油田酸化压裂废液中F^-在土壤中的迁移规律研究

通过土柱实验研究了大庆油田酸化压裂废液中氟离子（F^-）对土壤环境的影响，考察了酸化压裂废液中不同浓度的F^-在土壤中的迁移转化规律，以及不同酸度、不同的土壤质地对F^-在土壤中的迁移规律的影响，并探讨了相关作用机理。结果表明，油田酸化压裂废液中F^-对土壤环境产生明显的影响，随着废液中v浓度增加，F^-在黑钙土中的迁移深度增加；沿土壤深度方向发展，土层中F^-含量呈现降低趋势；随着F^-浓度的变化，F^-在黑钙土中的迁移基本符合负指数y=yo＋a·exp（-x/t）规律；而随着压裂废液中酸度的增加，土壤中粘土矿物Ca^2＋、Al^3＋等阳离子浓度增高，与水中氟形成难溶化合物，从而使得F^-在土壤环境中的迁移深度反而降低；F-在大庆地区3种典型土壤中的迁移深度符合黑钙土〉黄土〉碱土的规律；油田酸化压裂废液中F^-主要存在于在10cm深度的土壤表面层。

The Migration Rules of Fluoride Ion from Waste Acid Fracturing Fluid in soil

In process of oil production, acidification is a necessary operation to increase output, though it will produce wastes, especially the acid ingredient including hydrofluoric acid, hydrochloric acid, vitriol, etc. In this paper, the influence of fluorin ion（ F^-）in waste acid fracturing fluid on the soil environment of Daqing oil field was studied by earth column experiments. The concentration of F^-, acidity and different typical terrene soils on the influence of the migration rules and characteristics of F^- in the soil environment were investigated respectively, and the related mechanisms were also discussed. The results showed that the fluorin ion of waste acid fracturing fluid in the soil have a clear impact on the Daqing oil field environment, and the influence depth of F^- in the soil increases with the increasing of the concentration of F^-. The relation between the concentration of F^- and the influencing depth in the soil could be expressed by a negative exponential equation y=yo＋a· exp（-x/t ）, and the fitting effect was better than that of Temkin equation, Freundlich and Langmuir equation. Results also showed that the increasing of positive ion such as Ca^2＋ and Al^3＋ leads to the increasing of formation of insoluble compounds, which caused the influence depth of F^- in the soil decrease with the increasing of H＋. The migration of F^- in different terrene soils was different, and the correlations of the influencing depth in the different typical types of soils in Daqing oil field were chernozem〉loess〉alkali soil. Fluorin ion in the waste acid fractur- ing major presents in the 10 cm depth surface layer.