The Particularity and Direct Utilization Prospect of Deep Geothermal Resources In Eastern China

Eastern China, east of the Hu Huanyong line that connects Heihe and Tengchong cities, accounts for 36 percent of China's total land area, but 96 percent of the population. The area is generally dominated by plain, hilly, karst and Danxia landform, with large population density and developed economy, and an extremely strong demand for energy. The eastern region is rich in deep geothermal resources, and the rational development and utilization is of great significance to ensuring the security of energy supply and achieving the goal of carbon peak and carbon neutralization. In eastern China, there are three geological units adjacent to each other tectonically, for instance, the eastern section of the E-W-direction Central Asia Orogenic Belt, the North China plate and the South China plate from north to south successively, which are superposition regions of the three global tectonic regimes, i.e. Paleo-Asia, circum-Pacific and Tethys. Since the late Mesozoic, influenced by back-arc extension of the circum-Pacific regime, the second depression belt developed subsequently and were composed of a series of Meso-Cenozoic basins, including Songliao, Bohai Bay, southern the North China, northern Jiangsu, Jianghan, Sanshui, Beibuwan and so on. The complicated tectonic movements of multiple stages and various geodynamic mechanisms formed the structure of "overpass" mode for the earth’s crust and mantle in eastern China, while the shallow surface showed the patchwork distribution pattern of orogen and basin, uplift and depression in graceful disorder. Enter the Cenozoic, accompanying by series geological events, such as the Pacific plate westward subduction and Tancheng-Lujiang fault activities, the south China sea mantle plume activity and continuous spreading of oceanic crust, the Qinghai-Tibet plateau uplift and southeast extrusion, the deep geological structure and thermal mechanism of the different blocks in eastern China evolved differently and particularly, and formed the distinctive geothermal resources enrichment rules and distribution characteristics. Through the analysis of the deep geological structure, thermal mechanism and typical geothermal system in eastern China, the paper defined the geothermal geological settings, resource distribution characteristics and enrichment rules of the deep geothermal system in the eastern section of the Central Asia Orogenic Belt, North China plate and South China plate. The study shows that the deep geothermal resources in eastern China are huge, mainly distributed in the Meso-Cenozoic sedimentary basin area, but the resource abundance is relatively low, mainly with intermediate temperature geothermal resources, and lack of high temperature geothermal resources. The main geothermal reservoir types are 3 categories of sandstone porous, carbonate karst fracture and granite fracture. In terms of the development and utilization of geothermal resources, it is generally not suitable for geothermal power generation, but should be utilized directly. For instance, the northeast and North China are suitable for large-scale geothermal house-heating, the Yangtze River watershed is suitable for geothermal house-heating in winter and house-cooling in summer, and south China is suitable for geothermal house-cooling all the year round. At the same time, geothermal can also be used for high-profit-attached agriculture and tourism according to local conditions.