The medium-deep geothermal energy in China is abundant, with a great potential for development and utilization. To accelerate the exploitation of the medium-deep geothermal energy is important for promoting the rapid development of China's clean heating industry, with a diversified energy supply system and with the goals of the"carbon peaking and carbon neutrality" in the future. In the context of the efficient exploitation of the medium and deep geothermal energy, this paper reviews the researches of the heat extraction technology for exploiting the medium-deep geothermal energy, including various heat extraction technologies based on the doublet-well circulation, the closed-loop circulation in a single well, the circulation in a gravity heat pipe, the open-loop circulation in a single well, the circulation in a U-shaped well and the circulation in a multilateral radial well. The characteristics, the application conditions and the future researches of key heat extraction technologies are analyzed, as well as the development stage and the application scenarios of different heat extraction technologies. The suggestions for efficient exploitation of the medium-deep geothermal energy are proposed.

medium-deep geothermal energy  /  heat extraction technology  /  clean energy