| 煤岩水力压裂裂缝扩展形态试验研究 |
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| 引用本文： | 姜婷婷,张建华,黄刚. 煤岩水力压裂裂缝扩展形态试验研究[J]. 岩土力学, 2018, 39(10): 3677-3684. DOI: 10.16285/j.rsm.2017.0194 |
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| 作者姓名： | 姜婷婷 张建华 黄刚 |
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| 作者单位： | 1. 武汉理工大学 资源与环境工程学院，湖北 武汉 430070；2. 武汉理工大学 矿物资源加工与环境湖北省重点实验室，湖北 武汉 430070 |
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| 基金项目： | 国家自然科学基金(No. 51804236) |
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| 摘 要： | 通过室内水力压裂物理模拟试验系统，对大尺寸原煤进行了水力压裂模拟试验，根据水力裂缝的空间展布形态分析了煤岩储层水力裂缝的延伸规律，揭示了网状裂缝的形成机制。结果表明：水力裂缝易在弱层理处分叉和转向，发育的层理和裂缝系统等结构面为压裂形成裂缝网络提供了前提条件。泵压曲线呈现出的频繁波动是煤岩内产生网状裂缝的一个显著特征。水力裂缝的起裂与延伸有4种基本模式，裂缝网络的形成多为这4种基本模式的组合。地应力差异系数和泵注排量对煤层水力裂缝形态有较大影响。较小的地应力差异系数更利于网状裂缝的形成；较高的压裂液排量易形成相对简单的裂缝形态，导致压裂改造效果较差。该试验方法和试验结果可为现场水力压裂参数设计和优化提供参考和依据。
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| 关 键 词： | 真三轴试验 水力压裂 网状裂缝 层理 裂缝扩展 |
| 收稿时间： | 2017-05-22 |
Experimental study of fracture geometry during hydraulic fracturing in coal |
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| JIANG Ting-ting,ZHANG Jian-hua,HUANG Gang. Experimental study of fracture geometry during hydraulic fracturing in coal[J]. Rock and Soil Mechanics, 2018, 39(10): 3677-3684. DOI: 10.16285/j.rsm.2017.0194 |
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| Authors: | JIANG Ting-ting ZHANG Jian-hua HUANG Gang |
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| Affiliation: | 1. School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, China； 2. Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, Wuhan University of Technology, Wuhan, Hubei 430070, China |
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| Abstract: | In this study, hydraulic fracturing experiments were carried out on the large raw coal to investigate the influence of bedding planes on fracture propagation by using a true triaxial hydraulic fracturing experiment system. The extension rule of hydraulic fractures in coal was analysed to reveal the formation mechanism of net-cracking based on the spatial distribution. The results show that the hydraulic fracture tends to bifurcate and swerve at the weak bedding. Then the developed bedding and fracture system provide the premise conditions to establish a fracture network. From the pump pressure curve, its frequent fluctuation indicates a remarkable feature of the net-cracking in coal rock. There are four basic modes on the initiation and extension of hydraulic fractures, and the fracture network is the combination of the four modes. In-situ stress difference coefficient and injection displacement both have great influences on the hydraulic fracture geometry. The small in-situ stress difference coefficient is more likely to form the fracture network. However, a relatively simple fracture geometry is easily formed when the fracturing fluid displacement becomes high, which conversely results in a poor fracturing effect. The experimental methods and corresponding results can provide reference and basis for the design and optimisation of hydraulic fracturing parameters. |
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| Keywords: | true triaxial test hydraulic fracturing net-cracking bedding fracture propagation |
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