Master Thesis Lithofacies Identification and Reservoir Quality Variation of the Lower Acacus Formation, Concession NC100, Ghadames Basin, NW Libya.

Abstract

By viewing and describing the available 215ft of cores cut in Lower Acacus Formation from five wells in the study area (concession NC100), Ghadames Basin, NW Libya, the Lower Acacus Formation is divided into five lithofacies types including; 1) Bioturbated marine silty shale lithofacies, 2) Reworked marine sandstone lithofacies, 3) Distal delta front silty sandstone lithofacies, 4) Proximal delta front – coastal sandstone lithofacies, 5) Fluvial channel sandstone lithofacies. Furthermore, on the basis of GR-log motifs these identified lithofacies were grouped into four major categories, which are: 1) 1st category represented by bell shape GR-log motif corresponds with the fluvial channel lithofacies, 2) 2nd category of funnel shape GR-log motif corresponds with the gradational sequence of the shaly siltstone of distal delta front at the base to proximal delta front-coastal lithofacies at the top, 3) 3rd category of spiky shale GR-log motif corresponds to reworked marine sandstone lithofacies and 4) 4th category of thinly serrated to smooth “featureless” GR-log motif corresponds to bioturbated marine shale lithofacies. Suits of wireline logs were used to construct stratigraphic cross sections to reveal the paleogeography of the study area “concession NC100” and to examine the lateral relationships between sandstone units or lithofacies packages identified in cores.