海相–陆相–油页岩的力学响应差异性研究

Differential Study on the Mechanical Response of Marine Shale, Continental Shale, and Oil Shale

摘要: 页岩的典型层理结构与矿物组分主导特性直接影响水力压裂与井壁稳定等关键工程的成效。通过对比分析不同荷载及层理取向条件下海相–陆相–油页岩的力学参数差异性，揭示了荷载垂直和平行层理状态下的三种页岩力学响应规律。结果表明：在单轴压缩条件下，海相页岩强度最高，较陆相页岩高23~147 MPa，陆相页岩较油页岩高28~49 MPa。海相页岩垂直层理的弹性模量较陆相页岩低，但平行层理的弹性模量远高于陆相页岩，而陆相页岩的弹性模量比油页岩高出10~27 GPa；在三轴压缩条件下，海相页岩的强度与弹性模量均显著优于力学性能相近的陆相页岩与油页岩，其抗压强度与弹性模量分别高出74~111 MPa与7~39 GPa；在巴西劈裂条件下，海相页岩抗拉强度同样最高，整体上较陆相页岩高0~11 MPa，而陆相页岩整体上较油页岩高0~5 MPa。该力学差异主要受控于页岩矿物组成与结构，即海相页岩中丰富的脆性矿物构成了高强度刚性骨架，而陆相页岩中高含量的黏土矿物和油页岩中丰富的有机质显著弱化了其力学性能。研究结果揭示了不同页岩储层的力学行为本质差异，为海相页岩、陆相页岩以及油页岩储层的差异化高效开发与压裂优化提供了理论依据。

Abstract: The typical bedding structures and dominant characteristics of mineral composition in shale directly influence the effectiveness of key engineering processes such as hydraulic fracturing and wellbore stability. Through a comparative analysis of the differences in mechanical parameters of marine, continental, and oil shales under varying loads and bedding orientations, three mechanical response patterns of shale under loads perpendicular and parallel to the bedding were revealed. The results indicate that under uniaxial compression, marine shale exhibits the highest strength, exceeding continental shale by 23~147 MPa, while continental shale surpasses oil shale by 28~49 MPa. The elastic modulus of marine shale perpendicular to the bedding is lower than that of continental shale, but its elastic modulus parallel to the bedding is significantly higher. In contrast, the elastic modulus of continental shale is 10~27 GPa higher than that of oil shale. Under triaxial compression, both the strength and elastic modulus of marine shale are significantly superior to those of continental and oil shales with similar mechanical properties, with compressive strength and elastic modulus exceeding them by 74~111 MPa and 7~39 GPa, respectively. Under Brazilian splitting conditions, marine shale also demonstrates the highest tensile strength, generally exceeding continental shale by 0~11 MPa, while continental shale surpasses oil shale by 0~5 MPa. These mechanical differences are primarily governed by the mineral composition and structure of the shales. Specifically, the abundance of brittle minerals in marine shale forms a high-strength rigid framework, whereas the high clay mineral content in continental shale and the rich organic matter in oil shale significantly weaken their mechanical properties. The findings reveal the fundamental differences in the mechanical behavior of various shale reservoirs, providing a theoretical basis for the differentiated and efficient development and fracturing optimization of marine, continental, and oil shale reservoirs.