SCOTT, ALAN J.; Scott and Associates, and Anadarko Algeria Corporation, London, UK, DAVID A.WHELLER,Anadarko Algeria Corporation, London, UK

Abstract: Semi-Arid Lacustrine Cycles, a Controlling Mechanism for Triassic Reservoir Geometries and Characteristics, Berkine Basin, Algeria

In the past five years several major oil fields have been discovered in non-marine Triassic sandstones of the Berkine Basin,Algeria. Initial stratigraphic and sedimentologic studies recognised a cyclic depositional pattern and considered the reservoir sandstones to be fluvial in origin.

With continuing delineation drilling a variety of sandstone types have been delineated including a spectrum of fluvial systems, aeolian, and deltaic sand-rich facies.

The associated mudstones and shales were deposited in lacustrine and desiccated chott basins. The overall cyclicity of the Triassic involves both major base level changes and climatic lake level fluctuations. The role of these cycles and accommodation space provided by the chott basins is a significant factor influencing the distribution and geometries of the various reservoir sandstones.

A modern and Pleistocene chott system located along the southern margin of the Atlas Mountains of eastern Algeria and Tunisia provides an active analogue for the Triassic depositional model. The modern chott basins and the Triassic depositional systems can be compared using Landsat images of the modern chott and the detailed Triassic stratigraphic framework which is based on an excellent core database, wire-line log cross sections, and facies maps.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England