The Research On Improve Displacement Efficiency Of Highly Deviated Wells With Eccentric Annulus

With the accelerated pace of oil exploration and the development of drilling and completion technology, highly deviated wells and horizontal wells are used more and more widely. The displacement effect of cementing directly related to the smooth development of the wells construction and production, but greater challenges are brought to cementing displacement research in highly deviated wells with eccentric annulus inevitably. Therefore, it is necessary to study how to improve displacement efficiency of highly deviated wells with eccentric annulus.In order to better describe the rheological properties of the cement slurry and drilling fluid in the displacement process. This article using the Herschel-Bulkley mode. Through the use of displacement experimental device to research the influence laws of density difference, well inclination, the viscosity of the cement slurry, casing eccentricity and casing rotation speed on displacement interface stability. By the contrast between experimental phenomena and the simulation conclusions, further evidences of the feasibility of the numerical simulation method in the study of displacement efficiency.With engineering fluid dynamics software FLUENT and found the eccentric annulus cementing displacement model, further research influence laws of density difference, well inclination, the rheological parameters of cement slurry, casing eccentricity, displacement velocity and casing rotation speed on displacement efficiency in highly deviated wells with eccentric annulus by using the principles and methods of engineering fluid mechanics. The simulation results indicated that the displacement efficiency first increases then decreases with the increase of density difference, there is an optimal density difference makes the best displacement effect. Increase the liquidity index, consistency coefficient and dynamic shear force of cement slurry can improve displacement efficiency. On the contrary, the efficiency will drop when increase well inclination. The efficiency will be better when eccentric in a certain extent(0.1-0.3). The turbulence displacement effect is superior to that of laminar and plug flow. But laminar displacement with high-speed also can meet the needs of cementing in the field. In addition, rotating casing can significantly improve displacement effect. Rotating bushing cause cement slurry to do axial spiral displacement, meanwhile, drive and flush drilling fluid of retention area to improve the displacement efficiency. The research in this paper has some degree of guiding significances for improving displacement efficiency in highly deviated wells with eccentric annulus.