页岩气水平井压裂工况下水泥环力学特性的研究

Research on Mechanical Characteristics of Cement Ring under Fracturing Conditions of Shale Gas

摘要: 本文主要目的是探究在页岩气水平井压裂过程中的水泥环的物理性质。我们利用有限元建模技术来精确划分子单元格并设置约束条件，以深入了解射孔孔径、密度、方向角度及相位角等因素如何影响水泥环的压力状态。此外，我们也考察了分段压裂期间射孔段水泥环内的温度和压力的变化情况，同时还研究了套管内压、孔径和孔密度对水泥环封闭效果的影响模式。我们的实验表明，射孔参数的调整会对水泥环的压力分布产生重大影响，进而影响到井壁的安全性。当考虑到瞬间的热力和机械相互作用时，水泥环孔口处的失效概率会有所增加。虽然孔径和孔密度的变动对水泥环的剪切应力的影响相对较小，但这些结论为实际操作提供有价值的理论参考，有利于提升压裂设计的质量和增强井筒的安全性能。结论和建议部分总结了研究的主要发现，并提出了未来研究方向。

Abstract: The main purpose of this article is to explore the physical properties of cement sheath during the fracturing process of shale gas horizontal wells. We utilize finite element modeling technology to precisely divide sub-cells and set constraint conditions, aiming to gain a deep understanding of how factors such as perforation diameter, density, direction angle, and phase angle affect the pressure state of the cement sheath. Additionally, we investigate the changes in temperature and pressure within the cement sheath of perforated sections during staged fracturing. Furthermore, we examine the patterns of influence on the sealing effect of the cement sheath caused by changes in the internal pressure of the casing, aperture, and hole density. Our experiments indicate that adjustments to perforation parameters have a significant impact on the pressure distribution of the cement sheath, further affecting the safety of the wellbore. When considering the instantaneous thermal and mechanical interactions, the failure probability at the orifice of the cement sheath increases. Although variations in aperture and hole density have a relatively minor influence on the shear stress of the cement sheath, these conclusions provide valuable theoretical references for practical operations, contributing to improving the quality of fracturing designs and enhancing the safety performance of wellbores. The conclusion and recommendations section summarizes the key findings of the study and proposes directions for future research.