Geothermal energy potential of Main Dolomite formation in SW Poland

This paper evaluates the geothermal potential of the Main Dolomite formation in an oil and gas field on the Fore-Sudetic Monocline (SW, Poland). The reservoir characterization included a well-logging interpretation and developed 3D petrophysical and temperature models that provided information on storage potential, transport properties, and temperature conditions in the analyzed carbonate formation. Geothermal energy potential was assessed using heat in place (HIP) and recoverable heat (Hrec) parameters for water and CO2 systems, considering a 50-year plant lifespan. Petrophysical and temperature data classify reservoirs using unsupervised machine learning, identifying zones with high and low geothermal potential, noting a strong limestone and dolomite dichotomy. Dolomite horizon shows more promising reservoir quality with mean porosity and permeability of 0.045 and 0.4 mD, respectively, however, its mean thickness reaches 11.58 m at maximum. The calculated Hrec for a 50-year lifetime of a geothermal system varies across dolomite horizon. In the most promising areas of NNW, WSW, and E parts, the values of Hrec are 8.19, 3.47, and 1.34 MW for water, respectively, and 0.69, 0.29, and 0.11 MW for CO2 as working fluids. Remarkably, the energy locked in the NNW zone constitutes nearly 21% of the total geothermal energy potential within the entire dolomite horizons of the study area. The geothermal resources for the most perspective location within the dolomite horizon were estimated at 12.99 and 1.09 MW levels, using water and CO2 as working fluids, respectively, assuming 50 years of the project’s lifetime.