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首页» 过刊浏览» 2019» Vol.4» Issue(4) 347-353     DOI : 10.3969/j.issn.2096-1693.2019.04.031
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不同层理倾角页岩Ⅰ型裂缝断裂表现实验研究
马立科1, 2,曹函1, 2*,张政1, 2,高强1, 2,骆中山1, 2
1 中南大学地球科学与信息物理学院,长沙 410083 2 中南大学有色金属成矿预测与地质环境监测教育部重点实验室,长沙 410083
An experimental investigation of the fracture behaviors of type-Ⅰ cracks in shales with different bedding angles
MA Like1, 2, CAO Han1, 2, ZHANG Zheng1, 2, GAO Qiang1, 2, LUO Zhongshan1, 2
1 School of Geosciences and Info-physics, Central South University, Changsha 410083, China 2 Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University), Ministry of Education, Changsha 410083, China

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摘要  不同层理倾角页岩的Ⅰ型裂缝的断裂表现具有明显差异,进而影响其水力压裂裂缝扩展效果。本文基于页岩层理特性,采用中心切槽三点弯曲半圆盘实验方法探讨页岩天然层理面与Ⅰ型裂缝的夹角θ对其断裂韧性及破坏模式的影响。结果表明:试样的断裂韧性与夹角θ有良好的二次相关性;同时位移—压力的变化曲线显示,夹角θ的差异对加载过程中的峰值压力、位移和断裂类型有较大影响,其中夹角θ为45°和60°的试样在峰后压降阶段表现出延性断裂,而其它角度的试样则表现为脆性断裂;其次,断裂应变能随层理倾角的递增呈线性增长;不同夹角试样裂缝的断裂模式差异性主要表现为具有向层理面倾斜并贯穿的趋势。因此,开展页岩天然层理面与Ⅰ型裂缝的夹角对页岩的断裂韧性及破坏模式影响的研究,对水力压裂实施过程中技术参数的选取具有一定的理论指导意义,从而提升其压裂改造储层的增产效率。
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关键词 : 页岩Ⅰ型裂缝;层理倾角;断裂韧性;断裂应变能;断裂模式
Abstract

The fracture behaviors of type-Ⅰ cracks in shales with different bedding angles have obvious differences, which in turn affect hydraulic fracturing crack propagation. This paper is based on shale bedding properties, and uses the three-point bending half-disk experimental method to investigate the effect of the angle θ between the bedding plane and type-Ⅰ cracks on the fracture toughness and failure mode. The results show that there is a good secondary correlation between the angle θ and the fracture toughness of the sample. Also, the displacement-pressure curve indicates that a different θ will greatly influence the peak pressure, displacement and fracture type during the loading process. Samples with θ of 45° and 60° show ductile fracture in the post-peak pressure drop stage, while the samples at other angles showed brittle fracture. Moreover, the elastic strain energy increases linearly with increasing bedding angles. The difference in failure mode of cracks in different angle specimens is mainly manifested by the tendency to cracks inclined to the bedding plane and then penetrating the bedding plane. Therefore, the investigation of the influence of the angle between the bedding plane and type-Ⅰ cracks on the fracture toughness and failure mode of the shale has certain significance for guiding the selection of technical parameters during the hydraulic fracturing implementation process, which is beneficial to improving the productivity of fracturing and reforming reservoirs.

Key words: type-Ⅰ shale cracks; bedding angle; fracture toughness; fracture strain energy; fracture mode
收稿日期: 2019-12-30     
PACS:    
基金资助:国家自然科学基金项目(41302124) 和油气藏地质及开发工程国家重点实验室开放基金项目 (PLN201609) 共同资助
通讯作者: hancao@csu.edu.cn
引用本文:   
马立科, 曹函, 张政, 高强, 骆中山. 不同层理倾角页岩Ⅰ型裂缝断裂表现实验研究. 石油科学通报, 2019, 04: 347-353
链接本文:  
MA Like, CAO Han, ZHANG Zheng, GAO Qiang, LUO Zhongshan. An experimental investigation of the fracture behaviors of type-I cracks in shales with different bedding angles. Petroleum Science Bulletin, 2019, 04: 347-353.
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