Terpane Characterization of Crude Oils from Niger Delta, Nigeria: A Geochemical Appraisal

2区工程技术 Q1 Earth and Planetary Sciences

Journal of Petroleum Science and Engineering Pub Date : 2023-03-20 DOI:10.11648/j.pse.20230701.11

Mark Obinna Onyema, Michael Junior Ajie

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Abstract

: The geochemistry of crude oils from the Niger Delta, Nigeria, were evaluated using the characterization of C 19 to C 35 terpanes. Analyses of two representative crude oils from Western and Central Niger Delta showed abundances of C 19 to C 29 tricyclic terpanes constituted 12.09% and 29.74%, C 24 tetracyclic terpane 0.31% and 0.15% and C 27 to C 35 pentacyclic terpanes 87.61% and 70.12%, respectively. Diagnostic ratios of terpanes indicated relatively low abundances of C 23 , C 28 and C 29 tricyclic terpanes, low abundances of homohopanes, a significantly high abundance of oleanane and that the Niger Delta crude oils were derived from terrestrial organic matter source rocks deposited in an oxic environment during the Tertiary period. Multivariate oil-oil correlation plot showed the Western and Central Niger Delta crude oils are not distinct, but moderately related (genetically). However, diagnostic ratios of C 24 tetracyclic terpane, which was high and moderate and gammacerane, which was low and high, revealed crude oils from Western Niger Delta were derived from predominantly terrestrial source and crude oils from Central Niger Delta were derived from terrestrial source with input from marine organic matter, respectively. Tricyclic terpanes/hopanes and isomerization ratios of C 32 homohopanes indicated the Niger Delta crude oils were generated at high maturity, at top of the oil generation window.

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尼日利亚尼日尔三角洲原油萜烷特征:地球化学评价

利用c19至c35萜烷的表征，对尼日利亚尼日尔三角洲原油的地球化学进行了评价。对尼日尔三角洲西部和中部两种代表性原油的分析表明，c19 ~ c29三环萜烷的丰度分别为12.09%和29.74%，c24四环萜烷的丰度分别为0.31%和0.15%，c27 ~ c35五环萜烷的丰度分别为87.61%和70.12%。萜烷的诊断比值表明，c23、c28和c29三环萜烷丰度相对较低，同藿烷丰度较低，齐墩烷丰度显著较高，表明尼日尔三角洲原油来源于第三纪沉积于缺氧环境的陆相有机质烃源岩。多元油-油相关图显示，尼日尔三角洲西部和中部原油不明显，但有一定的相关性(遗传)。然而，c24四环萜烷(高、中)和伽马蜡烷(低、高)的诊断比值表明，尼日尔三角洲西部原油主要来自陆源，而尼日尔三角洲中部原油则主要来自陆源，并有海相有机质的输入。三环萜烷/藿烷和c32型藿烷异构化比值表明，尼日尔三角洲原油处于高成熟度，处于生油窗口的顶端。

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来源期刊

Journal of Petroleum Science and Engineering 工程技术-地球科学综合

CiteScore

11.30

自引率

0.00%

发文量

1511

审稿时长

13.5 months

期刊介绍： The objective of the Journal of Petroleum Science and Engineering is to bridge the gap between the engineering, the geology and the science of petroleum and natural gas by publishing explicitly written articles intelligible to scientists and engineers working in any field of petroleum engineering, natural gas engineering and petroleum (natural gas) geology. An attempt is made in all issues to balance the subject matter and to appeal to a broad readership. The Journal of Petroleum Science and Engineering covers the fields of petroleum (and natural gas) exploration, production and flow in its broadest possible sense. Topics include: origin and accumulation of petroleum and natural gas; petroleum geochemistry; reservoir engineering; reservoir simulation; rock mechanics; petrophysics; pore-level phenomena; well logging, testing and evaluation; mathematical modelling; enhanced oil and gas recovery; petroleum geology; compaction/diagenesis; petroleum economics; drilling and drilling fluids; thermodynamics and phase behavior; fluid mechanics; multi-phase flow in porous media; production engineering; formation evaluation; exploration methods; CO2 Sequestration in geological formations/sub-surface; management and development of unconventional resources such as heavy oil and bitumen, tight oil and liquid rich shales.