To study the evolution of physical properties of coal reservoirs with depth, both uniaxial and triaxial compression tests with acoustic emission monitoring were carried out on the coal reservoir at a depth of 2 000 m, and the confining pressure effects on the mechanical properties and acoustic emission characteristics of the coal reservoir under high confining pressure were quantitatively analyzed. The results show that although the peak strength of coal reservoirs is highly discrete, it still shows a strong positive correlation with confining pressure. The elastic modulus of coal reservoirs increases very slowly with the increase of confining pressure. The confining pressure ranges from 0 MPa to 50 MPa, and the average elastic modulus only increases by 2 GPa. As the confining pressure increases, the dispersion of modulus gradually decreases. The quiet period of acoustic emission of the coal reservoirs in the high confining pressure increases significantly compared with that of low confining pressure, Which shows that the confining pressure has an inhibitory effect on the crack propagation and destruction of coal reservoir. With the increase of the confining pressure, the accumulative acoustic emission count and accumulative released energy both increase, the high-amplitude events are significantly reduced, and the smaller-amplitude events run through the entire deformation and failure process of the sample. Parabola Mohr Coulomb strength criterion is more suitable for describing the variation of peak strength of coal reservoir under high confining pressure. The research results can provide theoretical guidance for coalbed methane exploitation and fracturing in deep coal measures reservoir with natural fractures.
|Translated title of the contribution||Effects of confining pressure on mechanical responses and acoustic characteristics of coal gas seams deeper than 2 000 m|
|Original language||Chinese (Traditional)|
|Number of pages||11|
|Journal||Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology)|
|Publication status||Published - 26 Aug 2021|