Assessment of Geological Controls on Reservoir Heterogeneity in Kingfisher Oilfield Lake Albert Basin, Western Uganda

Abstract

The Kingfisher oilfield is one of the key discovery fields found in the Albertine Graben located in the Lake Albert basin. The Kingfisher reservoir zones are characterized by variations in facies distribution, pressure regimes and fault uncertainty thus implying reservoir heterogeneity. An integrated approach, using seismic attributes and well data was adopted to assess the geological controls on reservoir heterogeneity in the Lake Albert basin. Faults were interpreted with the help of seismic attributes. Gamma-ray log signatures at different locations and three seismic attributes were used to determine reservoir architecture and geometry. Genetic inversion was used to estimate porosity distribution within the reservoir zones. Two fault trends, one oriented in NW-SE, and another set of faults oriented in NE-SW were observed. The interaction of these sets of faults resulted in the compartmentalization of the reservoir due to the alternating sand-shale lithology and high seismic activity in the area. Prominent channels trending in the northeast direction were dominant facies in the reservoir zones. The porosity of the study area ranges from 10%-30% with the sites of highest porosity (30%) observed to be along channels and some faulted zones in the north end. Porosity variation within the study mainly arose from the difference in sedimentary facies. The results confirm that faulting and facies distribution which link to the depositional environment are the two fundamental elements that defined the reservoir heterogeneity in Kingfisher reservoirs.