偏心环空流动的数值模拟研究

发布时间：2018-07-15 07:28

【摘要】：偏心环空流动现象普遍存在于石油工业的钻井和采油工程中。对于钻井工程来说,偏心环空流动的速度分布、压降分布规律将直接关系到钻进速度、井眼质量和钻井成本,是钻井工艺技术研究的重要目标。本文建立了偏心环空流动的物理模型和数值模型,采用标准k-?湍流模型和壁面函数法对不同网格密度的环空流动进行了数值计算,分析了网格密度对参量分布规律的相关性并优选了网格密度。数值模拟结果与前人PIV流动实验数据吻合良好,验证了本文的数值模拟方法。在此基础上,通过瞬态流动模拟分析了瞬时开泵流场速度与压降随时间的变化规律;通过稳态流动研究,得到了偏心度、初始速度及流变参数对流场速度分布、不均匀度及压降的影响规律;通过突扩偏心环空流动模拟,分析了突扩流场速度与压降的分布规律及不同因素对突扩流场漩涡强度的影响规律。采用双因素对比分析法,得出了转速与偏心度、初始速度和流变参数对流场的偏移角度、最大速度及流场不均匀度的交互影响规律。分析了不同流变参数下转速对偏心环空螺旋流场压降的影响规律,得出了流性指数、动切力、稠度系数和初始速度对临界转速的影响规律。将数据结果进行了多元非线性回归,得到压降梯度的拟合公式。编制了“环空流动模拟计算分析软件”并获得了相应的计算机软件著作登记证书,软件界面友好,功能全面,计算结果与前人实验数据吻合良好,能够满足实际工程需要。
[Abstract]:Eccentric annular flow exists in drilling and oil recovery projects in petroleum industry. For drilling engineering, the velocity distribution and pressure drop distribution of eccentric annulus flow will be directly related to drilling speed, borehole quality and drilling cost, which is an important goal of drilling technology research. In this paper, the physical and numerical models of eccentric annular flow are established, using the standard k-? The turbulent model and the wall function method are used to numerically calculate the annular flow with different grid densities. The correlation between the grid density and the parameter distribution is analyzed and the grid density is selected. The numerical simulation results are in good agreement with the previous PIV flow experimental data, which verifies the numerical simulation method in this paper. On this basis, the variation of flow field velocity and pressure drop with time are analyzed by transient flow simulation, and the distribution of eccentricity, initial velocity and flow velocity of rheological parameters are obtained through steady flow research. The distribution law of velocity and pressure drop of sudden expansion flow field and the influence of different factors on swirl intensity of sudden expansion flow field are analyzed through the simulation of sudden expansion eccentric annulus flow. By means of two-factor comparative analysis, the law of interaction between rotation speed and eccentricity, initial velocity and rheological parameters, flow field deviation angle, maximum velocity and flow field unevenness is obtained. The influence of rotational speed on the pressure drop of helical flow field in eccentric annulus is analyzed under different rheological parameters. The influence of flow index, dynamic shear force, consistency coefficient and initial velocity on critical speed is obtained. The fitting formula of pressure drop gradient is obtained by multivariate nonlinear regression. The software for simulation calculation and analysis of annular flow is compiled and the corresponding registration certificate of computer software is obtained. The software has friendly interface, comprehensive function and good agreement with previous experimental data, which can meet the needs of practical engineering.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE24

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