Citation: | WANG Liang,LI Ziwei,ZHENG Siwen,et al. A new method for calculating particle coal matrix scale and its application[J]. Coal Science and Technology,2024,52(2):115−125. DOI: 10.12438/cst.2023-0886 |
There are abundant complex pores in the coal matrix, which provide a large amount of storage space and migration channels for methane. Diffusion is involved in the gas migration from the pore to the fracture. The scale of the matrix determines to some extent the resistance to diffusion into the fracture, influencing the difficulty of methane diffusion. This study took the intrinsic connection between gas diffusion and coal matrix scale as the starting point, the quantitative relationship between methane concentrations and mass exchange rate within the dual pore structure of coal at different desorption moments was obtained by processing the data of the desorption transient process of particle coal. The matrix shape factor was calculated combined with the time-varying diffusion coefficient. A transient diffusion-based matrix scale calculation method for granular coal was proposed and experimentally validated. The results shown that the initial diffusion coefficients of larger particle coals with intact matrix morphology were essentially unchanged compared to smaller particle coals, so the value of the initial diffusion coefficient can characterize the degree of matrix destruction to some extent. The matrix shape factor decreased with the extension of desorption time and can be divided into sharp-decreasing phase, slow-decreasing phase and stable phase, in which the stable phase matrix shape factor can accurately reflect the matrix shape in the proposed steady state at the late stage of diffusion and is the most suitable for solving matrix scale. The method can reflect the change pattern of matrix scale variation during the damage process of granular coal pulverization and provide a basis for explaining the existence of diffusion-limited particle size. The three experimental particle size matrix scales of the Nuodong coal samples increased with the increasing particle size, 0.059 mm, 0.287 mm and 0.457 mm, respectively, and were non-differential in the large particle size range, proving the accuracy of the method. The particle coal matrix scale can be used to correct the calculation parameters of K1 values, rendering the gas loss calculation model equally applicable in coal samples with a high degree of pulverization.
[1] |
XUE Sheng,HUANG Qiming,WANG Gang,et al. Experimental study of the influence of water-based fracturing fluids on the pore structure of coal[J]. Journal of Natural Gas Science and Engineering,2021,88(11):103863.
|
[2] |
赵 伟,王 亮,陈向军,等. 受限空间煤粒瓦斯吸附扩散特性及模型适配差异分析[J]. 煤炭科学技术,2020,48(9):146−151.
ZHAO Wei,WANG Liang,CHEN Xiangjun,et al. Analysis of gas adsorption and diffusion characteristics of coal particles in confined space and model adaptation differences[J]. Coal Science and Technology,2020,48(9):146−151.
|
[3] |
程远平,刘清泉. 煤力学[M]. 北京:科学出版社,2017:74−77.
|
[4] |
程远平,胡 彪. 微孔填充:煤中甲烷的主要赋存形式[J]. 煤炭学报,2021,46(9):2933−2948.
CHENG Yuanping,HU Biao. Main occurrence form of methane in coal:micropore filling[J]. Journal of China Coal Society,2021,46(9):2933−2948.
|
[5] |
LIU Zhengdong,CHENG Yuanping,DONG Jun,et al. Master role conversion between diffusion and seepage on coalbed methane production:implications for adjusting suction pressure on extraction borehole[J]. Fuel,2018,223:373−384. doi: 10.1016/j.fuel.2018.03.047
|
[6] |
唐巨鹏,邱于曼,马 圆. 煤中CH4扩散影响因素的分子动力学分析[J]. 煤炭科学技术,2021,49(2):85−92.
TANG Jupeng,QIU Yuman,MA Yuan. Molecular dynamics analysis of influencing factors of CH4 diffusion in coal[J]. Coal Science and Technology,2021,49(2):85−92.
|
[7] |
卢守青. 基于等效基质尺度的煤体力学失稳及渗透性演化机制与应用[D]. 徐州:中国矿业大学,2016:33−37.
LU Shouqing. Mechanical failure and permeability evolution mechanism of coal based on equivalent matrix scale and its application[D]. Xuzhou:China University of Mining and Technology,2016:33−37.
|
[8] |
ZHOU Fengde,YAO Guangqing. Sensitivity analysis in permeability estimation using logging and injection-falloff test data for an anthracite coalbed methane reservoir in Southeast Qinshui Basin,China[J]. International Journal of Coal Geology,2014,131:41−51. doi: 10.1016/j.coal.2014.05.014
|
[9] |
GUO Haijun,TANG Hanlu,WU Yuchen,et al. Gas seepage in underground coal seams:application of the equivalent scale of coal matrix-fracture structures in coal permeability measurements[J]. Fuel,2021,288:119641. doi: 10.1016/j.fuel.2020.119641
|
[10] |
倪小明,张崇崇,王延斌,等. 气水两相流阶段煤基质收缩量预测方法[J]. 煤炭学报,2014,39(S1):174−178.
NI Xiaoming,ZHANG Chongchong,WANG Yanbin,et al. Prediction of coal matrix shrinkage in gas-water two-phase flow stage[J]. Journal of China Coal Society,2014,39(S1):174−178.
|
[11] |
张遵国,齐庆杰,曹树刚,等. 煤层吸附He,CH4和CO2过程中的变形特性[J]. 煤炭学报,2018,43(9):2484−2490.
ZHANG Zunguo,QI Qingjie,CAO Shugang,et al. Characteristics of coal deformation during its adsorption of He,CH4 and CO2[J]. Journal of China Coal Society,2018,43(9):2484−2490.
|
[12] |
张遵国,赵 丹,陈 毅. 不同含水率条件下软煤等温吸附特性及膨胀变形特性[J]. 煤炭学报,2020,45(11):3817−3824.
ZHANG Zunguo,ZHAO Dan,CHEN Yi. Isothermal adsorption and swelling deformation characteristics of soft coal under different mosisture content[J]. Journal of China Coal Society,2020,45(11):3817−3824.
|
[13] |
FENG Zengchao,ZHOU Dong,ZHAO Yangsheng,et al. Study on microstructural changes of coal after methane adsorption[J]. Journal of Natural Gas Science and Engineering,2016,30:28−37. doi: 10.1016/j.jngse.2016.01.044
|
[14] |
WEI Mingyao,LIU Jishan,ELSWORTH D,et al. Influence of gas adsorption induced non-uniform deformation on the evolution of coal permeability[J]. International Journal of Rock Mechanics and Mining Sciences,2019,114:71−78. doi: 10.1016/j.ijrmms.2018.12.021
|
[15] |
张遵国,陈 毅,唐 朝,等. 煤体CO2吸附/解吸变形特征及变形模型[J]. 煤炭学报,2022,47(8):3128−3137.
ZHANG Zunguo,CHEN Yi,TANG Chao,et al. Deformation characteristics and model of coal adsorption/desorption on CO2[J]. Journal of China Coal Society,2022,47(8):3128−3137.
|
[16] |
周 动,王 辰,冯增朝,等. 煤吸附解吸甲烷细观结构变形试验研究[J]. 煤炭学报,2016,41(9):2238−2245.
ZHOU Dong,WANG Chen,FENG Zengchao,et al. Experiment on the deformation of the meso-structure of coal during the methane adsorption and desorption[J]. Journal of China Coal Society,2016,41(9):2238−2245.
|
[17] |
LIU Zhengdong,LIN Xiaosong,Chengyuanping,et al. Experimental investigation on the diffusion property of different form coal:Implication for the selection of CO2 storage reservoir[J]. Fuel,2022,318:123691. doi: 10.1016/j.fuel.2022.123691
|
[18] |
赵 伟. 粉化煤体瓦斯快速扩散动力学机制及对突出煤岩的输运作用[D]. 徐州:中国矿业大学,2018:55−60.
ZHAO Wei. Diffusion dynamics of rapid desorption of gas from pulverized coal and its influence on transporting coal and rock in outbursts [D]. Xuzhou:China University of Mining and Technology,2018:55−60.
|
[19] |
赵 伟,王 凯,李成武,等. 基于流动扩散互竟关系的基质吸附态瓦斯表观扩散系数实验室测定准确性分析[J]. 煤炭学报,2022,47(2):860−869.
ZHAO Wei,WANG Kai,LI Chengwu,et al. Analysis on the accuracy of laboratory measurement of apparent diffusion coefficient of adsorbed gas in matrix based on the competition relationship between gas flow and gas diffusion[J]. Journal of China Coal Society,2022,47(2):860−869.
|
[20] |
KESHAVARZ A,SAKUROVS R,GRIGORE M,et al. Effect of maceral composition and coal rank on gas diffusion in Australian coals[J]. International Journal of Coal Geology,2017,173:65−75. doi: 10.1016/j.coal.2017.02.005
|
[21] |
李志强,刘 勇,许彦鹏,等. 煤粒多尺度孔隙中瓦斯扩散机理及动扩散系数新模型[J]. 煤炭学报,2016,41(3):633−643.
LI Zhiqiang,LIU Yong,XU Yanpeng,et al. Gas diffusion mechanism in multi-scale pores of coal particles and new diffusion model of dynamic diffusion coefficient[J]. Journal of China Coal Society,2016,41(3):633−643.
|
[22] |
范章群,夏致远. 煤基质形状因子理论探讨[J]. 煤田地质与勘探,2009,37(3):15−18.
FAN Zhangqun,XIA Zhiyuan. The theory solution of matrix factor in coalbed reservoir[J]. Coal Geology & Exploration,2009,37(3):15−18.
|
[23] |
LIU Qiangquan,CHENG Yuanping,WANG Haifeng,et al. Numerical assessment of the effect of equilibration time on coal permeability evolution characteristics[J]. Fuel,2015,140:81−89. doi: 10.1016/j.fuel.2014.09.099
|
[24] |
WANG J G,KABIR A,LIU J S,et al. Effects of non-Darcy flow on the performance of coal seam gas wells[J]. International Journal of Coal Geology,2012,93:62−74. doi: 10.1016/j.coal.2012.01.013
|
[25] |
MORA C A,WATTENBARGER R A. Analysis and verification of dual porosity and cbm shape factors[J]. Journal of Canadian Petroleum Technology,2009,48(2):17−21. doi: 10.2118/09-02-17
|
[26] |
赵 伟,程远平. 煤中瓦斯扩散理论与应用[M]. 徐州:中国矿业大学出版社,2020:177−182.
|
[27] |
薛文涛. 煤粒瓦斯扩散系数随放散时间的变化规律研究[D]. 焦作:河南理工大学,2016:44−47.
XUE Wentao. Study on the variation law of diffusion coefficient of methane from coal particle with diffusion time[D]. Jiaozuo:Henan Polytechnic University,2016:44−47.
|
[28] |
段正鹏,李志强,陈向军,等. 多尺度煤粒与瓦斯多尺度动扩散系数模型特征参数关系研究[J]. 中国安全生产科学技术,2018,14(6):97−102.
DUAN Zhengpeng,LI Zhiqiang,Chen Xiangjun,et al. Study on relationship between multi-scale coal particles and characteristic parameters of gas multi-scale dynamic diffusion coefficient model[J]. Journal of Safety Science and Technology,2018,14(6):97−102.
|
[29] |
程小庆,王兆丰,李志强. 动扩散系数新模型下不同粒径构造煤的瓦斯扩散特征[J]. 中国安全生产科学技术,2016,12(6):88−93.
CHENG Xiaoqing,WANG Fengzhao,LI Zhiqiang. Features of gas diffusion in tectonic coal with different particle sizesby new model of dynamic diffusion coefficient[J]. Journal of Safety Science and Technology,2016,12(6):88−93.
|
[30] |
王然鹏. 基于瓦斯解吸的煤基质形状因子研究[D]. 徐州:中国矿业大学,2019:19−21.
WANG Ranpeng. Study on coal matrix shape factor based on gas desorption[D]. Xuzhou:China University of Mining and Technology,2019:19−21.
|
[31] |
CHANG Mingming. Analytical solutions to single-and two-phase flow problems of naturally fractured reservoirs:theoretical shape factors and transfer functions[M]. Oklahoma:University of Tulsa,1995:115−278.
|
[32] |
SONG Haoran,LIN Baiquan,ZHONG Zheng,et al. Experimental study on methane diffusion kinetics in three typical metamorphic coals[J]. Fuel,2022,311:122601. doi: 10.1016/j.fuel.2021.122601
|
[33] |
程远平,周红星. 煤与瓦斯突出预测敏感指标及其临界值研究进展[J]. 煤炭科学技术,2021,49(1):146−154.
CHENG Yuanping,ZHOU Hongxing. Research progress of sensitive index and critical values for coal and gas outburst prediction[J]. Coal Science and Technology,2021,49(1):146−154.
|
[34] |
孔胜利,程龙彪,王海锋,等. 钻屑瓦斯解吸指标临界值的确定及应用[J]. 煤炭科学技术,2014,42(8):56−59,64.
Kong Shengli,Cheng Longbiao,Wang Haifeng,et al. Determination and application on critical value of drilling cuttings gas desorption indices[J]. Coal Science and Technology,2014,42(8):56−59,64.
|
[35] |
郜 阳,孙晓艳. 不同破坏程度下颗粒煤瓦斯扩散特性试验研究[J]. 安全与环境工程,2016,23(1):112−116.
GAO Yang,SUN Xiaoyan. Experimental study on gas diffusion characteristics of particle coal at different damage degrees[J]. Safety and Environmental Engineering,2016,23(1):112−116.
|
[36] |
程远平,雷 杨. 构造煤和煤与瓦斯突出关系的研究[J]. 煤炭学报,2021,46(1):180−198.
CHENG Yuanping,LEI Yang. Causality between tectonic coal and coal and gas outbursts[J]. Journal of China Coal Society,2021,46(1):180−198.
|
[37] |
贾 靳. 海孜煤矿86采区7#煤层粉化煤体瓦斯解吸规律研究[D]. 徐州:中国矿业大学,2015:1−5.
JIA Jin. Research on gas desorption characteristics of powering coal sample from 7# coal seam of 86 Mining Area of Haizi Coal Mine[D]. Xuzhou:China University of Mining and Technology,2015:1−5.
|
[38] |
李成武,王义林,王其江,等. 直接法瓦斯含量测定结果准确性实验研究[J]. 煤炭学报,2020,45(1):189−196.
LI Chengwu,WANG Yilin,WANG Qijiang,et al. Experimental study on accuracy of direct gas content determination[J]. Journal of China Coal Society,2020,45(1):189−196.
|
[39] |
姜海纳,程远平,安丰华. 淮北矿区煤层瓦斯含量直接测定法中有效取样时间研究[J]. 采矿与安全工程学报,2013,30(1):143−148.
JIANG Haina,CHENG Yuanping,AN Fenghua. Research on effective sampling time in direct measurement of gas content in Huaibei coal seams[J]. Journal of Mining & Safety Engineering,2013,30(1):143−148.
|