The demonstration of cyclic hydraulic treatments and of multi-stage stimulation in granites, granodiorites and/or tight sandstones is a crucial part of DESTRESS. The aim is to show a treatment method applied with reduced seismic and environmental risks and plannable results. Part of the work involves developing specific components for the multi-stage stimulation, such as a packer and fibre-optic connection device. The experience gained through the demonstration will provide good practices or standards for future applications. These practices are expected to evolve over time as experiments from demonstration sites and conclusions from data analysis become available. Evaluation of the results will include an economic aspect, comparing the cost of the treatment with the improvement in performance. Continuous knowledge transfer for implementation in other environments at various sites is also planned.
The soft stimulation method using the fatigue hydraulic fracturing concept will be applied at existing and newly developed EGS sites. The operations will be conducted after a careful assessment of the hazards, including induced seismicity. For each proposed demonstration site, a detailed work programme will be drawn up and pre-stimulation will be performed and evaluated in order to ascertain the hydraulic properties of the reservoir.
Application and adaption of the concept to selected sites will include individual scheduling of field stimulation treatments to demonstrate their utilisation for granites/granodiorites in Pohang, South Korea. As a fallback solution, volcanic rocks and tight sandstones in Groß Schönebeck, Germany, will be available. The granites at Haute-Sorne, Switzerland, have been chosen to demonstrate the feasibility of segmenting to selectively inject a stimulation treatment and to provide long-term reservoir management under deep geothermal conditions.