Mechanical Properties of Different Lithological Rocks: A Case Study of the Coal Measure Strata in the Eastern Margin of Ordos Basin, China

In this paper, the mechanical behaviors of different lithological rocks of coal measure strata from Shanxi Formation in the eastern margin of the Ordos Basin, China, were investigated through uniaxial compression tests, and the deformation characteristics and failure modes of different lithological rocks were investigated. On this basis, the energy evolution of different lithology rocks was also discussed. The results show that there are obvious differences in the mechanical properties of different lithology rocks in coal measure strata, resulting in different wellbore instability prevention measures and fracturing measures in different lithology strata. Under the uniaxial compression condition, the peak strain of different lithological rocks is obviously different, and the denaturation characteristics are also obviously different, and the failure modes of rocks are mainly the tensile fracture mode, suggesting that the rock samples have strong brittle characteristics. With the increase of the strain, the total energy of different lithological rocks of the coal measure strata increases, and the elastic energy first increases and then decreases rapidly, whereas the dissipated energy first increases slowly and then increases rapidly. Each energy at the peak point is different, and the average total energy of shale, silty shale, siltstone, fine sandstone, and coal is 0.022 J/cm(3), 0.045 J/cm(3), 0.052 J/cm(3), 0.042 J/cm(3), and 0.003 J/cm(3), respectively, indicating that there are obvious differences in the energy evolution laws of the different lithological rocks.

Automated summary

In this study, the mechanical behaviors and energy evolution of different lithological rocks in the coal measure strata of the Shanxi Formation in the eastern margin of the Ordos Basin, China, were investigated. The results showed significant differences in the mechanical properties and failure modes of the rocks, as well as variations in their energy evolution. This study provides insights for wellbore stability prevention and fracturing measures in different lithology strata.