Anisotropic Elastic-Waveform Inversion and Least-Squares Reverse-Time Migration of CASSM Data for Experiment I of the EGS Collab Project

Abstract

The EGS Collab project, supported by the U.S. Department of Energy’s Geothermal Technologies Office, is conducting field experiments at the Sanford Underground Research Facility (SURF) site to study the fracture creation using stimulation. A multi-level continuous active source seismic monitoring (ML-CASSM) system is used to monitor the fracture creation. Four fracture-parallel and two orthogonal wells with hydrophones and accelerometers are used to acquire active and passive seismic data during the field experiments. We apply 3D anisotropic elastic-waveform inversion to the CASSM data to obtain an elastic model for the experimental region. Using the inverted elastic model, we apply 3D anisotropic, acoustic least-squares reverse-time migration to the CASSM data to produce a high-resolution image. Our preliminary result of anisotropic elastic-waveform inversion shows the rock is anisotropic and heterogeneous. Our least-squares reverse-time migration detects the stimulation-created fracture, and the image shows that the fracture plane may not be isotropic either.