Stress Profiling in Enhanced Geothermal Systems (SPINE)
SPINE is about developing a new tool and protocols to conduct stress profiling in crystalline rock for a better estimation of stimulation efficiency and induced seismicity related to the creation of subsurface heat exchangers. It proposes to upgrade a borehole probe technology developed at LBNL, which allows the coupled measurement of stimulation pressures, flow rate, and 3D fracture displacements for the profiling of local stress perturbations in deep geothermal commercial applications. The key idea is that thanks to the direct measurement of the full borehole wall displacement field and injection pressure, one test might be sufficient for determining the local full stress tensor. No other in-situ method is currently able to provide such information. Thus, repeating the tests at different depth intervals along a borehole will allow true and direct profiling of the local stresses. These local stress measurements combined with far-field tectonic stress estimations conducted with other existing methods constrain which stress regime from fracture-dominated to matrix-dominated flow systems must be considered for optimization of geothermal well completion and stimulation protocols.
This approach is strongly innovative to better estimate the local stress perturbations related to fractures and faults. It gives a direct in-situ measurement and the proof that an identified fault or a fracture can move (eventually slip) and under which stress conditions. Thus, it overall contributes in de-risking induced seismicity that can be related to geothermal projects.
Project Leader Institution
Lawrence Berkeley National Laboratory LBNL
Project Contact
Funding
EC-Eranet- Cofund GEOTHERMICA
Partners
- Lawrence Berkeley National Laboratory
- UniNe
- ETH Zurich
- GES
- RWTH Aachen
- Solexperts