Currently, Turkey’s rich geothermal resources are used only to a small degree for the generation of the country’s electric energy needs. Turkey in this regard is a promising country to develop, test, and apply new methodology for the exploration, development, and operation of geothermal low/medium-enthalpy reservoirs. At the same time, all these three stages required for the conversion of geothermal energy into electric energy are associated with uncertainty and risk.
Our project (GEOPOT) will apply, in the region of Simav (Turkey), techniques developed in the parallel method-oriented MeProRisk project (RWTH, Aachen). This project is based on (1) a novel multi-stage strategy for the exploration of geothermal reservoirs and (2) prognostic simulation tools with risk assessment capabilities for the development and operation of geothermal reservoirs. The strategy consists of a combination of surface and borehole geophysics, petrophysics, geology, and numerical simulation technology. Simulations are performed on a hierarchy of models for flow and transport which differ in complexity and data quality: an initial zero-generation model is based on available a priori information. Then a combination of forward and inverse simulations is used to optimize location, depth, and number of exploration boreholes and quantify the uncertainty of the model’s predictions. In an iterative process, information on these boreholes is then used to generate the first-generation model. Simulations based on this model are tested against independent data from existing boreholes. Then, a calibrated version of the model is used again to optimize location, depth, and number of additional exploration boreholes. Information from these boreholes is then used to generate the second-generation model. This process is iterated until a model is obtained with sufficiently high prognostic probability to optimize location, depth, and number of production and injection boreholes for the reservoir to be developed.
Another part of the project addresses seismic risk assessment. Indeed, Simav’s geothermal reservoirs are located in a tectonically active area where seismicity is to be expected even without operation of a geothermal plant. However, as reinjection may trigger seismicity, seismic risk inherent to the development and operation of the geothermal reservoir has to be quantified. A level of ground tremors which would present a serious disturbance or threat to the local population needs to be quantified and avoided.
In terms of socio-economic issues and public acceptance, the population of Simav already benefits from geothermal energy as the district heating system is the largest in Turkey, still it needs to be convinced of the benefit derived from a local production of electric energy. 3D reservoir model simulations will be used to optimize and guarantee the parallel production of electricity and heat for space heating.
Finally, the scientific benefits of such a project lie in the development and verification of a unified exploration, production, and development technology with prognostic and risk assessment capability for geothermal steam reservoirs. This extends the currently available technology significantly and will enable a much better and qualitative judgment of the scientific and technological uncertainties and financial and environmental risks involved.