Joint inversion for anisotropic velocity model and event locations using S-wave splitting measurements from downhole microseismic data

摘要

An accurate low symmetry anisotropic velocity model is essential in microseismic imaging. Downhole microseismic acquisition usually cannot achieve sufficient ray coverage that is required to develop a low symmetry anisotropic model from travel times alone. To solve this problem, we add a new type of data, full S-wave splitting parameters (delay time of the slow S-wave δt and fast S-wave polarization direction Φ), to determine effective anisotropic models. A Genetic Algorithm (GA) inversion is adopted to solve the locations of events and the stiffness tensor of anisotropic medium simultaneously.