A field study report of Semiliki basin in Ntoroko District

Abstract

This report summarizes the field study was conducted in the tertiary Semliki basin found in Albertine Graben between 10th June to 23rd June, 2018. The study aimed at training on how to collect, and interpret geological, geophysical, structural stratigraphic, sedimentologically and structural data. Different methods were employed and materials were used simultaneously and the results were compared. That is to say; Geological method involved outcrop studies, logging, and structural measurements while geophysical methods involved seismic, well log interpretations. The materials and techniques ranged from handy geologic tools, for example a hand lens to lab equipment and software such as Geosoft. Different lithologies were encountered in the study area and these were mainly clays, silts, unconsolidated sands and conglomerates. While the probably stratigraphy had alternating argillaceous and arenaceous formations, starting with Kisegi sands, Kasande clays, Kakara sands, Oluka clays. The various observed structures and facies succession were used to determine or infer the different deposition processes and environment (typical of lacustrine, fluvial and deltaic), paleocurrent directions and paleo-environmental conditions, water energy levels. The findings from the field study revealed great hydrocarbons potential in Semliki basin, with a complete petroleum system. Turaco fault system and flower structures interpreted from seismic data are important structural traps for hydrocarbons. The stratigraphic logging revealed thick clays (seal) interbedded with sand layers (reservoir rock). Although the basin sediments are young (Tertiary), the surface indictors (Kibuku oil seep) and the high geothermal temperatures as witnessed at Sempaya hot springs, are positive indications of a high hydrocarbon potential of the area. The Petrophysical interpretation revealed the presence of hydrocarbon gas seen as a crossover from the Neutron-Density log. This highly calls for petroleum system evaluations to unravel the Semliki basin potential, which can add to the country’s resources and economy.