A heat loss analytical model for the thermal front displacement in naturally fractured reservoirs

•A model for the injection of cold water into a naturally fractured reservoir (NFR).•The NFR is modeled as two interconnected homogeneous systems, matrix and fracture.•Heat and mass balances are established for the water flow in the NFR.•Solutions for thermal and non thermal equilibrium between the water and the rock.•Type-curves are presented for the rate of advance of the thermal front.