This paper presents a new numerical model designed to simulate energy mining in naturally fractured faulted geothermal reservoirs. The model fully couples thermo-hydraulic (TH) processes with triple porosity-permeability properties in a unified geothermal reservoir simulation. This approach enables the investigation of multiphysical phenomena in fractured-faulted formations characterised by multiple pore media. Detailed investigations on the effects of these media on coupled transient fluid and heat flow capture basic features related to energy mining in deep geological formations. Case studies demonstrate that the model can provide a long-term assessment of deep geothermal reservoirs in naturally fractured and faulted porous media. The work provides fundamental insight into the heat transport and fluid flow through multiple pore media and the fracture-fault interface in deep geothermal reservoirs under various conditions and thus, provides a foundation for future research in the field of the enhanced energy recovery from geothermal reservoirs. (C) 2018 Elsevier Ltd. All rights reserved.