首页|Geochemical characteristics and origins of natural gases in the eastern Cote d'Ivoire Basin,West Africa

Geochemical characteristics and origins of natural gases in the eastern Cote d'Ivoire Basin,West Africa

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The gas sources in the eastern Cote d'Ivoire Basin(Tano Basin)are seldom reported and remain controversial due to multiple sets of potential source rocks and poorly documented geochemical characteristics of natural gases.The marine source rock potential from the Upper Albian to Turonian as well as the molecular composition and the stable carbon isotope composition of natural gases in the eastern Cote d'Ivoire Basin were studied in detail to investigate the origins of natural gases.The total organic carbon(TOC),hydrogen index(HI),and generation potential(S1+S2)of source rocks indicate that both sapropelic source rocks and humic source rocks developed during the late Albian,whereas sapropelic source rocks developed during the Cenomanian and the Turonian.The normal order of δ13CH4<δ13C2H6<δ13C3H8(δ13C1<δ13C2<δ13C3),the relationship between C2/C3 molar ratio and δ13C2-δ13C3,and the plot of δ13C1 versus C1/(C2+C3)collectively show that the natural gases are thermogenic due to the primary cracking of kerogen,including the typical oil-associated gases from Well D-1,the mixed oil-associated gases and coal-derived gases from Well G-1 and Well L-1.Based on the plot of δ13C1 versus δ13C2 and the established relationship between δ13C1 and equivalent vitrinite reflectance(Ro),we proposed that the natural gases are in a mature stage(Ro generally varies from 1.0%to 1.3%).Combined with results of basin modelling and oil-to-source correlation,the transitional to marine source rocks during the late Albian were thought to have made a great contribution to the natural gases.Our study will make a better understanding on petroleum system in the eastern Cote d'Ivoire Basin.

marine source rocks potentialmolecular compositionstable carbon isotopesUpper AlbianTano Basin

Li Li、Quan Li、Tao Cheng、Songling Yang、Yong Rao、Xinyu Liu、Wenjing Ding

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CNOOC International Ltd.,Beijing 100028,China

School of Natural Sciences,Macquarie University,Sydney,NSW,2109,Australia

CNOOC Research Institute,Beijing 100028,China

Major Science and Technology Project of CNOOCNational Natural science Foundation of ChinaNational Natural science Foundation of China

KJGG2022-09024220218442272177

2024

10.1007/s13131-024-2335-6

海洋学报(英文版)
中国海洋学会

海洋学报(英文版)

CSTPCD
影响因子：0.323
ISSN：0253-505X
年,卷(期)：2024.43(8)
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