北部湾盆地涠西南凹陷流沙港组和涠洲组烃源岩地化特征分析结果表明，流沙港组生烃潜力高于涠洲组，其中以流二段最优；2套烃源岩总体处于弱还原-弱氧化的沉积环境，伽马蜡烷含量甚微，C24四环萜的含量表明陆源有机质占有一定比例，各组段C27、C28、C29αααR型甾烷分布特征多为“V”型和反“L”型，且流二段的C30-4-甲基甾烷含量最为丰富。根据生标特征可将原油分为3类：Ⅰ类原油来源于流一段烃源岩；Ⅱ类原油源于流三段烃源岩；Ⅲ类原油可分为2个亚类，Ⅲ1类原油来源于流二段的泥页岩，Ⅲ2类原油为流一段和流二段混合来源，推断混源中流二段烃源岩生烃贡献较大。涠洲组原油与涠洲组烃源岩特征相差甚大，推测应源于其下部地层。%The geochemical analysis of source rocks from the Liushagang and Weizhou Formations has indicated that, source rocks of the Liushagang Formation have higher hydrocarbon generation potential than those of the Weizhou Formation and the 2nd member of the Liushagang Formation ( L2) has the highest quality. The Liushagang and Weizhou rocks deposited in a weakly-reducing to weakly-oxidizing environment, remaining in the lack of gamma-cerane, and the content of C24 tetracyclic terpane reflects that the origins of organic matter account for certain percentage of terrestrial plants. C27 , C28 and C29αααR regular steranes distribute in“V” and anti-“L” shapes in each formation. Moreover, the rich abundance of C30-4-methylsteranes appears in the L2 source rocks. Oil sam-ples can be divided into 3 types based on the characteristics of biomarkers. TypeⅠoils were mainly derived from the 1st member of the Liushagang Formation. Type Ⅱ oils mainly originated from the 3rd member of the Liu-shagang Formation. TypeⅢoils are divided into 2 groups. GroupsⅢ1 oils showed a close relation to the mudstones or oil shales in L2. GroupⅢ2 oils were mainly from mixed sources and largely from L2. Oils from the Weizhou Formation present no correlation with the Weizhou Formation source rocks, maybe from the lower formations.
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