基于气泡尺度的泡沫压裂液流变机理研究

从介观层次入手，以高压高剪切速率下气泡尺寸均匀分布的泡沫压裂液为基础，建立了一个二维泡沫压裂液物理模型．该模型视泡沫压裂液的最小组成单元为气泡，将气泡和周围液相以及气泡与气泡之间的作用力用弹簧表示，并从能量耗散的角度出发，成功推导了当泡沫质量（气相的体积分数）大于70％、剪切速率大于500s^-1时的泡沫压裂液流变特性的本构方程．利用该本构方程计算得到的泡沫压裂液有效黏度和试验结果对比最大误差只有9．7％，平均误差只有4．9％，所得结果明显地优于Reidenbach和Mathel等人给出的拟合公式．该模型不仅可以从机理上阐述泡沫压裂液的流变特性，而且还能够很好地表现出泡沫压裂液在泡沫质量较高时的有效黏度特性．更为主要的是该模型还可以用于解释泡沫压裂液的屈服应力和壁面滑夥现象．

Rheology Mechanism of Foam Fracturing Fluid at Bubble Scale

By using mesoscopic approach focusing on entire bubbles rather than films or vertices, a simple two dimensional model was proposed to study the rheology mechanism of foam fracturing fluid. In this model, the bubble was considered to be the element of foam fracturing fluid, and the forces between bubbles and between bubble and the surrounding liquid were represented by a spring. Based on this model and the energy dissipation principle, the constitutive equation was deduced successfully for foam fracturing fluid with foam quality higher than 70% and shear rate higher than 500 s^-1. The results are in better agreement with the experimental data of apparent viscosity than those by the Reidenbach and Mathel methods. The maximum and mean deviations between the calculated apparent viscosity using this correlation and the experimental results are 9. 7% and 4.9%, respectively. Especially, this model can also explain the yield stress and wall slip phenomena for foam fracturing fluid.