水泥浆流变性分析及其环空流动的数值模拟

Experimental study on rheological property for cement slurry and numerical simulation on its annulus flow

偏心环空流动的均匀性在固井工程中有重要影响。通过实验对三种不同配方的水泥浆进行流变性分析,得到适合水泥浆的最佳流变模式是赫切尔一巴尔克莱(H-B)模式。应用Fluent软件对外径0.24 m(9 1/2”),内径0.18 m(7”)的环空井筒内水泥浆流动进行了数值模拟,得到了偏心度、流速以及流体的流变参数对流动不均匀度的影响规律。模拟结果表明,偏心是引起环空流动不均匀的主要原因。随着偏心度的增加,流动均匀性降低;另外,提高流动速率以及降低流体的屈服应力、稠度系数和流性指数有利于环空流动的均匀性。

Uniformity of annulus flow is important in well cementation. Three cement slurries were tested on rheological performance. Based on the experimental data of theological property, numerical simulation analysis was conducted. It is demonstrated that the model of H-B is the optimum model. Annulus flow processes of cement slurry were simulated with FLUENT software. The inner and outer diameters of the simulated annulus wellbore are 0.18 and 0.24 meters respectively, and its length is 8 meters. The influences of eccentricities of casing, velocity, and theological property of the cement slurry on non-uniformity of the annulus flow were understood. The simulated results indicate that eccentricity is the main factor controlling annular flow, the flow is uniform with an low eccentricity. Velocity and rheological parameter also affect flow field, while increasing the velocity and decreasing the yield stress, the power-law index and the consistency index of the fluid are helpful to increase the uniformity of the annulus flow.