瓦斯事故是影响煤炭安全开采的主要灾害之一。低渗透性煤层瓦斯抽采难度大、效率低，一般采用CO₂驱替煤层瓦斯技术进行治理。然而，在CO₂驱替煤层瓦斯过程中，CO₂的扩散规律将会显著影响瓦斯驱替量以及抽采效率。鉴于此，本文利用理论分析、物理实验、分子模拟等手段。开展了煤的压汞实验、煤吸附CO₂实验，主要研究了压力和温度对CO₂在煤体内扩散规律的影响；结合分子模拟，对物理模拟实验得到的扩散规律进行验证。取得的主要研究成果如下：

（1）对实验煤样进行压汞实验测试，按照霍多特提出的孔隙分类方法，分析得到了实验煤样孔容主要以过渡孔和微孔为主，占比39.43%和57.58%，其次是大孔和中孔。

（2）不同温度下，CO₂气体的吸附曲线与Langmuir单分子层吸附模型一致。相同温度条件下，随着压力的增大，煤体对CO₂气体的吸附量增大；吸附常数a值与b值均随温度升高而减小。

（3）柱状原煤CO₂气体扩散的物理模拟实验过程中。压力恒定条件下，随着环境温度的上升，CO₂累计扩散量随着扩散时间的延长逐渐增加；CO₂扩散速度随时间的增加逐渐降低；CO₂扩散系数随着温度的升高而逐渐增大。温度恒定条件下，随着压力的增大，CO₂累计扩散量随着扩散时间的延长逐渐增加；CO₂扩散速度随时间的增加逐渐降低；CO₂扩散系数随着压力的增大而逐渐增加。

（4）基于分子模拟的CO₂在煤分子中的吸附和扩散过程中。当模拟温度为15℃、25℃、30℃、35℃时，采用巨正则蒙特卡洛方法，计算得到煤分子分别可以吸附14个、13个、12个、11个CO₂分子；随着温度的增大，CO₂在煤分子中的吸附量逐渐降低。CO₂在煤分子中的自扩散系数、校正扩散系数和传递扩散系数，均随着温度、压力的升高而增大。

Gas accident is one of the main disasters that affect the safety of coal mining. Gas extraction in low permeability coal seams is difficult and inefficient, so CO₂ displacing coalbed methane technology is generally used to control gas in coal seams. However, in the process of CO₂ displacing coalbed methane, the diffusion of CO₂ will significantly affect the gas displacement volume and extraction efficiency. In view of this, this paper usesd theoretical analysis, physical experiment, molecular simulation and other means, and carried out the mercury injection experiment and CO₂ adsorption experiment of coal. The influence of pressure and temperature on CO₂ diffusion in coal was mainly studied. Combined with molecular simulation, the diffusion law obtained from physical simulation experiment was verified. The main research results are as follows:

The mercury injection test was conducted on the experimental coal sample. According to the pore classification method proposed by Hodote, the pore volume of the experimental coal sample was mainly composed of transition pores and micropores, accounting for 39.43% and 57.58%, followed by macropores and mesopores.

The adsorption curves of CO₂ gas at different temperatures are consistent with the Langmuir monolayer adsorption model. At the same temperature, with the increase of pressure, the adsorption capacity of CO₂ gas increases. Both a and b values of adsorption constants decreased with the increase of temperature.

In the physical simulation experiment process of CO₂ gas diffusion in columnar raw coal, under constant pressure, with the increase of ambient temperature, the cumulative diffusion of CO₂ gradually increases with the extension of diffusion time. The diffusion velocity of CO₂ decreases with time. The diffusion coefficient of CO₂ increases with the increase of temperature. Under constant temperature, with the increase of pressure, the cumulative diffusion of CO₂ gradually increases with the extension of diffusion time. The diffusion velocity of CO₂ decreases with time. The diffusion coefficient of CO₂ increases gradually with the increase of pressure.

The adsorption and diffusion process of CO₂ in coal molecules based on molecular simulation. When the simulated temperature is 15℃, 25℃, 30℃ and 35℃, the coal molecules can adsorb 14, 13, 12 and 11 CO₂ molecules respectively by using Grand Canonical Monte Carlo (GCMC). With the increase of temperature, the adsorption amount of CO₂ in coal molecules decreases gradually. The self-diffusion coefficient, corrected diffusion coefficient and transfer diffusion coefficient of CO₂ in coal molecules all increase with the increase of temperature and pressure.

[1] 本刊编辑部.辉煌“十三五”奋进再出发[J].中国勘察设计,2020(12):5.

[2] 王利宁,彭天铎,向征艰,等.碳中和目标下中国能源转型路径分析[J].国际石油经济,2021,29(01):2-8.

[3] 朱彤,王蕾.国家能源转型:德,美实践与中国选择[M].浙江:浙江大学出版社,2015.

[4] 中国人民共和国统计局.2019年煤炭行业统计公报[R].2019.

[5] 朱云飞,王德明,李德利,等.2000-2016年我国煤矿重特大事故统计分析[J].能源与环保,2018,40(09):40-43.

[6] 诸利一,吕文生,杨鹏,等.2007-2016年全国煤矿事故统计及发生规律研究[J].煤矿安全,2018,49(07):237-240．

[7] 蒋星星,李春香.2013-2017年全国煤矿事故统计分析及对策[J].煤炭工程,2019,51(01):101-105.

[8] 张盈盈,郭巍,潘志栋.2017年我国煤矿死亡事故统计分析[J].内蒙古煤炭经济,2018(20):104-107.

[9] 兰泽全,李刚强.煤矿特别重大事故统计分析[J].华北科技学院学报,2017,14(02):72-77.

[10] 黄展博.结构异性煤体受载损伤演化特征及瓦斯流动规律研究[D].徐州:中国矿业大学,2018.

[11] 涂敏.低渗透性煤层群卸压开采地面钻井抽采瓦斯技术[J].采矿与安全工程学报,2013,30(5):766-772.

[12] Yuan Liang. Theory and practice of integrated coal production and gas extraction[J]. International Journal of Coal Science & Technology,2015,2(1):3-11.

[13] 李桂波,冯增朝,王彦琪,等.高瓦斯低透气性煤层不同瓦斯抽采方式的研究[J].地下空间与工程学报,2015,11(5):1362-1366.

[14] Wang Jiachen,Wu Renlun,Zhang Peng. Characteristics and applicationsof gas desorption with excavation disturbances in coal mining[J]. International Journal of Coal Science &Technology,2015,2(1):30-37.

[15] 袁亮,薛俊华,张农,等.煤层气抽采和煤与瓦斯共采关键技术现状与展望[J].煤炭科学技术,2013,41(9):6-11,17．

[16] 孙茂远,范志强.中国煤层气开发利用现状及产业化战略选择[J].天然气工业,2007,27(3):1-5.

[17] 车遥,黄文辉,刘大锰,等.中国煤层气资源开发的关键性问题及前景[J].石油天然气学报,2006,28(1):29-31.

[18] 程远平,俞启香,周红星,等.煤矿瓦斯治理-先抽后采的实践与作用[J].采矿与安全工程学报,2006,23(4):389-342.

[19] 刘金海,姜福兴,王乃国,等.深井特厚煤层综放工作面区段煤柱合理宽度研究[J].岩石力学与工程学报.2012.31(5):921-927.

[20] 董文敏.高瓦斯矿大采高工作面区段煤柱尺寸合理确定[J].煤炭科学技术,2007,35(12):67-70.

[21] 谢广祥,王磊,常聚才.煤柱宽度对综放工作面巷道位移的影响规律[J].煤炭科学技术,2008,36(12):28-30,45.

[22] 张宝安,黄明利,梁宏友.窄煤柱护巷机理的数值模拟分析[J].辽宁工程技术大学学报,2006,22(S1):91-92.

[23] 张开智,韩承强,李大勇,等.大小护巷煤柱巷道采动变形与小煤柱破坏演化规律[J].山东科技大学学报:自然科学版,2006,25(4):6-9.

[24] Han F.,Busch A.,Krooss B.M.,et al.CEU and CO2 sorption isotherms and kinetics for different size fractions of two coals[J].Fuel,2013,108:137-142.

[25] Yalcin E.,Durucan Methane capacities of Zonguldak coals and efactors affecting methane adsorption[J].Mining Science and Technology,1991,13(2):215-22.

[26] 王亮,程龙彪,蔡春城,等.岩浆热事件对煤层变质程度和吸附-解吸特性的影响[J].煤炭学报,2014,39(07):1275-1282.

[27] 孙瑞洁,贾喆,单亚飞,等.阻化剂对矿井采空区CO2封存与防火影响[J].辽宁工程技术大学学报(自然科学版),2020,39(05):409-415.

[28] Busch A.,Gensterblum Y.,Krooss B.M,et al.Methane and carbon dioxide adsorption-diffusion experiments on coal:upscaling and modeling[J].Intemational Journal of Coal Geology,2004,60(2-4):152-168.

[29] Gamson P.,Beamish B.Coal type,microstructure and gas flow behaviour of Bowen Basin coals[C].Symposium on coalbed methane research and development in Australia,1992.

[30] 张松航,张守仁,唐书恒,等.无烟煤中甲烷和二氧化碳混合气吸附运移规律[J].煤炭学报,2021,46(02):544-555.

[31] 苏现波,宋金星,郭红玉,等.煤矿瓦斯抽采增产机制及关键技术[J].煤炭科学技术,2020,48(12):1-30.

[32] Day S, Robyn Fry R S. Swelling of Australian coals in supercritical CO2[J]. International Journal of Coal Geology, 2008, 74(1):41-52.

[33] Kelemen S,Kwiatek L. Physical properties of selected block Argonne Premium bituminous coal related to CO2, CH4, and N2 adsorption[J]. International Journal of Coal Geology, 2009.

[34] 严伟.超临界CO2入无烟煤储层引起的渗透率变化模拟研究[D].中国矿业大学,2016.

[35] Hol S., Gensterblum Y., Spiers coal: A new technique compared with the C. J. Direct determination of total CO2 uptake by manometric method[J]. Fuel, 2013, 105: 192-205.

[36] Marecka A., Mianowski A. Kinetics of CO2 and CH4 sorption on high rank coal at ambient temperatures[J]. Fuel, 1998, 77 (14): 1691 1696.

[37] Li D., Liu Q,Weniger P., et al. High-pressure sorption isotherms and sorption kinetics of CH4 and CO2 on coals[J]. Fuel, 2010, 89 (3): 569-580.

[38] 童谣. CO2置换煤层CH4实验与驱替规律研究[D].辽宁工程技术大学,2019.

[39] Charriere D., Pokryszka Z., Behra P. Effect of pressure and temperature on diffusion of CO2 and CH4 into coal from the Lorraine basin (France)[J]. International Journal of Coal Geology, 2010, 81 (4): 373-380.

[40] Busch A., Gensterblum Y. CBM and CO2-ECBM related sorption processes in coal: a review[J].International Journal of Coal Geology, 2011,87 (2): 49-71.

[41] 杨志荣.煤焦与H2O和CO2的气化反应特性及动力学研究[D].太原理工大学,2016.

[42] 罗明坤,李胜,荣海,等.CH4与N2,CO2间竞争吸附关系的核磁共振实验研究[J].煤炭学报,2018,43(02):490-497.

[43] Ciembroniewicz A., Marecka A. Kinetics of CO2 sorption for two Polish coals[J]. Fuel, 1993, 72 (3): 405-408.

[44] Jian X., Guan P., Zhang W. Carbon dioxide sorption and diffusion in coals: Experimental investigation and modeling[J]. Science China Earth Sciences, 2012, 55 (4): 633-643.

[45] Pone J. D. N., Halleck P. M., Mathews J. P. Sorption capacity and sorption kinetic measurements of CO2 and CH4 in confined and unconfined bituminous coal[J]. Energy&Fuels, 2009, 23 (9): 4688-4695.

[46] Svabova M., Weishauptova Z., Piibyl O. The effect of moisture on the sorption process of CO2 on coalfJl. Fuel, 2012, 92 (1): 187-196.

[47] Siemons N., Wolf K.-H. A., Bruining J. Interpretation of carbon dioxide diffusion behavior in coals[J]. International Journal of Coal Geology 2007. 72(3): 315-324.

[48] 程波,熊云威.煤体瓦斯扩散系数测定方法的研究进展[J].矿业安全与环保,2018,45(02):106-110.

[49] 刘彦伟,魏建平,何志刚,等.温度对煤粒瓦斯扩散动态过程的影响规律与机理[J].煤炭学报,2013,38(S1):100-105.

[50] 张登峰,崔永君,李松庚,等.甲烷及二氧化碳在不同煤阶煤内部的吸附扩散行为[J].煤炭学报,2011, 36 (10): 1693-1698.

[51] Shen J., Qin Y., Fu X., et al. Study of high-pressure sorption of methane on Chinese coals of different rank[J].Arabian Journal of Geosciences, 2014, 8 (6): 3451-3460.

[52] 王倩倩.超临界二氧化碳流体对煤体理化性质及吸附性能的作用规律[D].昆明理工大学,2016.

[53] Tang X., Li Z., Ripepi N., et al. Temperature-dependent diffusion process of methane through dry crushed coal[J]. Journal of Natural Gas Science and Engineering, 2015,22: 609-617.

[54] 李志强,段振伟,景国勋.不同温度下煤粒瓦斯扩散特性试验研究与数值模拟[J].中国安全科学学报,2012, 22 (4): 38-42.

[55] 杨鑫,张俊英,王公达,等.瓦斯压力对瓦斯在煤中扩散影响的实验研究[J].中国矿业大学学报,2019,48(03):503-510+519.

[56] Cui X., Bustin R. M., Dipple G.insights from modeling of experimental gas Selective transport adsorption data of CO2, CH4,and N2 in coals[J]. Fuel, 2004, 83 (3): 293-303.

[57] 李希建,薛海腾,陈刘瑜,等.贵州地区突出煤层微孔结构及对瓦斯流动特性的影响[J].煤炭科学技术,2020,48(10):67-74.

[58] 韩思杰.深部无烟煤储层CO2-ECBM的CO2封存机制与存储潜力评价方法[D].中国矿业大学,2020.

[59] 张开仲.构造煤微观结构精细定量表征及瓦斯分形输运特性研究[D].中国矿业大学,2020.

[60] 任建刚,翁红波,宋志敏,等,吕闰生.强变形构造煤等静压原煤柱状煤样制作方法[J].煤矿安全,2018,49(06):66-69.

[61] 刘清泉.多重应力路径下双重孔隙煤体损伤扩容及渗透性演化机制与应用[D].中国矿业大学,2015.

[62] 任建刚.华北中南部中高煤级构造煤瓦斯扩散规律及控制机理研究[D].河南理工大学,2016.

[63] 张慧.原总隙的成因类型及其研究[J].原炭学报,2001,26(1): 40-44.

[64] 傅雪海,秦勇,韦重韬.原层气地质学[M].徐州:中国矿业大学出版社,2007.

[65] 吴世跃.原层中的祸合运动理论及其应用-具有吸附作用的气固祸合运动理论[M].北京:科学出版社,2009.

[66] 刘爱华,傅雪海,梁文庆,等.不同原阶原总隙分布特征及其对原层气开发的影响[J].原炭科学技术,2013, 41(4): 104-107.

[67] 安士凯,桑树勋,李仰民等.沁水盆地南部高原级原储层总隙分形特征[J].中国原炭地质,2011, 23(2): 17-21.

[68] 姜波,踞宜文.原造原原原及其储层物性特征[J].天然气工业,2004, 24(5): 27-29.

[69] 琚宜文,姜波,侯泉林等.华北南部原造原纳米级总隙原原演化特征及作用机理[J].地质学报,2005,79(2):269-285．

[70] 傅雪海,秦勇,张万红等.基于原层气运移的原总隙分形分类及自然分类研究[J].科学通报,2006,50(B10): 51-55.

[71] 刘正.低渗透煤层微观孔隙结构研究及应用[D].西安科技大学,2013.

[72] 秦勇,徐志伟,张井.高原级原总径原原的自然分类及其应用[J].原炭学报,1995,20(3): 266-271.

[73] 刘世奇,王鹤,王冉,等,Ashutosh Tripathy.煤层孔隙与裂隙特征研究进展[J].沉积学报,2021,39(01):212-230.

[74] 霍永忠,张爱云.原层气储层的显微总碎隙成因分类及其应用[J].煤田地质与勘探,1998,26(6): 28-32.

[75] 赵华伟,宁正福,赵天逸,等.恒速压汞法在致密储层孔隙结构表征中的适用性[J].断块油气田,2017,24(03):413-416.

[76] 秦勇.中国高原级原的显微岩石学特征及原原演化[M].徐州:中国矿业大学出版社,1994.

[77] 王原维,陈钟惠,张明,等.原储层岩石物理研究与原层气勘探选区及开发阴.石油实验地质,1997,19(2):133-138.

[78] 吴俊.原微总隙特征及其与油气运移储集关系的研究阴.中国科学:B辑,1993, 23(1):77-84.

[79] 宋志敏.变形原物理模拟与吸附一解吸规律研究[D].焦作:河南理工大学,2012.

[80] 吕闰原.受载瓦斯原贫变形渗流特征及控制机理研究[D].北京:中国矿业大学(北京),2014.

[81] 简星,关平,张巍.煤中CO2的吸附和扩散:实验与建模[J].中国科学:地球科学,2012,42(04):492-504.

[82] 何坚.页岩有机质纳米孔隙中CO2/CH4置换及运移机理研究[D].中国矿业大学,2019.

[83] 岳克明.常温常压下煤对CO吸附及解吸特性研究[D].中国矿业大学,2014.

[84] 李祥春,张梦婷,李忠备,等.气体吸附过程中煤比表面Gibbs函数变化规律[J].煤炭学报,2019,44(02):509-519.

[85] Zhao Y, Feng Y, Zhang X. Molecular simulation of CO2/CH4 self-and transport diffusion coefficients in coa1[J]. Fuel, 2016,165:19-27.

[86] Zhao Y, Feng Y, Zhang X. Selective Adsorption and Selective Transport Diffusion of CO2-CH4 Binary Mixture in Coal Ultramicropores[J]. Environmental Science&Technology,2016,50(17):9380-9389.

[87] Krishna R. Describing mixture permeation across polymeric membranes by a combination of Maxwell-Stefan and Flory-Huggins models[J]. Polymer, 2016,103:124-131.

[88] Liu X, Schnell S K, Simon J, et al. Diffusion Coefficients from Molecular Dynamics Simulations in Binary and Ternary Mixtures[J]. International Journal of Thermophysics,2013,34(7):1169-1196.

[89] Bokhove J, Kerkhof P J A M, Schuur B, et al. Maxwell-Stefan modeling of mass transfer in solvent impregnated resins[J]. Chemical Engineering Science, 2015,132:139-149.

[90] Guliants V V, Huth A J, Stueve J M. A molecular dynamics and grand canonical Monte Carlo study of silicalite-1 as a membrane material for energy-related gas separations[J]. Journal of Porous Materials, 2013,20(1):235-247.

[91] 李希建,徐浩.煤层甲烷吸附与解吸的MC模拟可行性分析[J].煤炭技术,2010,29(9):84-86.

[92] 吴丝竹,胡涛,周浩,等.不同氢化度氢化丁睛橡胶的结构表征与分子模拟[J].高等学校化学学报,2013, 34(04):1027-1032.

[93] 张国荣,卢咏来,高悦凯,等.不同压力条件下氢化丁睛橡胶的应力弛豫及分子动力学模拟研究[J].高分子学报,2012(03):272-277.

[94] 王奥,岳冬梅,刘彬,等.丁二烯一丙烯睛一异戊二烯三元共聚物的耐低温性能及分子模拟[J].合成橡胶工业,2017, 40(04):255-261.

[95] 罗开强,罗艳龙,刘昊北,等.链中改性溶聚丁苯橡胶对白炭黑分散性影响的实验研究和分子模拟[J].轮胎工业,2017,37(07):404-409.

[96] 李强国,陈新,张卓,等.实验与分子模拟法结合探究防老剂对天然橡胶热氧老化的防护机理[J].高分子材料科学与工程,2018, 34(01):106-111.