论文部分内容阅读
为了研究高煤级煤储层煤层气排采中气体的扩散行为,采用扫描电镜和压汞法对不同煤级煤的孔隙进行了观测和测试.根据气体分子运动理论和扩散理论,探讨了沁水盆地无烟煤储层煤层气排采的不同阶段气体扩散模式的动态演化.研究表明,煤层气排采过程中,孔隙内气体的扩散模式是动态变化的:相同排采阶段,同一孔径范围内的孔隙的扩散方式因压降不同而存在差异.不同排采阶段,同一孔隙可能会经历不同的气体扩散模式.对于无烟煤储层,Knudsen型扩散很弱,过渡型扩散贯穿于排采的整个过程.Fick型扩散主要发生排采初期,在排采末期主要出现在距离井筒较远地段.
In order to study the diffusion behavior of gas in coalbed methane discharge in high coal rank coal reservoirs, the pores of coal with different coal rank were observed and tested by scanning electron microscopy and mercury intrusion method.According to gas molecular motion theory and diffusion theory, The dynamic evolution of gas diffusion patterns during different stages of coalbed methane drainage in anthracite reservoir is studied.The results show that the gas diffusion patterns in the pores are dynamically changing during the process of coalbed methane drainage: in the same drainage stage, in the same pore size The pore diffusion varies with different pressure drops.The same pore may experience different gas diffusion modes in different drainage stages.For the anthracite reservoir, the Knudsen type diffusion is very weak, and the transitional diffusion runs through the whole process of drainage. Fick-type diffusion occurs mainly in the early stage of discharge, which occurs mainly in the long distance from wellbore at the end of discharge.