新疆石油地质

›› 2018, Vol. 39 ›› Issue (6): 1-1.doi: 10.7657/XJPG20180607

• 论文 •    

柴达木盆地西南地区天然气C5—C7轻烃地球化学特征

陈克非1，2，3，周世新1，2，李靖1，2，张臣1，2，3，张玉红1，2，3，李源遽1，2，3，马瑜1，2，3   

  1. (1.甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,兰州 730000;2.中国科学院 西北生态环境资源研究院,兰州 730000;3.中国科学院大学,北京 100049)
  • 出版日期:2019-01-01 发布日期:1905-07-19

Geochemical Characteristics of C5~C7 Light Hydrocarbons in Natural Gas of Southwestern Qaidam Basin

CHEN Kefei1,2,3, ZHOU Shixin1,2, LI Jing1,2, ZHANG Chen1,2,3, ZHANG Yuhong1,2,3, LI Yuanju1,2,3, MA Yu1,2,3   

  1. (1.Gansu Key Laboratory of Petroleum Resources & CAS Key Laboratory of Petroleum Resources Research, Lanzhou,Gansu 730000, China; 2.Northwest Institute of Eco-Environment and Resources, Chinese Academy of Science, Lanzhou, Gansu 730000, China; 3.University of Chinese Academy of Science, Beijing 100049, China)
  • Online:2019-01-01 Published:1905-07-19

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摘要： 以天然气中C5—C7轻烃组分为研究重点，结合天然气组分、碳同位素特征，对柴达木盆地西南地区英东、乌南和扎哈泉油田天然气母质类型、成熟度、油气生成温度和油气次生改造作用进行了研究。研究表明，英东、乌南和扎哈泉油田天然气C7化合物整体表现出正庚烷含量高的特征，乌南油田C7化合物中甲基环己烷含量较高，结合天然气碳同位素分析，认为英东、乌南和扎哈泉油田天然气主要为油型气，在乌南和扎哈泉油田有煤型气和混合气。庚烷值和异庚烷值指示天然气多处于成熟—高成熟演化阶段，甲烷碳同位素值计算获得天然气成熟度为0.8%~1.5%，平均为1.2%，说明天然气主要为成熟阶段产物。利用C7化合物计算得到天然气生成温度，生成温度能大致反映现今油气藏主体部分油气的形成温度；英东、乌南和扎哈泉油田油气生成温度（124~129 ℃）高于七个泉和狮子沟油田（108~109 ℃），表明在柴西南地区英东、乌南和扎哈泉油田天然气成熟度更高。通过轻烃研究识别出个别油气藏遭受了生物降解、蒸发分馏和水洗的次生改造作用。

Abstract: Focusing on the C5~C7 light hydrocarbons in natural gas, combined with natural gas components and carbon isotopes, the paper studies the organic precursor type and maturity, hydrocarbon generation temperature and secondary hydrocarbon reconstruction in Yingdong, Wunan and Zhahaquan oilfields in southwestern Qaidam basin. The results show that the C7 compounds in the natural gas of the 3 oilfields exhibit high n-heptane contents and the C7 compounds in Wunan oilfield have relatively high methylcyclohexane content. Based on the carbon isotope analysis, it is considered that the natural gas from Yingdong, Wunan and Zhahaquan oilfields mainly belong to oil-type gas, and coal-type gas and mixed gas are found in Wunan and Zhahaquan oilfields. The heptane and isoheptane values indicate that the natural gas are mostly in the mature-highly mature stage, based on the δ13C1-Ro% relationships, the calculated natural gas maturity is 0.8%~1.5% with the average value of 1.2%, indicating these gases were mainly generated in the mature stage. The calculated natural gas generation temperatures can roughly reflect petroleum forming temperatures of the main part of the modern reservoir. The petroleum generation temperatures in Yingdong, Wunan and Zhahaquan oilfields (124~129 ℃) are higher than those in Qigequan and Shizigou oilfields (108~109 ℃), showing that the natural gas maturity in Yingdong, Wunan and Zhahaquan oilfields are even higher. Through light hydrocarbon analysis, several oil and gas reservoirs suffered from biodegradation, evaporative fractionation and water washing have been identified

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