| Abstract |
Based on the sandstone thermal storage data of Guantao Formation in Lankao County, Henan Province, based on the simplified multi-porosity model, using COMSOL finite element multi-field coupled numerical simulation software, considering the effect of bedrock and caprock thermal compensation and seepage on the heat transfer process of geothermal reservoirs, a coupled seepage-heat transfer model of geothermal reservoirs with faults is established. The periodical one production, one injection model is adopted to simulate the long-term operation process of geothermal wells in different well spacing and different permeability formations. Through the analysis and comparison of the temperature field and flow field changes during the heat recovery operation of the thermal reservoir, the occurrence of the phenomenon of thermal breakthrough in the process of heat recovery on a long-term scale is studied. The research results show that: compared with production well, the bottom hole temperature of injection well has dropped sharply within 10 years, and is rapidly approaching the recharge water temperature (20°C). And because the low temperature area expands over time, the increase in bottom hole temperature of the injection well by thermal compensation is also rapidly reduced. There is a strong correlation between the bottom hole temperature and well spacing. With the increase of well spacing, the decrease of reservoir temperature caused by recharging has less influence on the bottom hole temperature, but it increases with time. During the development and utilization of geothermal resources in Lankao County, the spacing between wells should not be less than 500m, so as not only to ensure no thermal breakthrough during the operating life, but also to ensure the maximum utilization of recharging water. |