Imaging Steeply-Dipping Fault Zones Using a Novel Least-Squares Reverse-Time Migration Method

Abstract

Imaging fault zones plays an important role in exploration for geothermal energy. It is very challenging for conventional seismic migration imaging using primary reflection data to obtain high-resolution images of steeply-dipping fault zones. We develop a new least-squares reverse-time migration for high-resolution imaging of steeply-dipping fault zones. Our method uses a wavefield-separation imaging condition and updated source wavefields during each iteration step of least-squares reverse-time migration. We validate the improved imaging capability of our new method using synthetic surface reflection data for a 2D geophysical model constructed using geologic features found at the Soda Lake geothermal field. The model contains several steeply-dipping fault zones. Our least-squares reverse-time migration method significantly improves the images of steeply-dipping fault zones compared with those obtained using conventional reverse-time migration or conventional least-squares reveres-time migration. Our method provides a promising tool for site characterization of geothermal fields.