摘要
考虑煤层气解吸引起的温度变化及其对后续吸附气体的解吸、游离气体状态的影响,及气体扩散系数的动态变化及修正系数对窜流项的影响,基于孔隙-裂隙双重介质模型建立了煤层中气体解吸-扩散-渗流过程的气-固-热耦合模型,开展了煤层气抽采过程的数值模拟与机理分析。研究结果表明:(1)修正窜流项后的气-固-热耦合双重介质模型相对于窜流项修改前的模型与试验结果更为接近;(2)未修正Langmuir模型考虑了温度降低及其对气体扩散、渗流过程的影响,但没有考虑温度降低对气体解吸量的影响,会导致煤层气抽采量估计值偏大;(3)各向同性模型有可能得到与各向异性模型一致的气体含量曲线,但气体含量分布存在显著差异,渗透率各向异性导致的煤层整体在某方向的渗流优势要大于抽采孔布置形式导致的渗流优势;(4)扩散系数较高时,渗流过程是影响煤层气抽采效率的制约环节,必须考虑渗透率的各向异性特征对气体运移全过程的影响。
Considering the temperature change caused by desorption of coal-bed methane and its influence on desorption and free gas state of subsequent adsorption gas, dynamic change of gas diffusion coefficient and influence of correction coefficient on the interchanneling term, a gas-solid-thermal coupling model for desorption-diffusion-seepage process of coal-bed methane was established based on the pore-fracture dual medium model. The numerical simulation and mechanism analysis of the coal-bed methane extraction process were carried out. The results are concluded as follows. Firstly, compared with the model before the modification of the interchanneling term, the gas-solid-thermal coupling dual-medium model with the modified interchanneling term is closer to the experimental results. Secondly, the uncorrected Langmuir model considers the influence of temperature reduction on gas diffusion and seepage process, but does not consider its influence on gas desorption, which will lead to the large estimated value of coal-bed methane extraction. Thirdly, it is possible for isotropic model to get the same gas content curve as anisotropic model, but there is a significant difference in the distribution of gas content. The seepage advantage of coal seam in a certain direction caused by permeability anisotropy is greater than that caused by the layout of drainage holes. Fourthly, when the diffusion coefficient is high, the seepage process is the restriction link which affects the extraction efficiency of coal-bed methane. Thus, the influence of permeability anisotropy on the whole process of gas migration must be considered.
作者
刘泽源
魏晨慧
刘书源
张哲
张淼
LIU Zeyuan;WEI Chenhui;LIU Shuyuan;ZHANG Zhe;ZHANG Miao(School of Resources and Civil Engineering,Northeastern University,Shenyang,Liaoning 110819,China)
出处
《矿业研究与开发》
CAS
北大核心
2021年第6期97-104,共8页
Mining Research and Development
基金
国家自然科学基金资助项目(51304037,51761135102)
中央高校基本科研业务专项资金资助项目(N2101038)。
作者简介
刘泽源(1992-)男,天津人,硕士研究生,主要从事煤层气开采技术研究,E-mail:3237873344@qq.com;通信作者:魏晨慧(1984-)男,山西长治人,博士,副教授,主要从事岩石力学多物理场耦合理论研究,E-mail:weichenhui@mail.neu.edu.cn。
