机械式封隔器上压重与井口下放悬重关系研究

Analysis of Relationship between Load on Mechanical Packer and Lowering Hanging Load at the Wellhead

针对机械式封隔器坐封过程中,井口下放悬重与封隔器所受压重之间的力学关系开展系统研究。根据井口下放悬重以及钻具和井身结构尺寸,建立了油管柱螺旋屈曲的数学模型,由模型推导出油管柱与井壁之间的法向接触力以及摩阻力的数学模型,在此基础上根据管柱在井中的受力环境,建立了井口下放悬重载荷与井下封隔器所受压重作用力的计算力学和数学模型。采用VB2010平台开发了相应的计算软件,该软件已在四川某井上得到了应用。应用结果表明,封隔器上压重预测计算结果与现场实测数据非常接近,验证了建立的数学模型的可靠性和适用性。该项研究结果为机械式封隔器坐封力学安全性评价提供了理论依据。

To reveal the relation between the lowering hanging load at the wellhead and the corresponding load on mechanical packer during setting, a systematic study has been conducted. Based on the lowering hanging load at the wellhead and the dimension of drilling tool and wellbore configuration, a mathematical model of tubing string helical buckling is established, from which the mathematical models of the normal contact force and the frictional resistance between the tubing string and wellbore are derived. Then, the computational mechanics and mathematical model of lowering hanging load at the wellhead and the corresponding load on the packer are developed in respect to the force behaviors in the well. A software is developed based on VB2010 and has been applied at a well in Sichuan. The results show that the load on the packer calculated with the software matches closely with the site measurements, indicating the reliability and applicability of the mathematical model. The results of the study have provided theoretical basis for the safety evaluation of mechanical packer setting.