Investigation of the carbon storage potential of the Sundays River Trough in the Algoa Basin
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Date
2023
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University of the Western Cape
Abstract
Algoa Basin, South Africa, was extensively studied using data from three selected wells: AL 1/69, CK 1/68, and NA 3/70. These wells were chosen due to their positioning within tThe storage potential for carbon dioxide (CO2) within the Sundays River Trough, located in the he Sundays River The storage potential for carbon dioxide (CO2) within the Sundays River Trough, located in the Algoa Basin, South Africa, was extensively studied using data from three selected wells: AL 1/69, CK 1/68, and NA 3/70. These wells were chosen due to their positioning within the Sundays River Trough and the availability of geophysical wireline logs, conventional core analysis, geological well completion reports, and 2D seismic lines. Physical rock properties, such as lithology and reservoir zones, were identified, and quantitative parameters like volume of clay, porosity, and water saturation were determined. Permeability was calculated using basic log functions. The storage potential of CO2 was assessed by employing CO2SCREEN, and the total estimated storage potential for the Sundays River Trough was obtained. The 'Geological Storage of Carbon Dioxide' Atlas, published by the Council of Geosciences, provides estimates of the potential CO2 storage capacity in geological formations across the entire country. Previous studies have focused on investigating CO2 storage in geological formations, particularly saline aquifers, at a regional scale, with a primary focus on the Zululand Basin region. This research aims to enhance the ongoing understanding of CO2 storage potential, enabling the development of pilot programs and subsequent injection initiatives. By doing so, South Africa can actively contribute to the reduction of carbon emissions and effectively mitigate climate change. The total expected storage potential in the Sundays River Trough, considering the three selected areas surrounding wells AL 1/69, CK 1/68, and NA 3/70, amounted to P10= 13.37Mt, P50= 54.22Mt, and P90= 160.26Mt in the Sundays River formation and P10= 12.52Mt, P50= 50.45Mt, and P90= 147.97Mt in the Wood Beds formation withWell CK 1/68 exhibiting no storage potential, Based on the acceptable storage estimates of the Sundays River & Wood Beds formation and factoring in Smith et al. (2011) site screening criteria, the Sundays River Trough does have potential for CO2 storage. However, it leans towards negative site screening criteria due to low permeability and low porosity. The presence of old 2D seismic lines also plays a major role in determining that the Sundays River Trough may not be entirely suitable for storage.
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Keywords
Carbon capture and storage, Geological formations, Mesozoic basins, Salin aquifers