A field study project report of the Semliki Basin in the Albertine Graben of Western Uganda

Abstract

This project report provides an in depth of the Field exercise (geologic and stratigraphic logging) carried out in the Semliki basin of the Albertine graben. The main objective was to obtain field training on how to collect and interpret stratigraphic, petrographic, sedimentologic and structural data; which are very important in hydrocarbon exploration. The other objective is to identify the facies and depositional environments. The materials that were used in the field include; grain size scale, tape measure, Jacob staff, compass, hand lens and a geological hammer. The basement lithologies identified include; granitic gneiss and migmatite while sediment lithologies observed include sands and clays. The Semliki basin is composed of both primary and secondary structures. The primary structures observed include; planar bedding, mudcracks and stratification while secondary structures were joints, folds, foliations, quartz veins and faults. The general trend of these structures was found to be in NE-SW direction that was consistent with tectonic forces that affected the Semliki Basin. The facies and basin analysis revealed three depositional environments; lacustrine, fluvial and deltaic that occurred in the Semliki basin basin. Sedlog software was employed to generate group Flog and a combined log for the different groups. Through geophysical studies Semliki basin, sedimentary basins were identified through analysis of magnetic and gravity the datasets using GeoSoft/Oasis Montaj software. Techlog software was also used to analyze well log data from Turaco-2 well which revealed gas filled sand formation. The findings from the field exercise reveal a good potential for hydrocarbons in the Semliki basin through presence of good quality reservoir sands, potential lacustrine clay source rocks, traps and migrating pathways formed by the structural and stratigraphic deformation of this basin.