Least-squares elastic reverse-time migration of microseismic data using inverted moment-tensor sources

Least-squares elastic reverse-time migration (LSERTM) using microseismic sources is a low-cost and efficient method to image subsurface structures below and above microseismic event locations. However, explosive or vector sources conventionally used in elastic wavefield simulation are incapable of generating the realistic radiation patterns from microseismic sources. This limitation leads to disagreement between simulated and observed seismic phases. We develop an LSERTM method using a moment-tensor source for forward elastic-wavefield simulation. We validate the method using microseismic data acquired using a buried geophone string at the Aneth CO2-EOR field. We first locate the microseismic events and invert for their moment tensors. We then use these information to perform LSERTM, and obtain high-resolution images of interfaces below and above these microseismic events. These structural information can in turn help improve microseismic event location and moment-tensor inversion.