基于核磁共振和低温氮吸附的煤层酸化增透效果定量表征

发布时间：2018-03-26 00:39

本文选题：酸化增透　切入点：核磁共振　出处：《煤炭学报》2017年07期

【摘要】：针对某些煤储层中的孔隙和裂隙被方解石、白云石等矿物或杂质堵塞致使煤层渗透率降低的问题,提出一种煤层酸化增透方法。利用核磁共振(NMR)和低温氮吸附实验表征了煤样酸化前后的比表面积、孔隙体积、孔隙度、渗透率、孔径分布及核磁成像等特性参数,分析了酸化作用下煤的细观结构变化规律。测试结果表明,煤样经酸化处理后,饱和水状态的NMR信号量增加,残余水状态的NMR信号量降低,T_2谱的中大孔峰(T_220 ms)的变化较大,NMR所表征的总孔隙度、有效孔隙度、渗透率均增加,残余孔隙度、T_2截止值降低;低温氮吸附所表征的比表面积和总孔隙体积均增加,且主要集中增加在10 nm左右的孔隙,但高煤阶煤增加不明显。NMR图像直观地反映了煤样酸化前后内部孔隙结构的变化特征,为揭示酸化增透的微观演变过程提供了新的手段。煤样初始孔隙越发育或孔隙裂隙中可溶性矿物质越多,所表征的特征参数变化越大,酸化增透效果越好。
[Abstract]:In view of the problem that pores and fissures in some coal reservoirs are blocked by calcite, dolomite and other minerals or impurities, the permeability of coal seam is reduced. A method of coal seam acidizing antireflection was proposed. The specific surface area, pore volume, porosity, permeability, pore size distribution and nuclear magnetic resonance imaging of coal samples before and after acidification were characterized by NMR and low temperature nitrogen adsorption experiments. The variation law of meso-structure of coal under acidizing action is analyzed. The test results show that the amount of NMR signal in saturated water state increases after acidizing treatment. The NMR signal of the residual water state decreases the T220ms peak of the Tass _ 2 spectrum. The total porosity, effective porosity and permeability are all increased, and the residual porosity / T _ 2 cutoff value is decreased. The specific surface area and total pore volume of nitrogen adsorption at low temperature are both increased, and the pore volume is mainly increased at about 10 nm, but the increase of high rank coal is not obvious. The NMR image directly reflects the change characteristics of pore structure before and after acidification of coal sample. It provides a new means to reveal the microcosmic evolution of acidizing antitransmittance. The more developed the initial pores or the more soluble minerals in the pore fissures, the greater the change of characteristic parameters, and the better the antireflection effect of acidizing.
【作者单位】：辽宁工程技术大学矿业学院;河南理工大学深井瓦斯抽采与围岩控制技术国家地方联合工程实验室;中国矿业大学煤炭资源与安全开采国家重点实验室;
【基金】：国家自然科学基金资助项目(51674132) 深井瓦斯抽采与围岩控制技术国家地方联合工程实验室开放基金资助项目(G201602) 煤炭资源与安全开采国家重点实验室基金资助项目(SKLCRSM15KF04)
【分类号】：TD712.6

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