Research on structural layout and optimization of medium-deep multiple U-shaped wells based on continuous heating

Abstract At present, the application of U-shaped well heat extraction in medium-deep geothermal mining has become increasingly widespread, and how to improve the heat extraction efficiency and save costs has become a key research object. In order to solve the practical problem that the current single well heat is insufficient and multiple wells cannot achieve continuous heating, this paper aims to develop a new type of multi-U well heating system to achieve continuous heating temperature ≥35 °C. Through the analysis of well layout parameters and the design of injection well distribution structure, the optimization of the system is improved. Under the premise of the set range in this paper, the research shows that the optimal length of the horizontal section is 900 m. The increase of the length of the horizontal section is beneficial to the decrease of the number of injection wells, and the average heat extraction power increases by 31 kW for every 100 m increase. The greater the depth of the buried well, the less the number of injection wells required. The optimum length of the insulation section is 850 m ∼1200 m. In addition, through the optimization of the distribution structure and operation of the injection well, it is found that the heat loss caused by the thermal interference caused by the increase of the buried depth is less than its own positive benefit. It is recommended to adopt a multi-level branch well structure, and the injection well is operated in the order of well 3, well 2 , and finally well 1 . This study optimizes the new heat extraction system, which is of great significance to the higher requirements of medium-deep geothermal mining mode and heating system.