水平井双封隔器管柱力学分析

水力压缩式封隔器在坐封时会使管柱产生轴向应力,严重时会影响管柱的强度。以水平井双封隔器管柱为研究对象,考虑2个封隔器分别坐封时井口压力的大小,基于拉梅公式、广义胡克定律和杆件变形理论,推导了在井口压力的作用下管柱的轴向力、轴向应力及变形量计算公式。计算结果表明,当封隔器Ⅰ、Ⅱ先后以10 MPa和15 MPa井口压力坐封时,封隔器Ⅰ、Ⅱ之间的管柱轴向应力由49.94 MPa降低为15.08 MPa,而弯曲段到封隔器Ⅱ之间的管柱轴向应力由58.05 MPa 增加到107.96 MPa。由此可知,后坐封的封隔器会使其到弯曲段的管柱轴向应力增加,而使其到先坐封封隔器的管柱轴向应力降低,所以管柱的危险截面出现在后坐封的封隔器到弯曲段之间。

Mechanical Analysis of Double-packer String in a Horizontal Well

Axial stress of the string will be generated when the hydraulic compression packer is seated,which may affect the safety of the string.To address the issue,the double-packer string in a horizontal well is taken as the object.Considering the size of the wellhead pressure when the two packers are seated separately,on the basis of Lame formula,generalized Hooke's law and bar deformation theory,the equations for calculating the axial force,axial stress and deformation of the string under the action of wellhead pressure are deduced.The results show that,when the packers Ⅰ and Ⅱ have been sealed at 10 MPa and 15 MPa wellhead pressure,the axial stress of the string between the packers Ⅰ and Ⅱ is reduced from 49.94 MPa to 15.08 MPa,and the axial stress of the string between the bending section and the packer Ⅱ is increased from 58.05 MPa to 107.96 MPa.It can be seen that,the latter packer increases the axial stress of the string between the packer and the bending section when it is seated and causes the axial stress of the string between the first packer and the latter packer to be reduced.Therefore,the dangerous point locates between the final sealed packer and the curved section of the string.