摘要
采用CFD-DEM耦合计算模型,利用DEM软件建立大粒径(2 cm)、非球体岩屑颗粒的离散元模型,与FLUENT实现无缝耦合并行计算,颗粒间相互作用采用Hertz-Mindlin弹性接触模型,对大粒径的、非常规岩屑颗粒在水平井段的运移规律进行了数值模拟计算。基于钻井实测数据,建立水平井段环空内含不同形状(片状,立方体状及球状)相同等效球体粒径颗粒的计算模型,展示了井眼环空内颗粒运移、沉积状态,对环空钻井液流速、不同形状的岩屑颗粒运移速度进行了计算分析,本文还计算得到片状大粒径岩屑含量对钻井液携岩效果的影响规律。结果显示:2 cm等效体积球体粒径的颗粒在井眼环空内的运移状态较差,出现局部堆积;立方体状颗粒的运移效果最差,片状颗粒次之;在所选用计算条件下,片状颗粒含量大于10%时会加剧削弱携岩效果。计算结果可对钻井携岩问题的研究提供一定的参考价值。
By a CFD-DEM coupled simulation model,within which the discrete element model for non-spherical cuttings in size of 2 cm is built by a DEM software and is coupled with FLUENT,numerical computation is conducted on the migration of irregular and big-sized cuttings in the horizontal part of a well. The Hertz-Mindlin model for particles contact is adopted to simulate the elastic force among paritlces. From the practical data,an annulus model for the horizontal part of a drilling well is built with big-sized particles in various shapes,where platy,cubic and spherical particles with same equivalent volume sphere diameter are included. The migrating and depositing of cuttings in well annulus space are displayed. The flow velocity of drilling fluid,migrating velocity of the particles and the impact effect of the particle on the well-wall are obtained and discussed. Additionally,the effects from the content of the platy cuttings on the carrying ability of the drilling fluid is also studied. The results show,for particles in 2 cm equivalent volume sphere diameter,local deposition appears. The migration of the cubic particles behaves most poorly and impacts the well-wall hardest while the behavior of the platy particles takes the second place. In the chosen conditions,the carrying ability of the fluid on the platy cuttings decreases much faster when the content is over 10%. What is got in this paper can be kind of reference value for the further study on the cuttings-carrying in drilling engineering.
出处
《科学技术与工程》
北大核心
2017年第27期190-195,共6页
Science Technology and Engineering
基金
国家自然科学基金(51374228)
中国博士后科学基金(2017M612375)资助
