Javadpour and Nicot (2011) presented a novel idea of adding nanoparticles (NPs) to injected CO2 (aka. nano-CO2) to expedite convective mixing and decrease the potential of buoyancy flow of CO2. In this paper we implement that idea through the use of compositional numerical simulations.
Numerical simulation scheme is divided into two scenarios. The first scenario represents a saline aquifer of 20 m thickness, and extending 100 m laterally from the wellbore. This scenario is modeled to show the effect of nano-CO2 injection on field scale for 200 years. The second scenario represents a small part of the field scale model with dimension of 7.5 cm × 7.5 cm. These small scale models show density contrast effect on convective fingers at the brine/nano-CO2 interface.
Comparison of results between injection of nano-CO2 and normal CO2 clearly show that nano-CO2 exhibits the capability of improved mixing and reduced buoyancy driven flow in both scenarios. In scenario 1, nano-CO2 plume is able to dissolve deeper and move less laterally forward than the normal CO2 plume. In scenario 2, the CO2 dissolves and forms fingers due to gravity driven flow in a heterogeneous medium. The difference in length of convective fingers between nano-CO2 and CO2 increases with time.
Adding nanoparticles with the injected CO2 presents a great potential in quick mixing with the in-situ brine which will reduce the chances of leakage through the sealing. Injection of nano-CO2 can obviate the use of some of the monitoring techniques post injection. Waste materials such as depleted Uranium can be used as nanoparticles which favor economic feasibility of the proposed idea.