A geological and stratigraphic study report of Kibuku area, Semiliki basin, Albertine graben

Abstract

Semliki basin is one of the most prospecting basins for petroleum exploration in Uganda. Available data shows the presence of a petroleum system. Thus, a field exercise was carried out in the Kibuku area with a major aim of collecting and interpreting stratigraphic, petrographic, sedimentologic and structural data; which are very important in hydrocarbon exploration. In order to achieve this, surface geological and structural data were collected through study of the basement rocks and sediments. Seismic, Gravity and Aeromagnetic data were provided to students by the Department of geology and petroleum studies, Makerere University in form of images for interpretation. The method involved the study of the basement rocks along foothills of the northern Rwenzori block identifying the structures and measuring their trends. The strategy was moving from older basement rocks to young sediments. The data was collected in groups mainly by logging and discussion held at the established stations. The data obtained was analyzed, interpreted and presented. The lithology of the basement comprised of altered granites, granitic gneisses, schist and amphibolite while the lithology of sediments comprised of both fluvial and lacustrine sediments with Mt Rwenzori and the rift escarpment as the provenance. The major sedimentary environments are fluvial, deltaic and lacustrine. The thick well sorted less consolidated sands of Kisegi formation are believed to be the reservoir rock in the study area due to high quality sands with good permeability and large lateral extent. The cap rocks are the clays and shales as well as gypsum. The sediments are very young (Miocene in age) and shallow thus little possibility of hydrocarbons forming in the area. However, the presence of the Sempaya hot spring can play a very big role in providing the necessary temperature required to “cook” the organic matter in the shale. The hydrocarbons can then migrate to the reservoir and trapped by the sealing faults hence accumulation. This justifies the hydrocarbon potential of the study area. This report chapter is finalized with a chapter on conclusion and recommendations for future reference work.