Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (3): 402-409.DOI: 10.13745/j.esf.sf.2023.2.82

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Quantitative analysis of scaling tendency of karstic geothermal water coupled with CO2 degassing

LÜ Lianghua1,2,3(), WANG Shui1,3   

  1. 1. Jiangsu Provincial Key Laboratory of Environmental Engineering, Jiangsu Provincial Academy of Environmental Science, Nanjing 210036, China
    2. Nanjing Hydraulic Research Institute, Nanjing 210029, China
    3. Jiangsu Province Engineering Research Center of Soil and Groundwater Pollution Prevention and Control, Nanjing 210036, China
  • Received:2023-01-17 Revised:2023-04-11 Online:2024-05-25 Published:2024-05-25

Abstract:

Low-to-medium temperature fluid reservoirs hosted in carbonate rocks represent a promising yet relatively unknown hydrothermal geothermal system. Scaling of geothermal water, particularly underground scaling, poses a significant challenge in the sustainable utilization of geothermal resources. To address the limitations of current methods for analyzing karstic geothermal water scaling trends, a chemical thermodynamic simulation approach was employed to develop an enhanced method for quantitatively assessing scaling trends in geothermal water, considering CO2 degassing effects. This study focused on the influence of CO2 degassing on scaling trends. The scaling tendency of the Tangshan karstic geothermal area in Nanjing was quantitatively analyzed using the improved method. Results indicate that the geothermal water in the Tangshan area exhibits a propensity for carbonate scaling at the wellhead, primarily composed of CaCO3, and varying degrees of sulfate scaling in the middle and lower sections of the wellbore, with main components including CaSO4, SrSO4, and BaSO4. By addressing the limitations of existing scaling trend analysis methods, this study offers a theoretical foundation and methodological guidance for scale prevention and removal, thereby facilitating the sustainable utilization of geothermal water resources.

Key words: karstic geothermal water, sustainable utilization, analysis of scaling tendency, CO2 degassing, geochemical modeling, Tangshan

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