塔里木盆地海相碳酸盐岩沥青"A"的地球化学特征
Geochemical Characteristics of Bitumen "A" in Marine Carbonate Rock from the Tarim Basin
-
摘要: 塔里木盆地采集的海相碳酸盐岩样品经粉碎后在索氏抽提器中用氯仿溶液抽提,正己烷沉淀沥青质后,可溶有机质进行柱色层族组成分离,获得饱和烃、芳烃、非烃,饱和烃和芳烃直接进行气相色谱-质谱分析,非烃经三氟化硼-甲醇混合液酯化后进行气相色谱-质谱分析。结果显示,样品有机质的演化程度高,母质类型以水生生物为主,台地相成烃古环境为富含单质硫的微生物发育的咸化深水还原环境。样品有机质经历过强烈的环化-芳构化过程和去甲基化过程有利于以甲烷为主的天然气的生成。样品的芳烃馏分中检测到C31-16-one、C33-16-one和C35-18-one长链中位酮化合物,推断这些长链中位酮可能是有机酸盐存在的特征生物标识化合物。Abstract: The marine carbonate rocks were crushed in to powder before taking chloroform solvent extraction by the Soxhlet apparatus. The soluble organic components were separated by column chromatography to yield saturated hydrocarbon, aromatic hydrocarbon and non-hydrocarbon after the asphaltene was precipitated by hexane. The saturated hydrocarbon and aromatic hydrocarbon were directly measured by Gas Chromatography-Mass Spectrometry (GC-MS). The non-hydrocarbon was esterified by BCl3-CH3OH mixed solution before taking measurement by GC-MS. The analysis result showed that the organic matters have undergone a high degree of evolution and the kerogen type is dominated by the aquatic organisms. The platform facies hydrocarbon-generating paleoenvironment was sulphur microorganism enriched saline deep water reducing environment. The organic matters of samples have experienced the strong process of cyclization-aromatization and demethylation, which were helpful to the generation of natural gas mainly with methane. The detectable long mid-chain ketones (C31-16-one, C33-16-one and C35-18-one) in the aromatic hydrocarbon might be the particular biomarkers about the presence of the organic acid salts.