遇油膨胀封隔器与地层的适应性研究

Research on the Adaptability of the Oil-Swelling Packer to Formation

针对提出的封隔器密封性判据及结构设计方法,在对遇油膨胀封隔器胶筒在井下的接触压力及应力分布进行有限元计算分析的基础上,对该封隔器与地层的适应性进行了研究。研究结果表明,不同地层模型的胶筒最大安全下方压力与地层岩性的弹性模量成正比;泥岩、页岩和砂岩3种地层模型中的胶筒最大应力均低于胶筒的压缩永久变形强度,说明胶筒不会产生应力损坏;井壁地层岩石在井下三轴应力作用下的最大剪应力随胶筒接触压力的增大而线性增大,不同岩性地层下最大地层剪应力随封隔器接触压力的增大速率和地层的弹性模量成正比,地层剪应力的最大值处于地层岩石的45°方向上,最小值分布于其垂直方向上。

In light of the formulated sealing criterion of the packer and the design method of its structure, the a- daptability of the packer to formation was studied on the basis of the finite element calculation and analysis of the downhole contact pressure and stress distribution of the oil-swelling packer rubber. The findings show that the maxi- mum safety inferior pressure of the rubber of different formation models is directly proportional to the elastic modulus of formation ]ithology. The maximum stress of the rubber of the three formation models of mudstone, shale and sandstone is lower than the compression permanent deformation strength of the rubber, which shows that the rubber will not produce any stress damage. The maximum shear stress of the sidewall formation rock under the effect of downhole triaxial stress increases linearly with the increase of the rubber contact pressure. The maximum formation shear stress of different lithologic formations increases with the packer contact pressure, whose increase rate is di- rectly proportional to the elastic modulus of formation. The maximum value of formation shear stress appears at 45°of formation rock and the minimum value is at the vertical direction.