碳同位素分馏特征在烃源岩演化中的研究  

Research on Carbon Isotope Fractionation Characteristics in the Evolution of Source Rocks

作　　者：王建仁 汪超峰 宋静明 黄蒙 冯雄雄 WANG Jian-ren;WANG Chao-feng;SONG Jing-min;HUANG Meng;FENG Xiong-xiong(Xi'an Changli Oil and Gas Engineering Technology Service Co.,Ltd.,Xi'an Shaanxi 710000,China;Changqing Oilfield Company No.8 Oil Production Plant,Xi'an Shaanxi 710000,China;Xi'an Shiyou University,Xi'an Shaanxi 710065,China)

机构地区：[1]西安长立油气工程技术服务有限公司,陕西西安710000 [2]长庆油田分公司第八采油厂,陕西西安710000 [3]西安石油大学,陕西西安710065

出　　处：《当代化工》2022年第9期2235-2239,共5页Contemporary Chemical Industry

基　　金：国家科技重大专项,涪陵页岩气水平井多段压裂效果与生产规律分析研究(项目编号:2019ZX0506)。

摘　　要：以油砂岩、沥青、煤岩及泥岩样品金管模拟实验为依据,探讨了碳同位素分馏特征及其机理,计算了碳同位素反应速率系数、生烃转化率及同位素分馏因子,利用碳同位素动力学分馏模型,定量计算了储层裂解天然气的瞬时/累积碳同位素值。并以此为基础,分析预测了烃源岩生成产物的碳同位素分布随热演化的变化特征。实验结果表明:生烃母质具有较强的生气潜力,样品在热演化早期,其各组分之间会发生缩合反应,为高热演化阶段烃源岩继续生气提供烃源;甲烷稳定碳同位素整体分布比较广泛,样品的各温度点均可以观察到丙烷>乙烷>甲烷碳同位素值的现象,这与自然界广泛存在的正碳同位素序列相一致。在高-过成熟阶段,气态烃产物的碳同位素分馏最为明显,油砂岩样品的碳同位素分馏效应较大。综上所述,深化原油在深埋条件下同位素分馏特征的研究,无疑对过成熟地区天然气成因类型的判识和天然气成藏研究均具有重要的理论和现实意义。Based on the gold tube simulation experiment of oil sandstone,bitumen,coal rock and mudstone samples,the characteristics and mechanism of carbon isotope fractionation were discussed,and the carbon isotope reaction rate coefficient,hydrocarbon generation conversion rate and isotope fractionation factor were calculated.Fractionation model was used to quantify instantaneous/cumulative carbon isotope values of natural gas from reservoir cracking.Based on this,the variation characteristics of carbon isotope distribution with thermal evolution of products generated from source rocks were analyzed and predicted.The experimental results showed that the hydrocarbon-generating parent material had strong gas generation potential.In the early stage of thermal evolution of the sample,condensation reactions occurred between its components,providing hydrocarbon sources for the continued gas generation of source rocks in the high thermal evolution stage;the overall distribution of methane stable carbon isotopes was relatively extensive,and the phenomenon of propane>ethane>methane carbon isotope values was observed at each temperature point of the sample,which was consistent with the positive carbon isotope sequence widely existing in nature.In the high-over-mature stage,the carbon isotope fractionation of gaseous hydrocarbon products was the most obvious,and the carbon isotope fractionation effect of oil sandstone samples was larger.To sum up,deepening the research on the isotopic fractionation characteristics of crude oil under deep burial conditions will undoubtedly have important theoretical and practical significance for the identification of the genetic types of natural gas and the research on natural gas accumulation in over-mature areas.

关 键 词：烃源岩 金管模拟实验 碳同位素分馏 演化特征 

分 类 号：P59[天文地球—地球化学]