含CH_4煤岩注CO_2后力学性能及渗透性能试验研究

Research on mechanical properties and permeability of gas-containing coal injected with CO_2

为观察含CH_4煤岩注入CO_2后力学和渗透性能的变化,用自制三轴吸附解吸渗流试验装置开展试验,研究型煤试件内气体种类和注气压力对注CO_2煤岩强度、渗透性和应变等参数变化的影响。试验结果表明:含CH_4煤岩注入CO_2后,单轴压缩应力-应变曲线与未注入CO_2的总体变化趋势相同,但煤岩强度等参数随注气压力的变化而变化。注入等孔隙压CO_2后,含CH_4煤岩的强度和弹性模量均明显上升,但煤岩中CH_4渗透率呈现下降趋势;随着CO_2注入压力的增加,煤样的强度和弹性模量逐渐下降,而CH_4渗透率逐渐增强,注气压力每增加1 MPa,煤岩强度平均下降0.095MPa,CH_4气体渗透率平均增加1 m D。

For the sake of observing changes caused by CO_2 injection in mechanical properties and permeability of gas-containing coal,experiments were carried out by using a self-developed triaxial absorption and desorption seepage device,effects of composition of gases in briquettes and injection pressure on the coal strength,permeability,strain and other parameters were studied. The results show that after carbon dioxide injected in the coal containing gas,the stress and strain curve of the coal follows the same trend as the curve of the coal only containing gas under uniaxial compression,but the strength of the coal is a function of the injection pressure,that with carbon dioxide injected under the same pore pressure,the strength and elasticity modulus of the coal increase obviously,but the permeability rate of the methane in the coal decrease,that with injection pressure increasing,the strength and elasticity of the coal decrease,and the permeability rate rising,and that as the pressure increases by 1 MPa,the average intensity declines by0. 095 MPa,and the average permeability increases by 1 m D.