Infracambrian hydrocarbon source rock potential and petroleum prospectivity of NW Africa
Published:January 01, 2009
S. Lüning, S. Kolonic, M. Geiger, B. Thusu, J. S. Bell, J. Craig, 2009. "Infracambrian hydrocarbon source rock potential and petroleum prospectivity of NW Africa", Global Neoproterozoic Petroleum Systems: The Emerging Potential in North Africa, J. Craig, J. Thurow, B. Thusu, A. Whitham, Y. Abutarruma
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Proven Infracambrian hydrocarbon plays occur in various parts of the world, including Oman, the former Soviet Union, India, Pakistan and Australia. Organic-rich strata also occur in NW Africa, and gas shows originating from Infracambrian hydrocarbon source rocks are known from well Abolag-1 in the Mauritanian part of the Taoudenni Basin. The distribution of Infracambrian source rocks in North Africa is patchy and deposition commonly occurred in half-graben and pull-apart basins. In these intra-shelf basins, marine, organic-rich shales and limestones were deposited beneath the turbulent wave zone, away from the coarse siliciclastic Pan-African molasse detritus. On the West African Craton (including the Taoudenni Basin) organic-rich horizons were also deposited earlier, in pre- and syn-Pan-African times between 0.5 and 2 Ga (Ga is 109 years). The long-lasting sedimentation history in this area contrasts with that of the Pan-African regions, such as Oman, which lies in the Pan-African province of the East African Orogen, where preserved sediments are rarely older than 640 Ma. Infracambrian black phyllites in the Anti-Atlas region of Morocco were deposited on a continental slope of a short-lived ocean lying to the north of the West African Craton. Hydrocarbons generated during Infracambrian times from these deposits, however, have a low preservation potential.
Infracambrian organic-rich and/or black-pyritic deposits in North Africa are proven in the Taoudenni Basin, the Anti-Atlas and the Ahnet Basin. Thick carbonate successions exist in the Taoudenni Basin, indicating deposition in areas some distance from contaminating coarse siliciclastic hinterland influx. Infracambrian strata may also occur in the Tindouf Basin. However, their deep burial and consequent early maturation history may be unfavourable for the preservation of Infracambrian-sourced hydrocarbons in this area. Local development of Infracambrian source facies may also occur in the Reggane, Ahnet, Mouydir and Iullemeden basins, as indicated by black shales in wells MKRN-1 and MKRS-1 in the Ahnet Basin. Generally, however, these basins appear to be close to the active Pan-African orogenic belt and, consequently, probably received large quantities of coarse siliciclastic sediment, largely of continental facies, which may have diluted any significant hydrocarbon source potential.
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Global Neoproterozoic Petroleum Systems: The Emerging Potential in North Africa
Neoproterozoic successions are major hydrocarbon producers around the world. In North Africa, large basins with significant surface outcrops and thick sedimentary fills are widespread. These basins are now emerging as potential sources of hydrocarbons and are attracting interest from geological researchers in academia and the oil and gas industry.
This volume focuses on recent developments in the understanding and correlation of North African basin fills and explores novel approaches to prospecting for source and reservoir rocks. The papers cover aspects of petroleum prospectivity and age-equivalent global petroleum systems, Neoproterozoic tectonics and palaeogeography, sequence stratigraphy, glacial events and global climatic models, faunal and floral evolution and the deposition of source rocks.
The broader aim of this volume is to compare major environmental change, the emergence of life, the global carbon cycle and the implications for hydrocarbon exploration of well-studied Neoproterozoic successions worldwide.