前置液流变性对顶替界面稳定性影响的数值模拟

借助计算流体力学（CFD）软件FLUENT6．20，对环空井筒内水泥浆顶替过程进行了数值模拟，模拟环空井筒外径0．24m、内径0．18m、高8m。在顶替速度为0．4m／s、偏心度为0.4的条件下，计算得到了顶替界面形状以及前置液流变参数屈服应力、稠度系数和流性指数对顶替界面稳定性及顶替效率的影响规律，并对数值模拟结果进行了实验验证。数值模拟结果表明，降低前置液的屈服应力、稠度系数及流性指数有助于提高水泥浆和前置液之间界面的稳定性和顶替效率。固井设计时要考虑界面的稳定性，对前置液流变参数进行调整。

Numerical simulation on influence of rheological property of front fluid on stability of cement displacement interface

The displacement process of cement in annulus was simulated with computational fluid dynamics software of FLUENT 6. 20. The inner and outer diameters of the simulated annulus wellbore are 0. 18 m and 0. 24 m respectively, and its height is 8 m. The simulation was taken under the condition of eccentricity of 0. 4 and the displacement velocity of 0.4 m/s. The displacement interface figure and the influences of the rheological parameters of the front fluid on stability of displacement interface and displacement efficiency were obtained under different conditions of yield stress, power-law index and consistency index. The results of numerical simulation agree well with those of experiment. The simulated results indicate that decreasing the yield stress, power-law index and consistency index are helpful for improving the stability of cement displacement interface and displacement efficiency. Considering the stability of displacement interface, the rheological parameters of front fluid should be adjusted in cementing design.