Chen Naihan, Dong Xuelin, Ma Yinji
Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing 102249, China.
AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
Polymers (Basel). 2022 Feb 21;14(4):836. doi: 10.3390/polym14040836.
Packers based on shape memory polymers (SMPs) are an emerging technology that have the advantages of compact structure, easy manufacture, and adaptability to complex wells. This paper proposes a finite element model to simulate the setting process and mechanical response of an SMP packer. The investigated material is an epoxy-based thermal responsive SMP, whose relaxation modulus and thermal expansion coefficient were measured at different temperatures. Based on the experimental data, the model describes the viscoelastic behavior of the SMP using the generalized Maxwell model. The results show that the SMP packer could provide sufficient contact stress under downhole conditions, even after the stress was relaxed. A further parametric study revealed that the most significant factor in sealing effects is the wellbore pressure, followed by the interference between the packer and the annular, the seal length, the pre-compression, and the setting temperature. High downhole pressures require more significant contact stress and increase the risk of slip between the packer and casing wall by promoting shear stress. Increasing the seal length and interference enhances the contact stress and mitigates the shear stress to improve the seal performance. Pre-compression and setting temperatures are minor factors that have little influence on sealability.
基于形状记忆聚合物（SMP）的封隔器是一种新兴技术，具有结构紧凑、易于制造以及适用于复杂油井等优点。本文提出了一个有限元模型，用于模拟SMP封隔器的坐封过程和力学响应。所研究的材料是一种环氧基热响应SMP，其松弛模量和热膨胀系数在不同温度下进行了测量。基于实验数据，该模型使用广义麦克斯韦模型描述了SMP的粘弹性行为。结果表明，即使在应力松弛后，SMP封隔器在井下条件下仍能提供足够的接触应力。进一步的参数研究表明，影响密封效果的最重要因素是井筒压力，其次是封隔器与环空之间的干涉、密封长度、预压缩和坐封温度。高井下压力需要更大的接触应力，并通过增加剪应力增加封隔器与套管壁之间滑动的风险。增加密封长度和干涉可增强接触应力并减轻剪应力，从而提高密封性能。预压缩和坐封温度是对密封性影响较小的因素。
