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鲁卜哈利盆地B区块油气勘探获得天然气和凝析油。A2井奥陶系凝析油以小于nC17的正构烷烃为主,凝析油全油碳稳定同位素值为-26.55‰~-27.70‰。凝析油具有饱和烃含量高、不含沥青质、呈现饱和烃>芳烃>非烃的特征。庚烷值和异庚烷值分别为22%和2.38。凝析油生物标志化合物含量低,萜烷系列以藿烷为主,三环萜烷以C23三环萜烷为主,C24四环萜烷含量低,甾烷组成上具有C29≈C27>C28的分布特征,重排甾烷含量高。凝析油生物标志化合物特征与来源于志留系热页岩的古生界原油相似。生物标志化合物和金刚烷成熟度表明原油为成熟—高成熟的范畴。B区块不同层位的天然气均为湿气,天然气为有机成因油型气,天然气的成熟度为0.75%~1.35%。由于B区块凝析油、天然气成熟度相当,认为原油裂解气不是该区天然气的唯一成因。凝析油和天然气主要直接来源于志留系热页岩的热降解。
Oil and Gas Exploration in Block B, Ruboub Basin Get natural gas and condensate. The A2 Ordovician condensate is dominated by n-alkanes less than nC17, and the stable hydrocarbon isotope values of condensate oil are -26.55 ‰ -27.70 ‰. Condensate has high content of saturated hydrocarbons, free of asphaltenes, showing the characteristics of saturated hydrocarbons> aromatic hydrocarbons> non-hydrocarbons. Heptane and isoheptane values were 22% and 2.38, respectively. The content of biomarkers in condensate oil is low. The main alkane series are hopane, tricyclic terpane is C23 tricyclic terpane, C24 tetracyclic terpane is low, and sterane has C29≈C27> C28 Distribution characteristics, rearrangement sterane content is high. Condensate biomarker compounds are similar in character to Paleozoic oils derived from Silurian thermal shales. Biomarker compounds and adamantane maturity indicate that crude oil is a mature-high maturity category. The natural gas in different layers of Block B is all moisture, while the natural gas is organic-derived oil gas. The maturity of natural gas is 0.75% -1.35%. Due to the condensate oil in Block B and the similar degree of maturity of natural gas, it is considered that crude oil pyrolysis gas is not the only cause of natural gas in the area. Condensate and natural gas are mainly derived directly from the thermal degradation of the Silurian thermal shales.