The challenges posed by climate change demand new advancements in fracture mechanics. In line with the Paris Agreement of 2015, one effective approach to mitigate greenhouse gas emissions is the utilization of renewable energy sources, including geothermal energy, coupled with…
The challenges posed by climate change demand new advancements in fracture mechanics. In line with the Paris Agreement of 2015, one effective approach to mitigate greenhouse gas emissions is the utilization of renewable energy sources, including geothermal energy, coupled with continuous innovation and technological advancements. Geothermal energy remains an underutilized form of renewable energy, with the optimization of geothermal reservoirs relying on hydraulic fracturing to enhance permeability. To effectively carry out hydraulic fracturing, a thorough understanding of the fracture energy of the bedrock is essential. While experimental methods exist to measure fracture energy, the literature highlights certain limitations that have not been adequately addressed. An Enhanced Geothermal System (EGS) can be thought of as an underground heat exchanger designed to extract geothermal energy. The performance of these systems can be improved by increasing permeability with hydraulic fracturing, following the same technique used for hydrocarbon reservoirs. To understand hydraulic fracturing, whether it is implemented in an EGS or in a hydrocarbon reservoir, it is important to know the fracture parameters of the rock at stake, e.g., the fracture energy. We report here the use of a method based on an energy balance during hydraulic fracture tests. Specimens were prepared and they have been mechanically and hydromechanically characterized at 20 ºC and 100 ºC, a temperature representative of actual reservoir conditions. The fracture energy is obtained from a balance of kinetic, potential and pressure energies involved in the hydraulic fracture tests. The method provides fracture energies that are consistent with the literature data on similar materials. It is also found that the fracture energy increases upon heating.