${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$对粘土吸附性能影响研究

Study on the Influence of ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ on the Adsorption Performance of Clay

摘要: 钻井液发挥作用主要通过处理剂在粘土上的吸附作用，但在钻井过程中常常会遇到${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ 污染的问题，导致处理剂失效，使钻井液体系流变性和滤失性出现严重恶化。本文通过室内实验模拟CO₂侵入粘土基浆的性能，分析${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ 污染对粘土基浆的流变、滤失性能影响规律，从处理剂角度分析${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ 污染机理。研究结果表明：${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ 污染存在临界值，当${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ 浓度达到1564 mg/L时粘土基浆粘度和滤失量出现大幅上升的趋势，且随着污染程度的加重，粘土颗粒逐渐聚集，形成大颗粒、漏失通道增大；对RSTF吸附实验结果表明，污染前RSTF在粘土上吸附平衡量为103.21 mg/L，污染后吸附平衡量大幅减小，吸附等温线Langmuir方程比Freundlich方程能更好地描述RSTF在粘土颗粒上的吸附过程。

Abstract: Drilling fluids function mainly through the adsorption of the treatment agent on the clay, but ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ contamination is often encountered during the drilling process, leading to treatment agent failure and severe deterioration of the rheology and filtration loss of the drilling fluid system. In this paper, we simulate the performance of CO₂ intrusion into clay-based slurry through indoor experiments, analyze the influence law of ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ contamination on the rheological and filtration loss performance of clay-based slurry, and analyze the ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ contamination mechanism from the viewpoint of treating agent. The results of the study show that there is a critical value for ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ pollution, and when the concentration of ${\text{CO}}_3^{2-}{\text{/HCO}}_3^{-}$ reaches 1564 mg/L there is a trend of a large increase in the viscosity and filtration loss of the clay-based slurry and with the increase in the degree of contamination, the clay particles are gradually aggregated, large particles are formed, and the leakage channel is increased; the results of adsorption experiments on RSTF showed that the equilibrium amount of RSTF adsorbed on clay was 103.21 mg/L before contamination, and the equilibrium amount of adsorption was greatly reduced after contamination, and the adsorption isotherm Langmuir equation can better describe the adsorption process of RSTF on clay particles than Freundlich equation.