The Thermofacies Concept

The investigation and exploration of potential deep geothermal systems is based on detailed knowledge of their distinct reservoir characteristics. This is especially important in the exploration of potentially engineered geothermal systems and of mid to low enthalpy reservoir formations in greater depths, resp. In the early stages of geothermal reservoir exploration, characterization of the reservoir is mainly accomplished by evaluation of drilling data and seismic surveys. However, for the prognosis of 3D reservoir properties, the main geothermal parameters such as (1) permeability, (2) thermal conductivity, and (3) reservoir heat flow have to be quantified with respect to a 3D structural model. Outcrop analogue studies enable the determination and correlation of the necessary parameters, and based on detailed facies analysis, the geothermal exploration concept becomes more precise and descriptive. Finally, the detection of the spatiotemporal development of sedimentary facies within a specific exploration area may contribute to establish integrated structural 3D reservoir models. Thus, thermofacies – the facies dependence of geothermal parameters – become a key feature for reservoir prognosis, reservoir stimulation, and efficient reservoir utilisation. Here, a thermofacies approach on reservoir characterisation is presented and discussed.