Seismic monitoring of geothermal fields : A case study of Hellisheidi geothermal field

Abstract

The study of induced seismicity in geothermal fields can be used to understand the physics of the ongoing processes in the reservoir. Microseismic activity in reservoirs can result from brittle deformation of reservoir rocks due to mass extraction and reinjection. Careful installation of monitoring stations is the initial step of all monitoring procedures. Information gained from seismic monitoring forms the basis of mitigating risk associated with induced seismicity. Mitigation procedures can be divided into three steps: understanding the background seismicity to identify whether events are natural or induced; install a permanent, stand-alone surface-based seismic network; and implement risk management procedures. Seismic activity connected with reinjection of waste water at the Hellisheidi power plant is considered for this case study, and the seismic events recorded during a seismic swarm in 21 -22 April 2012 are analysed. Successful methodologies and processing methods that can be used to monitor geothermal field are discussed and compared with global scenarios.