沁水盆地煤储层孔隙分形特征及其对瓦斯吸附的影响
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摘要
为研究煤孔隙分形特征及其对瓦斯吸附特性的影响,针对沁水盆地8个煤样开展了低温液氮吸附试验,采用FHH分形理论探讨了煤表面孔隙分形特征,测试了各煤样的瓦斯吸附常数a、b值,并分析了孔隙分形维数对煤体瓦斯吸附的影响。研究结果表明,煤表面孔隙在不同压力段具有不同的分形特征,D1和D2分别代表煤表面微孔、中孔及大孔的分形特征。随变质程度的升高,D1与R0呈现出良好的线性正相关关系,而D2随R0的增加则呈现出先快后慢的抛物线变化。煤体瓦斯吸附特性与煤表面孔隙分形特征密切相关,分形维数D1、D2数值越大,a值越大,煤体瓦斯吸附能力也就越强;分形特征对吸附常数b值的影响较小。
In order to investigate the fractal characteristic of coal pore and its impact on methane adsorption property,low temperature liquid nitrogen gas adsorption experiments were conducted on eight coal samples collected from Qinshui Basin.FHH fractal theory was adopted to explore the pore fractal features of coal surface.The adsorption constants a and b were measured for each coal sample,and the effect of coal pore fractal dimension on methane adsorption was also analyzed.The research results show that different fractal features of coal surface pore were observed at different relative pressure stages.D1 and D2 represent the fractal features of micropore,mesopore and macropore,respectively.As coalification increases,D1 presents a good positively linear relationship with R0,but a parabolic correlation was found between D1 and R0.Methane adsorption is closely related to the pore fractal features of coal surface.The larger values of the fractal dimension D1 and D2,the greater the adsorption constant a,indicating the methane adsorption capacity is stronger.However,the adsorption constant b is less affected by the fractal features.
In order to investigate the fractal characteristic of coal pore and its impact on methane adsorption property,low temperature liquid nitrogen gas adsorption experiments were conducted on eight coal samples collected from Qinshui Basin.FHH fractal theory was adopted to explore the pore fractal features of coal surface.The adsorption constants a and b were measured for each coal sample,and the effect of coal pore fractal dimension on methane adsorption was also analyzed.The research results show that different fractal features of coal surface pore were observed at different relative pressure stages.D1 and D2 represent the fractal features of micropore,mesopore and macropore,respectively.As coalification increases,D1 presents a good positively linear relationship with R0,but a parabolic correlation was found between D1 and R0.Methane adsorption is closely related to the pore fractal features of coal surface.The larger values of the fractal dimension D1 and D2,the greater the adsorption constant a,indicating the methane adsorption capacity is stronger.However,the adsorption constant b is less affected by the fractal features.
引文
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[19]李波,张文泉,王长浩,等.含次生断裂构造煤层安全回采影响因素分析[J].矿业研究与开发,2018,38(1):101-104.LI Bo,ZHANG Wenquan,WANG Changhao,et al.Analysis on the influence factors of safe mining of the coal seam with the secondary fault[J]. Mining Research and Development,2018,38(1):101-104.
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[21]郭品坤,程远平,卢守青,等.基于分形维数的原生煤与构造煤孔隙结构特征分析[J].中国煤炭,2013,39(6):73-77.GUO Pinkun,CHENG Yuanping,LU Shouqing,et al. Based on the fractal dimension of primary coal and tectonically deformed coal pore structure characteristics analysis[J].China Coal,2013,39(6):73-77.
[2]聂百胜,柳先锋,郭建华,等.水分对煤体瓦斯解吸扩散的影响[J].中国矿业大学学报,2015,44(5):781-787.NIE Baisheng,LIU Xianfeng,GUO Jianhua,et al.Effect of moisture on gas desorption and diffusion in coal mass[J]. Journal of China University of Mining&Technology,2015,44(5):781-787.
[3]王博洋,秦勇,申建,等.鄂尔多斯盆地紫金山地区煤孔隙分形规律及其主控地质因素分析[J].高校地质学报,2017,23(3):499-510.WANG Boyang,QIN Yong,SHEN Jian,et al. The fractal regularity of coal porosity and its controlling geological factors in Zijinshan Area[J]. Geological Journal of China Universities,2017,23(3):499-510.
[4]于丽雅.常村矿构造煤储层特性及其影响因素[J].煤矿安全,2018,49(1):176-178.YU Liya.Reservoir characteristic of tectonic coal and its influencing factors in Changcun Coal Mine[J].Safety in Coal Mines,2018,49(1):176-178.
[5] CAI Y D,LIU D M,PAN Z J,et al.Pore structure and its impact on CH4adsorption capacity and flow capability of bituminous and subbituminous coals from Northeast China[J].Fuel,2013,103:258-268.
[6] WANG F,CHENG Y P,LU S Q,et al.Influence of coalification on the pore characteristics of middle high rank coal[J].Energy Fuels,2014,28:5729-5736.
[7]郑司建,姚艳斌,蔡益栋,等.准噶尔盆地南缘低煤阶煤储层可动流体及孔径分布特征[J].煤田地质与勘探,2018,46(1):56-60.ZHENG Sijian,YAO Yanbin,CAI Yidong,et al. Characteristics of movable fluid and pore size distribution of low rank coals reservoir in southern margin of Junggar Basin[J]. Coal Geology&Exploration,2018,46(1):56-60.
[8]王攀.高煤阶煤储层非均质性耦合模型及煤层内含气量影响因素权重分析[J].煤炭技术,2018,37(1):51-54.WANG Pan.Coupling model of reservoir heterogeneity and weight analysis of gas content effective factors in high-rank coal reservoir[J].Coal Technology,2018,37(1):51-54.
[9]秦兴林.水分影响下的烟煤瓦斯吸附特性[J].煤矿开采,2018,23(1):104-107.QIN Xinglin.Gas adsorption property of bituminous coal under water influence[J].Coal Mining Technology,2018,23(1):104-107.
[10]高为,易同生,金军,等.黔西地区煤样孔隙综合分形特征及对孔渗性的影响[J].煤炭学报,2017,42(5):1258-1265.GAO Wei,YI Tongsheng,JIN Jun,et al. Pore integrated fractal characteristics of coal sample in western Guizhou and its impact to porosity and permeability[J]. Journal of China Coal Society,2017,42(5):1258-1265.
[11]王海龙,刘鸿福,李伟,等.基于压汞技术的构造煤孔隙结构多重分形表征[J].煤矿安全,2016,47(1):33-37.WANG Hailong,LIU Hongfu,LI Wei,et al.Multifractal characterization of tectonically deformed coal pore structure based on mercury injection technology[J].Safety in Coal Mines,2016,47(1):33-37.
[12]王军.煤体表面分形对瓦斯吸附影响[J].煤矿开采,2017,22(3):9-11.WANG Jun. Influence of gas absorption by coal body surface fractal[J].Coal Mining Technology,2017,22(3):9-11.
[13]阎纪伟,要惠芳,李伟,等.μCT技术研究煤的孔隙结构和分形特征[J].中国矿业,2015,24(6):151-156.YAN Jiwei,YAO Huifang,LI Wei,et al.Pore structure and fractal characteristics of coals byμCT technology[J]. China Mining Magazine,2015,24(6):151-156.
[14]柳先锋,宋大钊,何学秋,等.微结构对软硬煤瓦斯吸附特性的影响[J].中国矿业大学学报,2018,47(1):155-161.LIU Xianfeng,SONG Dazhao,HE Xueqiu,et al. Effect of microstructures on methane adsorption characteristics of soft and hard coal[J]. Journal of China University of Mining&Technology,2018,47(1):155-161.
[15]杨博.中高阶煤储层分形特征对瓦斯吸附的影响研究[J].煤炭工程,2016,48(4):96-99.YANG Bo.Impact of fractal characteristics on methane adsorption in middle-high rank coal reservoirs[J]. Coal Engineering,2016,48(4):96-99.
[16] SHARON M S,MARIA D M,MARK A E,et al.Pore characteristics of Wilcox Group Coal,U.S.Gulf Coast Region:Implications for the occurrence of coalbed gas[J]. International Journal of Coal Geology,2015,139:80-94.
[17]袁梅,王玉丽,王珍,等.水-力耦合对含瓦斯煤渗透率影响的试验研究[J].工业安全与环保,2018,44(1):35-37.YUAN Mei,WANG Yuli,WANG Zhen,et al. Experimental study on the effect of water and effective stress on permeability of coal containing gas[J]. Industrial Safety and Environmental Protection,2018,44(1):35-37.
[18]安士凯,桑树勋,李仰民,等.沁水盆地南部高煤级煤储层孔隙分形特征[J].中国煤炭地质,2011,23(2):17-21.AN Shikai,SANG Shuxun,LI Yangmin,et al.Study on pore fractal characteristics of high-rank coal reservoirs in Southern Qinshui Basin[J].Coal Geology of China,2011,23(2):17-21.
[19]李波,张文泉,王长浩,等.含次生断裂构造煤层安全回采影响因素分析[J].矿业研究与开发,2018,38(1):101-104.LI Bo,ZHANG Wenquan,WANG Changhao,et al.Analysis on the influence factors of safe mining of the coal seam with the secondary fault[J]. Mining Research and Development,2018,38(1):101-104.
[20]柳先锋.煤表面微结构特征与电磁辐射机理研究[D].北京:中国矿业大学(北京),2018.
[21]郭品坤,程远平,卢守青,等.基于分形维数的原生煤与构造煤孔隙结构特征分析[J].中国煤炭,2013,39(6):73-77.GUO Pinkun,CHENG Yuanping,LU Shouqing,et al. Based on the fractal dimension of primary coal and tectonically deformed coal pore structure characteristics analysis[J].China Coal,2013,39(6):73-77.