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酸在裂缝中流动酸液的有效作用距离(L有效),是预测酸压增产效果和科学地进行酸压设计的重要参数。 本文采用数学物理模拟的方法,研究定常情况下酸在裂缝中流动时的有效作用距离。 采用平均滤失速度为常值的流动反应模式(图1),建立描述酸沿裂缝流动时浓度分布的数学规律,即对流扩散偏微分方程(1);我们采用有限差分法求解方程(1),给出电算数值解和确定灰岩酸液有效作用距离的实用图版。 我们采用预先在酸液中高压加入CaCO_3的办法,模拟酸压时酸岩反应的同离子效应,作出有效传质系数和酸浓度的关系曲线D_e=f(c),使所计算的酸液有效作用距离更符合实际。 本文在处理试验数据时,采用抛物线流的数值解,代替了文献[1]使用的柱塞流的解析解。因此,计算出的D_e值更准确。
The effective distance (L effective) for the acid to flow in the fracture is an important parameter for predicting the effect of acid pressure increase and for the scientific design of acid pressure. In this paper, the method of mathematical physics simulation is used to study the effective distance of the acid flowing in the fracture under the normal conditions. The mathematical law describing the concentration distribution along the fissure flow, ie the convection-diffusion partial differential equation (1), is established by using the flow-response model with average filtration velocity as a constant value (Figure 1). We use the finite difference method to solve Eq. (1) , Gives the calculation of numerical calculation and calculation of the limestone acid effective distance effective plate. We use the method of pre-adding CaCO_3 to the acid in order to simulate the same ion effect of acid-rock reaction under acid pressure and make the relation curve D_e = f (c) between the effective mass transfer coefficient and the acid concentration to make the calculated acid solution effective The role of distance more realistic. In this paper, the numerical solution of the parabola flow is used to process the experimental data instead of the analytic solution of the plunger flow used in [1]. Therefore, the calculated D_e value is more accurate.