Simulating cryogenic fracturing process with TOUGH-FEMM

The dry hot rock (DHR) is a widely distributed renewable and clean energy. Cryogenic fracturing, such as liquid nitrogen fracturing technology, in DHR not only avoids the consuming of water, but also enhances the fracturing with the rock damage induced by thermal stress. During fracturing, cryogenic fluid (extremely low temperature) is utilized to trigger sharp a thermal gradient and fracturing surrounding boreholes, which generates fracture networks and increase the permeability of DHR. In this work, the TOUGH-FEMM simulator, which links the TOUGH2 thermal-hydraulic simulator and a mechanical simulator based on hybrid the finite-element meshfree method (FEMM), is developed to model three-dimensional cracking induced by cryogenic injection. The results of the numerical simulations agree with the experimental results showing that the fracture network is generated and connected to the borehole. An increased connectivity between a production borehole and the fracture network can significantly enhance fluid and hydro carbon production.