Investigating the effects of conductive-convective heat transfer on hydraulic fracturing via a fully coupled THM analysis using an enriched EFG method

In this study, an eniched element free Galerkin framework is developed to investigate the effects of conductive-convective heat transfer on hydraulic fracturing. Weak and strong discontinuities are introduced in field variables using the enrichment strategy. The cohesive crack model is used in this study to simulate the process of initiation and propagation of fractures in saturated deformable porous media. The complicated process of hydraulic fracturing with thermal effects is simulated considering multiple components including fluid flow within the fracture, fluid flow through the host medium, fluid leak-off from the fracture into the surrounding porous rock, heat transfer within the fracture medium, heat transfer through the host porous rock, the heat exchange between the crack medium and the surrounding media, deformation of porous rock due to the hydraulic and thermal loading and crack propagation. To create the discrete equation system, Galerkin technique is applied, and the essential boundary conditions are imposed via penalty method. Then, the resultant constrained integral equations are discretized in space using EFG shape functions. For temporal discretization, a fully implicit scheme is employed. The final set of algebraic equations that form a non-linear equation system are solved using the iterative Newton-Raphson procedure. Numerical simulation results show the accuracy of the formulation as well as the performance of the program in coupling the heat transfer equation inside the crack with other governing equations.