土工基础

土工基础 ›› 2021, Vol. 35 ›› Issue (5): 628-634.

• 测试技术 • 上一篇    下一篇

液氮循环冷冻对岩石力学性能强度影响试验研究

黄路云1，李占省2，冒海军1,3,4，吴恒川4，王 洋1   

  1. （1.湖北工业大学 土木建筑与环境学院，武汉 430068；2.华北油田工程技术研究院研究院，河北任丘 062552；
    3.中国科学院武汉岩土力学研究所岩石力学与工程国家重点实验室，武汉 430071；4.西南科技大学 土木工程与建筑学院，四川绵阳 621000）
  • 收稿日期:2020-06-20 修回日期:2020-07-02 出版日期:2021-10-31 发布日期:2021-10-22
  • 作者简介:黄路云（1991-），男，硕士研究生，研究方向为多场耦合作用下岩石力学性能。

Experimental Study on the Effect of Liquid Nitrogen Cycling Freezing on the Mechanical Properties of Rock Mass

HUANG Luyun1, LI Zhangsheng2, MAO Haijun1,3,4, WU Hengchuan4， WANG Yang1   

  1. (1.School of Civil, Architecture and Environment, Hubei University of Technology, Wuhan 430068；
    2.Drilling and Production Technology Research Institute, Huabei Oilfield, Renqiu 062552；
    3.State Key Laboratory of Rock Mechanics and Engineering, Wuhan Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071；
    4.School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 62100)
  • Received:2020-06-20 Revised:2020-07-02 Online:2021-10-31 Published:2021-10-22

摘要： 液态氮气温度非常低（-195.8 ℃），在与地层岩石接触时，低温冷冻效应导致岩石内部结构产生损伤，物理力学指标降低，可作为压裂液对储层进行压裂改造。为研究液氮低温对岩石力学性能的影响，选择自然干燥样品、全饱和水样品（新疆灰岩、四川地区灰岩、四川灰色砂岩），在液氮浸泡前后及不同循环浸泡后对岩样进行抗拉及单轴抗压强度对比测试。结果表明，1）经液氮冻结后，岩石的单轴抗压强度、抗拉强度都降低；2）岩石在干燥状态下，液氮冻结对新疆地区灰岩强度的影响大于其它地区岩样的影响；3）在岩石水饱和状态下对于同种类型岩石而言，水饱和状态下能够加剧液氮冷冻效果，并对岩石产生损伤，随着循环次数增加岩石强度影响显著。研究结果可为进一步研究液氮压裂机制提供试验依据。

关键词: 液氮冷冻, 破坏模式, 抗压强度, 抗拉强度, 岩石损伤

Abstract: The temperature of liquid nitrogen state is very low (-195.8℃). When it contacts with the rock mass, the cryogenic effect will cause damage to the structure of the rock mass and reduce its physical and mechanical strength parameters. Therefore, the liquid nitrogen can be used as a fracturing fluid for the fracturing of the storage reservoir. In order to study the effect of the low temperature of the liquid nitrogen on the mechanical properties of rock mass, the naturally dried rock samples and fully saturated water samples (Xinjiang limestone, Sichuan limestone and Sichuan grey sandstone) were selected and compared with the tensile and uniaxial compressive strength of rock samples before and after soaking into the liquid nitrogen with different soaking cycles. The results show that, 1) The uniaxial compressive strength and the tensile strength of the rock samples are reduced after being frozen by the liquid nitrogen. 2) Under the natural dry state, the effect of the liquid nitrogen freezing on the strength of the Xinjiang limestone is greater than that of rock samples in other regions. 3) For the saturated same type of rock samples, the effect of the liquid nitrogen freezing can be intensified under the state of water saturation and the rock damage can be induced. The impact on rock strength is significant with the increase of soaking cyclic times. The results can provide the experimental basis for further research on the liquid nitrogen fracturing mechanism.

Key words: liquid nitrogen circulating freezing, failure mode, compressive strength, tensile strength, rock damage

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