Litho-seismo Stratigraphy and Basin Analysis of the Sirius 1 Prospect, Chalbi Sub Basin, Northern Kenya

Abstract

In recent years, global exploration for hydrocarbon accumulations in commercial quantities has become increasingly difficult, and as a result, exploration projects have extended into more geologically challenging areas. Previous fields that were explored but not developed such as the Chalbi sub-basin, in Northern Kenya, have now become suitable targets for reassessment. Sirius 1 was the first exploratory well to test the hydrocarbon potential of the Chalbi sub-basin. This study investigates the stratigraphy and basin architecture of the Sirius 1 prospect, to establish the implications of its structural and depositional history on its petroleum system. Petrophysical log data from the Sirius 1 well has been analyzed to define the lithostratigraphy and depositional environments of the formations encountered. Five major lithofacies have been highlighted. The results from the petrophysical evaluation have been integrated with seismic data adjacent to the well, to provide a basin scale perspective of their structural and stratigraphic setup. There is a distinct correlation between the lithological facies observed from the well and the seismic reflection character. The integration of well information with the seismic data aided the interpretation of the low resolution seismic data of the Chalbi sub-basin. The results highlight two major petroleum systems associated with different depositional environments. The seismic interpretation also provides a new perspective on the structural makeup of the Sirius 1 prospect. The Sirius 1 prospects lies on a series of tilted fault blocks that have had an implication on the preservation of stratigraphic traps. The localized variation in petroleum plays and the complex structural style of lacustrine basins such as the Chalbi sub-basin emphasizes the need for sub-basin scale analysis in exploring the resource potential.