High-Resolution Fiber-Optic Sensing System for Geothermal Fracture Imaging

Geothermal energy offers significant energy generation capacity to support America’s transition from fossil fuels to renewables. Enhanced Geothermal Systems (EGS) allows extraction of harder-to-reach geothermal energy by actively pumping cold fluids into hot basement rock. DOE and industry seek advanced computational methods to accurately image the subsequently generated fracture networks so that EGS output efficiency can be maximized. IFOS proposes the development of an innovative, photonic-computational-based geothermal fracture imaging solution – Geo-FracSense™ – to improve characterization of fractures both during and after fracturing operations. This cost-effective, robust, scalable, high-speed, precision computational imaging tool will target two major conventional technology pain points: low signal-to-noise ratio (SNR) of acoustic measurement, and massive data storage requirements required by current acoustic sensing systems’ reliance on time averaging. IFOS’ distributed optical fiber acts as a photonic computer, performing both signal processing and transport. Once signals are received by the IFOS optical interrogator, they are efficiently processed using algorithms to provide actionable intelligence to EGS field operators based on IFOS’ high-resolution acoustic emission, pressure, and temperature data. As DOE and industry seek to more precisely measure geothermal fracture dimensions, orientation relative to the wellbore, and fracturing fluid distribution and conductivity, the need for higher SNR and greater amounts of data for conventional systems will drastically increase. IFOS’ innovative fiber-optic approach has the potential to mitigate these problems, enabling more efficient and robust characterization of fractures. The use of intelligent signal processing algorithms will further streamline the data generation process. In Phase I the IFOS multidisciplinary team will demonstrate the feasibility of its fracture characterization system. In Phase II, the team will perform field validation of an integrated engineering prototype. The photonic computational intelligence provided by IFOS’ fracture characterization system will increase the energy efficiency of EGS production by giving operators greater understanding of fracture characteristics, enabling better production decisions and reducing environmental impacts of fracturing operations. The system has numerous spin-off applications in shale energy and structural health monitoring.