Reverse gas-lift technology for CO₂ storage into deep saline aquifers

We have developed an injection well design to reduce the cost of CO₂ sequestration. In this design, we propose a reverse gas-lift technology for simultaneous injection of CO₂ and water into aquifers. Saline water, which is produced at a location distant from the storage site, is pumped into a well through tubing; CO₂ is injected using the annular space between the tubing and the casing. One way gas-lift valves installed along the tubing allow the flow of CO₂ from the annulus into the tubing. This design makes the injection achievable at lower wellhead pressures, thereby, decreasing the compression costs. Simulation results demonstrate that the compression cost is lower than when a conventional injection scheme is used. The results also reveal that the proposed design can decrease the energy consumption for CO₂ sequestration. These results have implications for the large-scale implementation of CO₂ sequestration.