Properties of the Reservoir Rocks – Jdeir Formation In Sabratah Basin

Abstract

The Early Eocene Jdeir Formation in NW offshore Libya Sabratah Basin consists of a thick sequence ≈ 450ft of shallow marine carbonate that is overlain by Harshah Formation, Ghalil Formation and underlain by the Bilal Formation, Jirani Formation. This study evaluate the Biofabric analysis and interpretation of skeletal accumulations consisting of nummulite tests (larger foraminifera) based on : the imbrication features & on their ratio of small-bodies A-Forms to large-bodies B-Forms the Jdeir Formation NW Offshore Libya, Nummulites were displayed into four biofabrics : Small robust nummulite, Small flat nummulite, Large robust nummulite & Large flat nummulite. however, reflect various degrees of sedimentary reworking and winnowing of the original substratum by physical processes. For packstones with edge-wise imbrication and A-Forms strongly dominating over B- Forms, in situ winnowing of fine-grained matrix by waves can be inferred. In contrast, packstones composed of imbricated B-Forms suggest hydraulic sorting and selective removal of A-Forms by currents. Packstones composed almost entirely of A-Forms represent transport-sorted Allochthonous deposits. Biofabric analysis thus allows us to understand better the dynamics of this study measurement of porosity has found that: Φ = 5 to 10% (fair) and permeability P= 40 to 60md. This indicates a good quality of reservoir.