椭圆井眼偏心环空赫巴流体平板层流模型  

Plate Laminar Flow Model of Herbert Fluid in Eccentric Annulus of Elliptical Wellbore

作　　者：徐生江 刘可成 姚旭洋 周俊 王贵 汤明 Xu Shengjiang;Liu Kecheng;Yao Xuyang;Zhou Jun;Wang Gui;Tang Ming(Engineering Technology Research Institute of PetroChina Xinjiang Oilfield Company;School of Petroleum and Natural Gas Engineering,Southwest Petroleum University)

机构地区：[1]中国石油新疆油田分公司工程技术研究院 [2]西南石油大学石油与天然气工程学院

出　　处：《石油机械》2020年第12期27-34,共8页China Petroleum Machinery

基　　金：中国石油天然气股份有限公司项目“复杂地质目标降低成本钻井关键技术研究与应用”(2017E-0413)。

摘　　要：在定向井和水平井钻井过程中,由于岩石和地应力的各向异性,易形成非规则圆形井眼,导致井底压力难以准确预测。鉴于此,建立了基于平板层流假设的椭圆井眼偏心环空赫巴流体层流流动压降模型,开展了椭圆井眼偏心环空赫巴流体层流流动CFD仿真模拟,并利用仿真结果对平板模型进行验证,同时系统分析了环空几何参数、流体流变参数和流量等对压降梯度的影响规律。分析结果表明:压降梯度随流量、屈服值和稠度系数的增大呈拟线性或线性增加,随环空内外径之比和流性指数呈指数性增大,随井眼长短轴之比和偏心率的增大而降低;椭圆井眼对压降影响大于圆形井眼;平板模型预测结果与CFD模拟结果符合较好,误差仅为±5%。建立的椭圆井眼偏心环空平板层流模型为准确便捷预测椭圆井眼中的井底压力提供了理论依据。During the process of drilling directional and horizontal wells,due to the anisotropy of rock and insitu stress,it is easy to form irregular circular borehole,which makes it difficult to accurately predict the bottomhole pressure.In order to accurately predict the flow pressure drop in elliptical wellbore,a laminar flow pressure drop model of Herbert fluid in eccentric annulus of elliptical wellbore is established based on the assumption of plate laminar flow.The CFD simulation of laminar flow of Herbert fluid in eccentric annulus of elliptical well is carried out.The simulation results are used to verify the flat plate model.Meanwhile,the geometric parameters of annulus,fluid rheological parameters and flow rate are analyzed systematically to find out the influence law of pressure drop gradient.The results show that:the pressure drop gradient increases exponentially with the increase of flow rate,yield value and consistency coefficient,exponentially increases with the ratio of inner and outer diameter of annulus and fluidity index,and decreases with the increase of ratio of long and short axes and eccentricity;the influence of elliptical hole on pressure drop is greater than that of circular hole;the prediction results of flat plate model are in good agreement with CFD simulation results,and the error is only±5%.The established plate laminar flow model of eccentric annulus in elliptical wellbore provides a theoretical basis for accurate and convenient prediction of bottom hole pressure in elliptical wellbore.

关 键 词：椭圆井眼 偏心环空 赫巴流体 平板模型 层流流动 

分 类 号：TE21[石油与天然气工程—油气井工程]