梅河盆地油页岩特征及成因

梅河盆地为古近纪富含油页岩的小型断陷盆地。岩芯观察、薄片鉴定、有机碳、热解和工业分析等测试分析表明,梅河盆地发育高灰分中含油率型油页岩,油页岩中有机质处于未熟状态;黏土矿物以高岭石和伊利石为主,富含石英等稳定组分,U、Mo等元素较为富集,轻重稀土分异程度高。油页岩突变沉积于煤层之上,且上覆深灰色泥岩,表明其形成于半深湖-深湖环境;Sr/Ba比值和伽马蜡烷含量较低、V/(V+Ni)0.5,表明油页岩形成于缺氧的淡水中。油页岩中有机质来源较为复杂,黑色油页岩有机质丰度含量较高,以高等植物来源为主,油页岩产油率(含油率/TOC)较低;褐色油页岩TOC相对较低,有机质以湖泊生物为主,具有较高的产油率。

Characteristics and origin of oil shale in Meihe Basin

Meihe Basin is a small Paleogene fault-depression basin which is rich in oil shale.Analysis of core and slides observation,organic carbon,pyrogenation and industry shows that the Meihe oil shale is a middle in oil content with high ash in type,and its organic matter is immature.Meanwhile kaolinite and illite are the main clay minerals in Meihe oil shale,enriched by stabilizing components such as quartz.Elements in Meihe oil shale like U,Mo are relatively rich,and its heave and light REE is high in differentation degree.Oil shale deposited over the coal layers in mutation,covered by the dark gray mudstone,which indicates that the oil shale developed in semi-deep and deep lake environment.Sr/Ba value and gammacerane value are lower,and V/ （V ＋ Ni） value is greater than 0.5,which indicates the oil shale forming in anoxic freshwater.The sources of organic matter in oil shale are more complex,such as high TOC content black oil shale containing mainly high plants with low oil production rate （oil content/TOC）,and relatively low TOC content of brown oil shale having much more aquatic organic matter with high oil production rate.