柴达木盆地北缘井下石炭系烃源岩的发现及其地质意义

Discovery of Carboniferous source rocks in the north margin of Qaidam Basin and its geological significance

在柴达木盆地北缘,尕丘1井首次钻遇了石炭系海陆交互相地层。该井石炭系烃源岩的碳质泥岩有机碳含量平均为1.85%,灰岩有机碳含量平均为0.42%;灰岩母质类型属于Ⅱ型干酪根;烃源岩成熟度中等。尕丘1井石炭系烃源岩与马北2等井的原油生物标志物、柴达木盆地北缘不同油田(或油井)及烃源岩的伽马蜡烷/C31升藿烷值分布特征以及尕丘1井周边井天然气中氩同位素分布特征均有一定的可比性和相关性,说明该套烃源岩在柴达木盆地北缘可能曾经发生过生烃、运移和聚集成藏的过程。

The Carboniferous Formation of paralic facies in the north margin of Qaidam Basin was drilled in the Gaqiu-1 Well for the first time. The organic matters of the Carboniferous hydrocarbon source rock are abundant. The total organic carbon （TOC） in carbargillite is 1.85 percent in average, and TOC in limestone is 0. 42 percent. The type of organic matter in limestone is type-Ⅱ kerogen. The maturity of hydrocarbon source rock in this area is Midium. The biomarker data of Mabei-2 Well, distribution of Gammacerane/C31 homohopane ratio of different oilfield or drillings and other hydrocarbon source rocks, and the distribution of Ar（argon） isotope of the wells nearby are all correlation with the Carboniferous hydrocarbon source rock of Gaqiu-1 Well. It is suggested that hydrocarbon generation, oil and gas migration and reservoir formation may be induced by the found source rock in the area.