长江科学院院报 ›› 2020, Vol. 37 ›› Issue (5): 99-107.DOI: 10.11988/ckyyb.20190058

• 岩土工程 • 上一篇    下一篇

页岩水力压裂裂缝起裂和扩展断裂力学模型

侯振坤1, 程汉列2, 海金龙3, 张道平3, 高如超4   

  1. 1.广州市建筑科学研究院有限公司,广州 510440;
    2.中海艾普油气测试(天津)有限公司,天津 300457;
    3.中国石油长庆油田分公司第三采油厂,银川 750001;
    4.中交第二航务工程局有限公司,武汉 430040
  • 收稿日期:2019-01-16 出版日期:2020-05-01 发布日期:2020-06-10
  • 通讯作者: 程汉列(1989-),男,陕西汉中人,工程师,硕士,从事油气田开发及油藏工程研究。E-mail:chenghl0405@sina.com
  • 作者简介:侯振坤(1988-),男,河南周口人,博士后,主要从事水力压裂开采页岩气、桩基工程等研究。E-mail:zhenkunhoucqu@163.com
  • 基金资助:
    国家自然科学基金项目(51908225,51678171);中国博士后科学基金项目(2019M662918,2019M652899,2019M662917);广东省基础与应用基础研究基金区域联合基金-青年基金项目(2019A1515110836)

Fracture Mechanics Model of the Initiation and Growth of HydraulicFissures During Hydraulic Fracturing of Shale

HOU Zhen-kun1, CHENG Han-lie2, HAI Jin-long3, ZHANG Dao-ping3, GAO Ru-chao4   

  1. 1. Guangzhou Institute of Building Science Co., Ltd., Guangzhou 510440, China;
    2. COSL-EXPROTesting Services(Tianjin) Co., Ltd., Tianjin 300457, China;
    3. No.3 Oil Production Plant of PetrochinaChangqing Oilfield Company, Yinchuan 750001, China;
    4. CCCC Second Harbour Engineering Co., Ltd.,Wuhan 430040, China
  • Received:2019-01-16 Online:2020-05-01 Published:2020-06-10

摘要: 结合大尺寸真三轴水平井水力压裂物理模拟试验,对龙马溪组页岩的起裂、扩展以及扩展过程中水力裂缝与天然裂缝的相互作用进行了详细的力学分析,并基于断裂力学和流体力学理论知识,建立了水力裂缝起裂和扩展力学模型,推导了相应的断裂力学判据。结果表明:①起裂方式可以分为3类,即页岩本体张性起裂、沿天然裂缝(层理面)的剪切起裂、沿天然裂缝(层理面)的张拉起裂;②水力裂缝扩展过程中,随着裂缝长度的增加,泵压逐渐减小,最终趋于一个略大于最小水平主应力的稳定值;③水力裂缝与天然裂缝的相互作用类型可根据天然裂缝是否开启分为以下5类,即剪切天然裂缝后穿过、直接穿过天然裂缝、从天然裂缝一端穿过、同时从天然裂缝两端穿过、从某一弱面穿过。研究结果可为页岩气藏水平井压裂开采提供有力技术支持。

关键词: 龙马溪组页岩, 水力压裂, 裂缝起裂与扩展, 物理模拟, 泵压曲线, 相互作用, 天然裂缝

Abstract: Physical modelling of large-scale true triaxial test on hydraulic fracturing of shale horizontal well is performed to study in detail the law of the initiation and growth of hydraulic fissures in Longmaxi Formation shale, the fracturing mechanics and the interaction between hydraulic fracture and natural fracture. On the basis of fracture mechanics and fluid mechanics theories, the mechanical model of hydraulic fracture initiation and expansion was established, and the corresponding fracture mechanics criterion was derived. Results indicate that: (1) The crack initiation mode can be divided into three categories, namely, tensile cracks started with shale, shear fractures started with natural fracture (bedding plane), and tensile cracks started with natural fracture. (2) During the extension of hydraulic fracture, the pump pressure decreases with the elongation of crack length and finally tends to a stable value, which is slightly bigger than the minimum horizontal principal stress. (3) According to whether the natural fracture is open, the interaction between hydraulic fracture and natural fracture can be divided into the following five types: penetration through the sheared natural fracture, penetration through the natural fractures directly, penetration through one end of the natural fracture, penetration through the natural fracture from two ends of the natural fracture synchronously, and penetration through the natural fracture from a weak surface. The research results offer strong technical support for horizontal well fracturing of shale gas.

Key words: Longmaxi Formation shale, hydraulic fracture, crack initiation and propagation, physical modelling, pump pressure-time curve, interaction, natural fracture

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