泥质岩有机质的赋存状态及其对泥质岩封盖能力的影响

应用荧光显微镜法,首次对济阳坳陷下第三系泥质岩中有机质的赋存状态进行了研究。下第三系泥质岩有机质的赋存状态可划分为顺层富集型、分散型和局部富集型等三种类型。有机质呈顺层富集型分布的泥质岩,其有机质丰度大多较高,主要沉积于半深湖-深湖相中。有机质呈分散型分布的泥质岩,其有机质丰度变化范围较大,大多形成在河流-三角洲相、滨-浅湖相或浊流沉积中。结合部分揭示泥质岩封盖能力的定量分析数据,下第三系泥质岩可概括出以下三种不同的组合特点:①泥质岩中有机质丰度高且有机质呈顺层富集型状态赋存时,泥质岩封盖能力差;② 泥质岩有机质丰度高且有机质呈分散型状态赋存时,泥质岩具有一定的封盖能力;③ 泥质岩有机质丰度低且有机质呈分散型状态赋存时,泥质岩封盖能力较好,因此,泥质岩中有机质的赋存状态对泥质岩的封盖能力有着不可忽视的影响。在研究评价泥质岩对油气藏的封盖能力时可作为重要的依据之一。

Occurrence of Organic Matter and Its Effect on Sealing Ability of Argillaceous Rock

Occurrences of organic matter in Paleogene argillaceous rock of Jiyang depression are primarily studied by means of fluorescent microscopy. The occurrences of organic matter in Paleogene argillaceous rock are classified into three types which are named as “enrichment type、dispersion type and part-enrichment type”, respectively. “Enrichment type” means that the organic matters are distributed plentifully along bedding plane in the rock, which deposited mainly in moderate depth-deep lake facies and is rich in organic matter; “Dispersion type” means that the organic matter are scattered randomly in the rock that deposited mostly in fluvial-delta facies or shore -shallow lake facies or turbidity current deposist, which is various in abundance of organic matter; (c) “part enrichment type”is intermediate one with the property of both “ enrichment type" and “dispersion type”. Combined with part quantitative analysis data about seaing ability of argillaceous rocks, three different composition properties are concluded as follows : (1) The sealing ability of the argillaceous rock was worse when organic matters were rich and occurred with “enrichment type” in the argillaceous rock, (2) The argillaceous rock had a certain sealing ability when organic matters were rich and occurred with “dispersion type”in the argillaceous rock, (3) The sealing ability of the argillaceous rock was better when organic matters were poor and occurred with “dispersion type” in the argillaceous rock. Thus,the effect caused by occurrence of organic matter no the sealing ability of argillaceous rock should not be ignored. It can be one of the important basis for us to evaluate sealing ability of argillaceous rock over oil-gas reservoir.