泥质烃源岩密度分组及有机质赋存类型初探

选取济阳坳陷沙河街组深湖相暗色泥岩为研究对象,通过不同密度ZnBr2重液浮选,将样品分离成多个密度组分,对各组分检测透射光、荧光、X光衍射等,揭示不同组分有机质赋存类型的差异性.分析结果表明,①组分(密度ρ<1.6g.cm-3)以颗粒有机质为主,有机质与矿物无明显紧密结合关系;②,③组分(1.6g.cm-3<ρ<2.2g.cm-3,ρ>2.2g.cm-3)多见无定形有机质分散于细粒矿物相中,呈橙黄-亮黄色荧光,反映有机质与矿物颗粒紧密共生的赋存特征.进一步对不同密度组分有机质分配的研究表明,①组分结合了烃源岩总有机质质量不到1%;②,③组分结合了烃源岩中90%以上质量的有机质.这反映了有机质和矿物颗粒共生的赋存形式在有机质保存中不可忽视的重要地位.

An Exploratory Study on Density Fractionation and Organic Matter Preservation of Muddy Source Rock

The black muddy rock samples were selected from the deep lake facies of the Shahejie formation,tertiary,in Jiyang depression.By floating with different densities ZnBr2 heavy solution,the samples were divided into many density fractions.A series of detections,including transmission light,florescence,XRD and so on,revealed the difference of organic matter preservation in the different fractions.The analysis results indicate in the fraction ①(ρ <1.6 g·cm-3),the free organic particles are dominant and the minerals do not combine with the organic particles closely.In the fractions of ② and ③(1.6 g·cm-3<ρ <2.2 g·cm-3,ρ >2.2 g·cm-3),the organic amorphous distributes in the fine mineral phase and shows orange and light yellow fluorescence.It indicates the organic matter combines with mineral closely.Further analysis on the organic matter distribution indicates that the fraction ① combines with less than 1% organic matter in the source rock;the fraction ② and ③ combine more than 90% organic matter of the source rock.It reflects the organic matter combining with the mineral is very important way of the organic matter preservation.