【摘要】 烃源岩在高成熟演化阶段或正常原油经油藏次生改造作用形成轻质油的过程中,往往伴随烃类芳构化作用的发生,芳构化作用涉及的C–H键断裂过程导致稳定C、H同位素的分馏。本文考察了正丁基环己烷(BCH)在黄金管封闭模拟体系下的分子演化特征,主要探讨了水和S对BCH热演化过程的影响。结果表明,随热演化程度增强(Easy Ro增大),烃类芳构化程度增强。水分子可能通过抑制环上H原子自由基裂解而降低烃类芳构化的速率和程度,增加了甲苯与甲基环己烷之间的H同位素分馏。单质S能极大地促进BCH芳构化作用的发生。结合塔里木盆地塔中深层轻质油藏开展应用探讨,认为环烷烃芳构化是轻质油藏演化中的一个重要地球化学过程,其中几个典型化合物(正庚烷、甲苯、甲基环己烷)的含量变化和稳定H同位素演化特征,在轻质油藏地质地球化学演化研究中对探讨原油热演化程度等具有重要指示意义。更多还原

【Abstract】 Aromatization frequently occurs during the generation of light oil from source rocks at high-maturity evolutionary stages or from normal crude oil through secondary reservoir modification. The rupture of C–H bonds,integral to aromatization, induces the fractionation of stable hydrocarbon isotopes. This study investigates the molecular evolution characteristics of n-butylcyclohexane(BCH) within a closed system, simulated using gold tubes, aiming to discern the impacts of water and sulfur on the thermal evolution of BCH. Results indicate an escalation in the degree of hydrocarbon aromatization with increasing thermal evolution(Easy Ro increases). Water molecules demonstrate a mitigating effect on hydrocarbon aromatization by impeding the free-radical cleavage of hydrogen atoms on the ring and facilitating the hydrogen isotope fractionation of toluene and methylcyclohexane. The introduction of elemental sulfur significantly promotes the aromatization of BCH. Lastly, in the Discussion section concerning deep light oil reservoirs in the middle Tarim Basin, it is proposed that the aromatization of cycloalkanes constitutes a crucial geochemical process in the evolution of light oil reservoirs. The content variations and stable hydrogen isotope evolution characteristics of several typical cycloalkanes(n-heptane, toluene, and methylcyclohexane) are deemed of great significance in the geological and geochemical evolution of light oil reservoirs.更多还原