Guizhou depression has experienced three stages of tectonic evolution, i.e., the early Proto-Tethys rift basin and the late orogenic fold,ancient Tethys rift basin stage,and the Neo-Tethys oroganic transformation phase.With the large-scale transgression in the early Devonian,there developed platform sag and slope fades dark shale and coal-bearing coast swamp fades framework in this area,which mainly included Lower Devonian Tangding Formation black shale,Middle Devonian Luofu Formation black shale and lower Carboniferous Yanguan Formation black shale.Researches have shown that the upper Paleozoic marine shale,characterized by high abundance of organic matter,good types and high-over- mature stage of evolution,has favorable conditions for shale gas.Up to date,Upper Paleozoic shale has been found in many gas shows in Guizhong depression,which has similar geological condition to typical shale gas basins in eastern United States (Appalachian,Ford Voss and Michigan basin). According to the analogy method,the amount of Upper Paleozoic shale gas resources is preliminarily estimated to be about 12.34x 1012m3 in the depression, which indicates that the area had huge shale gas resource potential.%桂中坳陷经历了原特提斯早期裂陷成盆、晚期褶皱造山,古特提斯阶段再度裂陷成盆与新特提斯阶段造山改造3个盆地世代的构造演化过程.自早泥盆世开始的大规模海侵作用,使得本区堆积了从台沟相到斜坡相沉积的深色泥页岩、到滨海沼泽相的含煤建造,主要分布下泥盆统塘丁组、中泥盆统罗富组和下石炭统岩关组3套黑色泥页岩.研究表明,本区上古生界海相页岩有机质丰度高、类型好、处于高-过成熟演化阶段,具有页岩气形成与富集的有利地质条件,是南方页岩气探采值得关注的重点区域.目前已在该坳陷上古生界页岩中发现了较多气显示,具有与美国东部典型页岩气盆地(阿巴拉契亚、福特沃斯、密执安等盆地)相似的地质条件;经采用类比法预测初步估算,全坳陷上古生界页岩气资源量约为12.34×1012m3,表明该区具有巨大的页岩气资源潜力.
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