鄂尔多斯盆地东部下二叠统太原组天然气的生成与储集

NATURAL GAS GENERATION AND RESERVE IN TAIYUAN GROUP OF LOWER PERMIAN IN EAST OF ORDOS BASIN

鄂尔多斯盆地东部地区太原组广泛发育的气源岩为生物灰岩、暗色泥岩和煤。这3套气源岩有机质类型以腐殖-腐泥型和腐殖型为主并具有较高的有机碳含量和热演化程度,生气能力强,为太原组气藏的形成提供了充足的气源。该区北部的浅水三角洲砂体和南部的灰岩为天然气的储集提供了有利的场所,并与同组的三角洲平原分流河道洼地、沼泽相泥质岩共同构成了太原组气藏的自生自储型顶盖式组合。受沉积相以及构造区带的控制,在该区中部及西部可形成较大规模的岩性圈闭气藏,而在南部、北部以及东缘应寻找以小型背斜圈闭为主的气藏。

There are some kinds of gas source rocks, i.e. biologic limestone, black mudstone and coal in Taiyuan group of lower Permian in east part of Ordos basin. In there three gas source rocks, organic substance being mainly composed of humic material-sapropel and humic material have high organic carbon content, high extent of thermal evolvement and high potential of generating gas. It provides enough gas for forming of gas reservoir in Taiyuan group. The sandstone in north and limestone in south being the major places where gas accumulate, plus billabong in deltaic plain separating river channel and mudstone in swamps environment together constitutes the combination of self generation-self reserve-upper caprocks. Under control of sedimentary facies and trip of geologic conformation, we can find some massive lithologic trap in middle and westward of research area, meanwhile, we should also focus on finding small anticlinal trap in south, north and east of research area.