LMS makes the headlines: limiting induced seismicity

© 2020 LMS EPFL

© 2020 LMS EPFL

A recent article by researchers at the LMS has introduced a strategy to precondition the stress field of a potential Enhanced Geothermal System prior to stimulation. By altering the stress state, the eventual shear stimulation that is required to make the reservoir economical is predicted to be less likely to result in large seismic events.

Enhanced Geothermal Systems (EGSs) are hampered by a number of issues, preventing their widespread implementation as a green, renewable source of energy.

Recent work by the Laboratory of Soil Mechanics (LMS) has suggested a stimulation technique which, based on the community’s understanding of rock mechanics, is expected to reduce the risk of induced seismicity while still allowing for reservoir stimulation. In essence, this strategy consists of altering the stress field prior to stimulation such that a more favorable stress field is present in the reservoir. This is accomplished by the slow, long term injection of cold fluid. After the stress field has been sufficiently altered, reservoir stimulation can proceed as before, with the high pressure injection of fluid, except now shear failure occurs in a stress state which is less likely to yield large earthquakes.

While this strategy is supported by our knowledge of the subsurface and seismology, it is still untested. As such, in order for it to become a viable method of reducing the risk of induced seismicity, meso-scale testing must be first carried out.

This work has been published in a recent paper in Geophysical Journal International, and has made several headlines in the media such as in Le Nouvelliste, La Liberté, Think Geo-Energy and La Côte.