外加压力液影响含瓦斯煤解吸特性实验研究

发布时间：2018-07-21 09:48

【摘要】：煤层注水是防治煤与瓦斯突出的重要技术措施之一,但是目前对其防突机理的认识并不深入,主要表现之一就是对注水影响煤的瓦斯解吸效应存在分歧,本文针对该问题主要采用实验研究和理论分析的方法对外加压力液对含瓦斯煤解吸特性的影响进行研究。在实验煤样的制备、煤样基础参数测试以及表面活性剂优选的基础上,利用自制的高压注水煤层气恒温解吸实验台,对不同注水压力、不同吸附平衡压力、不同注入溶液以及不同变质程度煤样的瓦斯解吸过程进行了测试,然后,测试了不同注水压力下煤样的含水率、残存瓦斯含量和孔隙结构特征,并结合宏观的实验现象和理论分析,从微观上探讨了外加压力液对含瓦斯煤解吸特性的影响机理。实验结果表明:(1)加压注水后,瓦斯的累计解吸量和解吸速度均降低,并且注水压力越大,降低幅度越大,煤样含水率和残存瓦斯含量越大;除微孔孔容在注水前后变化不明显外,煤样的大孔、中孔和小孔孔容在注水后都增大,其总孔容、平均孔径和孔隙率也出现不同程度的增加;综合分析后认为压力水扩孔产生的毛细管力降低作用小于孔隙尺度加深产生的毛细管力增加作用,毛细管力整体增大,对瓦斯解吸过程的阻碍作用增强,导致压力水抑制瓦斯解吸作用更为明显;(2)吸附平衡压力越大,煤样吸附瓦斯量就越大,而且注水过程对压力水的阻碍作用越强,压力水能够进入的孔隙尺度越大,毛细管力则越小,对瓦斯解吸的抑制作用越弱,累计解吸量和解吸速度也就越大;(3)和注纯水相比,注复配的表面活性剂溶液AES+CaCl_2(0.4+0.4)增大了毛细管力,进入的孔隙尺度更深并且解吸过程阻力更大,对瓦斯解吸的抑制作用更强,累计解吸量和解吸速度也就越小;(4)煤的变质程度越高,吸附瓦斯的能力越强,其吸附量就越大,注水后更易形成较高压力的瓦斯气体,克服毛细管阻力的能力越强,累计解吸量和解吸速度也就越大。
[Abstract]:Water injection in coal seam is one of the important technical measures to prevent coal and gas outburst, but the understanding of its mechanism is not deep. One of the main manifestations is the disagreement on the effect of gas desorption on the effect of water injection. This paper mainly adopts the method of experimental research and theoretical analysis to add pressure liquid to gas coal. On the basis of the preparation of the experimental coal samples, the testing of the basic parameters of coal samples and the optimization of the surface active agents, the gas desorption process of different water injection pressure, different adsorption equilibrium pressure, different injection solution and different metamorphic coal samples was made on the basis of the experimental coal sample preparation, the test of coal sample base parameters and the optimization of the surface active agent. After testing, the water content of coal samples under different water injection pressure, residual gas content and pore structure characteristics are tested, and combined with macroscopic experimental phenomena and theoretical analysis, the influence mechanism of applied pressure liquid on the desorption characteristics of gas containing coal is discussed from microcosmic. The experimental results show that (1) the accumulative desorption amount of gas after pressurized water injection The greater the water injection pressure, the greater the water injection pressure, the greater the reduction, the greater the water content and the residual gas content of the coal samples; the large pores, mesoporous and pore volume of coal samples increase after water injection, and the total pore volume, the average pore size and porosity also increase in different degrees except for the pore volume in the water injection. After analysis, the effect of capillary force reduction produced by pressure water enlargement is less than the increase of capillary force resulting from the deepening of pore scale, the capillary force is increased as a whole, the hindering effect of gas desorption process is enhanced, and the effect of pressure water to suppress gas desorption is more obvious; (2) the greater the pressure of adsorption equilibrium, the larger the coal sample is to adsorb gas. Moreover, the more the water injection process has hindered the pressure water, the larger the pore size is, the smaller the pore size of the pressure water, the smaller the capillary force, the weaker the inhibition of the gas desorption, the greater the accumulative desorption and desorption speed. (3) the capillary force is increased by the surfactant solution AES+CaCl_2 (0.4+0.4), which is injected and mixed with pure water. The deeper pore size and greater resistance to the desorption process, stronger inhibition of gas desorption, the smaller the accumulative desorption and desorption speed; (4) the higher the degree of coal modification, the stronger the ability to adsorb gas, the greater the adsorption capacity, the more easily formed gas gas after water injection, and the stronger the ability to overcome the capillary resistance. The greater the amount of absorption and desorption is.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD713.3

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