王洪建, 刘大安, 黄志全, 袁广祥, 吕晓春, 牛晶蕊, 赵子江, 石晓闪. 2017: 层状页岩岩石力学特性及其脆性评价. 工程地质学报, 25(6): 1414-1423. DOI: 10.13544/j.cnki.jeg.2017.06.003
    引用本文: 王洪建, 刘大安, 黄志全, 袁广祥, 吕晓春, 牛晶蕊, 赵子江, 石晓闪. 2017: 层状页岩岩石力学特性及其脆性评价. 工程地质学报, 25(6): 1414-1423. DOI: 10.13544/j.cnki.jeg.2017.06.003
    WANG Hongjian, LIU Da'an, HUANG Zhiquan, YUAN Guangxiang, LÜ Xiaochun, NIU Jingrui, ZHAO Zijiang, SHI Xiaoshan. 2017: MECHANICAL PROPERTIES AND BRITTLENESS EVALUATION OF LAYERED SHALE ROCK. JOURNAL OF ENGINEERING GEOLOGY, 25(6): 1414-1423. DOI: 10.13544/j.cnki.jeg.2017.06.003
    Citation: WANG Hongjian, LIU Da'an, HUANG Zhiquan, YUAN Guangxiang, LÜ Xiaochun, NIU Jingrui, ZHAO Zijiang, SHI Xiaoshan. 2017: MECHANICAL PROPERTIES AND BRITTLENESS EVALUATION OF LAYERED SHALE ROCK. JOURNAL OF ENGINEERING GEOLOGY, 25(6): 1414-1423. DOI: 10.13544/j.cnki.jeg.2017.06.003

    层状页岩岩石力学特性及其脆性评价

    MECHANICAL PROPERTIES AND BRITTLENESS EVALUATION OF LAYERED SHALE ROCK

    • 摘要: 页岩气储层的岩石力学特性对压裂改造效果影响极大,开展页岩破坏机理、力学特性和脆性评价方面的研究,可以为页岩气开采中大规模体积压裂提供技术支持。本文对龙马溪组黑色炭质页岩进行单轴压缩试验,得到以下结论:(1)黑色页岩具有明显的层状薄片矿物结构,矿物主要成分为石英和方解石,结构面固有强度较高;(2)由于强结构面的影响,倾斜层理试件具有较高的弹性模量与单轴抗压强度,但是总体积应变量较小;平行或者垂直层理试件的弹性模量与单轴抗压强度较小,总体积应变量反而大;(3)随着层理倾角β的增大,层状页岩单轴压缩试验测得的起裂应力水平指标表现为"中间小两头大"的U型规律,即层理倾角为30°或60°时测量值较小,而0°或90°时较大;(4)岩石脆性是可压裂性的关键因素,层理角度为30°或者60°时,脆性指标较大,页岩的可压裂性更强,脆性指标的变化规律大致呈倒U型。本文的研究对评价页岩的可压裂性、提高压裂改造效果具有重要的现实意义和应用价值。

       

      Abstract: The mechanical properties of shale gas reservoir have great influences on fracturing effect. It is of great necessity to investigate damage mechanism, mechanical properties and brittleness evaluation of shale rock and then to provide technical support for large-scale volume fracturing of shale gas exploitation. This paper conducts uniaxial compression tests on black carbonaceous shale of Lungmachi Formation. The test results indicate the follows. The black shale rock has obvious layered flake mineral structure. Its main mineral components are quartz and calcite, which causes the structure surface having high strength. Due to the effects of strong structure surface, shale rock with inclined bedding plane has larger values of elastic modulus and uniaxial tensile strength and the minimum total volumetric strains. However, when the bedding plan is parallel or vertical to the loading direction, the shale rock has smaller values of elastic modulus and uniaxial tensile strength and the maximum total volumetric strain. When the bedding angle β is increasing, the trend of crack initiation index behaves like a U-shaped curve, which is to say, the initiation crack indexes have smaller values at the β of 30° or 60° whereas bigger values at the β of 0° or 90°.It can be seen that brittleness is the key factor to rock fracturing. At the β of 30° or 60°, the rock has larger brittleness index with high fracturing variations of brittleness behave as an inverted U-shaped curve. The study of evaluating shale rock fracturing capability and improving the fracturing effect has important practical significance and application value.

       

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