Project description

The GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs) project started at the beginning of the year 2010 after successful contract negotiations with the European Commission. EC funding of € 5.3 Mio is granted for 3.5 years.

The project will address several of the major challenges the development of geothermal energy is facing, including the mitigation of induced seismicity to an acceptable level. The specific goals of GEISER are:
• to understand why seismicity is induced in some cases but not in others
• to assess the probability of seismic hazards depending on geological setting and geographical location
• to propose licensing and monitoring guidelines for local authorities, including a definition acceptable ground motion levels
• to investigate strategies for ‘soft stimulation’ that sufficiently improve the geothermal reservoir’s hydraulic properties without producing earthquakes that could be felt or cause damage

To address these objectives, four main topics have been identified:

1. Analysis of induced seismicity from representative geothermal reservoirs throughout Europe, with input from experts and data from regions outside continental Europe (Berlín, El Salvador; The Geysers, USA; Bouillante, French Antilles). Induced earthquakes will be analysed with respect to their relationship with injection parameters, local stress fields, and geological settings. These datasets will be 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 will be investigated to better constrain the mechanisms involved during fluid injection. A variety of modelling approaches, as well as laboratory experiments, will be employed.

3. Consequences of induced seismicity will be addressed 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) will be used to quantify the probability of triggering larger earthquakes and to define the potential damage caused by ground shaking. This activity will propose 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” will be proposed. The optimisation of a monitoring network and a real-time monitoring system will be 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 will be included to address the proper handling of risk.

The project is broken down into 7 work packages (WP), each lead by one of the partners. KIT and GEOWATT are involved in work packages 4 and 6.

WP4: Understanding the Geomechanical Causes and Processes of Induced Seismicity.
Different modelling approaches and laboratory experiments will be performed to investigate some of the key factors influencing induced seismicity: The goal is to come to a better understanding of the basic physical mechanisms that induce microseismicity and to deliver management and production scenarios with relative estimates of the stress-state changes for different geothermal settings.

WP6: Strategies for EGS operations with respect to Induced Seismicity (Mitigation).
The objective of WP6 is to provide strategies to operators and regulatory bodies to achieve this. These strategies are targeted at guidelines for regulatory bodies for the selection, licensing and long-term operation of EGS sites in different geological settings, at developing the concept of “soft stimulation”, at proper monitoring of induced seismicity, and at a minimization of the risk.

The GEISER project is coordinated by GFZ Potsdam and involves 12 additional partners: BRGM, ISOR, TNO, ETHZ, STATOIL, GEOWATT, NORSAR, ARMINES, EOST, KNMI, AMRA, INGV.