Analysis and Research on Numerical Simulation of the Main Factors Affecting Cementing Displacement Efficiency at Horizontal Wells

Abstract:

There are many factors which affect the displacement efficiency in the cementing process at horizontal wells. In these factors, the eccentricity of casing, rheological property of flushing fluid and density difference between flushing fluid and drilling fluid are prominent. In order to understand the influence of various factors on horizontal cementing, three-dimensional model of eccentric horizontal well was established by CFD software and numerical simulation study was made on drilling fluid being displaced by flushing fluid by means of VOF method. The inner and outer diameters of the simulated wellbore and casing are 177.8mm（7in）and 215.9mm（81/2in）respectively, the length of annulus is 300m, the displacement velocity is 1m/s and the casing eccentricity is selected 0，0.2，0.3 and 0.4 separately according to the specific example. The simulated results indicate that the eccentricity of casing at horizontal wells is unfavorable to cementing displacement efficiency, and increasing flow behavior index and decreasing consistency index are helpful for improving the stability of displacement interface, reducing its length and enhancing displacement efficiency as well. Meanwhile, when the positive density difference between flushing fluid and drilling fluid is formed, it is conducive to the improvement of displacement efficiency.