Analysis of the Mechanical Anisotropic Properties of Shale
Shale is an important rock in oil and gas exploration and development. Its mechanical properties directly affect the safety and efficiency of oil and gas extraction. Due to the special internal structure, complex mineral composition and bedding structure of shale, the relationship between different stress directions and the bedding plane significantly influences its mechanical behavior. Therefore, this study aims to explore this influence law. In the research, shale specimens with different bedding angles were designed. Through uniaxial compression tests, the relationships between stress changes and deformation of the specimens, the ability to resist elastic deformation, and the maximum bearing strength under unidirectional pressure were analyzed. The results show that the stress - deformation changes of all specimens went through four stages: initial pore closure, elastic deformation, yield stage approaching the ultimate strength, and final failure stage. The ability to resist elastic deformation shows a "V - shaped" pattern of first decreasing and then increasing with the increase of the bedding angle, and it is the strongest when the bedding angle is 90°. The maximum bearing strength under unidirectional pressure shows a "U - shaped" pattern. The strength is the highest when the bedding angle is 0° and 90°, and the lowest when it is 60°. The maximum value is approximately six times the minimum value. This study indicates that there are significant differences in the mechanical properties of shale in different directions. This variance is related to the bedding structure of shale, the distribution of internal minerals, and the development of micro - fractures. The research findings can provide a reference for engineering practices such as ensuring the stability of the drilling wellbore and reservoir stimulation during the process of oil and gas extraction.
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