Carbone dioxide sequestration using downhole water sink (DWS) technology: Effects of well placement on trapping efficiency, leakage, and reservoir pressure
DOI:
https://doi.org/10.31699/IJCPE.2026.1.2Keywords:
CO₂ sequestration; depleted reservoirs; downhole water sink (DWS); leakage index; saline aquifers; trapping efficiency; Reservoir pressure management; well placement; CO₂ trapping mechanismsAbstract
Geological CO₂ sequestration is a widely accepted technique that consists of safely and securely hiding carbon emissions from human activities by storing them underground. It is considered the main method of carbon dioxide capturing and sequestration because of its large-scale application. Use of Downhole Water Sink (DWS) systems and other advanced reservoir control technologies is driven by the necessity to manage effectively the reservoir pressure change, the CO₂ plume migration, and the leakage pathways. The effectiveness of the DWS technology in providing better CO₂ storage performance in a depleted reservoir surrounded by a saline aquifer has been the focus of this research. The study analyzed three operational scenarios to evaluate how the different distances between the DWS wells and the CO₂ injectors would affect the storage efficiency, the leakage behavior, and the management of the reservoir pressure. Scenario 1 had DWS wells located right under the CO₂ injectors which caused negative hydrodynamic interactions, decreased the total trapped CO₂ and increased the leakage indices. Scenario 2 had a tiny lateral offset which led to small improvements in trapping and tiny increases in leakage, implying partial but still insufficient mitigation of injector-sink interference. In Scenario 3, with a 10-grid offset between the injection and extraction wells, achieved the maximum CO₂ storage efficiency, where trapping gained 2.79% (431,235 tons) at a CO₂ injection rate of 20 MMSCF/day and a DWS flow rate of 12,500 bbl/day. Leakage did not change, maintaining a Leakage Index of +0.06898 which indicated only a slight increase that was barely noticeable when compared to the more varying responses in Scenarios 1 and 2. In addition, the operation of DWS in Scenario 3 led to a peak pressure of the reservoir that was lower than that of the case without DWS, as the pressure dropped from about 6150 psi to 5100–5794 psi, thus relieving some of the stress on the formation. Although no specific fracture pressures or geomechanical analyses were performed, the pressure drop is likely to create better injection conditions and also enhance the integrity of the storage area. The overall results show that the DWS wells, when placed and managed properly and strategically, can not only increase the CO₂ trapping efficiency but also stabilize the leakage behavior and provide pressure control, thus making the geological CO₂ sequestration more reliable.
Received on 04/01/2026
Received in Revised Form on 10/02/2026
Accepted on 13/02/2026
Published on 30/03/2026
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