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民和盆地构造位置处于祁连山褶皱系东部，是一个中新生代发展起来的断、坳山间盆地。盆地中西部中侏罗统窑街组蕴藏着丰富的煤炭资源，煤层气局部富集于窑街、炭山岭煤田。煤岩有机地球化学及煤层甲烷碳同位素研究表明，该区煤层气具有油型与煤型混合气特征。煤层气分布具有明显的分带现象，由浅到深分别为ＣＯ２—Ｎ２带、Ｎ２带、Ｎ２—ＣＨ４带、ＣＨ４带。煤层气富集主要受煤的变质程度，顶、底板岩性，出露程度，埋藏深度及构造等因素的控制，且多分布于背斜、断块等构造的高部位。

COAL SEAM GAS CHARACTERISTICS AND GEOLOGICAL CONDITIONS IN MINHE BASIN

Located in the east part of Qilian Mountain fold Series,Minhe Basin is a rift downwarp intermont basin developed in Mesozic Cenozoic era.Coal resources are very rich in Yaojie formation of Middle Jurassic Series in the middle west part of the Basin,and the coal seam gas partially enriches in Yaojie and Tanshanling coal fields.Through studying the coal rock organic geochemistry and coalbed methane carbon isotope,it is indicated that the coal seam gas in the area has the characteristics combined oil type gas and coal type gas.The contents of coal seam gas distributions are mainly CO 2 N 2,N 2,N 2 CH 4 and CH 4 from shallow to deep.The enrichment of coal seam gas is mainly controlled by coal metamorphic degree,coal roof and floor lithologies,exposure degree,buried depth,structures etc.,and the coal seam gas is mostly distributed in the top of anticlines and fault blocks.