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Geothermal Geological Characteristics and Potential Evaluation of Middle and Deep Layers In Puyang Area, Henan
This paper systematically analyzes the tectonic background, thermal storage characteristics, caprock distribution, geothermal field characteristics, and geothermal water chemical characteristics of geothermal formation in Puyang area.It is considered that deep and large faults such as the Liaolan and Changyuan faults are the main heat-controlling faults formed by the Puyang geothermal, and the average geothermal gradient in the region is 3-3.5℃/100m.Neogene Guantao Formation sandstone and Ordovician-Cambrian karst are the best available thermal reservoirs, and the depth and characteristics of thermal storage are controlled by structure.The top surface of the Neogene Guantao Formation is buried at a depth of 900-1200m, and the bottom surface is buried at a depth of 1000-1700m. The maximum single-layer sand body is 25.3m thick, with a porosity of 16.9-26.6%, and a thermal storage temperature of 50-70℃. Type SO4•Cl-Na type, salinity 5000-10000mg/L.The burial depth of the Ordovician-Cambrian karst thermal reservoir top surface varies widely, ranging from 800 to 5000 m. The thermal reservoir top depth in Dongpu and Linqing sags is 3000 to 5000 m. The depth of the storage roof is mostly shallower than 2500m, the chemical types of geothermal water are SO4•Cl-Ca•Na, SO4•Cl-Na•Ca type, and the salinity is 2000-3500mg/L.Compared with sandstone thermal storage, shallowly buried Ordovician-Cambrian thermal storage has a high degree of development of karst fractures, strong geothermal water circulation and recharge, low salinity, and easy recharge, which is very conducive to development and utilization. The thermal storage method calculates the recoverable resources of Neogene sandstone thermal storage of 17177×106GJ, and the recoverable resources of Ordovician-Cambrian karst thermal storage of 13560×106GJ.