Bedretto Reservoir Project

The Bedretto Reservoir Project addresses questions associated with the validation of stimulation procedures and the sustainable utilization of heat exchangers in the deep underground. It is a follow-up of the Grimsel "In-situ Stimulation and Circulation (ISC)" project, which successfully carried out pressure fluid injection experiments in crystalline rock mass.

The Bedretto project wants to show that the construction of a heat exchanger that is sustainable over several decades can be planned and controlled with the aid of hydraulic stimulation processes. The experiments will be carried out on larger scales (hundreds of meters) compared to the Grimsel ISC project (tens of meters). The larger scale implicates longer boreholes, which allow more realistic experiments to be carried out, applying different stimulation concepts.

Similar to the Grimsel ISC project, the Bedretto project will perform in-situ stimulation concepts tests while monitoring hydro-seismo-mechanical key parameters at a high spatial resolution. The addressed questions are:

1. Which stimulation concepts are appropriate for enhancing the permeability by orders of magnitudes while minimizing induced seismicity?
2. What are the relationships between the hydro-mechanical response, the stimulation concept, permeability creation, effective porosity, and induced seismicity?
3. How can micro-seismicity be minimized?
4. What are the heat exchanger properties of the reservoir?

First research experiments started in Spring 2019. They will be financed by several projects: SNSF, Swiss Federal Office of Energy SFOE, European Union, and industry partners.

Currently, no research laboratory exists in Switzerland where experiments, like the ones planned in the framework of the Bedretto project, can be conducted. A disused access tunnel of the Matterhorn Gotthard railway has proven to be a suitable location for such a research laboratory due to its geology and accessibility. Now, the Department of Earth Sciences of ETH Zurich, supported by the Swiss Competence Center for Energy Research (SCCER), is establishing the "Bedretto Underground Laboratory for Geoenergies" in this tunnel.

Construction works to enable the experiments begin in summer 2018. The total budget of the Bedretto Lab infrastructure is 4 Mio CHF, whereby ETH supports the project with 3 Mio CHF and Swisscom contributes 1 Mio CHF.