中文摘要：

沁水盆地石炭-二叠系煤岩中具有丰富的煤层气资源,测井显示煤岩顶板致密砂岩中亦赋存天然气。从沁水盆地煤岩生烃演化史入手,分析了煤岩顶板致密砂岩游离气的充注过程,探讨了游离气从煤岩到顶板砂岩的运移机理。煤岩为顶部砂岩提供气源,在浓度差的控制下,扩散是游离气运移的主要方式;煤岩生气关键时刻亦为砂岩气充注关键时刻,生烃增压作用为渗流提供了必要的压力差和微裂隙通道;当扩散和渗流同时产生时,孔隙大小的变化可使这两种运移方式相互转化。

英文摘要：

The Carboniferous and Permian coal rocks in Qinshui basin are rich in coalbed methane resources,and logging results show the occurrence of natural gas in tight sandstone on coal rock roof.Starting from the hydrocarbon generation evolution of coal rock,this paper discussed the filling process and migration mechanism of tight sandstone free gas on coal rock roof.Under the control of the cencentration difference,diffusion is the main way of free gas migration when the coal rocks provide the source of gas for the top sandstone.At the critical moment of hydrocarbon generation,which is also the critical moment of sandstone gas filling,seepage plays an important role in free gas migration,owing to the necessary pressure difference and micro-cracks migration channel produced by the hydrocarbongenerating pressurization.When diffusion and seepage occur at the same time,the change of the pore size can make the mutual transformation between those two kinds of migration methods.