Source Rock Hunter

This project being undertaken by PhD studentJianpang Wang (Chinese Gov. Scholarship) has commenced, supervised by Prof Kevin Taylor and Prof Jonathan Redfern.

The aims are to characterise the Cenomanian/ Turonian source rocks outcropping onshore Morocco and correlate with the offshore penetrations. Geochemical data will be collated and new data produced from examination of outcrop and cuttings data.

The study will address the controls and processes of source rock development and enrichment. It is anticipated this will extend south along the Atlantic margin and also include an element of basin modelling. This will contribute to the NARG Source Rock Hunter project.

Early work on regional source rocks was undertaken by postdoctoral researcher Dr Sebastian Luning, supported by Stefan Lubeseder and Dr Jonathan Redfern. This work aimed to assess the source rock quality of Palaeozoic shales from outcrop studies, that had proved difficult to quantify due to intense weathering. The project included the analysis of a number of methods to allow more accurate regional mapping of source rock facies including surface exposures. Based on their characteristic uranium gamma-radiation and pyrite framboid distribution, the original organic richness of the Silurian / Upper Devonian shales in weathered outcrops was mapped in Libya. A model for the distribution of the rich source rocks was developed. Fieldwork was carried in the Moroccan Anti-Atlas where the Frasnian and Silurian hot shales were studied at outcrop using a portable gamma-ray spectrometer. The unit is typically marked by enrichment in uranium. Additional fieldwork was carried out on the Silurian Tannezuft Shales outcrops documented in Ghat (SW Libya) and Algeria for the Silurian and Devonian source facies.

The project was continued by Dr Alvaro Jimenez Berracosso (now with Repsol). New field investigations were carried out in north central Tunisia, examining the organic-rich sediments of the Bou Dabbous Fm (lower Eocene). The research addressed the controls on the development of the organic richness and assess its distribution stratigraphicaly and aerially, in order to improve source rock quality predictions.

Other research (oncluding proprietary consulting projects) has focused on the Silurian (Tanezuft Shales) in Libya and Morocco, Cenomanian/ Turonian and Toarcian source rocks.

Future work will initially focus on the Cenomanian / Turonian in Morocco, with Prof Kevin Taylor from the University of Manchester. These outcrops, integrated with available offshore well and seismic data, will provide an analogue for offshore source intervals along the Atlantic margin. Development of the online database is continuing for all the main source horizons and potentially significant intervals.

NARG has also been working on basin modelling projects, integrated to petroleum system analysis, since its inception. We have access to the lasts basin modelling software, and through collaborations, can undertake heat flow and subsidence history analysis (FT, Vr etc). The capability is enhanced now through the membership of TU Delft.

Publications:

Burwood R., Redfern J., and Cope M. (2003) Geochemical evaluation of East Sirte Basin (Libya) petroleum systems and oil provenance. In Petroleum Geology of Africa: New Themes and Developing Technologies, Vol. 207 (ed. T. J. Arthur, D. S. MacGregor, and N. R. Cameron), pp. 203-204. Geological Society of London Special Publication.

Lüning, S., Craig, J., Loydell, D. K., Storch, P. & Fitches, W. R. (2000): Lowermost Silurian 'hot shales' in North Africa and Arabia: Regional Distribution and depositional model. Earth Science Reviews 49: 121-200.

Lüning, S., Adamson, K., Craig, J. (2003a): Frasnian 'Hot Shales' in North Africa: Regional Distribution and Depositional Model. In: Arthur, T. J., Macgregor, D. S., Cameron, N. (Eds.), Petroleum Geology of Africa: New Themes and developing technologies, Geol. Soc. (London) Sp. Publ. 207: 165-184.

Lüning, S., S. Kolonic, D. Loydell, J. Craig (2003b): Reconstruction of the original organic richness in weathered Silurian shale outcrops (Murzuq and Kufra basins, southern Libya). GeoArabia 8: 299-308.

Lüning, S., S. Kolonic, E. M. Belhadj, Z. Belhadj, L. Cota, G. Baric, T. Wagner (2004): Integrated depositional model for the Cenomanian-Turonian organic-rich strata in North Africa. Earth-Science Reviews 64: 51-117.

Underdown, R., and Redfern, J., (2007), The importance of constraining regional exhumation in basin modelling: a hydrocarbon maturation history of the Ghadames Basin, North Africa., Petroleum Geoscience, V 13, p 1-19

Underdown, R., and Redfern J., (2007), Constraining the burial history of the Ghadames Basin, North Africa: An integrated analysis using sonic velocities, vitrinite reflectance data and apatite fission track ages. Basin Research, Volume 19, Number 4, pp. 557-578 (22)

Underdown, R., and Redfern, J., (2008), Petroleum Generation and Migration in the Ghadames Basin, North Africa: A 2D Basin Modelling Study, AAPG Bulletin, V. 92, No. 1 , pp. 53-76.

Bodin S., E. Mattioli, S. Frohlich, J.D. Marshall, L. Boutib, S. Lahsini, J.Redfern (2010). "Toarcian carbon isotope shifts and nutrient changes from the Northern margin of Gondwana (High Atlas, Morocco, Jurassic): Palaeoenvironmental implications." Palaeogeography, Palaeoclimatology, Palaeoecology, 297, pp 377-390.

Reports:

Additional reports are available of the Jurassic source rocks of Fuerteventura, and regional source rock analysis of the Silurian in Morocco and Libya.

PhD Thesis:

2006: Dr Ruth Underdown (now a school teacher): Assessing the impact of regional unconformities on the maturation and migration of hydrocarbons within the Ghadames Basin, North Africa. NARG Funded.