FLOODPLAIN DEPOSITS AND SOIL CLASSIFICATION: THE PREDICTION OF CHANNEL SAND DISTRIBUTION WITHIN THE TRIASSIC ARGILO-GRESEUX INFERIEUR (TAG-I), BERKINE BASIN, ALGERIA.

N. Sabaou*¹, D.E. Lawton², P. Turner³  and D. Pilling⁴

¹ Badley Ashton & Associates Ltd., Winceby House, Winceby, Horncastle, Lincolnshire, LN9 6PB.

² BHP Billiton Petroleum (International Exploration) Pty. Ltd., Neathouse Place, Victoria, London, SW1V 1LH.

³ School of Geography, Earth and Environmental Sciences, The University of Birmingham, Birmingham, B15 2TT.

⁴ PM Geos Limited, 3^rd Floor, 24 Market Street, Aberdeen, AB11 5PL.

* author for correspondence, email: nsabaou@badley-ashton.co.uk

Middle to Late Triassic fluvio-lacustrine sandstones referred to as the Trias Argilo-Grèseaux Inférieur (TAG-I) are an important hydrocarbon reservoir in the Algerian Berkine Basin. Three depositional sequences have been identified within the TAG-I and a fourth sequence overlies it, forming part of the “Trias Argilo-Carbonaté”. Subtle changes in the style of sedimentation through these sequences have been identified and are attributed to periodic rises in base-level together with changes in subsidence rate and climate, leading to basinward, progradational shifts of the fluvial systems. The palaeoclimate changed from semi-arid to sub-humid with seasonal wetting and drying, as indicated by the evolved style of the deposition, the abundance of vegetation and the nature of associated palaeosols. The presence of sphaerosiderites in green palaeosols is a clear indication of the occurrence of wetland conditions. Palaeosol development and maturity are useful aids to stratigraphic correlation and as an indication of the proximity of reservoir channel sandstones. With improved prediction of the sandbodies’ location, better models of reservoir distribution can be made leading to an enhanced field development plan.

JPG Home (opens in this window)