Scaling Spot Prediction and Analysis of Influencing Factors for a Geothermal Well in Boye County, Hebei Province

Calcium carbonate scaling in geothermal wells seriously hinders the sustainable development and utilization of geothermal energy. In order to provide a theoretical basis for the implementation of scale inhibition technology in geothermal wells, the scaling spots of a geothermal well in Boye County of Hebei Province were numerically simulated. Based on the casing program of geothermal wells, the influencing factors and scaling spot depth prediction were studied by using WELLSIM. The results showed that fluid temperature at the bottomhole calculated from the composition of outlet fluids was 128.0 ℃. The geothermal fluid pressure drops rapidly as it rose along the wellbore. A flash occurred at the depth of 56.10 m, the dryness and CO₂ partial pressure sharply changed accordingly. The flash depth of geothermal fluids migrated downwards with the increase of CO₂ mass fraction, NaCl mass fraction and geothermal fluid flow rate, in which CO₂ mass fraction played the decisive role. In field scale prevention practice, the setting depth of the submersible pump and the injection depth of the scale inhibitor should be below the flash depth of 56.1 m. The research shows that the flash depth can be adjusted by controlling the wellhead pressure and flow rate to accomplish the collaborative optimization of geothermal exploitation and scale prevention.