Oldroyd-B流体在孔隙壁面残余油上的作用力分析

Mechanics Analysis of Oldroyd-B Fluid Acting on the Residual Oil on Pore Wall

为了分析计算粘弹性流体驱替残余油的微尺度力,从水动力学角度探索非牛顿流体的流变特性,选取Oldroyd-B本构方程来模拟粘弹性流体,并结合连续性方程和运动方程得到了粘弹性流体在微孔道中的流动方程,利用边界条件计算得到流动的流场,结合应力张量理论,计算出粘弹性流体作用在残余油上的法向偏应力和水平应力差,计算结果表明:沿流动方向,粘弹性流体的弹性越大,法向偏应力越大;垂直于流动方向,法向偏应力近似对称分布;随着粘弹性流体的弹性变化,水平应力差的变化趋势发生了变化,威森伯格数We越大,残余油所受的水平应力差先逐渐增加,达到峰值后降低,这种趋势更有利于残余油的变形,为下一步分析残余油的变形,并从主体上分离奠定了基础.

In order to analyze and calculate the microscope force of viscous-elastic fluid flooding residual oil and explore the dynamic rheological properties of non-Newtonian fluid from the angle of hydrodynamics, the flow equation of viscous-elastic fluid in the micro pore can be derived by selecting Oldroyd-B fluid constitutive equation and combining the continuity equation and motion equation. Then, the flow field can be calculated under the boundary condition, and with the theory of stress tensor, the horizontal stress difference and normal deviatoric stress of viscous-elastic fluid acting on the residual oil can be calculated. The results show that： along the flow direction, the greater the elasticity of viscous-elastic fluid is, the greater the normal deviatoric stress is; perpendicular to the direction of flow, the normal deviatoric stress is approximate symmetric distribution. As the elasticity of viscous-elastic fluid changes, the variation trend of horizontal stress difference changes. As the value of We increases, horizontal stress difference on the residual oil gradually increase first, but decrease after reaching the peak. This trend is more advantageous to the deformation of the residual oil which lay the foundation for further analysis of deformation of the residual oil and separating from the main body.