准噶尔盆地玛湖凹陷西斜坡百口泉组含油储集岩分子与碳同位素地球化学特征及其意义

发布时间：2018-03-31 00:39

  本文选题：百口泉组　切入点：连续型油气藏　出处：《地球化学》2017年03期

【摘要】：在准噶尔盆地玛湖凹陷斜坡区下三叠统百口泉组地层中发现大面积连片岩性油气藏。对西斜坡百口泉组一段和二段8个含油储集岩样分别提取自由态组分、束缚态组分和油气包裹体组分,并进行GC、GC-MS和GC-IRMS分析。结果表明,3类油气组分三环萜烷主峰含量远高于C_(30)藿烷,反映充注到百口泉组(T1b)储层的原油均具有很高的成熟度,相当于Ro1.20%。生物标志物指标β-胡萝卜烷/(β-胡萝卜烷+nC20)、伽马蜡烷/(C_(30)藿烷+伽马蜡烷)、三环萜烷/(三环萜烷+藿烷)、Ts/(Tm+Ts)、C_(29)Ts/(C_(29)藿烷+C_(29)Ts)、C_(30)重排藿烷/(C_(30)重排藿烷+C_(30)藿烷)和甾烷C_(21)/(C_(21)+∑C_(29))比值均显示从自由态组分、束缚态组分至油气包裹体组分成熟度依次降低的特征,表明油气组分在油藏充注过程中不断升高。与此相反,Pr/nC_(17)和Ph/nC_(18)比值以及正构烷烃单体碳同位素组成显示从自由态组分、束缚态组分至油气包裹体组分成熟度依次升高的特征,表明油气组分从成藏早期至晚期成熟度降低。由于充注的原油为不同成熟度油气组分混合产物,生物标志物在原油中属于微量及痕量组分,而Pr、Ph和正构烷烃属于常量组分,Pr/nC_(17)和Ph/nC_(18)比值以及正构烷烃单体δ~(13)C值更能代表主体原油的成熟度。因此,对于玛湖凹陷西斜坡油气藏,主体原油成熟度从成藏早期至晚期是降低的。根据8个油砂样3类油气组分的成熟度可以推断油气充注期介于晚侏罗世-白垩纪之间。盖层密封性是控制这类油气藏成藏的重要因素。在晚侏罗世之前,下伏二叠系盖层一直阻止了油气沿断层运移。至晚侏罗世-白垩纪,下伏盖层的密封性遭受破坏,油气才从下伏二叠系沿断层运聚至百口泉组一段和二段储层(T_1b~(1 2))。由于上覆百三段(T_1b~3)和克拉玛依组(T_2k)盖层自始至终保持密封状态,百口泉组一段和二段储层(T_1b~(1 2))成为玛湖凹陷油气的最终归宿。
[Abstract]:In the lower Triassic Baikouquan formation in Mahu sag, Junggar Basin, a large area of lithologic reservoirs were found in the Baikouquan formation. Free fractions were extracted from 8 oil-bearing reservoir samples in the first and second member of Baikouquan formation on the West Slope, respectively. The results show that the main peak content of tricyclic terpene is much higher than that of C ~ (30) cariane, which reflects the high maturity of the crude oil injected to the T1b) reservoir of Baikouquan formation, and the analysis of the bound state and hydrocarbon inclusion components by GC GC-MS and GC-IRMS shows that the main peak content of tricyclic terpene is much higher than that of C ~ (30). The biomarker index of 尾 -carotene rne (尾 -carrodane nC20) and tricyclic terpene rne (TsP ~ (TM) TsP / C ~ (29) TsP / C29) and steric terpene (C) and steric terpene (n / c / C ~ (30)) and steroidal terpene (n / c / c ~ (30)) and steric terpene (n / c / c ~ (30)) and steroidal terpene (n / c / c ~ (30)) and steric / steric terpene respectively (n / C / C ~ (30)) and steric terpene (n / n C ~ (20) C ~ (30) C ~ (30) C ~ (30)). The ratio of C / D 21) 鈭，

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