Hydrogen isotopic compositions of individual alkanes as a new approach to petroleum correlation: case studies from the Western Canada Sedimentary Basin
Hydrogen isotopic compositions of individual alkanes as a new approach to petroleum correlation: case studies from the Western Canada Sedimentary Basin
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DOI：
10.1016/s0146-6380(01)00116-4
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发表时间：
2001-01-01
影响因子：
3
通讯作者：
Fowler, MG
中科院分区：
文献类型：
--
作者：
Li, MW;Huang, YS;Fowler, MG
采用气相色谱-热转换-同位素比值质谱法测定了原油中正构烷烃和非环类异戊二烯烷烃的碳结合氢同位素组成。对于大多数烷烃，该技术的精度优于千分之3，相比之下，样品之间的Δ D变化范围很大（高达千分之160）。这些原油选自加拿大西部沉积盆地的主要成因油族，烃源岩的年龄范围从奥陶纪（可能还有寒武纪）到白垩纪。原油中烷烃的氢同位素组成受三个因素控制：生物合成前体的同位素组成、源水δ D值和沉积后过程。脂质的生物合成来源和/或途径的遗传差异反映在正构烷烃内的氢同位素变异性小，但正构烷烃和姥鲛烷/植烷之间的δ D值差异大得多。WCSB中从古生代到上白垩纪石油的氢同位素组成向较轻的转变反映了特殊的沉积环境和/或陆地有机质的微小贡献。湖相原油的δ D值明显低于海相原油，而源岩沉积在蒸发环境中的原油的δ D值也很高，这表明了源水δ D值的强烈影响。热成熟可能会在一定程度上改变石油中烷烃的δ D值，但二次石油运移似乎没有任何显着的影响。来自寒武纪源岩的油仍然保留了源有机质和源水的氢同位素组成的强烈特征，这一事实表明，Δ D值对于油源对比和古环境重建非常有用。皇冠版权所有（C）2001由爱思唯尔科学有限公司出版。保留所有权利。
Isotopic compositions of carbon-bound hydrogen in individual n-alkanes and acyclic isoprenoid alkanes, from a number of crude oil samples, were measured using gas chromatography-thermal conversion-isotope ratio mass spectrometry. The precision of this technique is better than 3 parts per thousand for most alkanes, compared to the large range of deltaD variation among the samples (up to 160 parts per thousand). The oils were selected from major genetic oil families in the Western Canada Sedimentary Basin, with source rocks ranging in age from Ordovician (and possibly Cambrian) to Cretaceous, The hydrogen isotopic composition of alkanes in crude oils is controlled by three factors: isotopic compositions of biosynthetic precursors, source water deltaD values, and postdepositional processes. The inherited difference in the lipid's biosynthetic origins and/or pathways is reflected by a small hydrogen isotopic variability within n-alkanes, but much larger differences in the deltaD values between n-alkanes and pristane/phytane. The shift toward lighter hydrogen isotopic compositions from Paleozoic to Upper Cretaceous oils in the WCSB reflects a special depositional setting and/or a minor contribution of terrestrial organic matter. The strong influence of source water deltaD values is demonstrated by the distinctively lower deltaD values of lacustrine oils than marine oils, and also by the high values for oils with source rocks deposited in evaporative environments. Thermal maturation may alter the deltaD values of the alkanes in the oil to some extent, but secondary oil migration does not appear to have had any significant impact. The fact that oils derived from source rocks that could be of Cambrian age still retain a strong signature of the hydrogen isotopic compositions of source organic matter, and source water, indicates that deltaD values are very useful for oil-source correlation and for paleoenvironmental reconstructions. Crown Copyright (C) 2001 Published by Elsevier Science Ltd. All rights reserved.