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裂缝中流动酸液的有效穿透距离,是压裂酸化施工设计和预测增产效果的一个重要参数。迄今为止,国内外的研究者,在解决这一问题时,均未考虑酸—岩流动反应过程中,酸浓度下降和反应产物浓度升高对氢离子传质速度的影响。我们的研究发现,同离子效应对氢离子有效传质系数的影响较大,是一个不可忽视的重要影响因素。 本文在系统试验研究的基础上,给出不同浓度的盐酸和四川二迭系阳新灰岩反应时,氢离子有效传质系数与余酸浓度的关系曲线,用数理统计的方法,给出了无因次氢离子传质系数与无因次余酸浓度及流动雷诺数函数关系的经验方程。将此经验方程代入并求解变系数的对流扩散偏微分方程,即可获得考虑酸浓度变化和同离子效应时的酸液有效穿透距离的计算方法。也可用分段迭加计算法来近似计算这一距离。
The effective penetration distance of flowing acid in fractures is an important parameter for fracturing and acidizing construction design and prediction of yield increase. So far, researchers at home and abroad have not considered the influence of acid concentration drop and reaction product concentration on hydrogen ion mass transfer rate in acid-rock flow reaction when solving this problem. Our study found that the effect of the same ion on the effective mass transfer coefficient of hydrogen ions is a significant factor that can not be ignored. Based on the systematic experimental research, the curves of the effective mass transfer coefficient of hydrogen ions and the concentration of residual acid are given when the hydrochloric acid is different from that of the Yangxin limestone of the Second Permian of Sichuan. The results of mathematical statistics show that Empirical equation for the relationship between the mass transfer coefficient of secondary hydrogen ions and the concentration of non-dimensional acid and the function of flow Reynolds number. This empirical equation can be used to solve the convection-diffusion partial differential equation with variable coefficients, and the calculation method of the effective penetration distance of acid solution considering the change of acid concentration and the same ion effect can be obtained. This distance can also be approximated using a piecewise iterative calculation.