Tian Qizhong, Yang Lianzhi, Zhang Jie, Xing Zhenzhong
Institute of Ocean Engineering and Technology, Ocean College, Zhejiang University, Zhoushan 316021, China.
Petroleum Engineering Technology Research Institute, Sinopec Shengli Oilfield Company, Dongying 257001, China.
Polymers (Basel). 2024 Sep 9;16(17):2543. doi: 10.3390/polym16172543.
During the cyclic injection and extraction process in underground storage wellbores, the cement sheath undergoes loading and unloading stress cycles. In this study, we investigated the mechanical properties of latex-modified cement stone (LMCS), widely used in oil and gas wells, through uniaxial and triaxial cyclic loading and unloading tests. The aim of the study was to determine the effect of various loading conditions on the compressive strength and stress-strain behavior of LMCS. The results show that the stress-strain curve of LMCS exhibits a hysteresis loop phenomenon, with the loop intervals decreasing throughout the entire cyclic loading and unloading process. As the number of cycles increases, the cumulative plastic strain of the LMCS increases approximately linearly. Under uniaxial cyclic loading and unloading conditions, the elastic modulus tends to stabilize. However, under triaxial conditions, the elastic modulus increases continuously as the number of cycles increases. This result provides data for engineering predictions. Furthermore, a comparison of the uniaxial and triaxial cyclic loading and unloading of LMCS shows that its cumulative plastic strain develops rapidly under uniaxial conditions, while the elastic modulus is larger under triaxial conditions. These findings provide a valuable reference for constructing underground storage wellbores.
在地下储存井筒的循环注入和采出过程中，水泥环会经历加载和卸载应力循环。在本研究中，我们通过单轴和三轴循环加载与卸载试验，研究了广泛应用于油气井的乳胶改性水泥石（LMCS）的力学性能。该研究的目的是确定各种加载条件对LMCS抗压强度和应力 - 应变行为的影响。结果表明，LMCS的应力 - 应变曲线呈现出滞后回线现象，在整个循环加载和卸载过程中回线区间逐渐减小。随着循环次数的增加，LMCS的累积塑性应变近似线性增加。在单轴循环加载和卸载条件下，弹性模量趋于稳定。然而，在三轴条件下，弹性模量随着循环次数的增加而持续增大。这一结果为工程预测提供了数据。此外，对LMCS单轴和三轴循环加载与卸载的比较表明，其累积塑性应变在单轴条件下发展迅速，而弹性模量在三轴条件下更大。这些发现为地下储存井筒的建设提供了有价值的参考。
