Project report of study area: Semiliki Basin (Albertine Graben)
Abstract
The Kibuku are is located within the Semliki basin of the western arm of the East African Rift System. It forms part of petroleum exploration license block 3, which is in the Albertine Graben, Uganda. Both Uganda and democratic Republic of Congo share the Semliki basin. The Ugandan portion of the Semliki basin covers the southern part of the Lake Albert, plus a landward area of the south of the lake. The area’s pre-rift basement lithology consists of altered granites and granitic gneisses, felsic and maficrocks and the post-rift lithology is made up of sedimentary rocks mainly of lacustrine and fluvial nature believed to have their source of province in the Rwenzori ranges. The sediments are stratigraphically divided into Kisegi formation at the base, Kasande formation, karaka formation, Oluka formation Nyaburogo formation, and Katorogo being the youngest formation. Basing on the basin and facies analysis, the depositional environment of the Kibuku area along the road cut ranges from fluvial, lacustrine to deltaic. The province of these sediments is probably the basement rocks of Rwenzori Mountain since the pebbles and conglomerate observed to be in contact with the basement had a similar mineralogy with the basement rock of Rwenzori Mountains. The Semliki basin is a sub-basin in the south of the greater Albertine Graben and the most prospective region for oil and gas exploration in Uganda. The sediments in this basin are of mid-Miocene to recent age, which are underlain by possible Jurassic to early Triassic age sediments resting uncomfortably over the basement rocks. These sediments predominantly comprise of sandstones and claystones, and the basement comprises igneous and high grade metamorphic rocks such as granites, granitic gneisses among others. Structural and stratigraphic data was collected and interpreted to make informed conclusion about the petroleum system and potential of Semliki basin. The area has being subjected to a number of structures in both sediments and the basement rocks due to intensive tectonism. These include joints, faults and veins and structures such as beddings, cross-bedding, laminations, unconformities, mud diapers and folds among others exist in the soft sediments. These sediment represent a petroleum play for hydrocarbon accumulations in which necessary elements of petroleum system were identified such. These include excellent-good potential for reservoir and seal as well as circumstantial evidence of mature source rocks, possible seals, traps and hydrocarbon-migration pathways.