Errors in microseismic events locations introduced by neglecting anisotropy during velocity model calibration in downhole monitoring

Microseismic monitoring is the only tool to provide locations of microseismic events induced e.g. during hydraulic fracturing unconventional reservoirs. Obtained become a baseline for evaluation stimulation effectiveness. However, due several factors, they can be different from true ones and lead misinterpretation. Most important inaccuracy velocity model used in location procedure, which often amplified by seismic anisotropy. Even though anisotropy common feature organic-rich mudrocks, it neglected current industry practice. The usual approach produce set isotropic models, valid limited subsurface area only, compensate effects. Here we explore how accuracy events' affected when neglecting building using traveltimes calibration shots. We analyse mislocations synthetic modelling that simulates an ongoing multi-stage treatment vertically-transverse (VTI) media, monitored with single vertical borehole. Finally, quantitative interpretation errors expected present VTI being neglected. most result demonstration spatially are single-stage models terms correct event locations, despite performing accurate calibration. Also, show gain constructed. As ultimate solution reduce errors, propose account inverting parameters even part data available.