School of Mechanical & Civil Engineering, China University of Mining and Technology, D11 Xueyuan Road, Beijing, 100083, China.
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology at Beijing, Beijing, 100083, China.
Sci Rep. 2023 Jun 27;13(1):10421. doi: 10.1038/s41598-023-35398-9.
The influence and mechanism of porous structure on the deformation failure of cement sheaths under hydraulic pressure is still unclear. To solve this problem, a net slurry cement sheath and a liquid silicon cement sheath were prepared by using a cement material and a liquid silicon suspension. The distributions of the pore radius and spatial location were analyzed using computed tomography scanning and statistics to obtain their probability density distribution functions. Based on the distribution functions, the single-layer and double-layer porous reconstruction models of the net slurry cement sheath and liquid silicon cement sheath were constructed using a FLAC 3D program. A series of numerical simulations were conducted to study the deformation failure of the cement sheaths under in situ stress and hydraulic pressure. The effects of the porous and double-layer structures on the breakdown pressure, plastic failure zone, radial deformation, and stress distribution of the cement sheaths were analyzed. As a result, the mechanisms for the influence of the porous and double-layer structures on the failure mode, failure path, and interaction between the cement sheath and metal casing were revealed. The results of this research provide a theoretical basis for an in-depth understanding of the failure mechanisms of porous cement sheaths.
多孔结构对水压作用下水泥环变形破坏的影响及作用机制仍不明确。为解决这一问题，采用水泥材料和硅溶胶悬浮液分别制备了网络浆液水泥环和液体硅水泥环，利用计算机断层扫描和统计学分析手段对孔隙半径及其空间位置分布进行分析，得到其概率密度分布函数。基于分布函数，采用 FLAC 3D 程序分别构建了网络浆液水泥环和液体硅水泥环的单层和双层多孔重构模型，通过一系列数值模拟研究了水泥环在原地应力和水压作用下的变形破坏情况，分析了多孔和双层结构对水泥环破裂压力、塑性破坏区、径向变形以及应力分布的影响。揭示了多孔和双层结构对水泥环破坏模式、破坏路径以及水泥环与套管相互作用的影响机制。研究结果为深入认识多孔水泥环的破坏机理提供了理论依据。
