松辽盆地NGN1井上白垩统青山口组一段有机质演化

以NGN1井全取芯井为标杆,通过岩芯观察、地球化学分析和显微组分镜下鉴定,揭示青山口组一段的有机质演化规律。NGN1钻井位于松辽盆地东南缘,青一段由底至顶分别为灰绿色泥质粉砂岩-深灰色泥岩、油页岩-灰色泥岩-灰绿色粉砂质泥岩沉积,揭示了由滨浅湖-半深湖-滨浅湖的沉积环境演化。TOC、S2、含油率以及HI呈现增大-高值-减小的趋势,而半焦含量和块状密度则呈相反的变化趋势。青一段泥岩中主要的有机质显微组分为层状藻、孢子体和骨屑等,有机质含量与单位面积显微组分、藻类相对含量均呈明显的正相关,并结合有机质判别图解,说明有机质类型主要为I型和II1型,来源以湖泊藻类为主。泥岩中的陆源有机质含量较少,说明湖泊生物控制着有机质的来源,浅湖由于水体较浅、水底含氧,保存条件较差,导致泥岩中的有机质丰度较低,半深湖-深湖水体较深,保存条件良好,促进有机质的富集,因此垂向上沉积环境演化是导致有机质变化的主要因素。

Organic matter evolution in the first member of Qingshankou Formation in Well NGN1, Upper Cretaceous,Songliao Basin

According to the core observation， geochemical analysis and maceral identification， we indicate the law of the organic matter evolution in the first member of Qingshankou Formation by the Well NGN1． The Well NGN1 is located in the southeast of Songliao Basin． There is gray- green argillaceous siltstone- dark gray shale，oil shale- gray mudstone- gray- green silty mudstone from bottom to top in the first member of Qingshankou Formation． It reveals that the evolvement of sedimentary environment is from shallow lake to semi- deep lake to shallow lake． TOC，S 2 ，FA and HI show the increase- a high value- decrease trend，and semi- coke content and bulk density are showing the opposite trend． By the maceral identification of oil shale polishsection， the main organic maceral are la- malginite，sporinite and fish bone． The maceral identification shows that the organic matter content has a positive correlation with the relative content of macersl and algae components per unit area． Combined with organic discrimi- nation diagrams， it is explained that the organic matter type is mainly type I and II 1 ， and the main source of organic matter is lake algae． Terrestrial organic matter content is very little in the mudstone，so it illustrates that the lake biology is the organic matter sources． The poor storage conditions of the shallow lake lead to lower abundance of or- ganic matter in mudstone． The good preservation conditions of semi- deep lake and deep lake promote the enrich- ment of organic matter． Therefore， sedimentary environment evolution is the main factor of the change of the organic matter in vertical direction．