Comparative Analysis of CO2 Storage Capacity on Saline Aquifers in the Niger Delta

The recent clamour for net-zero gas emissions has increased the demand for further research in carbon capture, storage and utilization as a means to further reduce green gas emissions. Therefore, this paper has identified trapping index parameters to evaluate CO2 storage capacity in the Niger Delta of Nigeria. This was carried out by assessing two major trapping mechanisms that affect the efficiency of the carbon injection and storage within the saline aquifer. In this work, we conducted a numerical simulation to compare the CO2 storage capacities of two reservoirs with saline aquifers. We considered some minor reservoirs not suitable for commercial development due to their minimal oil in place values and net pay thickness of less than 30 ft. These reservoirs are charged with aquifers which were simulated to study the storage capacity of CO2 at downhole conditions. The impact of the reservoir structure, permeability and pressure regimes are some of the parameters that were observed to affect CO2 storage capacity. CO2 was continuously injected into the aquifers via injector wells at 80% of their fracture pressure. Crestal monitoring wells ensured the pressure distribution around the cap rock did not exceed fracture pressure limits. The results were compared and simulation-based inferences were made for each reservoir. The results showed similar migration patterns for each reservoir however there was a significant difference in the residual trapping mechanism of both reservoirs. This impacted the overall CO2 storage capacity at the end of the simulation run. The results obtained from this work can be applied to other reservoirs in the Niger Delta where commercial development is not expected due to their hydrocarbon in-place volumes.