Advanced InSAR Techniques for Geothermal Exploration and Production

Abstract

InSAR is a remote sensing tool that has applications in both geothermal exploration and in the management of producing fields. The technique has developed rapidly in recent years and the most evolved algorithms, now capable of providing precise ground movement measurements with unprecedented spatial density over large areas, allow, among other things, the monitoring of the effects of fluid injection and extraction on surface deformation and the detection of active faults. Multi-interferogram approaches have been used at several geothermal sites in the US and abroad. Two examples are presented here with the aim of illustrating how these techniques are being used for different stages of geothermal exploration and management. In both cases, multiple advanced InSAR techniques were used to quantify surface expression patterns, with a focus on the SqueeSAR™ approach, the latest breakthrough in InSAR technology. The first case study examines the Salton Sea area (California), where multi-interferogram InSAR provided an overview of surface deformation at a producing geothermal reservoir. Surface deformation in this area was complex, and the added detail provided insight into the interplay of tectonics and production activities. The second example involves the use of InSAR within a suite of tools for exploration of the San Emidio geothermal field in Nevada, as part of a DOE funded initiative. This project aimed to develop geophysical techniques to identify and map large aperture fractures for the placement of new production/exploration wells. Additional InSAR studies have also been carried out at several areas in Nevada, including the Brady and Desert Peak fields and in California at the Geysers field. These studies, along with ongoing developments in radar satellite technology and in the field of InSAR, show considerable promise for the future monitoring of geothermal production facilities.