Distribution and significance of C~_(40) alkanes in the extracts of Cretaceous source rocks from the Songliao Basin |
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作者单位: | FENG ZiHui(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
FANG Wei(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
ZHANG JuHe(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
LI ZhenGuang(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
HUANG ChunYan(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
WANG Xue(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
ZHAO QinLing(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ;
HUO QiuLi(Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing 163712, China) ; |
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基金项目: | 国家重点基础研究发展计划(973计划) |
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摘 要: | Source rock extracts and crude oils from the Songliao Basin were analyzed by high-temperature gas chromatography (HTGC), gas chromatography-mass spectrometry (HTGC-MS) and gas chromatography-isotope ratio-mass spectrometry (GC-IRMS), for high molecular-weight alkanes. The distributions of n-alkanes in the Nenjiang Formation extracts are in the C14―C63 range; a bimodal distribution occurs in the C-21 and C21―40 regions. The C30―C37 n-alkanes are accompanied by C29―C35 hopanes, whereas the high molecular-weight C45―C47 n-alkanes co-occur with abundant isoalkanes, alkylcyclohexanes and alkylcyclopentanes. The high δ 13C values of the n-alkanes and the microscopic maceral compositions indicate a highly diversified organic source input for the Nenjiang Formation source rocks, ranging from aquatic plants, blue alge-bacteria, to land plant material. In contrast, n-alkanes in the rock extracts of the Qingshankou Formation are characterized by a single modal distribution, with relatively low abundances of C29―C35 hopanes, but high molecular-weight isoalkanes, alkylcyclohexanes and alkylcyclopentanes. The relatively low δ 13C values of C22―C44 n-alkanes and organic material compositions indicate that the source rocks in the Qingshankou Formation contain dominantly type I algal organic matter. The relative abundance of C 40 compounds in source rocks changes little at low maturity stage, but decreases drastically at higher maturity levels, with a concurrent reduction in the odd/even carbon predominance. In crude oils, in contrast, the relative abundance of C 40 compounds appears to relate closely with the oil source and oil viscosity.
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收稿时间: | 23 October 2006 |
修稿时间: | 9 May 2007 |
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