Characteristics of geothermal resources in sedimentary basins

As a renewable clean energy, geothermal resources play an important role in sustainable development. As the sedimentary basin type geothermal resources are mostly distributed in the population gathering areas such as the plain basin, it is important to study the geothermal resources of the sedimentary basin. Based on the analysis of geothermal reservoir distribution and hydrochemical characteristics of sedimentary basins in China, the authors evaluated the geothermal resources of sedimentary basins. The geothermal resources of sedimentary basins are mainly medium and low temperature geothermal resources, and they constitute the main type of geothermal resources in China, accounting for 89% of the total geothermal resources. Moreover, they have the characteristics of wide reservoir space, large thickness, abundant types of geothermal resources, large reserves of geothermal resources, medium and low temperature geothermal water and high availability of resources. The chemical types of geothermal water in sedimentary basin type generally change from low-mineralized water such as HCO₃-Na and HCO₃-Cl-Na through ClHCO₃-Na type and to high-mineralized water such as Cl-Na type in drainage area or closure state. The salinity increases from shallow to deep part as well. The thermal resources in thermal basins account for 54% of the total reserves in major sedimentary basins, 59% of the total recoverable reserves in major sedimentary basins, 42% in warm basins, 40% in recoverable reserves, 4% in cold basins and 1% in recoverable reserves. Therefore, geothermal resources exploration should be further strengthened, geothermal resources recharge should be actively carried out to ensure sustainable development and utilization, geothermal resources comprehensive utilization should be promoted, and geothermal resources monitoring network should be established.