西南石油大学学报(自然科学版) ›› 2022, Vol. 44 ›› Issue (4): 1-13.DOI: 10.11885/j.issn.1674-5086.2020.07.20.01

• 地质勘探 •    下一篇

长宁地区富有机质页岩脆性及与裂缝发育关系

赵圣贤1, 刘勇2, 冯江荣1, 范存辉3, 季春海1   

  1. 1. 中国石油西南油气田分公司页岩气研究院, 四川 成都 610051;
    2. 中国石油西南油气田分公司气田开发管理部, 四川 成都 610051;
    3. 西南石油大学地球科学与技术学院, 四川 成都 610500
  • 收稿日期:2020-07-20 发布日期:2022-07-28
  • 通讯作者: 范存辉,E-mail:fanchswpi@163.com
  • 作者简介:赵圣贤,1987年生,男,汉族,四川绵阳人,高级工程师,硕士,主要从事页岩气勘探开发等方面的研究工作。E-mail:zhaoshengxian@petrochina.com.cn
    刘勇,1981年生,男,汉族,甘肃玉门人,高级工程师,博士,主要从事非常规油气田勘探开发及油气藏工程研究。E-mail:castledream@petrochina.com.cn
    冯江荣,1987年生,女,汉族,四川射洪人,工程师,主要从事石油地质及油气田开发研究。E-mail:fengjr123@petrochina.com.cn
    范存辉,1980年生,男,汉族,河南洛阳人,副教授,博士,主要从事非常规储层构造解析、裂缝评价等方面的教学与科研工作。E-mail:fanchswpi@163.com
    季春海,1984年生,男,汉族,天津河东人,高级工程师,硕士,主要从事页岩气开发地质方面的研究。E-mail:jich01@petrochina.com.cn
  • 基金资助:
    中国石油重大科技专项(2016E-0611);国家科技重大专项(2016ZX05062);中国工程院重点咨询研究项目(2018-XZ-20)

Brittleness Characteristics of Organic-rich Shale and Its Relationship with Fracture Development of Changning Area

ZHAO Shengxian1, LIU Yong2, FENG Jiangrong1, FAN Cunhui3, JI Chunhai1   

  1. 1. Shale Gas Research Institution, Southwest Oil&Gas Field Company, PetroChina, Chengdu, Sichuan 610051, China;
    2. Gas Field Development Management Department, Southwest Oil&Gas Field Company, PetroChina, Chengdu, Sichuan 610051, China;
    3. School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2020-07-20 Published:2022-07-28

摘要: 页岩的脆性控制着裂缝的形成和演化,对页岩气层的体积改造和页岩气的增产极为关键。以川南长宁地区龙马溪组页岩为例,通过岩石矿物、地球化学和岩石力学等实验对龙一1亚段的矿物组分、有机地球化学、孔隙-裂缝结构以及力学性质进行测试,分析不同脆性矿物、有机质以及埋深的页岩脆性特征及其与裂缝发育的关系。结果表明,龙一1亚段脆性最高者为富有机质硅质页岩岩相,石英、长石和黄铁矿等脆性矿物的总含量大于50%,它们能够调节岩石断块的剪切滑移,所积累的能量大于完成岩石整体剪切破坏过程所需的能量;有机质及其在成熟过程中所产生的有机孔隙与微裂缝可促进裂缝的拓展、贯通以及连接,有机碳含量越高,裂缝系统越发育;随着埋深增加,页岩的脆性下降,岩石破裂模式由复杂的劈裂型向单一的剪切型转变;龙一11、龙一12小层脆性矿物和有机碳含量最高,脆性指数分别达到了61.31%和60.70%,为压裂甜点层段。

关键词: 富有机质页岩, 脆性, 裂缝, 控制机制, 可压性, 甜点

Abstract: The brittleness of shale controls the formation and evolution of fractures, which is crucial to the volume transformation of shale gas reservoir and the production increase of shale gas well. Taking Longmaxi Formation in Changning area of South Sichuan as an example, the mineral composition, organic geochemistry, pore fracture structure and mechanical properties of the lower Long 1 sub section were tested by rock and mineral, geochemical and mechanical experiments. Combined with experimental method of scanning electron microscopy, the relationships between the fracture development and different shale characteristics of brittle minerals, organic matter and buried depth were analyzed. The results show that the organic-rich siliceous shale facie has the highest brittleness in lower Long 1sub section. The total content of brittle minerals such as quartz, feldspar, and pyrite is greater than 50%. They can regulate the shear slip of rock blocks, and the energy accumulated in the rock is greater than the energy required to complete the overall rock failure. The organic matter and the organic pores and microfractures produced in the process of maturity can promote the development, connection and connection of fractures. The higher the organic carbon content, the more developed the fracture system. With increasing burial depth, the brittleness of the shale decreases, and the rock failure mode changes from a complex cleavage type to a single shear type. The 1st and 2nd sublayers of lower Long 1 sub section have the highest content of brittle minerals and organic carbon, with brittleness indices of 61.31% and 60.70%, respectively. They can be selected as sweet spot section with good fracturing performance, and complex fractures can be formed after fracturing.

Key words: organic-rich shale, brittleness, fracture, control mechanism, compressibility, sweet spot

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