Fiber Optic High Temperature Seismic Sensor

The DOE is seeking the development of seismic sensors to support the subsurface monitoring of geothermal reservoirs during reservoir stimulation and operation. It is anticipated that these sensors will need to operate within a frequency range from sub-Hz to multi-kHz and be compatible with packaging for downhole deployment. Additional requirements include a capability to operate within the temperature range from -20oC to +250oC and a lifetime of 5000 hours. To address this need, this project will develop a new Fiber Optic High Temperature Seismic Sensor based on an innovative, micro bending design that uses graded-index multimode fibers that are stable at elevated temperatures. Using optical time domain reflectrometry with a diode laser for interrogation, the sensor will provide sensitivity over a wide frequency range. The proposed sensor will be environmentally stable and hardened against high-temperature damage. The sensor¿s architecture will permit several fiber optic sensors to be installed along one terminated fiber, thereby enabling directional seismic sensitivity. Commercial Applications and other Benefits as described by the awardee: A seismic sensor that provides for high-temperature endurance (250oC for 5000 hrs) and high bandwidth (0.1-10 kHz) should find commercial applications in geothermal well monitoring, environmental monitoring, and security systems for industrial and household use.