The goal of geothermal reservoir management is to economically recover as Much energy as possible from the reservoir. This paper presents the development of improved techniques for monitoring and predicting two-phase mass and heat transport in fractures. Partitioning tracers can yield valuable, early information about fracture properties used within a semi-analytical approach for calculating enthalpy production from the fractured system. This is demonstrated for a synthetic model with a fracture network. The comparisons of the semi-analytical solutions with the simulation results show that the model predicts enthalpy production is easy, fast and ideally suited for sensitivity studies. Published by Elsevier Ltd.