ESTIMATION OF DEEP FORMATION TEMPERATURE AND GEOTHERMAL RESOURCE POTENTIAL ASSESSMENT IN THE LOWER YANGTZE AREA, EAST CHINA

Geothermal energy is now becoming an increasingly important new energy and has attracted much attention, owing to its friendly environment and renewability. The Lower Yangtze area (LYA) that locates at east China, is one of the most developed regions in China, with many mega-cities, dense population and huge demand for energy. Geothermal energy is considered as a better solution for energy issue in the LYA in future; however, the resource potential of this area has not yet been assessed well, due to a lack of understanding its accurate geothermal condition. Here we integrate newly retrieved temperature data and rock thermal properties, to estimate the temperatures-at-depth of 1000~4000 meters, and accordingly suggest the potential targets for geothermal energy exploration. Our results show that the present-day geothermal gradient of the LYA vary from 16 degree Celsius/km to 41degree Celsius/km, with a mean of 30 degree Celsius/km; the heat flow values for the LYA fall within 48~80 mW/m², with a mean of 60 mW/m². The estimated temperature-at-depth of 1000 meters ranges from 30 to 54 degree Celsius, and that of 2000 meters is between 50 and 95 degree Celsius; at the depth of 3000 meters, the temperatures vary from 65 to 130 degree Celsius, while for the 4000 meters, the temperatures range from 80 to 170 degree Celsius. This indicates that the LYA is of relatively high geothermal regime and has a great geothermal energy potential. In addition, the spatial pattern of the estimated deep subsurface temperature for the LYA shows strongly lateral variation, featured by high in the north and low in the south, as a result of differential magmatism, faulting and local tectonics. The high temperature anomalies in the northern LYA would be the feasible targets for geothermal energy exploration.