Browsing by Author "Patel , Malikah"

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    Using geophysical applications for aquifer characterisation of paleowaters: a case study of the Bredasdorp basin, South Africa
    (University of the Western Cape, 2024) Patel , Malikah
    Reservoir depletion in the Bredasdorp Basin has come with many rising challenges, such as exorbitant decommissioning costs and deteriorating pipelines. However, a depleted offshore reservoir also has many opportunities that can be explored. This research study looks closely at offshore aquifers occurring in the Central Bredasdorp Basin, South Africa, as an alternative source of water. Groundwater usage accounts for 56% of South Africa’s population, either as sole or combined with surface water resources. Therefore, exploring different water sources is essential to the sustainability of our water resource management and security. Offshore aquifer research bridges the gap between two research groups, petroleum geology and hydrogeology, but is very rarely a reality, as data is not publicly available due to propriety rights restrictions. Integration of seismic and well log data acquired by the petroleum industry has demonstrated the effectiveness for offshore fresh groundwater modelling. Groundwater reserves below the seafloor are now becoming a common global phenomenon with brackish to low salinity water regarded as a substitute over sea waters, as the price of desalination processes rapidly decrease. This study focusses on the 14A aquifer, whereby water salinities measuring below a threshold of 30 ppt is regarded as fresh water. The aquifer was interpreted across an area of ~2300 km2 using a 3-dimensional seismic survey to map the aquifer boundaries, along with wireline data from twenty-two wells to extract critical aquifer parameters like porosity, water saturation, water salinity and permeability. The evaluation identified primarily sandstone and shale lithologies, with sand packages ranging from 4 m to 125 m of gross sand. Porosities in the aquifer range between 10-17% while core analysis indicated permeability values between 3mD and 639 mD in sandstone layers, suggesting good production potential in these intervals. The aquifer, measuring 18.72 km3 in size, is correlatable across a distance of ~ 35 km.