为选择合适的气体作为主动测压法测定钻孔煤层瓦斯压力中的补偿气体,从煤对CH4、CO2和N2的吸附性研究入手,证实了煤层对CH4和N2的吸附-解吸是可逆的,而对CO2的吸附解吸是不可逆的,并分析了CO2作为补偿气体对CH4的吸附-解吸平衡产生的影响,最终提出了N2更适合作为补偿气体。通过现场实践表明:CO2作为补偿气体测得的瓦斯压力存在一定的误差,误差可达0.05～0.20 MPa,而N2作为补偿气体时误差较小,能够较准确测得煤层原始瓦斯压力。

In order to select suitable gas for the active pressure measuring method to measure the compensation gas in the gas pressure of the borehole seam, fro m the study on the Absorbability of CH4, CO2 and N2 to the seam, the adsorption-desorption of CH4 and N2 to the seam was reversible and the adsorption-desorption of CO2 was irreversible. The paper analyzed that the CO2 as the compensation gas would influence the adsorption-desorption balance of the CH4.Finally, N2 was provi ded as the suitable gas as the compensation gas.The site practices showed that there was a certain error existed in the gas pressure measured with the CO2 as the Co mpensation gas and the error could be at 0.050 .20 MPa. When N2 as the compensation gas, the error is much smaller and the seam in-situ gas pressure could be accur ately measured.

国家自然科学基金重点资助项目(50834005)；国际科技合作资助项目(2008DFB70100)；