乌伦古拗陷石炭系烃源岩再认识

The Further Understanding of Carboniferous Source Rocks in Wulungu Depression

乌伦古拗陷是否发育石炭系烃源岩以及烃源岩发育层位一直存在争议。在乌伦古拗陷伦6井北发现了石炭系姜巴斯套组烃源岩露头,证实了乌伦古拗陷确实发育石炭系烃源岩。该剖面烃源岩以泥岩、粉砂质泥岩为主,为一套滨浅海相沉积。烃源岩潜力分析结果表明,该套烃源岩有机质丰度高,ITOC平均为1.23%;有机质类型好,以II1型为主,利于生油;烃源岩处于高成熟演化阶段。同时,烃源岩的饱和烃、芳烃特征反映该烃源岩形成于还原的微咸水环境,说明该区滨浅海相的沉积环境有利于烃源岩的发育,能够形成规模的源岩层,具备良好的勘探前景。

Whether Carboniferous source rock develops and its developing stratigraphic position of the real source rock in Wulungu Depression are always in dispute. The Jiangbasitao formation source rocks found in the north of Lun 6 well verify that Carboniferous source rock does exist in this area. The mudstone and the silty mudstone deposited in the shore and shallow sea are the main source rock types. The source rocks are medium-good with the average organic carbon in 1.23%. The type of organic matter is mainly IIl type, which contributes to oil generation. The source rocks are in the high-maturity stage. Some geochemical characteristics including saturated hydrocarbon and aromatic hydrocarbon are that the source rocks are developed in the reductive and brackish water environment. It indicates that the shore and shallow sea is favorable to source rock, which facilitates the abundant source rocks forming and possess good prospects for exploration.