高煤级煤储层条件下的气体扩散机制  

Study of the gas diffusion mechanism in high-rank coal reservoirs

作　　者：张小东[1] 刘炎昊[1] 桑树勋[2] 刘浩[1] 

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454000 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《中国矿业大学学报》2011年第1期43-48,共6页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(40602017);国家重点基础研究发展计划(973)项目(2006CB202204);河南理工大学博士基金项目(6485l3)

摘　　要：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.For studying on the gas diffusivity properties under the processing of coalbed methane（CBM） recovery in high rank coal reservoir,the pore shapes of coal samples with different ranks have been observed under scanning electron microscopy（SEM）,and the pore structure parameters tested by mercury intrusion porosimetry（MIP）.Using the Qinshui basin as an example,the change in gas diffusion models is discussed at different stages of CBM recovery in anthracite reservoir based on the kinetic theory and diffusion theory of gas molecular.The result shows that the gas diffusion model dynamically changes in CBM recovery.At the same stage of CBM recovery,the gas diffusion models are different within the pores having identical pore diameters because of the pressure drop,and at different stages,different diffusion models run within the same pore.For the high rank coal reservoir,Knudsen diffusion runs very weak,transitional diffusion spreads as the whole recovery proceeds,but Fick diffusion mainly appears in initial recovery in CBM wells or may run in the area far from CBM wells in the end of gas recovery.

关 键 词：高煤级煤储层 沁水盆地 孔隙结构 扩散模式 动态演化 

分 类 号：P618.11[天文地球—矿床学]