Stress Profiling in Enhanced Geothermal Systems (SPINE)

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This project is about developing a new tool and test 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 is organized into four inter-related work packages aiming to develop instrumentation and test protocols at the laboratory, the intermediate field-laboratory and the geothermal project scales: (1) borehole instrument testing and upgrading at relevant geothermal temperatures and pressures, (2) field-scale demonstration of stress profiling in the highly controlled environments of two major underground research laboratories, SURF (USA) and BULG (Switzerland), (3) laboratory-scale testing of protocols in fully controlled 3D stress regimes, and (4) forward and inverse 3D stress analyses using fully coupled Thermo-Hydro-Mechanical (THM) numerical modeling conducted at different scales.

In this project, LIH Aachen will focus on reproducing the stimulation protocols at the decimeter laboratory scale, apply them to all types of stress conditions, and couple the models with induced micro-seismicity. The stimulation will be conducted using mini-SIMFIP probes for fluid injection into a fractured cubic rock sample (0.3x0.3x0.45 m) under true triaxial stress conditions which are comparable with in-situ stress conditions at Bedretto rock laboratory. The key outcome of this project will be benchmarking and improvement of the stress inversion algorithm for the 3D dislocation data against the true triaxial test results with fully controlled boundary conditions. Moreover, a unique dataset on stress perturbations in fractured crystalline rock at the laboratory scale will be collected and used as direct input for the development and further validation of the numerical simulators.

Project Team:
Florian Amann
Mohammadreza Jalali
Julian Osten
Leonie Soltek (RWTH Extern)

Funding Agency and Project Partners