煤中可溶有机质对煤与瓦斯突出危险的影响研究

发布时间：2018-08-31 13:10

【摘要】：煤是一种复杂的有机岩石,除含大分子固体骨架外,还含大量可溶于有机溶剂的小分子有机物,它们存在于煤基质的孔隙甚至大分子网络结构中,必然会对煤层煤与瓦斯突出危险产生一定影响。本文立足于煤体结构,在测试全煤样和抽提残煤的孔隙结构、瓦斯吸附特性、力学强度参数等方面基础上,深入分析了可溶有机质对突出参数的影响规律,进而揭示了其对煤与瓦斯突出危险的作用机制。采用四氢呋喃溶剂对3种不同变质程度的煤样分别进行微波辅助抽提,得到抽提物(可溶有机质)与抽提余物(抽提残煤)。采用N2吸附法系统地测试了全煤样和抽提残煤孔隙结构参数。结果表明,可溶有机质被抽提后,煤体总孔体积增大,比表面积减少,平均孔径增大,起到了增孔、扩孔作用,说明煤中可溶有机质抽提后,简化了煤孔隙结构,降低了煤中微小孔比例,使煤体结构相对简单化。开展了抽提前后煤样的甲烷等温吸附实验,分析了抽提前后各煤样对甲烷的吸附特性变化规律。结果表明,抽提抽提残煤的甲烷吸附量均低于全煤样,说明煤中小分子有机物的存在可提高煤吸附甲烷的能力。通过抽提前后煤体的抗压强度、抗拉强度等力学实验,研究了可溶有机质对煤体力学性能的影响。结果表明,3种不同变质程度煤样的抽提残煤,在相同实验条件下其煤体抗压强度、抗拉强度及弹性模量均高于全煤样,且突出煤抽提前后力学性质参数变化明显。表明可溶有机质被溶出后,使煤体蠕变能力减弱,简化了煤的孔隙结构,使煤基质的内部孔隙趋于均相化和简单化,降低了煤层煤与瓦斯突出的危险性。实验室模拟测试了抽提前后煤体的煤与瓦斯突出参数,分析了煤体抽提前后其突出参数指标的变化规律。结果表明,抽提残煤的瓦斯含量、瓦斯放散初速度、瓦斯钻屑解吸指标K1值及△h2等突出参数指标均比全煤样小。说明煤中可溶有机质的存在对煤与瓦斯突出有一定的促进作用。根据可溶有机质对煤体孔隙结构、吸附特性和力学性质等参数的影响规律,深入分析了可溶有机质对突出参数指标的耦合关系,进而揭示了煤中可溶有机质对煤与瓦斯突出的作用机制,研究成果对进一步降低煤层煤与瓦斯突出危险性的相关技术具有一定的指导意义。
[Abstract]:Coal is a kind of complex organic rock, which contains not only macromolecular solid skeleton, but also a large number of small molecular organic compounds soluble in organic solvents, which exist in the pores of coal matrix and even in the network of macromolecules. The danger of coal seam and gas outburst will be affected. Based on the coal structure, the influence of soluble organic matter on the outburst parameters is deeply analyzed on the basis of testing the pore structure of whole coal sample and extracting residual coal, gas adsorption characteristics, mechanical strength parameters and so on. The mechanism of its action on the danger of coal and gas outburst is revealed. Three kinds of coal samples with different degrees of metamorphism were extracted by microwave assisted extraction with tetrahydrofuran solvent, and the extractives (soluble organic matter) and residue (extraction of residual coal) were obtained. The pore structure parameters of whole coal sample and extracted residual coal were systematically measured by N2 adsorption method. The results show that when the soluble organic matter is extracted, the total pore volume of coal body increases, the specific surface area decreases, the average pore size increases, and the pore size increases, which indicates that the pore structure of coal is simplified after the extraction of soluble organic matter in coal. The ratio of micropore in coal is reduced, and the coal structure is relatively simplified. The isothermal adsorption experiments of methane from coal samples before and after extraction were carried out, and the characteristics of methane adsorption of coal samples before and after extraction were analyzed. The results show that the methane adsorption capacity of the residual coal is lower than that of the whole coal sample, which indicates that the presence of small molecular organic compounds in the coal can improve the methane adsorption capacity of the coal. The influence of soluble organic matter on the mechanical properties of coal was studied by mechanical experiments such as compressive strength and tensile strength of coal before and after extraction. The results show that the compressive strength, tensile strength and elastic modulus of the three kinds of coal samples with different metamorphic degrees are higher than those of the whole coal samples under the same experimental conditions, and the mechanical properties of the coal samples before and after extraction are obviously changed. The results show that the soluble organic matter can weaken the creep ability of coal body, simplify the pore structure of coal, make the internal pores of coal matrix homogenize and simplify, and reduce the danger of coal and gas outburst in coal seam. The parameters of coal and gas outburst before and after extraction were tested by laboratory simulation, and the variation law of outburst parameters before and after extraction was analyzed. The results show that the gas content, the initial velocity of gas release, the K1 value of gas drilling debris desorption index and the outburst parameters such as H2 are smaller than those of the whole coal sample. It shows that the existence of soluble organic matter in coal can promote coal and gas outburst to some extent. According to the influence of soluble organic matter on pore structure, adsorption characteristics and mechanical properties of coal body, the coupling relationship of soluble organic matter to outburst parameters is analyzed. The mechanism of the action of soluble organic matter in coal on coal and gas outburst is revealed. The research results have certain guiding significance for further reducing the risk of coal and gas outburst in coal seam.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD713

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