黄河口凹陷湖相烃源岩发育机制

 渤海海域黄河口凹陷为典型的富生烃断陷盆地，发育有沙河街三段（E2s3）、沙河街一段（E3s1）和东营组下段（E3dL）3套湖相烃源岩。E2s3和E3s1源岩有机质丰度高，有机质类型以IIA为主，个别为III型，姥植比均小于2.0；E3dL烃源岩有机质丰度中等，有机质为混合II型偏向IIB型，姥植比大于2.0。针对不同层系烃源岩的差异，通过对凹陷构造-沉积演化和古气候分析以及古盐度计算，探讨凹陷充填样式，建立与源岩发育的关系。E2s3为平衡充填型湖盆，发育的源岩有机质丰度最高，是优质湖相源岩发育的最有利湖泊类型。E3s1为欠充填型湖盆，水质略咸化，发育的源岩有机质丰度略低于E2s3。E3dL由平衡充填型湖盆过渡到过充填型湖盆，有机质丰度变化大，生烃潜力明显低于欠充填型湖盆和平衡充填型湖盆。

Development Mechanism of Lacustrine Source Rocks in Yellow River

The YRM (Yellow River Mouth) sag is a typical Paleogene rich oil and gas rift basin. There are three sets of source rocks, which lie in Shahejie 3 Member (E2s3), Shahejie 1 Member (E3s1) and the lower Dongying Formation (E3dL), respectively. The E2s3 and E3s1 source rocks are characterized by high abundance of organic matter mainly of type IIA (exceptionally, III) and with Pristane/Phytane ratios all less than 2.0; the E3dL source rocks are characterized by medium abundance of organic matter mainly of type II (mostly, IIB) and with Pristane/Phytane ratios more than 2.0. To find out the difference of source rocks in different layers, the structural-sedimentation evolution and the paleoclinmate are analyzed, and the paleosalinity of this sag is calculated to obtain the filling pattern and the relationships with source rock building. In E2s3 phase, the lacustrine is characterized with balanced filled source rocks of high abundance. It is the most favorable one to develop high quality source rocks. In E2s3 phase, the lacustrine is characterized with underfilled source rocks of good abundance (less than E2s3). And in E2s3 phase, the lacustrine is characterized with overfilled source rock of heterogeneous abundance. Obviously, its hydrocarbon generation potential is less than the other two.