Effect of local thermal non-equilibrium on thermoporoelastic response of a borehole in dual-porosity media

Heat transfer coefficient of solid skeleton-to-pore fluid can be calibrated by a method obtained from the Kozeny-Carman equation. The temperatures of pore fluid and solid skeleton fulfill local thermal equilibrium (LTE) instantaneously in low-permeability geomaterials characterized with large specific surface. However, temperature of fracture fluid differs from those of pore fluid and solid skeleton due to insufficient heat transfer, which cannot be modeled by the LTE models. Besides, the key parameters including the fracture spacing and initial entropy controls heat and fluid mass transfer process, thus influencing the pressures of pore and fracture fluids. Model results showed that LTNE can result in significant difference in effective stress field due to the THM coupling, and then abet the failure potential of the fractured dual-porosity medium positively. Finally, the semi-analytical solutions provide a benchmark for numerical modeling and an evaluation of thermoporoelastic response.