石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (5): 1127-1140.doi: 10.11743/ogg20220510

• 油气地质 • 上一篇    下一篇

四川盆地侏罗系页岩层系岩相类型及储集特征

李倩文1(), 刘忠宝1, 陈斐然2, 刘光祥1, 张殿伟1, 李鹏1, 王鹏威1   

  1. 1.中国石化 石油勘探开发研究院，北京 102206
    2.中国石化 勘探分公司，四川 成都 610041
  • 收稿日期:2021-12-09 修回日期:2022-07-12 出版日期:2022-10-01 发布日期:2022-09-02
  • 第一作者简介:李倩文（1992—），女，硕士，助理研究员，非常规油气地质评价及勘探规划。E?mail： liqw2018.syky@sinopec.com。
  • 基金项目:
    国家科技重大专项(2017ZX05036-004);中国石油化工股份有限公司科技部项目(P19017-2)

Lithofacies types and reservoir characteristics of Jurassic shale in the Sichuan Basin revealed by the Da’anzhai Member， Well Y2， Yuanba area

Qianwen Li1(), Zhongbao Liu1, Feiran Chen2, Guangxiang Liu1, Dianwei Zhang1, Peng Li1, Pengwei Wang1   

  1. 1.Petroleum Exploration and Production Research Institute，SINOPEC，Beijing 102206，China
    2.Exploraiton Company，SINOPEC，Chengdu，Sichuan 610041，China
  • Received:2021-12-09 Revised:2022-07-12 Online:2022-10-01 Published:2022-09-02

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摘要：

陆相页岩层系岩性复杂、非均质性强，制约了储层甜点优选和探井部署。为查明四川盆地侏罗系页岩层系不同岩相类型的储集特征和含气能力，以元坝地区Y2井自流井组大安寨段为例，采用有机碳含量测定、全岩X射线衍射、岩石薄片鉴定、聚焦离子束扫描电镜、高压压汞—氮气吸附联合测定以及物性分析等手段，划分了大安寨段二亚段（后文简称大二亚段）页岩及夹层的岩相类型，并针对不同岩相类型开展储集物性、孔隙结构、含气性及可压性研究，在此基础上评选了优势岩相和岩相组合。结果表明，Y2井大二亚段页岩层系可划分为3大类6亚类页岩岩相，2大类6小类夹层岩相以及3种宏观岩相组合。页岩孔隙类型以粘土矿物层间孔、方解石溶蚀孔等无机孔为主，为页岩气的赋存提供了储集空间。计算页岩总含气量为2.59～4.38 m3/t，游离气平均占比67 %，具有较好的勘探潜力，但优势岩相的脆性矿物含量仅为50 %，可压性较差。综合评价认为，AB-Ⅰ型岩相组合中页岩页理和纹理发育，生烃条件好，含气量和游离气比例较高，存在可压性较好的夹层，是元坝地区Y2井大二亚段最有利的勘探储层类型。

关键词: 岩相, 夹层, 页岩, 大安寨段, 侏罗系, 元坝地区, 四川盆地

Abstract:

The continental shale strata are generally lithologically complicated and highly heterogeneous， making it difficult to pinpoint sweet spots and deploy exploratory wells. To evaluate the reservoir characteristics and gas-bearing capacity of different lithofacies types of Jurassic shale sequences in the Sichuan Basin， the Da’anzhai Member （Well Y2） in the Yuanba area was taken as an example. Experimental methods including TOC content measurement， whole-rock mineral composition analysis， thin section observation， FIB-SEM， mercury injection-N2 adsorption measurements as well as tests for physical properties were performed to classify the lithofacies types of shale and interlayers in the second sub-member of the Da'anzhai Formation （hereinafter referred to as the J1da2） and then to single out the lithofacies or lithofacies assemblages with the highest hydrocarbon potential based on physical properties， pore structure， gas content and occurrence as well as fracability. Results show that the shale can be divided into three categories and six sub-categories of lithofacies types， and the interlayers into two categories and six sub-categories for lithofacies types， which can be further grouped into three lithofacies assemblage types from a macro perspective. The shale contains mostly inorganic pores such as interlayer pores within clay minerals and dissolved pores of calcite， providing storage space for gas. The total shale gas content is calculated to be 2.59-4.38 m3/t， in which the free gas accounts for an average of 67 %， indicating a good exploration potential. However， the brittle mineral content of shale lithofacies is barely 50 %， indicating a poor fracability. It is concluded that type AB-Ⅰ lithographic assemblages in the sub-member are the most promising exploration targets as they are observed to contain well developed cleavage and lamellation fractures， favorable hydrocarbon generation conditions， higher gas content and proportion of free gas as well as brittle interlayers， all indicating the most promising exploration targets of all types.

Key words: lithofacies, interlayer, shale, Da’anzhai Member, Jurassic, Yuanba area, Sichuan Basin

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