Optical Multi-Component Seismic Array for Long-Term Monitoring of Geothermal Wells

We propose using a hybrid optical sensor array consisting of Distributed Acoustic Sensing (DAS) array and three-component (3C) fiber-optic point sensors to both long-term and short-term monitor of geomechanical changes in and around geothermal wells. The proposed acoustic monitoring system will not involve any failure-prone electronic components in the borehole, a prior obstacle to field-worthiness. Instead, we use a proven optical interferometric technique to precisely measure acoustic signals in the well in or near the heat reservoir, using passive sensors constructed from rugged materials and hightemperature fiber. The 3C sensors are designed for deployment in several form factors and a variety of geothermal well configurations, i.e., behind casing, on tubing or on wireline. We also propose an automatic processing of the data based on migration imaging letting the DAS data tell the location along the well and distance from the well, and the 3C data to tell in which direction.. Phase I work will involve system design and optimization, developing the analysis workflow, and modeling system performance in realistic scenarios. This will reduce risk and accelerate development towards a pilot system in Phase II. Commercial Applications and Other Benefits: • New capabilities over state of the art seismic including wider bandwidth, narrow diameter, and long lifetime, enabling new applications and encouraging long term deployments. • Provides an essential tool for subsurface monitoring to improve outcomes in Geothermal Energy development, a key technologies to combat climate change. • Future applications could include defense, security, and infrastructure monitoring, where the value of acoustic monitoring are clear but cost-effective solutions are lacking. • Well-established market for seismic and acoustic sensing in oil and gas exploration, well development, and life of well monitoring. This solution will be competitive in cost and specs.