Optimization of Enhanced Geothermal System Operations Using Distributed Fiber Optic Sensing and Offset Pressure Monitoring

Abstract

Enhanced Geothermal Systems (EGS) have emerged as a promising method to generate electricity from geothermal resources in areas that lack natural fractures and/or faults needed to connect injector/production well sets, virtually eliminating dry hole risk. EGS leverages much of the learnings from the past two decades of unconventional developments, connecting horizontal wells with multi-stage stimulations to create connectivity to flow water between wells to mine heat from the subsurface. This paper presents a case study in measuring EGS fracture geometry, utilizing measurements from vertical and horizontal permanent fiber optic cables and offset pressure monitoring. The Devon Quantification of Interference (DQI) analysis is also applied to multi-stage stimulated geothermal wells, integrated with fracture and reservoir simulation. Fervo Energy, a first mover in EGS, is leading the way in developing this technology. Devon, an industry leader in unconventional oil and gas development, leverages their learnings in this field to optimize EGS operations. Optimal well spacing and completions design, much like in oil and gas, are critical to optimizing for a successful EGS development. Analysis of strain rate in offset well and multi-well microseismic recorded with fiber optic cables during stimulation and well testing allowed to characterize stimulated reservoir volume created by hydraulic stimulation and optimize well placement. The DQI analysis examined the well-to-well connectivity of the multi-stage stimulation between the two wells in the case study, providing insight into the conductive fracture geometry. The paper also discusses the execution of well preparation, stimulation, and high-level well performance. This study provides valuable insights into the development of EGS using vertical and horizontal permanent fiber optic cables and offset pressure monitoring. The findings suggest that this approach can be effective in optimizing EGS operations. Fervo Energy’s expertise in EGS development, combined with Devon’s expertise in unconventional oil and gas development, can be leveraged to further advance EGS technology at scale and generate electricity from geothermal resources. This paper serves as a valuable resource for operators looking to optimize EGS operations.