Influence of Long-Term Surface Water Reinjection on Thermal Reservoir of Wentang Fault
Fan Binghong
Bai Ximin
Ye Hailong
Zhou Guobin
Li Yanyan
Zeng Ziqi
Chen Jin
Wang Zheng
Abstract：Fractured geothermal reservoir reinjection has garnered significant attention for its remarkable effectiveness in enhancing geothermal water supply capacity,raising water levels,and mitigating resource and environmental issues associated with geothermal exploitation.This study focuses on the Yichun Wentang geothermal field,employing time series analysis and hydrogeochemical methods to analyze long-term monitoring data of reinjection volume,extraction volume,water temperature,water level,and water quality during surface water reinjection and extraction processes.The study summarizes the dynamic variations in the geothermal field's temperature field,fluid field,and chemical field,and investigates the sustainability and safety of long-term reinjection in fractured reservoirs.The results indicate that reinjection volume is the primary factor influencing the dynamic changes in the temperature,fluid,and chemical fields.Long-term reinjection raises the geothermal field's water level by 3.952-4.986 m,increases the dynamic amplitude of water level fluctuations by 13.4 times,and reverses the planar distribution direction of water levels.When the reinjection volume remains below the threshold,the production well's water temperature exhibits an inverse correlation with reinjection volume,delayed by 3-12 months;exceeding the threshold leads to a"cliff-like"decline in temperature.Long-term reinjection causes an overall decrease in well temperatures,with a maximum reduction of 6.8-10.0℃,though stabilization occurs after controlling reinjection volume.Reinjection water directly"dilutes"geothermal water,shifting hydrochemical types in the Piper diagram toward surface water characteristics,transitioning from HCO3-Na type to HCO3·SO4-Na·Ca type.Long-term monitoring confirms that the geothermal field remains safe and controllable when reinjection volume is maintained below 9,734 m3/d,increasing resource availability by 414%.Surface water reinjection in fractured reservoirs demonstrates good feasibility and safety,provided the reinjection volume does not exceed the threshold.
Keywords：Wentangfracture-controlled convectiongeothermalsurface water reinjectionreservoir dynamicshydrogeology
Publication Date：2025-12-30
Online Publishing Date：2026-01-26(First online date of this platform, not the publication date of the document)
Pages：15( 4894-4908 )