Geothermal energy production potential of an Eocene-aged, hot, and geopressured system; A case study of the Keşan Formation in Thrace Basin, Türkiye

The current carbon-neutral targets of governments and the energy industry have renewed their interests in the use of alternative renewable energy sources for energy production. One of the interest areas is to use oil and gas reservoirs for geothermal energy production for direct and indirect usage. In this study, we examine extensive field data recorded in our study area in the Thrace Basin, Türkiye, which covers 480 km² and 1000 m portion of Eocene aged Keşan Formation's thickness in the area including seismic, well tops, geochemistry, and wireline logs to predict its volumetric heat in-place and geothermal energy production potential. We built a numerical 3D geocellular model that integrates such different sources of data recorded in drilled three key wells in the field by using a commercial simulator and besides we run the simple probabilistic anaytical uncertainty propagation method (AUPM) in another mathematical simulator to predict the reservoir's heat in-place and producible power potential. The main reason for considering two different approaches is to show that a simple method of AUPM can be considered as an alternative to a more complex 3D geocellular model to obtain “quick” answers for decision making, particularly at the exploration phase of the resource. The probable estimates (P50), i.e., 90% probability that the true, unknown resource potential in MWe will be that size or larger than the estimated value of P50, from both methods agree within 4%. The average of the estimated P50 values from these two methods is equal to 3265 MWe producible in 25-year project lifetime with a load (or capacity) factor of 0.9 and 75% turbo-generator power conversion efficiency. These results indicate that the region is a good candidate for geothermal energy production, with resource temperatures measured between 140 and 190 °C which are the statistical minimum and maximum temperature values determined by the commercial software by using the recorded static gradient survey's temperature data as wireline in three key wells. This is the first study presenting the geothermal energy production potential of Eocene-aged, hot, and geopressured gas and hot water bearing Keşan Formation in the Thrace Basin, Türkiye.