注气驱替中CO2置换煤体CH4行为特性

李菁华, 张磊, 薛俊华, 张村, 黄梦牵

李菁华, 张磊, 薛俊华, 等. 注气驱替中CO2置换煤体CH4行为特性[J]. 煤炭学报, 2021, 46(S1): 385-395. DOI: 10.13225/j.cnki.jccs.2020.1134
引用本文: 李菁华, 张磊, 薛俊华, 等. 注气驱替中CO2置换煤体CH4行为特性[J]. 煤炭学报, 2021, 46(S1): 385-395. DOI: 10.13225/j.cnki.jccs.2020.1134
LI Jinghua, ZHANG Lei, XUE Junhua, et al. Characteristic of binary gas displacement adsorption on coal in CO2-ECBM[J]. Journal of China Coal Society, 2021, 46(S1): 385-395. DOI: 10.13225/j.cnki.jccs.2020.1134
Citation: LI Jinghua, ZHANG Lei, XUE Junhua, et al. Characteristic of binary gas displacement adsorption on coal in CO2-ECBM[J]. Journal of China Coal Society, 2021, 46(S1): 385-395. DOI: 10.13225/j.cnki.jccs.2020.1134

注气驱替中CO2置换煤体CH4行为特性

基金项目: 

国家自然科学基金资助项目(51704274,51974239)

中国科协“青年人才托举工程”资助项目(2017QNRC001)

北京市自然科学基金资助项目(8184082)

详细信息
    作者简介:

    李菁华(1997-),男,河南襄城人,硕士研究生。E-mail:ljhcumt@cumt.edu.cn

    通讯作者:

    薛俊华(1963-),男,江苏泰州人,教授,博士生导师。E-mail:xuejunhua2003@163.com

  • 中图分类号: P618.11

Characteristic of binary gas displacement adsorption on coal in CO2-ECBM

  • 摘要: 在注气驱替过程中,渗流驱赶和注气置换是促采煤层气的关键作用。为研究注气置换作用的行为特性,以注气驱替尾气CH4体积分数变化特征值为控制参数,在竞争吸附试验基础上,设计了研究注气置换作用的动态置换试验及对照试验。通过对比2类试验结果,发现注气置换作用可细分为压力势差和注气强化CH4解吸2种子作用,并分析了2种子作用的变化特性,最终构建了描述动态置换行为的函数表达式。研究结果表明:①动态置换试验中共解吸CH4 0.024 098 mol,变压解吸试验中共解吸CH4 0.017 855 mol,注CO2有效提高了煤体CH4解吸量。②在压力势差作用下,固定时间内煤体CH4的解吸总量随试验的进行呈先上升后下降的趋势;CO2强化解吸作用则主要集中在试验初期,并随试验进行而快速衰减。③综合压力势差和强化解吸2种子作用,对动态置换试验进行拟合分析,得到的拟合曲线呈现出先下降后上升、再下降的双峰值复杂趋势;④分析发现2种子作用相对强弱关系的转变,是动态置换试验拟合曲线呈现双峰特征的本质原因。
    Abstract: The stripping effect and displacement effect are two key effects in ECBM technique(injected gas for enhanced coal bed methane recovery).In order to study the changing characteristic of the displacement effect, the characteristic values of the CH4 partial pressure with the time step which occurs in the fracture system during ECBM has been refined.With the characteristic curve, the dynamic displacement adsorption experiment and the controlled experiment have been designed based on the the long-term displacement adsorption test methodology.It is found that the pressure gradient of CH4 and the desorption enhancement of CH4 by CO2 are two basic functions in the displacement effect, by comparing two test results.The changing characteristics of two basic functions have been studied with test results.Finally, the mathematic form of the displacement effect has been built.It is shown that① 0.017 855 mol CH4 has transformed into free state from adsorbed state in the desorption test, and 0.024 098 mol in the dynamic displacement adsorption test.The differences prove that CH4 has been effectively promoted by strongly adsorbed gas CO2.② The production rate of CH4 which driven by pressure gradient, first increases at the initial stage and then decreases at the last stage.The production rate of CH4 is proportional to the pressure difference between the CH4 partial pressure with the initial adsorption pressure, and is inversely proportional to the slope of the characteristic curve(negative) of the CH4 partial pressure.③ With the test results it is found that the desorption enhancement of CO2 is concentrated in the initial stage and gradually decays as the test operates.With the first derivative function of EX-Langmuir function to the CH4 partial pressure, it is found that the essence of the desorption enhancement of CO2 is that CO2 has an effect on reducing the adsorption capacity of coal for CH4.As the increase of the CO2 partial pressure, that effect has been constantly enhanced, but the extent of enhancement is decreasing.④ By combined the function of pressure gradient and the function of the desorption enhancement of CO2,the dynamic displacement adsorption test result has been fitted, which exhibits a complex trend of down, rise, and down.The transformed relationship of two functions is the essential reason of the double peak of the fitted curve.
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    6. 周西华,韩明旭,白刚,兰安畅,付志豪. CO_2注气压力对瓦斯扩散系数影响规律实验研究. 煤田地质与勘探. 2021(01): 81-86+99 . 百度学术
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    其他类型引用(12)

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出版历程
  • 收稿日期:  2020-07-02
  • 修回日期:  2020-08-07
  • 网络出版日期:  2023-05-23

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