石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (4): 1020-1032.doi: 10.11743/ogg20230417

• 方法技术 • 上一篇    下一篇

岩石热解方法应用于页岩油气研究需注意的几个问题

张谦1(), 金之钧1,2,3(), 朱如凯4, 刘全有1,2, 张瑞1, 王冠平5, 陈万利6, Littke Ralf7   

  1. 1.北京大学 地球与空间科学学院 能源研究院，北京 100871
    2.页岩油气富集机理与有效开发国家重点实验室，北京 102206
    3.中国石化 石油勘探开发研究院，北京 102206
    4.中国石油 勘探开发研究院，北京 100083
    5.中国地质大学（北京） 能源学院，北京 100083
    6.中国科学院 深海科学与工程研究所 海底资源与探测技术重点实验室，海南 三亚 572000
    7.德国亚琛工业大学 石油与煤地质及地球化学研究所，德国 亚琛52056
  • 收稿日期:2023-02-20 修回日期:2023-05-19 出版日期:2023-08-01 发布日期:2023-08-09
  • 通讯作者: 金之钧 E-mail:amadozhang@pku.edu.cn;jinzj1957@pku.edu.cn
  • 第一作者简介:张谦（1989—），男，讲师、博士后，页岩油气勘探开发。E-mail： amadozhang@pku.edu.cn。
  • 基金项目:
    国家自然科学基金项目(42090020);中国博士后科学基金项目(2021TQ0003)

Remarkable issues of Rock-Eval pyrolysis in the assessment of shale oil/gas

Qian ZHANG1(), Zhijun JIN1,2,3(), Rukai ZHU4, Quanyou LIU1,2, Rui ZHANG1, Guanping WANG5, Wanli CHEN6, Ralf Littke7   

  1. 1.Institute of Energy，School of Earth and Space Sciences，Peking University，Beijing 100871，China
    2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development，Beijing 100083，China
    3.Petroleum Exploration and Production Research Institute，SINOPEC，Beijing 102206，China
    4.Research Institute of Petroleum Exploration & Development，PetroChina，Beijing 102206，China
    5.School of Energy Resources，China University of Geosciences （Beijing），Beijing 102206，China
    6.Laboratory of Marine Geophysics and Georesources，Institute of Deep-sea Science and Engineering，Chinese Academy of Sciences，Sanya，Hainan 572000，China
    7.Institute of Geology and Geochemistry of Petroleum and Coal，RWTH Aachen University，Aachen 52056，Germany
  • Received:2023-02-20 Revised:2023-05-19 Online:2023-08-01 Published:2023-08-09
  • Contact: Zhijun JIN E-mail:amadozhang@pku.edu.cn;jinzj1957@pku.edu.cn

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摘要：

岩石热解方法自问世以来被广泛地应用于烃源岩的研究，其可以简便、快捷地评价岩石的含油特性、干酪根的生烃特征以及有机质的丰度、类型和成熟度，但该方法有其适用的范围，且岩石热解数据不合理的解释会增加页岩油气勘探的风险。基于近年来发表的大量实验测试数据，总结了在岩石热解分析数据解释中经常出现的3个问题。①对于高-过成熟的样品，其应用性受到限制；利用氢指数（HI）、氧指数（OI）、岩石最高热解峰温（Tmax）以及热解过程中产生的烃类（S2）与二氧化碳（S3）数量的比值（S2/S3）来划分有机质的类型，应尽量针对有机质成熟度（镜质体反射率，Ro）低于1.35 %的烃源岩。② Tmax的有效性取决于S2峰的大小及其是否对称，Tmax的准确性依赖于有机质的类型和Ro；残余烃与黄铁矿含量会对Tmax的准确性造成一定的影响。对于Ⅰ，Ⅱ和Ⅲ型有机质，为确保测试获得的Tmax准确、有效，烃源岩的Ro应不高于1.70 %。③含油饱和度指数（OSI）被用来表征页岩油的可动潜力，OSI大于100 mg/g指示页岩油甜点。值得注意的是，OSI并不能直接指示页岩中的含油饱和度，对于有机质含量较高的层段，OSI通常低于100 mg/g，而较低的总有机碳含量也能导致OSI大于100 mg/g。目前，大多数论文所报道的极具潜力的页岩油储层，只有极少数OSI高于100 mg/g。因此，将OSI大于100 mg/g作为一个评价页岩油可动性和甜点的参数值是否合适值得进一步思考。建议针对不同类型的沉积盆地和不同的页岩地层建立各自的OSI评价标准。此外，不同岩性的样品在存储和制备过程中轻烃损失量差异较大，应对多岩相共生页岩油储层采用分岩相评价方法。

关键词: 甜点评价, 含油饱和度指数, 成熟度, 有机质类型, 岩石热解, 页岩油气

Abstract:

Rock-Eval pyrolysis has been widely used in assessing source rocks from the very beginning. Although this approach can evaluate oil content， hydrocarbon generation， as well as the abundance， type， and thermal maturity of organic matter in a simple and rapid way， it is noteworthy that this technique has some limitations in application， and improper interpretation of pyrolytic data may bring more risks to shale oil/gas exploration. This study summarizes three main pitfalls commonly seen in previous publications based on massive experimental results. First， the use of hydrogen index （HI）， oxygen index （OI）， the temperature of maximum pyrolysis yields （Tmax）， and the ratio of S2/S3 to discriminate kerogen of diverse types should target source rocks with maturity less than 1.35 % Ro； the feasibility of the technique to highly-to-over-mature source rock samples is limited. Second， the validity of Tmax depends on the area of S2 and whether it is in normal distribution， and the accuracy of Tmax relies on kerogen type and thermal maturity； moreover， residual hydrocarbon and pyrite content have some effects on the accuracy of Tmax. To obtain accurate Tmax values， the maturity of source rocks of types Ⅰ， Ⅱ， and Ⅲ should not be larger than 1.70 % Ro. Third， the oil saturation index （OSI） has been used to indicate the mobility of shale oil， and a value larger than 100 mg/g TOC suggests sweet spots of shale oil. However， it should be noted that OSI could not directly provide information on the saturation of oil in shale. OSI values are generally smaller than 100 if the rocks are very organic-rich， and a small TOC value could also lead to a large OSI value （more than 100 mg HC/g TOC）. Besides， only a few shales bear OSI higher than 100 mg HC/g TOC， although many of the shales have been proven commercially successful. Therefore， the applicability of OSI larger than 100 mg HC/g TOC as a parameter for shale oil mobility merits further consideration. We suggest using individual OSI criteria for different types of sedimentary basins and shale formations. Moreover， the loss of light hydrocarbons during the storage and preparation of rock samples is strongly dependent on rock lithofacies， and thus， classified assessment should be adopted for shale oil reservoirs of multiple lithofacies.

Key words: sweet spot assessment, oil saturation index （OSI）, thermal maturity, organic matter type, Rock-Eval pyrolysis, shale oil and gas

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