基于化学动力学的地层硫酸钡结垢模型研究

成垢离子在地层中发生沉淀反应的规律与普通水溶液中的不尽相同。多孔介质渗流过程中的扩散与沉淀反 应的反应系数需要通过岩芯流动实验中所测得的出口端钡离子浓度拟合得到。在已有的岩芯结垢模型与地层结垢模 型求解方法中，需要分别假设入口端与近井地带边界处的钡离子与硫酸根离子的浓度比远小于1，这一假设使模型有 很大的局限性。采用罗巴托与牛顿法求解岩芯结垢模型，取消了关于离子浓度比的假设；并详细推导了地层结垢模 型，修正了控制方程中的二阶项系数，研究了低硫酸根离子浓度的海水作为注入水的情况下，不同无因次扩散系数，无 因次化学反应系数，边界浓度比对地层结垢模型中阻力系数的影响。结果表明，采用低硫酸根离子浓度注入水降低边 界离子浓度比，阻力系数将大大降低；若离子浓度比与无因次反应系数降低相同的百分比，前者将导致更大的阻力系 数减幅。

Study on Barium Sulfate Scale Model Based on Chemical Kinetics

Reaction of ions in porous media were not the same as in common water solution Diffusion and reaction coefficients in porous media had to be calculated by fitting core scale model with measured outlet barium concentration in core flooding test. The original solvers of both core and formation scale model made the assumptions that barium and sulfate ion ratio should be far less than 1，which largely restricted the model′s application. By using Lobatto and Newton methods to solve core scale model without the assumption upon ion ratio we obtained the formation scale model，and modified the coefficient of second order term in the control equation. We also studied the effects of different dimensionless diffusion coefficients，dimensionless reaction coefficients and influence of ion ratios on impedance coefficient of formation scale model when injecting low sulfate seawater. The results showed that low sulfate seawater could greatly lower the ion ratio and would decrease the impedance coefficient greatly，and that with the same percentage of decrease in ion ratio and dimensionless reaction coefficient，the former would result in greater reduction of impedance coefficient.