Variations in the physical and mechanical properties of rocks from different depths in the Songliao Basin under uniaxial compression conditions

With the development of deep energy resources, understanding variations in the physical and mechanical properties of rocks at different depths is significant. In this paper, core samples from ten different burial depths (1000 m, 1300 m, 1600 m, 1850 m, 2600 m, 3500 m, 4800 m, 5100 m, 5600 m, and 6400 m) were collected from the Songke No. 2 (SK-2) well and the Daqing Oilfield. To the best of our knowledge, this is the first study involving the physical property and uniaxial compression testing of rock cores from such a large range of burial depths. The experimental results show that the content of weak phase minerals decreases with increasing depth. The change in the hard phase minerals varies nonlinearly with depth. From 3500 to 5600 m, the content of hard phase minerals decreases, while the content of the middle phase minerals increases. The elastic modulus exponentially increases with increasing depth, while Poisson’s ratio decreases with increasing depth. Additionally, the uniaxial compressive strength displays a nonlinear logarithmic increase with increasing depth. Finally, the effects of petrophysical properties on the mechanical behavior of rock at different depths are discussed. The elastic modulus, Poisson’s ratio, and compressive strength all have a negative correlation with the content of weak phase minerals. These results have important value for studying the mechanics of rocks at different depths.