A combination of Petrophysical logs from five representative wells and 3D seismic volume acquired in OSCAR Filed, Niger Delta, Nigeria, has been analysed to study the carbon-dioxide (CO2) sequestration potential of ‘OSCAR Field’ The aim of the study was to estimate the volume of CO2 that can be potentially stored in the aquifers and evaluate the risk of CO2 leakages from the cap rock. The sand aquifers were correlated across the five wells to evaluate their thicknesses and lateral extent. Porosity, permeability, formation water resistivity, and net sand thickness were estimated across the five wells. The Horizons corresponding to the top of the aquifers were mapped, time and depth structured maps were generated for structural analysis and volumetric estimations. The risk of CO2 leakages through sealing layers was evaluated in terms of cap rock integrity and pore pressure sealing mechanism. Results of the study showed that the four aquifers namely, L20, N30, M40, and P50, are laterally extensive across the five wells and have thicknesses ranging from 14 to 352 m. The individual CO2 storage capacity of L20, M30, N40, and P50 aquifers was estimated to be 6.97x1010 tons, 1.48x1010 tons, 7.78x109 tons and 1.49x1010 tons, respectively. The combined aquifer storage capacity was estimated to be 1.07x1011 tons. The sealing layers were found to be moderately ductile, sufficiently thick for CO2 storage caprock, and laterally extensive covering the aquifer surface area. The cap rocks are categorized to have low risk potential for CO2 leakages. The study concluded that the aquifers are good and safe for CO2 sequestration, have a low risk of leakages. In terms of CO2 volume and risk of leakages, the study ranked L20 as the best aquifers.

Note: This paper was accepted into the Technical Program but was not presented at IMAGE 2021 in Denver, Colorado.

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