New progress in the study of hydrocarbon accumulation and exploration insights in Central and Western African Rift System

doi:10.3969/j.issn.1672-7703.2025.01.012

Abstract

Abstract: There are multiple petroliferous basins in Central and Western African Rift System (CWARS), with abundant oil and gas resources.Based on the study of the control of CWARS basins orientation and regional stress field direction on basin formation, relationship between tectonic evolution of CWARS and source rock development, as well as the sedimentary filling and hydrocarbon accumulation patterns of rift basins in different directions, the author presents the latest study progress of basin formation, hydrocarbon generation and hydrocarbon accumulation in CWARS. In addition, hydrocarbon accumulation patterns in various types of basins and exploration practice in typical basins are analyzed, which clarify the high-efficiency exploration practices and future exploration fields and orientations in CWARS. The study results show that, controlled by basin orientation and direction of regional stress field, multi-stage superimposed and single-stage rift basins were developed in CWARS. Among them, multi-stage rift processes occurred in NW–SE trending basins in the Early Cretaceous, Late Cretaceous,and Paleogene, forming the main hydrocarbon accumulation pattern of “lower source rock and upper reservoir, and hydrocarbon accumulation above source rock”. While a single-stage rift process experienced in the NE–SW trending basins in the Early Cretaceous, forming hydrocarbon accumulation patterns of “integrated source rock and reservoir, and hydrocarbon accumulation inside source rock” in the Lower Cretaceous and “upper source rock and lower reservoir, and hydrocarbon accumulation below source rock” in the Lower Cretaceous and buried hill.The diverse tectonic settings and geological evolution processes determined that terrigenous marine source rock was developed in the Upper Cretaceous in Western African Rift System and continental facies source rock was developed in the Lower Cretaceous in Central African Rift System. The thick, high-quality and mature source rocks provided a material basis for hydrocarbon enrichment in CWARS. The exploration practice in Melut Basin indicates that the key to achieving the high-efficiency exploration of overseas oil and gas projects relies on the rapid identification of oil-rich sags and the subsequent deployment of connected 3D seismic data. The major fields and orientations for the future exploration in CWARS include intra-source rock hydrocarbon accumulation combination in NW-SE trending multi-stage superimposed rift basins such as Termit and Melut, intra-source rock lithological oil reservoirs in NE-SW trending single-stage rift basins such as Bongor and Doseo, as well as traps outside source rock in oil-rich sags.

Key words: hydrocarbon accumulation pattern, oil-rich sag, high-efficiency exploration, outside source rock play, Central and Western African Rift System

CLC Number:

TE122.11

Shi Zhongsheng, Ma Feng, Pang Wenzhu, Chen Bintao, Xue Juo, Dai Hansong, Xu Fei, Ma Lun. New progress in the study of hydrocarbon accumulation and exploration insights in Central and Western African Rift System[J]. China Petroleum Exploration, 2025, 30(1): 156-167.

References

[1] Wood Mackenzi. Asset report of Doba oil project[R]. 2023,4,1-19.
[2] 窦立荣，史忠生，庞文珠，等. 中西非裂谷系富油凹陷石油地质特征与勘探方向[J]. 石油勘探与开发，2024,51(1):1-13.
Dou Lirong, Shi Zhongsheng, Pang Wenzhu, et al . Petroleum geological characteristics and exploration targets of the oil-rich sags in the Central and West African Rift System[J]. Petroleum Exploration and Development, 2024,51(1):1-13.
[3] Bumby A J, Guiraud R. The geodynamic setting of the Phanerozoic basins of Africa[J]. Journal of African Earth Sciences, 2005,43(1/3): 1-12.
[4] Guiraud R, Maurin J C. Early Cretaceous rifts of Western and Central Africa: an overview[J]. Tectonophysics, 1992,213(1/2): 153-168.
[5] Fairhead J D. The Mesozoic West and Central Africa Rift System (WCARS) and the older Kandi Shear Zone (KSZ): rifting and tectonics of North Africa and South America and fragmentation of Gondwana based on geophysical investigations[J]. Journal of African Earth Sciences, 2023,199:1-20.
[6] 熊利平，王骏，殷进垠，等．西非构造演化及其对油气成藏的控制作用[J]．石油与天然气地质，2005，26(5):641-646．
Xiong Liping, Wang Jun, Yin Jinyin, et al . Tectonic evolution and its control on hydrocarbon accumulation in West Africa[J]. Oil & Gas Geology, 2005,26(5):641-646.
[7] Genik G J. Petroleum geology of Cretaceous-Tertiary rift basins in Niger, Chad, and Central African Republic[J]. AAPG Bulletin, 1993,77(8):1405-1434.
[8] Genik G J. Regional framework, structural and petroleum aspects of rift basins in Niger, Chad and the Central African Republic (C.A.R.)[J]. Tectonophysics, 1992,213(1/2):169-185.
[9] 童晓光，窦立荣，田作基，等. 苏丹穆格莱特盆地的地质模式和成藏模式[J]. 石油学报，2004,25(1):19-24.
Tong Xiaoguang, Dou Lirong, Tian Zuoji, et al . Geological modeand hydrocarbon accumulation mode in Muglad passive rift basin of Sudan[J]. Acta Petrolei Sinica, 2004,25(1):19-24.
[10] 窦立荣. 陆内裂谷盆地的油气成藏风格[J]. 石油勘探与开发，2004,31(2):29-31.
Dou Lirong. Formation style of oil accumulations in interior basins[J]. Petroleum Exploration and Development, 2004,31(2):29-31.
[11] 窦立荣，潘校华，田作基，等. 苏丹裂谷盆地油气藏的形成与分布：兼与中国东部裂谷盆地对比分析[J]. 石油勘探与开发，2006,33(3):255-261.
Dou Lirong, Pan Xiaohua, Tian Zuoji, et al . Hydrocarbon formation and distribution of rift basins in Sudan: a comparative analysis of them with rift basins in East China[J]. Petroleum Exploration and Development, 2006,33(3):255-261.
[12] 张光亚，余朝华，黄彤飞，等. 非洲地区裂谷盆地类型及油气成藏特征[J]. 中国石油勘探，2020,25(4):43-51.
Zhang Guangya, Yu Chaohua, Huang Tongfei, et al . Types and hydrocarbon accumulation characteristics of rift basins in Africa[J]. China Petroleum Exploration, 2020,25(4):43-51.
[13] 窦立荣，肖坤叶，胡勇，等. 乍得Bongor 盆地石油地质特征及成藏模式[J]. 石油学报，2011,32(3):379-386.
Dou Lirong, Xiao Kunye, Hu Yong, et al . Petroleum geology and a model of hydrocarbon accumulations in the Bongor Basin, the Republic of Chad[J]. Acta Petrolei Sinica, 2011, 32(3):379-386.
[14] 窦立荣. 苏丹迈努特盆地油气成藏机理和成藏模式[J]. 矿物岩石地球化学通报，2005,24(1):50-57.
Dou Lirong. Formation mechanism and model of oil and gas accumulations in the Melut Basin, Sudan[J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2005,24(1):50-57.
[15] 窦立荣，肖坤叶，杜业波，等. 乍得Doseo 走滑反转盆地油气成藏特征和勘探发现[J]. 石油勘探与开发，2022,49(2):215-223.
Dou Lirong, Xiao Kunye, Du Yebo, et al . Exploration discovery and hydrocarbon accumulation characteristics of the Doseo strike-slip and inverted basin, Chad[J]. Petroleum Exploration and Development, 2022,49(2):215-223.
[16] 薛罗，史忠生，马轮，等. 南苏丹Melut 盆地北部坳陷烃源岩热演化特征及油气地质意义[J]. 中国石油勘探，2020,25(6):79-86.
Xue Luo, Shi Zhongsheng, Ma Lun, et al . Thermal evolution characteristics of source rocks and their petroleum geological significance in the northern depression of Melut Basin, South Sudan[J]. China Petroleum Exploration, 2020,25(6):79-86.
[17] 史忠生，薛罗，牛慧赟，等. 中非Melut 盆地远源岩性油藏成藏条件与勘探对策[J]. 中国石油勘探，2017,22(6):87-95.
Shi Zhongsheng, Xue Luo, Niu Huiyun, et al . Accumulation conditions of far-source lithologic reservoirs and exploration strategy in Melut Basin, Central Africa[J]. China Petroleum Exploration, 2017,22(6):87-95.
[18] 史忠生，庞文珠，陈彬滔，等. 南苏丹Melut 盆地下组合近源白垩系成藏模式与勘探潜力[J]. 岩性油气藏，2020,32(5):23-33.
Shi Zhongsheng, Pang Wenzhu, Chen Bintao, et al . Hydrocarbon accumulation models and exploration potential of nearsource Cretaceous in the lower assemblage of Melut Basin, South Sudan[J]. Lithologic Reservoirs, 2020,32(5):23-33.
[19] Guiraud R, Bosworth W, Thierry J, et al . Phanerozoic geological evolution of Northern and Central Africa: An overview[J]. Journal of African Earth Sciences, 2005,43(1/3): 83-143.
[20] 张光亚，黄彤飞，刘计国，等．中西非叠合裂谷盆地形成与演化[J]．岩石学报，2022,3838(9):2539-2553.
Zhang Guangya, Huang Tongfei, Liu Jiguo, et al . Formation and evolution of West and Central African superimposed rift basins[J]. Acta Petrologica Sinica, 2022,38(9):2539-2553.
[21] 王涛，王洋，袁圣强，等.Termit 盆地上白垩统Yogou 组烃源岩埋藏史、热演化史和生烃史模拟[J]. 地质科技通报，2023,42(6):151-161.
Wang Tao, Wang Yang, Yuan Shengqiang, et al . Simulation of burial history, thermal evolution history, and hydrocarbon generation history of the Upper Cretaceous Yogou Formation source rocks in the Termit Basin[J]. Bulletin of Geological Science and Technology, 2023,42(6):151-161.
[22] Scotese C R. PALEOMAP PaleoAtlas for GPlates and the Paleo Data Plotter Progra, PALEOMAP Project, 2016. [2024-08-26].http://www.earthbyte.org/ paleomap-paleoatlas-for-gplates/.
[23] 史忠生，方乐华，薛罗，等. 中非Melut 盆地与我国东部裂谷盆地的类比及意义[J]. 地球科学，2019,44(2):588-602.
Shi Zhongsheng, Fang Lehua, Xue Luo, et al . Analogy between Melut Basin of Central Africa and rift basins of east China and implication[J]. Earth Science, 2019,44(2):588-602.
[24] 刘计国，郑凤云，毛凤军，等. 尼日尔Termit 盆地古近系Sokor1 组储层特征及其主控因素[J]. 岩石学报，2022,38(9):2581-2594.
Liu Jiguo, Zheng Fengyun, Mao Fengjun, et al . Reservoir characteristics and its controlling factors of the Paleogene Sokor1 Formation in Termit Basin, Niger[J]. Acta Petrologica Sinica, 2022,38(9):2581-2594.
[25] Liu J, Zhang G, Li Z, et al . Oil charge history of Paleogene-Eocene reservoir in the Termit Basin (Niger)[J]. Australian Journal of Earth Sciences, 2019, 66(4): 597-606.
[26] Benkhelil J. Cretaceous deformation, magmatism, and metamorphism in the Lower Benue Trough, Nigeria[J]. Geological Journal, 1987,22(S2):467-493.
[27] 姜雪，吴克强，刘丽芳，等. 构造活动对富生油凹陷烃源岩的定量控制：以中国近海古近系为例[J]. 石油学报，2014,35(3):455-461.
Jiang Xue, Wu Keqiang, Liu Lifang, et al . Quantitative control of tectonic activity for source rocks in rich oil kitchen sags: a case study of Paleogene in China offshore[J]. Acta Petrolei Sinica, 2014,35(3):455-461.
[28] Chen Liang, Jia Hancheng, Dou Lirong, et al. The characteristics of source rock and hydrocarbon charging time of Precambrian granite reservoirs in the Bongor Basin, Chad[J]. Marine and Petroleum Geology, 2018,97:323-338.
[29] 肖坤叶，赵健，余朝华，等. 中非裂谷系Bongor 盆地强反转裂谷构造特征及其对油气成藏的影响[J]. 地学前缘，2014,21(3):172-180.
Xiao Kunye, Zhao Jian, Yu Chaohua, et al . Structural characteristics of intensively inversed Bongor Basin in CARS and their impacts on hydrocarbon accumulation[J]. Earth Science Frontiers, 2014, 21(3): 172-180.
[30] 赵文智，何登发，李小地，等．石油地质综合研究导论[M]．北京：石油工业出版社，1999．
Zhao Wenzhi, He Dengfa, Li Xiaodi, et al . Introduction to comprehensive study of petroleum geology[M]. Beijing: Petroleum Industry Press, 1999.
[31] 赵文智，邹才能，汪泽成，等．富油气凹陷“满凹含油”论：内涵与意义[J]. 石油勘探与开发，2004,31(2):5-13.
Zhao Wenzhi, Zou Caineng, Wang Zecheng, et al . The intension and signification of “Sag-wide Oil-Bearing Theory”in the Hydrocarbon-rich Depression with terrestrial origin[J]. Petroleum Exploration and Development, 2004,31(2):5-13.
[32] 陈云林．论富油洼陷及其意义[J]. 勘探家，1999,4(2):8-11．
Chen Yunlin. Concept of oil-rich subsag and its Significance[J]. Petroleum Explorationist, 1999,4(2):8-11.
[33] 赵贤正，王权，金凤鸣，等．渤海湾盆地富油凹陷二次勘探工程及其意义[J]．石油勘探与开发，2015,42(6):723-733.
Zhao Xianzheng, Wang Quan, Jin Fengning, et al . Reexploration program for petroleum-rich sags and its significance in Bohai Bay Basin, East China[J]. Petroleum Exploration and Development, 2015,42(6):723-733.
[34] 史忠生，王天奇，薛罗，等. 中非Melut 盆地高砂地比地层成藏特征与富集规律[J]. 天然气地球科学，2017,28(2):262-271.
Shi Zhongsheng, Wang Tianqi, Xue Luo, et al . Reservoir characteristics and enrichment rule of highly sandy formation in Melut Basin,Central Africa[J]. Natural Gas Geoscience, 2017, 28(2):262-271.
[35] 史忠生，王天琦，方乐华，等. 南苏丹Melut 裂谷盆地扇体的发现及油气意义[J]. 天然气地球科学，2015,26(1):81-89.
Shi Zhongsheng, Wang Tianqi, Fang Lehua, et al . Discovery of Fans in Melut Rift Basin,South Sudan and Its Petroleum Geological Significance[J]. Natural Gas Geoscience, 2015,26(1):81-89.
[36] 中国地质调查局. 我国最新油气资源储量数据解析[EB/OL].（2013-04-25）[2024-08-30]. https://www.cgs.gov.cn/xwl/ddyw/201603/t20160309_281707.html.
China Geological Survey. Analysis of the latest oil and gas resource reserve data in China[EB/OL].（2013-04-25）[2024-08-30]. https://www.cgs.gov.cn/xwl/ddyw/201603/t20160309_281707.html.
[37] 史忠生，薛罗，马轮，等.Melut 盆地北部远源油藏类型、特征及勘探启示[J]. 地质科技通报，2021,40(5):22-32.
Shi Zhongsheng, Xue Luo, Ma Lun, et al . Types, characteristics, and implications on the exploration of far-source oil reservoirs in the north Melut Basin[J]. Bulletin of Geological Science and Technology, 2021,40(5):22-32.
[38] 袁选俊，谯汉生. 渤海湾盆地富油气凹陷隐蔽油气藏勘探[J]. 石油与天然气地质，2002,23(2):130-133.
Yuan Xuanjun, Qiao Hansheng. Exploration of subtle reservoir in prolific depression of Bohai Bay Basin[J]. Oil & Gas Geology,2002,23(2):130-133.