电场实时加载下煤层气解吸-扩散特性实验研究

    Experimental study on desorption diffusion characteristics of coalbed methane under real time electric field loading

    • 摘要: 为探究电场实时加载下煤层气解吸-扩散特性,揭示电场强化煤层气高效抽采的机理影响特征,设计并研发了可控电场强度下煤层气解吸-扩散实验系统;实验探究了电场加载下煤体的CH4和CO2解吸-扩散变化特征,并通过幂函数扩散模型计算各场强作用下的CH4扩散系数。结果表明:不同吸附质在电场实时加载下煤层气解吸量均得到一定程度提升,但电场对CO2解吸量影响特征更加明显,同时电场能够强化煤体瓦斯的初始解吸速度;与未加电场相比,特征场强为30、60、90 kV/m时CH4初始解吸速率提升了6.9%、15.3%、14.6%,而CO2依次提升了3.4%、6.7%、9.2%;电场加载下煤体CH4幂函数扩散模型能够高度的与实验值相吻合,扩散系数具有随着加载场强的增大而逐渐增大变化特征,电场有利于煤中甲烷的解吸、扩散。

       

      Abstract: In order to explore the desorption diffusion characteristics of coalbed methane under real-time electric field loading and reveal the effect of electric field on efficient extraction of coalbed methane, the desorption diffusion test system of coal under controllable electric field strength was designed and developed independently. The desorption diffusion characteristics of CH4 and CO2 in coal under electric field loading were investigated experimentally, and the diffusion coefficient under each electric field strength was calculated by power function diffusion model. The results show that: under the real-time loading of electric field, the desorption capacity of coal is improved to a certain extent, but the influence of electric field on the desorption capacity of CO2 is more obvious. At the same time, the electric field can strengthen the initial desorption speed of coal gas. Compared with no electric field, the initial desorption speed of CH4 increases by 6.9%, 15.3%, 14.6% when the characteristic field strength is 30, 60, 90 kV/m, and the CO2 increases by 3.4%, 6.7%, 9.2%; on the other hand, the results of power function diffusion of CH4 in coal under electric field loading show that the diffusion model can be highly consistent with the experimental values, and the diffusion coefficient increases with the increase of the loading field strength. The electric field is conducive to the desorption and diffusion of methane in coal.

       

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