New model of heat transport in the filled fracture system

Abstract:

Understanding thermal energy transfer in filled fracture system is critical to investigate geothermal distribution in discrete fracture networks. Many fractures are filled with sediments in the field, and the heat transfer in such a system is less studied than others. In this study, a model of heat transfer in a filled fracture system surrounded by infinite rock matrix is presented. As the primary conduit for mass and heat transport, the fracture is considered as a highly porous space filled with sediments. The model considers the processes of heat conduction and convection in the fracture, and heat conduction in the surrounding matrix. The thermal transport in the fracture and its surrounding matrix are coupled in this model. The mathematical models are developed and solved for such a coupled heat transfer problem to analyze the spatial-temporal heat distribution in a filled fracture system. The simulation results from this model are compared with the preexisting solutions of heat transfer under similar scenarios. Furthermore, the relative importance of each transport component is evaluated explicitly. The solutions of convection- and conduction-dominant flow fields are also developed and discussed. Lastly, the sensitivity analysis is applied to assess the impact of certain parameters on the geothermal distribution in the filled fracture system.