Evaluation Of The Paleogene Geothermal Resources Potential In Baxian Sag,Jizhong Depression

Having unique advantages over the other renewable energy sources such as solar energy,wind energy and tidal energy,geothermal energy will certainly occupy a larger share in the future energy consumption structure.The Baxian Sag is located in the center of the Beijing-Tianjin-Hebei"Capital Economic Circle"and serves as the main oil-generating sag in the North China Oilfield.It also has geothermal resources with great development prospects.Through the evaluation of the geothermal resource potential of the Paleogene in Baxian Sag,the calculation of its potential geothermal resource reserves and suggestions for its exploitation and utilization are very important for improving the evaluation work of geothermal resources in Baxian Sag,adjusting the regional energy structure,increasing the supply of clean energy as well as effectively improving the quality of the atmospheric environment.Studies have shown that the formation of the Baxian Sag is affected by the upwelling of the upper mantle and the thermal diapirism of the mantle.The heat flow from the mantle is conducted to the overlying sedimentary strata through the basement faults and the high-conductivity carbonate rocks of the basement,which constitute the main heat source of the basin.The geothermal flow in Baxian Sag is between 52-75m W/m².After"normalization",the geothermal gradient is between 2.6-4.4?/100m and the formation temperature of1000-4000m is between 40-160?which has good geothermal field characteristics.In this study,the Paleogene Dongying Formation and Shahejie Formation Es₁-Es₃Member formations were selected as the thermal reservoirs in the study area.The thermal reservoir temperature was calculated to be between 43.8-145.4?which belongs to low-temperature geothermal resources.The groundwater type of Dongying Formation in Baxian Sag is mainly Na HCO₃type and the Shahejie Formation is mainly Ca Cl₂type.The salinity is high,which is basically greater than 4g/L.The stratum is well sealed and the groundwater movement is driven by the formation of potential energy from the water level difference and the pressure difference so that the mudstone compacted water is the main source of groundwater.According to the calculation of"Heat Storage Method",the total geothermal resources in the Paleogene Ed₁-Es₃Member of Baxian Sag are calculated to be 1.819×10²⁰J,converted to standard coal is 6.177×10⁹t.The total geothermal water reserve is 1.115×10¹¹m³and the total recoverable geothermal water is 2.788×10¹⁰m³.The total geothermal water resource is3.847×10¹⁹J,converted into standard coal is 1.312×10⁹t.The total recoverable geothermal water resource is 8.912×10¹⁸J,converted into standard coal is 3.042×10⁸t.Using the single-well productivity calculation model combined with the economics of well depth,it is concluded that the central area of the Wen'an slope in the Baxian Sag is suitable for the exploitation of single-well geothermal water production capacity.Its single-well production capacity is more than 200m³/d and its groundwater is suitable for industrial water.