropic VTI media and double-couple seismic sources. The small traveltime misfits, typical quality assessment criteria, are not always accurate. The artificial addition of isotropic layers may reduce the misfit but it may also produce nonphysical model, negative Poisson ratios, shifted locations.