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Project: The impact of re-injection of geothermal fluids on fluid flow properties and mechanical stability in fractured/faulted limestone reservoirs.

2019-11-01 – 2022-10-31


One of the emerging techniques for sustainable energy production is the use of geothermal energy: heat is extracted from the deep subsurface, used for heating or the production of electricity, and then re-injected in the reservoir. The goal is set out to increase the worldwide energy production from geothermal energy from 84.8 TWh in 2017 to 1400 TWh/year in 2050. Therefore, deep and typically less permeable reservoirs are more frequently targeted. Production of deep geothermal energy mostly depends on water circulation in engineered networks of man-made and/or pre-existing fractures and faults. The life expectancy of geothermal systems is typically limited due to decreases in production over time. Also, there is a risk of induced seismicity related to the production of deep geothermal energy. Both the production potential and the mechanical stability can be linked to micro-physical processes at the grain scale within the fractures and faults. We propose an experimental investigation to quantify the long-term changes in fluid flow regime and mechanical stability due to the injection of under- and supersaturated fluids into fractured and faulted analogues of dense limestone reservoirs. We will perform experiments under in-situ reservoir conditions, which can be visualized using X-ray tomography. Based on the observed changes within the fractures and faults, changes in frictional properties, controlling the mechanical stability of the system, will be determined.