烃源岩中支链烷烃化合物的检出及意义

DISTRIBUTION OF BRANCHED ALKANES IN THE SOURCE ROCKS AND ITS SIGNIFICANCE

以板桥地区烃源岩为例，对烃源岩中的支链烷烃化合物进行了详细的研究。烃源岩中的支链烷烃主要包括异构、反异构、单甲基中间交链烷烃和类异戊二烯烷烃。在板桥地区烃源岩中，共检测到各类支链烷烃６１种，对它们的结构进行了鉴定；对其分布特征及生源意义作了初步探讨，推测这类化合物大多反映烃源岩中细菌微生物生源输入的贡献。

The GC/MS analysis of branched alkanes in source rocks of Banqiao region shows that there is a relatively high abundance of branched alkanes. Sixty one peaks have been verified and their structures have been given in the text, which include iso-alkanes, anteiso-alkanes, mid-methyl branched alkanes(X compounds), and isoprenoid hydrocarbons. Iso-alkanes and anteisoalkanes are ubiquitous in the source rocks. The carbon number of these iso-alkanes ranges from C_(16) to C_(29). They often have no strong odd-even-carbon predominance (slight even-carbon predominance). Normally the content of iso-alkanes is higher than that of anteiso-alkanes. X_(18) compounds have higher abundance in most samples. The possible origin of these compounds (iso-alkanes, X compounds, long-chain isoprenoids hydrocarbons, etc. ) have been discussed herein. Authors postulate that microbial source may be the main potential origin for these hydrocarbons.