To counter the strength problem of drill string in well of large curvature and small diameter, well axis was taken as datum mis. Based on description of deflection of well an's and on analysis of three dimensional...To counter the strength problem of drill string in well of large curvature and small diameter, well axis was taken as datum mis. Based on description of deflection of well an's and on analysis of three dimensional forces of a small section of drill string, equilibrium differential equations of large deflection drill string were established. The internal forces were found by Longe-Kutta method. The stresses were found by using them and the strength prerequisite was established. Stresses of drill string in lateral horizontal well H767 were computed. The results are in agreement with those of finite element model and soft-rope rigidified model. But the method is simpler for computation than finite element model and is more perfect than soft-rope rigidified model. Curvature of the well is too large and there is stress concentration so that the fraction accident of drill string occurs.展开更多
在CO_(2)捕集、利用与封存(CCUS)工程中,环空带压现象常被归因于封隔器密封失效,但试压验证表明其密封性完好。本文提出该现象源于CO_(2)注入过程中温压相态耦合诱发的附加应力累积,导致封隔器等效轴向载荷超过解封极限。基于流体力学...在CO_(2)捕集、利用与封存(CCUS)工程中,环空带压现象常被归因于封隔器密封失效,但试压验证表明其密封性完好。本文提出该现象源于CO_(2)注入过程中温压相态耦合诱发的附加应力累积,导致封隔器等效轴向载荷超过解封极限。基于流体力学中的质量守恒定律、能量守恒定律和动量定理,结合EXP-RK相态方程,构建了温压—相态—应力多场耦合模型,系统量化了注入温度、注入压力、注入量及注入时间对井筒应力场的协同影响。通过长庆油田某注入井实测数据验证,模型预测井底压力误差为2.83%、温度误差为1.75%,显著优于传统单场模型。研究表明:(1)注入温度与注入量是相态演化主控因素,液态—超临界态转化界面随注入温度降低和注入量的增加显著下降;(2)注入温度、注入压力与注入量通过温度效应、鼓胀效应和摩阻效应主导封隔器应力累积。临界阈值分析表明:在其余两个参数保持恒定的条件下,当目标区块注入温度≤6.5℃、注入压力≥18.06 MPa或注入量≥2.61 t/h时,等效载荷超过解封极限(60 k N),触发解封行为。展开更多
文摘To counter the strength problem of drill string in well of large curvature and small diameter, well axis was taken as datum mis. Based on description of deflection of well an's and on analysis of three dimensional forces of a small section of drill string, equilibrium differential equations of large deflection drill string were established. The internal forces were found by Longe-Kutta method. The stresses were found by using them and the strength prerequisite was established. Stresses of drill string in lateral horizontal well H767 were computed. The results are in agreement with those of finite element model and soft-rope rigidified model. But the method is simpler for computation than finite element model and is more perfect than soft-rope rigidified model. Curvature of the well is too large and there is stress concentration so that the fraction accident of drill string occurs.
文摘在CO_(2)捕集、利用与封存(CCUS)工程中,环空带压现象常被归因于封隔器密封失效,但试压验证表明其密封性完好。本文提出该现象源于CO_(2)注入过程中温压相态耦合诱发的附加应力累积,导致封隔器等效轴向载荷超过解封极限。基于流体力学中的质量守恒定律、能量守恒定律和动量定理,结合EXP-RK相态方程,构建了温压—相态—应力多场耦合模型,系统量化了注入温度、注入压力、注入量及注入时间对井筒应力场的协同影响。通过长庆油田某注入井实测数据验证,模型预测井底压力误差为2.83%、温度误差为1.75%,显著优于传统单场模型。研究表明:(1)注入温度与注入量是相态演化主控因素,液态—超临界态转化界面随注入温度降低和注入量的增加显著下降;(2)注入温度、注入压力与注入量通过温度效应、鼓胀效应和摩阻效应主导封隔器应力累积。临界阈值分析表明:在其余两个参数保持恒定的条件下,当目标区块注入温度≤6.5℃、注入压力≥18.06 MPa或注入量≥2.61 t/h时,等效载荷超过解封极限(60 k N),触发解封行为。
