A Geological and stratigraphic study report of Kibuku Area, Semiliki Basin, Albertine Graben

Abstract

This report is a written account of the field trip to Kibuku area in the Semliki Basin of the Albertine Graben, Western Uganda. This field trip is a requirement for the award of a Bachelor’s degree in Petroleum Geoscience and Production. The report is comprised of a detailed compilation of findings from the Semliki basin field study in the Albertine area. It entails the materials, methods used to achieve the main objective; collection and interpretation of stratigraphic, petrographic, sedimentological and structural data. It goes ahead to highlight the petroleum system as well as the petroleum potential of the area. We were able to gather information about the area through the use equipment and methods explained in chapter Two. Some of methods that were used include desktop studies, Stratigraphic logging, Lithology and grain size analysis, Porosity analysis, colour analysis, Bedding analysis, analysis of sedimentary structures, Geophysical methods and interpretation of seismic sections. The Semliki basin is generally filled with Middle Miocene to Recent sediments exhibiting a fining upward sequence (characteristic of fluvial systems) from conglomerates (overlying the basement rock) to sands to silts to clays. It is structurally wedge shaped and majorly comprises faults, joints, laminations and bedding planes, cross beds, foliations, quartz veins, unconformities, soft sediment deformation structures among others. The southern part of this basin has the highest elevation but the smallest thickness of accumulated sediments whereas the depocentre (5km thickness of sediments) is in the northern part of the Semliki basin. A stratigraphic log of the area logged by group 4 also showed that the logged area is majorly composed of sandstones and clays. The sandstones varied in colors from white, yellow, brown and red. The clays were majorly clay in colour, with some yellow and brown layers. The yellowish and reddish coloration is attributed to iron mineralization. A detailed study of this area in included in Chapter three. Generally, the sediments in the Semliki basin represent a petroleum play for hydrocarbon accumulations, in which the necessary elements of a valid petroleum system were identified as evidenced by the abundance of excellent reservoirs, regionally mature source rocks, traps, intraformational and regional seals as well as hydrocarbon-migration pathways in the basin.