Evaluation of the geothermal energy potential of oil wells in Batman region

The increasing global energy demand and the environmental impacts of fossil fuels have accelerated the shift toward geothermal energy, a renewable and sustainable resource. Oil wells in the Southeastern Anatolia Region of Türkiye, which account for a significant portion of the country's petroleum production, possess considerable geothermal potential due to the formation temperatures they contain. In this study, the geothermal energy potential of oil wells operated by the Turkish Petroleum Corporation (TPAO) in the Şelmo field, located within the borders of Batman Province, was evaluated in accordance with United States Geological Survey (USGS) standards. The primary reservoir targets of the study are the Maastrichtian-aged Garzan and Sinan formations, which are widely distributed in the Batman region and are also known to host hydrocarbon production. Accordingly, a Monte Carlo simulation was performed by assigning probability distributions (e.g., uniform, triangular) to subsurface parameters that vary both laterally and vertically, such as reservoir area, net pay thickness, porosity, and formation temperature. Based on the simulation results, the Şelmo field is estimated to have 85.7 PJ of recoverable heat capacity and a thermal power of 90.6 MW under the most probable scenario (P50). This level of thermal power is sufficient to heat approximately 282 decares of greenhouse area over a period of 30 years. Within the scope of the study, a chemical analysis of the produced water from the field was conducted. The results indicate that the water is highly mineralized and characterized as a Na–Cl type, representing fossil water formed through long-term water–rock interaction. It was also determined that the water has a potential for carbonate scaling and poses a corrosion risk due to its high chloride content. Accordingly, the use of corrosion-resistant alloys, the application of chemical inhibitors, and regular monitoring during production operations are recommended. This study makes significant contribution to the literature by presenting a reliable reservoir model for integrating existing or abandoned oil wells in the region into the economy as a clean and sustainable energy source. It further demonstrates that geothermal resources obtained from such fields can provide substantial economic benefits to regional development through direct-use applications, such as greenhouse heating.