This paper is the result of geological survey engineering.
Objective The Taiyuan Basin is one of the areas where its distribution of beneficial Karst geothermal reservoir and demand of urban heating are well matched. The research on the evolution of Karst geothermal system and the characteristics of genetic elements in Taiyuan Basin has a great significance for the overall development of geothermal resources in this area and the understanding of the distribution of geothermal resources in rift basins.
Methods Based on the previous research and the latest data of 54 geothermal wells, we analyze the heat source, geothermal reservoir distribution and hydrothermal dynamic characteristics of karst geothermal system in Taiyuan Basin, and also evaluate the geothermal resources by 8 effective structural units.
Results The results show as flow: (1) The strata of karst thermal reservoir in Taiyuan Basin are mainly developed in the Lower Paleozoic Ordovician, ,which is widely distributed in North China Plate. And the evolution of the karst geothermal reservoir has gone through five stages, i.e. the epigenic karstification at the end of the Early Paleozoic, the direct caprock deposition in the Late Paleozoic, the initial formation of the karst geothermal system during Mesozoic, the transformation during the Neogene and the final setting during the Quaternary. (2)The heat source of the geothermal system comes from the high terrestrial heat flow (up to 79.12mW/m2) generated by the Cenozoic rift basin, and the heat transfer mode can be divided into two different types: the strong convection type at the edge of the basin and the heat conduction type inside the basin. (3) The geothermal reservoir property is in the longitudinal and horizontal zonation. In the vertical direction, 15-20 effective reservoir sections are identified, with a accumulated thickness of 160~180m, which can be divided into 3-4 layers of main water-bearing section; on the plane, the favorable reservoir belt is mainly controlled by NE trending concealed structure, and the main water-bearing layer is easy to generate a "over-flow" phenomenon during the migration process. The Ordovician reservoir in the middle of the basin with moderately buried (about 400~1900 m) and high temperature (30-75℃) charcteristics is the most favorable exploration and development area. (4) According to the geothermal reservoir volume method, the total geothermal resources of the karst geothermal system in Taiyuan Basin are estimated to be 8.303 billion GJ, which is equivalent to 283 million tons of standard coal.
Conclusions The annual exploitation of geothermal resources can meet the heating area of 15.02 million square meters. At present, the developed resources only account for 23.3% of the exploitable resources, the development potential is huge.
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