Induced seismicity in the development of EGS—benefits and drawbacks

The development of a successful Enhanced/Engineered Geothermal System (EGS) reservoir at commercial scale has proved an elusive goal—despite the prospects of an immense resource and a near-limitless supply of sustainable baseload power. Key challenges relate to both creating and sustaining a high-throughput reservoir from an initially very low permeability deep reservoir and in achieving this with minimal induced seismicity. In the following we (i) explore the nature of early- and late-time induced seismicity anticipated in such projects, (ii) observed at contemporary and historic sites, and explore how this may be linked to permeability evolution through (iii) permeability-seismicity scaling and in (iv) coupling with the evolving rate and state properties of the reservoir.