页岩气储层纳米级孔隙中气体的质量传输机理及流态实验
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摘要
为了探究页岩气储层纳米级孔隙中气体的质量传输方式、机理、气体流态,以及页岩表观渗透率的合理表示方法,首先基于前人的研究成果,从微观和宏观的角度综合分析了页岩纳米孔隙中气体的质量传输机理;然后通过开展致密页岩中气体渗流实验,对纳米孔隙中气体的真实流态进行了分析,讨论了孔隙尺寸、压力等参数对页岩渗透率的影响;进而对不同页岩表观渗透率模型进行了比较,探讨了其合理的表示方法。研究结果表明:(1)页岩纳米孔隙中游离气质量传输方式主要为滑脱流、努森扩散及斐克扩散,吸附气质量传输方式主要为表面扩散,气体流态为滑脱流或过渡流,不存在连续流,并且孔隙越小、压力越低,滑脱流越弱,努森扩散越强;(2)在相同的实验条件下,Darcy渗透率最低,B-K表观渗透率和Civan表观渗透率非常接近,Klinkenberg表观渗透率居中,APF表观渗透率与Wu表观渗透率最高且出现了曲线交替;(3)在Wu表观渗透率中,滑脱流在滑脱区和过渡区都是气体质量主要的传输方式;(4)在APF表观渗透率中,滑脱流是滑脱区气体质量主要的传输方式,而努森扩散则是过渡区气体质量主要的传输方式。
In order to explore the mass transfer mode and mechanism and the flow regime of gas in nano-scale pores of shale gas reservoirs and to develop a method for expressing the apparent permeability of shale reasonably, it is necessary to comprehensively analyze the mass transfer mechanism of gas in nano-scale pores of shale gas reservoirs from microscopic and macroscopic perspectives based on previous research results. After gas seepage in tight shale was experimentally studied, the real flow regime of gas in nano-scale pores was analyzed, and the effects of pore size, pressure and other parameters on shale permeability were discussed. Finally, the reasonable expression method of apparent permeability was discussed by comparing different apparent permeability models. And the following research results were obtained. First, the mass transfer mode of free gas in nano-scale pores of shale gas reservoirs is mainly slippage flow, Knudsen diffusion and Fick diffusion, and that of adsorbed gas is mainly surface diffusion. The flow regime of gas is slippage flow or transitional flow without continuous flow. Besides, the smaller the pores and the lower the pressure, the weaker the slippage flow and the stronger the Knudsen diffusion. Second, under the same experimental conditions, the Darcy permeability is the lowest, the Klinkenberg apparent permeability is the medium, and both APF and Wu apparent permeability are the highest. Their curves of APF and Wu apparent permeability alternate. The Beskok–Karniadakis(B–K) apparent permeability and the Civan apparent permeability are very close. Third, in the model of Wu apparent permeability, the slippage flow is the main mass transfer mode of gas in the slippage and transition zones. Fourth, in the model of APF apparent permeability, the slippage flow is the main mass transfer mode of gas in the slippage zone while Knudsen diffusion is the main mass transfer mode in the transition zone.
In order to explore the mass transfer mode and mechanism and the flow regime of gas in nano-scale pores of shale gas reservoirs and to develop a method for expressing the apparent permeability of shale reasonably, it is necessary to comprehensively analyze the mass transfer mechanism of gas in nano-scale pores of shale gas reservoirs from microscopic and macroscopic perspectives based on previous research results. After gas seepage in tight shale was experimentally studied, the real flow regime of gas in nano-scale pores was analyzed, and the effects of pore size, pressure and other parameters on shale permeability were discussed. Finally, the reasonable expression method of apparent permeability was discussed by comparing different apparent permeability models. And the following research results were obtained. First, the mass transfer mode of free gas in nano-scale pores of shale gas reservoirs is mainly slippage flow, Knudsen diffusion and Fick diffusion, and that of adsorbed gas is mainly surface diffusion. The flow regime of gas is slippage flow or transitional flow without continuous flow. Besides, the smaller the pores and the lower the pressure, the weaker the slippage flow and the stronger the Knudsen diffusion. Second, under the same experimental conditions, the Darcy permeability is the lowest, the Klinkenberg apparent permeability is the medium, and both APF and Wu apparent permeability are the highest. Their curves of APF and Wu apparent permeability alternate. The Beskok–Karniadakis(B–K) apparent permeability and the Civan apparent permeability are very close. Third, in the model of Wu apparent permeability, the slippage flow is the main mass transfer mode of gas in the slippage and transition zones. Fourth, in the model of APF apparent permeability, the slippage flow is the main mass transfer mode of gas in the slippage zone while Knudsen diffusion is the main mass transfer mode in the transition zone.
引文
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[14]刘圣鑫,钟建华,刘晓光,李勇,邵珠福,刘选.致密多孔介质气体运移机理[J].天然气地球科学.2014,25(10):1520-1528.Liu Shengxin,Zhong Jianhua,Liu Xiaoguang,Li Yong,Shao Zhufu&Liu Xuan.Gas transport mechanism in tight porous media[J].Natural Gas Geoscience,2014,25(10):1520-1528.
[15]吴剑,常毓文,梁涛,郭晓飞,陈新彬.页岩气在基质纳米孔隙中的渗流模型[J].天然气地球科学,2015,26(3):575-579.Wu Jian,Chang Yuwen,Liang Tao,Guo Xiaofei&Chen Xinbin.Shale gas flow model in matrix nanoscale pore[J].Natural Gas Geoscience,2015,26(3):575-579.
[16]Darabi H,Ettehad A,Javadpour F&Sepehrnoori K.Gas flow in ultra-tight shale strata[J].Journal of Fluid Mechanics,2012,710(12):641-658.
[17]邓佳.页岩气储层多级压裂水平井非线性渗流理论研究[D].北京:北京科技大学,2015.Deng Jia.Nonlinear seepage theory of multistage fractured horizontal wells for shale gas reservoirs[D].Beijing:University of Science and Technology Beijing,2015.
[18]杨峰,宁正福,胡昌蓬,王波,彭凯,刘慧卿.页岩储层微观孔隙结构特征[J].石油学报,2013,34(2):301-311.Yang Feng,Ning Zhengfu,Hu Changpeng,Wang Bo,Peng Kai&Liu Huiqing.Characterization of microscopic pore structures in shale reservoirs[J].Acta Petrolei Sinica,2013,34(2):301-311
[19]Wu KL,Chen ZX,Li XF,Xu JZ,Li J,Wang K,et al.Flow behavior of gas confined in nanoporous shale at high pressure:Real gas effect[J].Fuel,2017,205(11):173-183.
[20]王登科,魏建平,付启超,刘勇.基于Klinkenberg效应影响的煤体瓦斯渗流规律及其渗透率计算方法[J].煤炭学报,2014,39(10):2029-2036.Wang Dengke,Wei Jianping,Fu Qichao&Liu Yong.Coalbed gas seepage law and permeability calculation method based on Klinkenberg effect[J].Journal of China Coal Society,2014,39(10):2029-2036.
[21]章梓雄,董曾南.粘性流体力学[M].北京:清华大学出版社,2011.Zhang Zixiong&Dong Zengnan.Viscous fluid mechanics[M].Beijing:Tsinghua University Press,2011.
[22]Etminan SSR,Javadpour F,Maini BB&Chen ZX.Measurement of gas storage processes in shale and of the molecular diffusion coefficient in kerogen[J].International Journal of Coal Geology,2014,123(1148):10-19.
[23]Javadpour F.Nanopores and apparent permeability of gas flow in mudrocks(shales and siltstone)[J].Journal of Canadian Petroleum Technology,2009,48(8):16-21.
[24]吴克柳,李相方,陈掌星.页岩气纳米孔气体传输模型[J].石油学报.2015,36(7):837-889.Wu Keliu,Li Xiangfang&Chen Zhangxing.A model for gas transport through nanopores of shale gas reservoirs[J].Acta Petrolei Sinica,2015,36(7):837-889.
[25]雷征东,覃斌,刘双双,蔚涛.页岩气藏水力压裂渗吸机理数值模拟研究[J].西南石油大学学报(自然科学版).2017,39(2):118-124.Lei Zhengdong,Qin Bin,Liu Shuangshuang&Yu Tao.Imbibition mechanism of hydraulic fracturing in shale gas reservoir[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(2):118-124.
[26]张艳玉,李冬冬,孙晓飞,宋兆尧,石达友,苏玉亮.实际状态下的页岩气表观渗透率计算新模型[J].天然气工业.2017,37(11):53-60.Zhang Yanyu,Li Dongdong,Sun Xiaofei,Song Zhaoyao,Shi Dayou&Su Yuliang.A new model for calculating the apparent permeability of shale gas in the real state[J].Natural Gas Industry,2017,37(11):53-60.
[2]吴克柳,李相方,陈掌星.页岩气有机质纳米孔气体传输微尺度效应[J].天然气工业,2016,36(11):51-64.Wu Keliu,Li Xiangfang&Chen Zhangxing.Micro-scale effects of gas transport in organic nanopores of shale gas reservoirs[J].Natural Gas Industry,2016,36(11):51-64.
[3]杜殿发,赵艳武,张婧,刘长利,唐建信.页岩气渗流机理研究进展及发展趋势[J].西南石油大学学报(自然科学版).2017,39(4):136-144.Du Dianfa,Zhao Yanwu,Zhang Jing,Liu Changli&Tang Jianxin.Progress and trends in shale gas seepage mechanism research[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(4):136-144.
[4]Klinkenberg LJ.The permeability of porous media to liquids and gases[J].Drilling&Production Practice,1941,2(2):200-213.
[5]Beskok A&Karniadakis GE.A model for flows in channels,pipes,and ducts at micro and nano scales[J].Nanoscale and Microscale Thermophysical Engineering,1999,3(1):43-77.
[6]Civan F.Effective correlation of apparent gas permeability in tight porous media[J].Transport in Porous Media,2010,82(2):375-384.
[7]Javadpour F,Fisher D&Unsworth M.Nanoscale gas flow in shale gas sediments[J].Journal of Canadian Petroleum Technology,2007,46(10):55-61.
[8]Hadjiconstantinou NG.The limits of Navier-Stokes theory and kinetic extensions for describing small-scale gaseous hydrodynamics[J].Physics of Fluids,2006,18(11):111301-111319.
[9]Holt JK,Park HG,Wang Y,Stadermann M,Artyukhin AB,Grigoropoulos CP,et al.Fast mass transport through sub-2-nanometer carbon nanotubes[J].Science,2006,312(5776):1034-1037.
[10]Roy S,Raju R,Chuang HF,Cruden BA&Meyyappan M.Modeling gas flow through microchannels and nanopores[J].Journal of Applied Physics,2003,93(8):4870-4879.
[11]糜利栋,姜汉桥,李俊键,李涛.页岩储层气体扩散机理[J].大庆石油地质与开发,2014,33(1):154-159.Mi Lidong,Jiang Hanqiao,Li Junjian&Li Tao.Mechanism of gas diffusion in shale reservoirs[J].Petroleum of Geology and Oilfield Development in Daqing.2014,33(1):154-159.
[12]糜利栋,姜汉桥,李俊键,田野.页岩储层渗透率数学表征[J].石油学报,2014,35(5):928-934.Mi Lidong,Jiang Hanqiao,Li Junjian&Tian Ye.Mathematical characterization of permeability in shale reservoirs[J].Acta Petrolei Sinica,2014,35(5):928-934.
[13]Fathi E&Akkutlu IY.Nonlinear sorption kinetics and surface diffusion effects on gas transport in low-permeability formations[C]//Paper 124478 presented at the SPE Annual Technical Conference and Exhibition,4-7 October 2009,New Orleans,Louisiana,USA.
[14]刘圣鑫,钟建华,刘晓光,李勇,邵珠福,刘选.致密多孔介质气体运移机理[J].天然气地球科学.2014,25(10):1520-1528.Liu Shengxin,Zhong Jianhua,Liu Xiaoguang,Li Yong,Shao Zhufu&Liu Xuan.Gas transport mechanism in tight porous media[J].Natural Gas Geoscience,2014,25(10):1520-1528.
[15]吴剑,常毓文,梁涛,郭晓飞,陈新彬.页岩气在基质纳米孔隙中的渗流模型[J].天然气地球科学,2015,26(3):575-579.Wu Jian,Chang Yuwen,Liang Tao,Guo Xiaofei&Chen Xinbin.Shale gas flow model in matrix nanoscale pore[J].Natural Gas Geoscience,2015,26(3):575-579.
[16]Darabi H,Ettehad A,Javadpour F&Sepehrnoori K.Gas flow in ultra-tight shale strata[J].Journal of Fluid Mechanics,2012,710(12):641-658.
[17]邓佳.页岩气储层多级压裂水平井非线性渗流理论研究[D].北京:北京科技大学,2015.Deng Jia.Nonlinear seepage theory of multistage fractured horizontal wells for shale gas reservoirs[D].Beijing:University of Science and Technology Beijing,2015.
[18]杨峰,宁正福,胡昌蓬,王波,彭凯,刘慧卿.页岩储层微观孔隙结构特征[J].石油学报,2013,34(2):301-311.Yang Feng,Ning Zhengfu,Hu Changpeng,Wang Bo,Peng Kai&Liu Huiqing.Characterization of microscopic pore structures in shale reservoirs[J].Acta Petrolei Sinica,2013,34(2):301-311
[19]Wu KL,Chen ZX,Li XF,Xu JZ,Li J,Wang K,et al.Flow behavior of gas confined in nanoporous shale at high pressure:Real gas effect[J].Fuel,2017,205(11):173-183.
[20]王登科,魏建平,付启超,刘勇.基于Klinkenberg效应影响的煤体瓦斯渗流规律及其渗透率计算方法[J].煤炭学报,2014,39(10):2029-2036.Wang Dengke,Wei Jianping,Fu Qichao&Liu Yong.Coalbed gas seepage law and permeability calculation method based on Klinkenberg effect[J].Journal of China Coal Society,2014,39(10):2029-2036.
[21]章梓雄,董曾南.粘性流体力学[M].北京:清华大学出版社,2011.Zhang Zixiong&Dong Zengnan.Viscous fluid mechanics[M].Beijing:Tsinghua University Press,2011.
[22]Etminan SSR,Javadpour F,Maini BB&Chen ZX.Measurement of gas storage processes in shale and of the molecular diffusion coefficient in kerogen[J].International Journal of Coal Geology,2014,123(1148):10-19.
[23]Javadpour F.Nanopores and apparent permeability of gas flow in mudrocks(shales and siltstone)[J].Journal of Canadian Petroleum Technology,2009,48(8):16-21.
[24]吴克柳,李相方,陈掌星.页岩气纳米孔气体传输模型[J].石油学报.2015,36(7):837-889.Wu Keliu,Li Xiangfang&Chen Zhangxing.A model for gas transport through nanopores of shale gas reservoirs[J].Acta Petrolei Sinica,2015,36(7):837-889.
[25]雷征东,覃斌,刘双双,蔚涛.页岩气藏水力压裂渗吸机理数值模拟研究[J].西南石油大学学报(自然科学版).2017,39(2):118-124.Lei Zhengdong,Qin Bin,Liu Shuangshuang&Yu Tao.Imbibition mechanism of hydraulic fracturing in shale gas reservoir[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(2):118-124.
[26]张艳玉,李冬冬,孙晓飞,宋兆尧,石达友,苏玉亮.实际状态下的页岩气表观渗透率计算新模型[J].天然气工业.2017,37(11):53-60.Zhang Yanyu,Li Dongdong,Sun Xiaofei,Song Zhaoyao,Shi Dayou&Su Yuliang.A new model for calculating the apparent permeability of shale gas in the real state[J].Natural Gas Industry,2017,37(11):53-60.