Petrophysical characterizations and shale distribution analysis of Kissenda reservoir sands, Gabon

Abstract

A gas field in western Gabon is penetrated by an exploration site N field with a major fault dividing the well locations. The upthrown block and the downthrown block have different characterization based on the history of Gabon Basin located in Equatorial West Africa, as part of the salt basin complex. In addition to major fault separating the blocks, four wells are selected in this study to identify each block. Petrophysical properties was undertaken by using wireline logs to generate each well composite. These properties include shale volume, total porosities, water saturation and permeability. The presence of shale in sandstone reservoir can affect the producibility rate of the reservoir. Shale volume and density porosity are cross-plotted using the Thomas-Stieber method to determine the shale distribution of both blocks, including the distribution types of laminar shale, dispersed shale and structural shale. Based on this method, the upthrown block has relatively small grain diameters with mostly laminar-dispersed shale distributions, while in downthrown block the grain diameters are four times larger with more dynamic shale distributions.