DETERMINATION OF SOME PETROPHYSICAL PROPERTIES OF RESERVIOR ROCK: CASE STUDY OF THE LOWER SHIRE BASIN

The petrophysical calculations are crucial step in determination of properties of reservoir rock since it helps in petroleum exploration. It facilitates key decision on whether further stages of exploration can be carried out. This paper has described the determination of petrophysical properties of reservoir rock in Malawi, which was carried out on the block six of the hydrocarbon potential areas, which is lower shire basin specifically in Chiromo area. Therefore, enhancing our knowledge of reservoir rock characteristics and their role in hydrocarbon storage and flow dynamics is vital for informing exploration strategies and maximizing the potential of Block 6 in the Lower Shire Basin. The study aims at determining the porosity and permeability of reservoir rocks in the Lower Shire Basin, to understand their potential for hydrocarbon accumulation, by evaluating petrophysical properties, including, porosity, and permeability, and determining the fluid saturated in the reservoir rock. The methods used to include, fluid saturation for porosity determination, gas permeameter for permeability determination and dean-stark method for fluid saturation determination, and literature review provide more of the lithology of the area. It is discovered that Petrophysical properties, which include porosity, permeability, fluid saturation, and lithology, provide essential insights into how hydrocarbons are stored, transmitted, and produced within geological formations. Accurate assessment of these properties is fundamental for making informed decisions regarding exploration, drilling, and production strategies. The results of the study show the variations in porosity and permeability across different rock types in the Lower Shire Basin, and the fluid presence in the reservoir rock. The findings of this research contribute to the broader understanding of sedimentary basins in Malawi, and ultimately provides essential data to guide future research and resource exploitation endeavours in the region.

This paper has described the determination of petrophysical properties of reservoir rock in Malawi, which was carried out on the block six of the hydrocarbon potential areas, which is lower shire basin specifically in Chiromo area. Therefore, enhancing our knowledge of reservoir rock characteristics and their role in hydrocarbon storage and flow dynamics is vital for informing exploration strategies and maximizing the potential of Block 6 in the Lower Shire Basin. The study aims at determining the porosity and permeability of reservoir rocks in the Lower Shire Basin, to understand their potential for hydrocarbon accumulation, by evaluating petrophysical properties, including, porosity, and permeability, and determining the fluid saturated in the reservoir rock. The methods used to include, fluid saturation for porosity determination, gas permeameter for permeability determination and dean-stark method for fluid saturation determination, and literature review provide more of the lithology of the area.

The Chiromo which is in Lower Shire Basin exhibits a stratigraphic complexity influenced by its consolidated sedimentary rocks from the Karroo and Cretaceous periods. The lower shire basin occupies the southern end of Malawi rift. The basin developed during the karoo time and re-activated during the Cenozoic time due to the rifting associated with the EARS (Casting, 1990). A region in southern Malawi, located between latitudes 15°30'S and 16°45'S and longitudes 34°15'E and 35°15'E, near the Malawi-Mozambique border, has been identified as a potential area for hydrocarbon resources. This area's potential is attributed to previous research in the lower Shire basin, which indicated high levels of organic matter in the deep water due to a slow flow rate allowing for accumulation, a condition favorable for hydrocarbon formation. Furthermore, the presence of coal deposits, derived from organic remains under pressure within sedimentary sequences, strengthens the likelihood of petroleum source rocks. Geologically, the area lies within the Malawi Rift, a part of the Mozambique belt, and is underlain by metamorphic rocks, specifically para- and orthogneiss crystalline rocks (Carter & Bennet, 1973). Notably, the Chiromo domains are well-known Karoo sedimentary regions within this study area. Detailed geological accounts of this area are documented in various publications of the Geological Survey of Malawi, including work by Habgood (1965). The sandstones and grits in the basin have demonstrated remarkable porosity and permeability, essential parameters for effective hydrocarbon reservoirs. Specifically, porosity values highlight the excellent storage capacity of these rocks for hydrocarbons, indicating that they can retain significant volumes of oil and gas (Ahmed & Farman, 2023). Meanwhile, the permeability values observed, suggest that these formations facilitate the movement of hydrocarbons, which is crucial for both migration and production.

Traditional authority: TA Mlolo

District: Nsanje

Coordinates: -16.43315, 35.16045