Summary of the European GEISER Project (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs)

Abstract

The GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs) project was funded by the European Commission from 2010 until 2013. The project addressed onr of the major challenges the development of geothermal energy is facing: the mitigation of induced seismicity to an acceptable level. To address this objective, four main topics were addressed: 1. Analysis of induced seismicity from representative geothermal reservoirs throughout Europe (Soultz, Basel, Gross Schoenebeck, Iceland, Campi Flegrei) with input from experts and data from regions outside continental Europe (Berlín, El Salvador; The Geysers, USA; Paralana and Cooper Basin, Australia). Induced earthquakes were be analysed with respect to their relationship with injection parameters, local stress fields, and geological settings. These datasets were compared with other project data where injection did not cause significant seismicity. 2. Understanding the geomechanics and processes involved in creating induced seismicity. The influence of factors such as temperature, poro-elasticity, fluid injection rate, existing fault segments, and time dependent effects were investigated to better constrain the mechanisms involved during fluid injection. A variety of modelling approaches, as well as laboratory experiments were employed. 3. Consequences of induced seismicity by providing an assessment of the seismic hazard presented by earthquakes triggered through human activity in comparison to hazards triggered by natural seismicity. Results from (1) and (2) were used to quantify the probability of triggering larger earthquakes and to define the potential damage caused by ground shaking. This activity resulted in proposed guidelines for licensing and site development for local authorities and industry. 4. Strategies for the mitigation of induced seismicity. On the basis of the recommendations formulated in (3) and of the results of (1) and (2), strategies for soft injection have been proposed. The optimisation of a monitoring network and a real-time monitoring system were presented to help authorities and operators minimize the seismic hazard and manage the risks during operations and production. Experience of past seismic events caused by the mining and the oil and gas industries have been included to address the proper handling of risk.