不同煤级煤的沥青质H~1-NMR分析及其地球化学意义

本文采用核磁共振(H'—NMR)分析,对来自鄂尔多斯盆地不同煤级煤(?)0.43%—1.80%),的沥青质结构组成特征和演化机理进行了探讨。研究表明煤沥青质分子结构组成与腐殖型母质密切相关,其基本结构单元可能是核心由2~3以上的芳环组成,取代烷基较多而短,以2~3个碳原子为主,芳香缩台程度低,结构松散．沥青质在热演化过程中和平酪根一样也经历了形成、解聚、凝缩和聚合等演化阶段。依据实验得到的沥青质各类氢相对含量、取代基的平均碳数和芳香度等结构参数不仅丰富了煤系热演化程度的指标、揭示了煤成烃的机理,而且为油源对比提供了新参数．经过数据处理所建立的各参数间的相互关系,如f_a~H与H_A和B,为直接利用H'—NMR资料提供了方便。

H~1-NMR ANALYSIS OF ASPHALTENE IN COAL OFDIFFERENT RANKS AND ITS GEOCHEMICAL SIGNIFICANCE

Basrd on the H'-NMR analysis of asphaltene in coal of different ranks ( R" mn0. 43 -1.80%) from Ordos basin , this paper discusses the structural composition and evolutional mechanism of the asphallene. It is shown that there is a close relation between structural composition of the asphaltene and original matter of humic type. The asphaltene under goes such different evolution stages as formation, depolycondensation, polycondensation and polymerization . which are similar to the evolution characteristics of kerogen. Thus, during the formation of hydrocarbon the asphallene is regarded as the material of "interim type". Many structure parameters of the asphaltene are obtained from H'-NMR, in which relative content (%) of various hydrogens (H ) , average number of carbon atoms for alkyl substituent ( N) and aromaticity (fH0) and their regular change with thermal evolution may provide new indexes for oil source rock correlation and coalification degree identification as well as reveal the mechanism of coal formed hydrocarbons. Finally, interrelation among the parameters established by data process is very helpful to the direct use of H'-NMR in formation.