Speaker
Description
Deep enhanced geothermal systems (EGS) in crystalline rock frequently exhibit induced seismicity during hydraulic stimulation, yet post stimulation tests might show reversible permeability enhancement and inadequate connectivity for sustainable circulation, as reported for the 6 km–deep St1 Deep Heat project in Espoo, Finland. This contrast between strong seismic response and poor long term hydraulic performance raises a fundamental question: under what hydromechanical (HM) conditions can fluid injection trigger numerous earthquakes without producing sustained permeability enhancement at reservoir scale?
To explore this question, a fully coupled HM model in conjunction with the discrete fracture network (DFN) approach is developed to represent a high stress crystalline reservoir with low matrix permeability and pre existing fractures. The framework links pressure driven flow with stress dependent fracture normal deformation, shear slip, and elastic closure, allowing investigation of reversible versus persistent permeability enhancement under idealized injection–shut in protocols.
By systematically varying key parameters such as fracture orientation relative to the stress field, effective normal stiffness, shear induced dilation, and network connectivity, the study aims to identify regimes in which seismic slip primarily activates isolated or poorly connected fractures that close once pressure declines. The resulting insights are intended to improve our understanding to clarify the conditions leading to “seismicity without sustained permeability enhancement”.
| Country | Sweden |
|---|---|
| Acceptance of the Terms & Conditions | Click here to agree |
