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珠江口盆地珠一和珠二坳陷所产原油饱和烃馏分中,检测到两个新的C15倍半萜烷,文献资料将其鉴定为2,2,4a,7,8-五甲基-反-萘烷和2,2,4a,7,8-五甲基-顺-萘烷,相当于18α(H)和18β(H)-奥利烷中的D/E环构成的二环倍半萜烷.珠二坳陷那些高姥植比和富含陆源三萜类奥利烷、双杜松烷的凝析油中,这类新倍半萜烷相对丰富;而在珠一坳陷那些富含4-甲基甾烷、贫陆源三萜类和低姥植比的湖相原油中其含量明显偏低,表明新C15倍半萜烷在成因和来源上与陆源有机质有关,它们在研究区具有指示原油母源的作用.不同结构的倍半萜烷母源不同,它们在珠江口盆地原油中与指示沉积环境氧化还原性的指标Pr/Ph比呈现完全不同的相关性:Pr/Ph比与指示陆源有机质输入的新倍半萜烷和杜松烷的含量正相关,而与指示细菌输入的补身烷和重排补身烷的含量负相关,可能反映新倍半萜烷的形成需要偏氧化的地球化学条件.扩展至烃源岩中发现,恩平组碳质泥岩和泥岩中新倍半萜烷含量迥异,高姥植比(>7.0)的碳质泥岩中其丰度远高于低姥植比(约为2.17)的泥岩,但后者与同样低姥植比(约为2.29)的文昌组腐泥型湖相泥岩中含量相当,因此陆源有机质可能只是新倍半萜烷形成的充分条件,而偏氧化的沉积-成岩环境可能才是此类新标志物形成的必要条件.
Two new C15 sesquiterpenes were detected in the saturated hydrocarbon fractions of crude oil produced in Zhu 1 and Zhu 2 Depression of the Pearl River Mouth Basin. The literature data identified them as 2,2,4a, 7,8-pentamethyl- Trans-decalin and 2,2,4a, 7,8-pentamethyl-cis-decalin, corresponding to the bicyclic times of the D / E ring in 18α (H) and 18β Semi-terpanes. In Zhuzilu depression, those new breeds of sesqui-terpenoids are relatively abundant in condensate oil containing high ratio of basking and rich terrigenous terpenoids, The content of lanthanum oil, which is rich in 4-methyl-sterane, terrigenous terrigenous terrestrial source and low-pristine planting ratio, is obviously low, indicating that the new C15 sesquiterpenes are related to terrigenous organic matter in genesis and origin, The study area has the function of indicating the source of crude oil.Different structures of sesquiterpenes have different parental origin, and they all show completely different correlations with the Pr / Ph ratio, which indicates the redox index of sedimentary environment in the crude oil of the Pearl River Mouth Basin: Pr / The Ph ratio was positively correlated with the contents of neoesenes and junkanes indicating input of terrigenous organic matter and negatively with the contents of leffantin and rearranged alkanes indicating bacterial input, possibly reflecting neoteric sebacic alkanes Formation needs Partial oxidation of geochemical conditions.Expanded into source rocks, it was found that Enbon group carbonaceous mudstone and mudstone neo-sesquiterpanes content is very different, Gaosu planting ratio (> 7.0) carbonaceous mudstone abundance is much higher In the Lower Cretaceous (about 2.17%), the latter is comparable in content to the Wenchang Formation sapropel-type lacustrine mudstone with the same low-primal planting ratio (about 2.29), so that the terrigenous organic matter may be only a new sesquiterpene The formation of sufficient conditions, and the partial oxidation of sedimentary - diagenetic environment may be the formation of such new markers necessary.