西南石油大学学报(自然科学版)

• 地质勘探 •    下一篇

牛蹄塘组页岩气储层有机质微生物来源的证据

张廷山1,2 *,伍坤宇1,2,杨洋1,2,罗玉琼1,龚齐森3   

  1. 1.“油气藏地质与开发工程”国家重点实验室· 西南石油大学,四川成都610500;
    2. 西南石油大学地球科学与技术学院,四川成都610500;3. 重庆市能源投资集团页岩气投资有限公司,重庆南岸400060
  • 出版日期:2015-04-01 发布日期:2015-04-01
  • 通讯作者: 张廷山,E-mail:zts_3@126.com
  • 基金资助:

    国家自然科学基金(41302023);教育部博士点基金(20125121130001);四川省教育厅科研基金(13ZB0190)。

Evidence of Microbial Origin of Organic Matters of Niutitang
Shale Gas Reservoir

Zhang Tingshan1,2*, Wu Kunyu1,2, Yang Yang1,2, Luo Yuqiong1, Gong Qisen3   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    2. School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    3. Shale Gas Investment Limited Company,Chongqing Energy Investment Group,Nan′ an,Chongqing 400060,China
  • Online:2015-04-01 Published:2015-04-01

摘要:

针对牛蹄塘组页岩气储层中有机质来源的问题,从微体古生物化石和有机地球化学两方面开展了研究。采
用环境扫描电镜–能谱系统(ESEM – XEDS)对岩芯中的微生物化石形态和化学组成进行了研究;此外,还采用气相色
谱–质谱法(GC – MS)对岩芯抽提物进行了检测。结果表明,牛蹄塘组页岩中发现的微生物化石C 和N 元素含量较
高(大于30%),从外部形态大致可将其分为3 类:同心环状结构,表面光滑的球体以及细胞壁开口的球体。岩芯抽提
物检测结果表明,牛蹄塘组页岩nC12 ∼ nC32 的正构烷烃均有检出,且具有低碳数(主峰碳nC16)偶碳优势;此外,抽提
物中还检出了含量较高的类异戊二烯烃,包括,姥鲛烷、植烷和角鲨烯。这些微生物化石的发现和有机地球化学组成
特征为晚震旦—早寒武世扬子浅海微生物的繁盛和牛蹄塘组烃源物质的微生物起源提供了有力的证据。

关键词: 页岩气储层, 有机质, 微生物化石, 有机地球化学, 牛蹄塘组

Abstract:

Evidences of microbial origin of organic matters of Niutitang shale gas reservoir were discussed from both micropaleontological
and organic geochemical perspectives. The environmental scanning electronic microscope-energy dispersive
spectrometry system(ESEM – XEDS)was applied to analyze the morphology and chemical compositions of microfossils;
in addition,the extracts of shale core were tested by using gas chromatography-mass spectrometry(GC – MS)method. Results
indicate that all the microbial fossils discovered in Niutitang shale are of high N and C content(more than 30%)and all the
fossils can be subdivided into three types,including concentric circularity shape,smooth coccoid shape and coccoid shape with
a surface crack. The extracts test results indicate that normal paraffin ranging from nC12 ∼ nC32 were detected,and is characterized
by light n-paraffin and even-carbon-number predominance(main peak is nC16). In addition,some isoprenoid were also
detected from extracts e.g. pristine,phytane,and squalene. The discovery of microorganism fossils and organic geochemical
characteristics of shale cores provides strong evidences for flourishing of microorganism in Yangtze Shelf Sea during Sinian to
Early Cambrian period and the microbial origin of hydrocarbon source materials of Niutitang Formation.

Key words: shale gas reservoir, organic matters, microbial fossil, organic geochemistry, Niutitang Formation