Robustness of HTI Parameters Estimation in Downhole Microseismic Surveys

Passive seismic monitoring is a conventional technique used for mapping hydraulic fracturing treatment assuming that microseismic events occur due to fracture development. Only recently specialists started to account for anisotropy in microseismic data processing although it seems to be a natural assumption in many cases. Here we consider simultaneous microseismic event location and estimation of parameters for horizontally transversely-isotropic model with horizontal symmetry axis (HTI). It is the simplest model that accounts for azimuthal anisotropy. We discovered that all anisotropic parameters of HTI model (including the symmetry axis azimuth) are well constrained by our kinematic inversion. We also discovered that errors in polarization analysis do not strongly influence estimation of HTI anisotropic parameters. Estimating anisotropic HTI parameters can be important for engineers as they are related to rock physics, lithology, internal fractures or regional stress.