【作者】 何春生；

【导师】 刘巨保；

【作者基本信息】 东北石油大学 ， 石油与天然气工程， 2014， 博士

【摘要】 连续油管相对于常规螺纹连接油管而言，具有起下作业无需上扣、卸扣等优点，在钻井和修井、压裂和酸化作业中得到广泛应用，但其工作寿命低、使用成本高以及轴向加压困难是连续油管井下作业中面临的关键技术问题。本文采用理论分析、数值模拟和实验方法对无损伤及有损伤连续油管起下作业寿命预测、井筒内轴向受压屈曲行为开展了系统和深入的研究。根据连续油管的失效形式和原因，归纳定义了描述连续油管损伤的几何参数为：壁厚减薄量Δ t、椭圆度Φ，凹陷深度H，局部表面机械损伤长度x、宽度w、深度h。针对连续油管工作状态采用电子万能拉伸实验机CMT5105为加载机构，研制了专用的加压设备、拉弯和拉直工装等实验装置。选取工程上常用的23’’8和11’’4连续油管为试件，开展了无损伤及椭圆度、壁厚、凹坑等有损伤连续油管的拉弯和拉直疲劳寿命及累积损伤实验，取得了大量实验数据，经数据分析及回归处理，得到了连续油管椭圆度、壁厚及损伤参数随循环次数变化的计算公式。根据连续油管的工作状态，分析了连续油管通过注入头、导向架、滚筒及在井筒内的力学行为，建立了地面及井筒内连续油管非线性有限元分析方法，得到注入头处、导向架、滚筒及在井筒内连续油管危险截面的广义应力(轴向应力、环向应力以及径向应力)及应变计算公式。根据连续油管的损伤形式，采用数值模拟及数学回归方法得到了凹坑和凹陷对连续油管产生的应力集中系数计算公式；采用弹性力学理论，推导了椭圆度损伤连续油管均布内外压力、注入头连续油管局部挤压力下的环向和径向应力计算公式；采用能量法建立了无损及有损伤连续油管的疲劳寿命预测计算方法，经室内实验和现场试验验证，其理论预测的疲劳寿命以及损伤几何参数误差均小于20%。选取直井、斜直井、弯曲井中的连续油管为研究对象，基于能量法推导了井筒内连续油管在井底轴向压力作用下，沿径向和圆周方向发生正弦屈曲、螺旋屈曲的多次失稳临界载荷计算公式。根据受压管柱发生正弦或螺旋屈曲的几何形状，综合考虑井眼轨道曲率和井斜、屈曲后连续油管与井筒的接触摩擦状态，采用拉格朗日乘数法描述井筒的滑动位移边界条件，推导了直井、斜直井、弯曲井中受压连续油管与井筒的接触力、摩阻力及变形计算公式。针对井筒内连续油管发生正弦或螺旋屈曲问题，研制了专用的管柱后屈曲实验装置，得出管柱试件在不同载荷作用下发生正弦、螺旋屈曲的失稳临界载荷、摩阻力变化规律，其实验结果与理论计算结果基本一致，为连续油管钻修作业提供了理论依据。更多还原

【Abstract】 Compared with the conventional threaded tubing, coiled tubing had the advantagesof no buckling, no shackling in the roundtrip. It was widely used in drilling, workover,fracturing, acidizing operations. However, it had been a key technical problem aboutcoiled tubing drilling operation that its low working life, high cost and difficulty axialcompression. This paper which adopted theoretical analysis, numerical simulation andexperimental method aimed at the life prediction of coiled tubing roundtrip operation,within the well casing axial compression buckling behavior to carry out the research.According to the failure forms and reasons of the coiled tubing, the geometryparameter of describing the damage of coiled tubing was defined: wall thicknessthinning amount Δt, ovality Φ, depth of pip H, local surface mechanical damagelength x, width w, depth h. Adopt existing electronic universal tensile testing machineCMT5105, develop the special pressure equipment, stretch bending and straighteningequipment, etc. Choose the23’’8and11’’4coiled tubing which commonly used inengineering as the test specimens, carry out no damage and damage including ovality,wall thickness, depth of pip, etc coiled tubing fatigue life bent and straight cumulativedamage experiment. A lot of experimental data were obtained. Through data analysisand the regression process, the coiled tubing ovality, wall thickness, and calculationformula of damage parameters changing with cycles were obtained.According to the working state of the coiled tubing, coiled tubing was analyzedthrough the injection head, guide frame, roller and mechanical behavior in the wellcasing. The coiled tubing in the ground and well casing non-linear finite elementanalysis method were established. The site, guide frame, cylinder head and coiledtubing within the well casing dangerous section of generalized stress (axial stress,circular stress) and radial stress and strain calculation formula were obtained. Accordingto the damage form of coiled tubing, using the numerical simulation and mathematicalregression method, the pits and sag calculation formula of the stress concentration factorin coiled tubing were obtained. Using elastic mechanics theory, with the hoop stress of coiled tubing ovality damage calculation formula was deduced. A nondestructive anddamage calculation method of the coiled tubing fatigue life prediction was established.Through indoor experiment and field test, its theory to predict the fatigue life ofgeometric parameters and damage error were less than20%.Select the coiled tubing in the vertical wells, slant wells and curved wells as theresearch object, coiled tubing within the well casing based on energy method in bottomhole pressure under the action of the sinusoidal and spiral buckling instability criticalload formula were deduced. According to sinusoidal or helical buckling compressionstring geometry, considering well casing trajectory (curvature and hole deviation),coiled tubing sinusoidal buckling, spiral deformation after contacting with well casingstatus, bring in the coiled tubing gravity and the friction resistance along the axial workitem to Lagrange multiplier method. The vertical wells and slant wells, bendingcompression coiled tubing in the well with well casing contact force, friction anddeformation calculation formula were obtained. Aimed at coiled tubing in well casingpost-buckling occurred sinusoidal or helical deformation problems, special roof boltspost-buckling experiment device was developed. Draw roof bolt’s change law underdifferent load in the sinusoidal and helical buckling instability critical load and friction.Its experimental results were basically identical with the theoretical calculation results,provided a theoretical basis for coiled tubing drilling and repairing work.更多还原