【作者】 李茂生；

【导师】 闫相祯；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2007， 博士

【摘要】 国内外研究表明,钻柱失效大多发生在轴向载荷和扭矩载荷最小的底部钻具部位上,这种现象和钻具的转速以及钻具和井壁之间的环空间隙密切相关。论文结合国家自然基金资助项目《复杂钻井条件下钻井新技术研究》(50234030),对小环空条件下钻柱的动力学和可靠性进行了深入研究,所取得的成果在石油钻井行业有良好的应用前景。本论文的主要研究内容总结如下:(1)考虑环空间隙的钻柱动力学理论分析直井中的旋转钻柱是一个多支点的十分复杂的自激横振系统。对这样一个系统进行理论分析和数值模拟十分困难。论文首先研究了单根钻柱的运动状态以及由涡动所引起的弯曲应力。钻柱的横向振动是在钻井液中发生的,钻井液对钻柱横向振动的影响不可忽略,论文从理论上研究了考虑环空间隙的情况下钻井液对钻柱横向振动固有频率的影响。钻柱的纵向振动是研究钻柱的动力学特性一个重要方面,论文对钻柱系统的纵向振动进行了系统分析,使用有限元方法对钻柱纵向振动模型进行了数值仿真,同时对钻柱的纵向振动以及其谐响应特性进行了动力学模拟。钻柱的涡动与钻柱的动力学特性密切相关,涡动过程中的钻柱会消耗更多的能量,钻柱的涡动特性和钻柱与井壁之间的间隙密切相关,论文对底部钻具组合的涡动特性进行了分析。(2)钻柱与井壁碰撞的拉格朗日模型和ALE流固耦合模型依据钻柱与井壁之间碰撞的特点,将拉格朗日方法引入钻柱与井壁碰撞的分析中。利用动量方程、质量守恒方程和能量方程,采用时间积分方法,求解了应力与位移之间关系的微分方程,得到了考虑参考构形和当前构形的三维空间钻柱和井壁的常应变多项式的位移函数。采用8节点6面体单元建立了钻柱和井壁碰撞的整体刚度矩阵。研究了钻柱与井壁碰撞机理,以及碰撞过程中钻柱的应力场和应变场的变化情况。建立井眼、钻柱、地层与钻井液系统的混合欧拉-拉格朗日方法的流固耦合计算模型。用ALE(任意欧拉-拉格朗日)方法分析碰撞过程中钻柱—钻井液系统的动力响应,ALE方法可允许流体区域变形与移动。描述流体区可采用ALE参考系,固体区用拉格朗日参考系。得出了考虑钻井液影响下的钻柱与井壁碰撞时的应力应变变化情况。(3)环空间隙对普通钻井和套管钻井的影响研究了在普通钻井和套管钻井中钻柱和套管的涡动频率、磨损以及疲劳失效分析,从而分析环空间隙对钻柱和套管的力学参数的影响。随着环空间隙的减小和转盘转速的增加,钻柱的疲劳强度是降低的,套管钻井中的套管比钻杆更容易发生疲劳失效事件。(4)考虑环空间隙的钻柱可靠性研究结合国内外在钻柱可靠性研究方面的成果,并基于论文的研究进展,率先将环空间隙对钻柱动力学的影响以及数值仿真技术引入钻柱的可靠性分析中。套管钻井过程的环空间隙比正常钻井时要小,论文讨论了环空间隙这一钻井参数对套管钻井可靠性的影响以及如何避开钻柱振动的共振区。更多还原

【Abstract】 The domestic and foreign research indicated that, the position with failure of the drill pipe mostly occurs in the part which the axial load and the torque load is in the smallest spot, some scholars and the overseas research facility think it is closely related with rotational speed and clearance between the drilling tool and the wall of a well. This article unifies the national natural fund subsidization project“the new drilling engineering research under complex drilling condition well”(50234030), and study dynamic and reliability research of drill stem considered clearance between drill stem and formation, the achievement obtained had the good application prospect in the petroleum well drilling profession. The summary in the present paper research is as follows:(1) Theory analysis of drill stem considered clearance between drill and formationThe rotary stem in vertical well is a very complex self exciting vibration system with much supporting. It is extremely difficult to carry on the theoretical analysis and the numerical simulation to this kind of system. This article first studied the transverse vibration as well as the bending stress of a single drill stem which caused by the whirling motion.Because the drill stem vibrates in the drilling fluid, the influence caused by the drilling fluid can not be ignored. This article studied how the drilling fluid influences the transverse vibration natural frequency thinking of clearance between the drill stem and the formation.The longitudinal vibration is important in the dynamic character. This article studied the longitudinal vibration of the drill stem and numerical simulation of longitudinal vibration is calculated using finite element method. This method can simulate longitudinal vibration and the harmonic response of the drill stem. The whirl of the drill stem can affect the dynamic character of drill stem greatly, it is thought more energy would be used to overcome the friction while whirling. The whirl character is greatly correlated with clearance between the drill stem and formation. The whirl character of the bottom hole assembly is studied in this article.(2) Lagrange model and ALE fluid and solid coupling model of collision between drill stem and the wall of a wellBased on the collision characteristic between the drill stem and the wall of a well, the Lagrange method was introduced to the collision analyzes between the drill stem and the wall of a well. The matrix differential equations containing strain and stress were obtained using the momentum equation, the mass-conservation equation, the energy equation and time integral method. The non-polynomial displacement function considering the reference configuration and the current configuration three-dimensional space drill stem and the wall of a well also found. The integral stiff matrix was established using 8-node hexahedron solid elements to solve the collision between the drill stem and formation. This article studied collision mechanism and stress field and the strain field change situation during the contact process.The arbitrary Lagrange-Euler (ALE) fluid-solid coupling model of well, stem and formation is established. The drill-drilling fluid system in collision is studied by ALE method The ALE method allows deformation and displacement in fluid area. This article uses ALE method to describe the fluid, and use Lagrange to describe the solid area. Stress and strain of the drill stem is obtained considering the fluid influence.(3) How the clearance influencing the normal drilling and casing drillingThis article finally discussed how the clearance influences the normal drilling and casing drilling, from whirling frequency, tool wear and fatigue failure of drill stem. When the clearance between the drill stem and formation decreased and the rotate speed increased, the fatigue strength of drill tem will decrease. The fatigue failure in casing drilling occurs more than normal drilling.(4) The drill stem reliability research considering clearanceThis article using clearance analysis and CAE technology studied the drill stem reliability, combining the domestic and foreign research aspect the achievement and based on this article research progress. Casing drilling reliability considering clearance and how to avoid casing and drill stem resonance point also was taken into account , because the clearance in normal drilling process are different from casing drilling process.更多还原