Numerical simulation of microseismic wavefields with moment-tensor sources

Microseismic monitoring has been a key technology in the exploitation of unconventional reservoirs. Numerical simulation of various types of microseismic sources is the foundation for source location and source mechanism inversion. In this paper, equations of equivalent body forces with stress components and particle velocity components are derived, then they are included in the finite difference method (FDM) to simulate moment-tensor sources. The microseismic wavefields of different moment-tensor sources in three-dimensional isotropic media and transversely isotropic media with a vertical symmetry axis (VTI) are simulated and analyzed. Through the forward modeling of surface star-array monitoring, the feasibility of source mechanism inversion with P-wave first motion for surface microseismic monitoring has been preliminarily demonstrated.