Mechanism exploration on improving coal rock permeability by heat treating
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摘要: 为了探索煤岩渗透率与温度的关系及其机理,通过加热实验研究了二者在 200 ℃以内的关系,通过 X衍射分析、电镜扫描等手段,并从煤化学、煤地质学等角度对其机理进行了分析。结果表明:初始渗透率在 0.5 mD以内的煤岩,经加热处理后其渗透率可显著增至 15 mD以上。分析认为:煤岩热处理后渗透率提高的机理为:煤岩脱水以及部分挥发组分的逸散会产生新的渗流孔隙;甲烷分子的解吸以及基质凝胶化组分脱水,导致煤基质收缩;煤岩中碳氢原子发生氧化生成气态产物并逸散,形成了微小裂缝并降低了煤岩的致密程度;热应力作用下煤岩内部变形不均产生了微小裂缝。最后提出可以对煤层注入热 CO2提高采收率。Abstract: This paper investigated the relationship between coal rock permeability and heating temperature in less than 200 ℃ through laboratory experiments. And by means of X-ray diffraction analysis and Scanning Electron Microscope, the influence of heat on coal rock permeability was analyzed from perspective of coal chemistry and coal geology. The results shows that coal rock permeability could be significantly increased from less than 0.5 mD to 15 mD by heat treating. Analyzing results indicate that mechanisms may be ex-plained as follows: Firstly, dehydration of coal rock and partly volatile components releasing of coal rock will form new pores. Secondly, desorption of methane molecules and dehydration of gelatinous micro-component in the matrix lead to the shrinkage of coal matrix. Thirdly, coal rock generates hydrocarbon gases after oxidizing reaction of carbon and Hydrogen atoms, and the gas releasing forms tiny cracks and reduces the degree of coal rock compaction. Fourth, coal rock encounters inhomogeneous deformation under thermal stress, and produces uneven small cracks. Finally, the paper proposes a new mode of coal bed methane (CBM) exploitation to enhance CBM recovery by injecting thermal CO2. Above researches may be of great help to the exploitation of CBM reservoirs with low permeability in China.
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Key words:
- coal rock /
- heating treatment /
- permeability /
- micro-cracks /
- mechanism
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[14]唐书恒 .晋城地区煤储层特征及多元气体的吸附—解吸特性[D].徐州:中国矿业大学,2001.: [1]叶建平,史保生,张春才 .中国煤储层渗透性及其主要影响因素[J].煤炭学报,1999,24(2):118-122.
[2]杨新乐 .低渗煤储层煤层气注热增产机理的研究[ D]. 阜新:辽宁工程技术大学,2009.
[3]ZHAO Yangsheng, QU Fang, WAN Zhijun, et al. Experimental investigation on correlation between permeability variation and pore struction during coal pyrolysis[J]. Transport in Porous Media, 2010, 82(2), 401-412.
[4]李志强,鲜学福 .煤体渗透率随温度和应力变化的实验研究[ J].辽宁工程技术大学学报:自然科学版, 2009,28(S0):156-159.
5]WANG G X, MASSAROTTO P, RUDOLPH V .An improved permeability model of coal for coalbed methane recovery and CO2 geosequestration[J]. International Journal of Coal Geology, 2009, 77:127-136.
[6]刘均荣,吴晓东 .岩石热增渗机理初探[ J].石油钻采工艺,2003,25(5):43-49.
[7]陈金刚,张世雄,秦勇,等 .煤基质收缩能力内在控制因素的试验研究[ J].煤田地质与勘探, 2004,32(5):26-
28.
[8]PAN Zhejun, CONNEL L D, CAMILLERI M. Laboratory characterization of coal reservoir permeability for primary and enhanced coalbed methane recovery [J]. International Journal of Coal Geology, 2010,(82): 252-261.
[9]邱晓玲 .煤岩成分中水分变化规律刍议[ J].煤, 2003,12(6):48-49.
[10]严荣林,钱国胤 .煤的分子结构与煤氧化自燃的气体产物[J].煤炭学报,1995,20(S0):58-65.
[11]李增华 .煤炭自燃的自由基反应机理[ J].中国矿业大学学报,1996,25(3):111-114.
[12]刘均荣,吴晓东 .热处理岩石微观实验研究[ J].西南石油大学学报:自然科学版,2008,30(4):15-18.
[13]郭树才 .炼焦工艺学[ M].北京:冶金工业出版社, 1961.
[14]唐书恒 .晋城地区煤储层特征及多元气体的吸附—解吸特性[D].徐州:中国矿业大学,2001.: -

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