Geologic And Stratigraphic Logging Project Report Of Semilki Basin-Albertine Graben-Ntoroko District Western Uganda
Abstract
This report details the observations and analyses made during the field excursion conducted from 13th to 22nd JUNE 2022 and post-field data analysis and interpretation. The study was carried out in the Semliki Basin. The Semliki Basin is situated in the Albertine Graben in Western Uganda Ntoroko district . It has a total area of approximately 740 km2 and comprises of three (3) Petroleum Exploration Blocks (Block 3B, 3C and 3D). Geophysical surveys suggest a maximum of 6 km sedimentary succession in the basin. The general stratigraphy of The Semliki basin consists of Kisegi, Kasande, Kakara, Oluka, Nyaburogo, Nyakabingo and Nyabusosi formations in that order.
The fieldwork was carried out in areas of Kichwamba road cut , Kisegi hill at the quarry, along Kisegi River, along Kibuku road cut, Makondo fault area , Turaco area and Sempaya hot springs. Activities carried out during the field work included sedimentary logging, depositional system reconstruction, stream sediment studies, and structural measurements.
Some of the identified sedimentary structures in the area include faults , joints ,folds , cross beds , disconformities , mud cracks , troughs and planar beds. Major lithologies consist of clays , sandstones , claysilts with depositional environments ranging from fluvial to alluvial. The mineralogy consisting of gypsum and calcite( mainly in the travertine rocks).
Materials used include Jacob’s stuff , Global Positioning System (GPS), geologic compass , geologic hammer , hoes , spades , graph sheets, grain size chart. They were used to measure, record and store geological data.with the close guidance of our lecturers from the department of geology & petroleum studies.
The main objective of the field excursion was to obtain a hands on field training on how to collect and interpret stratigraphic, petrographic, sedimentologic and structural data; which are very important in hydrocarbon exploration.
The vast structural and stratigraphic data collected was then analyzed and used to make conclusions about the petroleum potential of Semliki basin. Elements of the petroleum system such as reservoir rocks (sandstones), seal (clays), hydrocarbon-migration pathways among others were observed. With the most interesting and vivid evidence of an active petroleum system being the Kibuku oil seepage ( figure 43) , Sempaya Hot springs(figures 5&6) with in the Semliki area also indicate the presence of high enough thermal gradients for oil maturation.