共查询到19条相似文献,搜索用时 247 毫秒
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起下钻时的钻柱和液柱系统纵向振动过程分析 总被引:1,自引:0,他引:1
本文建立了钻柱、钻柱内液柱和环空液柱的系统纵向振动方程,分析了起下钻时波动压力和反压差的影响因素,阐明了井下钻柱所受载荷的变化与大钩载荷的变化具有相同规律,为井下工况的预测、井下事故原因分析及井眼轨道控制系统控制信号的确定提供理论依据。 相似文献
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基于软件GPS平台的高动态数字中频信号模拟与实现 总被引:1,自引:0,他引:1
在有限的实验条件下,为验证高动态软件GPS接收机信号的捕获和跟踪模型,提出了一种基于软件GPS接收平台的高动态GPS数字中频信号模拟方法.介绍了软件GPS接收平台的基本结构框架,并根据高动态环境下伪随机码的多普勒效应及本地振荡器的频率误差对接收信号的影响,推导并建立了一种较精确的高动态GPS数字中频信号模型.为使模型适用于更加复杂的环境,通过设置接收信号的噪声幅值来调整信噪比大小,以确定所需的信号强度;在信号参数的设置过程中调整入射信号与反射信号的幅度比值及反射信号的时间延迟参数,以模拟不同程度的多路径效应对中频信号的影响.仿真结果表明了该方法的有效性. 相似文献
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等曲率井中有重钻柱屈曲的非线性有限元分析 总被引:3,自引:0,他引:3
建立了等曲率井中有重钻柱屈曲的平衡方程及对应的泛函表达式,用有限元法对等曲率井
中有重钻柱屈曲过程进行了分析,给出了钻柱正弦屈曲和螺旋屈曲临界载荷的定义. 力学模
型中考虑了重力、钻柱上端井斜角和井眼轨迹曲率半径对屈曲的影响. 分析结果表明:载荷
增大时,钻柱的下端先出现局部屈曲,随后屈曲向钻柱上部扩展,导致钻柱发生整体屈曲,
屈曲位移、井壁约束力线密度和钻柱弯矩都呈周期性变化;重力对等曲率井中钻柱的屈曲有
较强的抑制作用,其影响不可忽略;井眼轨迹曲率半径越小,钻柱上端井斜角越大则对钻柱
屈曲的抑制作用越强. 相似文献
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通过对套铣筒这种特殊结构钻柱的分析,在现有钻柱力学模型研究的基础上,针对套铣筒结构特点(大筒径、薄壁筒型钻柱),建立套铣筒与井壁接触力学模型,通过分析套铣管柱在井下屈曲状态以及与井壁接触压力的计算,对套铣筒进行力学分析以及摩阻力计算. 相似文献
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基于物理中面概念和经典薄板理论,应用有限元法研究了机械工程中的二维传输结构作轴向运动时的面外自由振动特性.根据实际工程结构特点及设计要点,考虑受双向预张应力作用的传输薄板结构模型,由哈密顿原理出发严格导出了结构的有限元动力学方程,得到了体现轴向传输结构特性的陀螺矩阵.该矩阵具有反对称结构,这与加权余量法所得的陀螺矩阵结构不同.采用3节点三角形单元离散求解域,且单元不受轴向运动影响,给出了单元密度对计算结果精度的影响.分析了传输结构预张应力和轴向速度与自由振动固有频率的关系;考察了不同结构的陀螺矩阵对数值结果的影响.将部分结果与ANSYS软件模拟对比,显示出良好的一致性,证明了本文方法的有效性.研究结果可为典型传输带等结构的振动控制提供参考,建模方法可为ANSYS等计算软件添加轴向运动结构新模块提供理论依据. 相似文献
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通过对套铣筒这种特殊结构钻柱的分析,在现有钻柱力学模型研究的基础上,针对
套铣筒结构特点(大筒径、薄壁筒型钻柱),建立套铣筒与井壁接触力学模型,通过分析套铣
管柱在井下屈曲状态以及与井壁接触压力的计算,对套铣筒进行力学分析以及摩阻力计算. 相似文献
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Buckling of drill and tubing strings in drill or casing holes will affect the life of the string and cause difficulties in drilling and in oil production. A number of theoretical models have been developed to study the buckling load and the post-buckling configuration of the strings under some idealized conditions. However, verification of these theories in practice or in laboratory has not been extensively reported.In this paper work on laboratory buckling tests of strings is presented and the results are compared with theoretical formulas. The results indicate that the process of string buckling can be divided into two stages, namely plane buckling and spatial buckling. In the spatial buckling the string-buckling configuration can roughly be represented by a helix. The relation between the buckling force and the helical pitch, obtained from the laboratory tests, is similar to that predicted by helical buckling theories. The friction between the string and the wall of the confining tube causes a nonuniform buckling shape and prohibits further buckling at some critical loads. The buckling theories do not cover these effects and may thus induce significant errors in predicting the string-post-buckling configuration. An approximate formula for estimating the friction force is proposed, which provides more accurate results. Further studies of the friction effect are suggested. 相似文献
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本文提供了一种简单的确定性数值方法,来分析在平稳随机地震荷载作用下的结构随机地震响应及动力可靠度。该方法基于有限元动力分析软件,以单位加速度脉冲函数作为地震荷载的输入,当计算出结构的脉冲响应函数后,再运用傅立叶变换得到随机激励和结构响应之间的传递函数,由此来计算结构的均方根响应和峰值响应。基于此方法,分析了挡土结构物在平稳随机地震荷载作用下的位移、弯矩、基底水平合力、基底竖向合力以及沿墙高的土压力极值的随机地震响应及动力可靠度。从分析结果可以看出:用Kanai谱模型的计算值比欧进萍谱模型的计算值更趋保守,而把响应过程当作马尔可夫过程似比泊松过程更精确。 相似文献
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In the view of fluid-structure interactions and rotor dynamics, this paper models the lateral vibration of a vertical downward rotating elastic drill string conveying mud subjected to supporting stabilizers, bit torque and longitudinal thrust. The dynamic model involves the rotational inertia of the drill string tube cross section, the gyroscopic effect caused by rotation, the damping due to friction with the surrounding fluid, the gravity force and mud buoyancy. Damped natural frequency, stability and resonance of the drill string system are determined by quadratic eigenvalue problem and investigated at influences of the stabilizer, rotational angular speed, mud flowing velocity, bit torque and thrust. As a result, the drill string can lose stability both at simultaneous and separate influences of the mud conveying, bit torque and thrust, whereas the rotation, stabilizer and gravity of the drill string can improve system stability; the rotational angular speed causing system resonance decreases with the increase of the mud flowing velocity, bit torque and thrust. 相似文献
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刘延强 《应用数学和力学(英文版)》2000,21(11):1292-1299
IntroductionDrillstringismoreeasilydamagedsothataccidentinproductionoccursmoreofteninlateralhorizontalwellthaningeneralwellbecausethediameterofdrillstringissmallandthelargecomplementarydeflectionloadsondrillstringarisesbythewellboreofverylargecurvatu… 相似文献
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The problem of determining the critical states and the postbuckling deformation of drill strings in the cavities of curvilinear boreholes is posed. The process of elastic bending of the drill string is associated with the motion of its axial line along the corresponding channel surface. On the basis of the theory of flexible curvilinear rods, a specially chosen moving system of axes is used to construct nonlinear ordinary differential equations describing the contact interaction between the drill string tube and the borehole wall. Themoving reference system allows us to separate the desired variables and decrease the order of the resolving equations. As an example, we solve the problem of stability of drill strings lying at the bottom of a cylindrical cavity in a rectilinear inclined borehole. The critical values of the axial forces are determined and the buckling modes are constructed. It is also shown that they have the form of edge effects typical of singularly perturbed equations. The developedmethods can be used in design of a curvilinear borehole and its possible driving conditions to determine the admissible values of the axial force and the torque at the point of the drill string suspension so as to prevent its bifurcation buckling. 相似文献
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THREE-DIMENSIONALNONLINEARANALYSISOFDRILLSTRINGSTRUCTUREINANNUIUSLiuYan-qiang(刘延强)LuYing-min(吕英民)(DepartmentofEngineeringmech... 相似文献
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卡点预测是处理卡钻事故的关键。利用管柱扭转变形的特性,设计了无钻杆接头的单一管柱和有钻杆接头的组合管柱,并分别建立了卡点预测计算公式。利用管柱力学实验平台、四分量传感器、数据无线传输系统、HP数据采集系统和相关数据处理软件,对两种管柱进行了扭转实验。本次实验结果为:对于单一管柱,相对误差为-1.88%;对于组合管柱,当不考虑钻柱接头的影响时,相对误差为-3.8%,考虑钻柱接头的影响时,相对误差为-1.02%。实验结果表明:扭转法可用于直井中钻柱卡点预测,钻杆接头和钻柱加厚部分对卡点计算的影响较大,用带有修正系数的计算公式预测精度较高。 相似文献