Nanoparticle-Stabilized CO₂ Foam Flooding

The efficacy of several nanoparticles [silica (Si), nanoclays, fly ash and iron oxide (IO)] in stabilizing CO₂ foam is studied via flow experiments in a microfluidic device. The resulting foam is characterized using modified bulk foam tests. Size and uniformity of nanoparticle (NP) dispersions are quantified using dynamic light scattering. Results indicate that the size distribution and surface charge of the particles are influential parameters on the stability and formability of the foam, which in turn have a direct relationship with oil recovery performance. Si, nanoclays and fly ash NPs assisted by surfactant mixtures generate stable foams and result in high ultimate oil recoveries (over 90%). Even though IO-surfactant mixtures generate foams with relatively inferior stability characteristics and ultimate recovery, approximately three quarters of the IO NPs are recovered once exposed to a magnetic field. Unlike nanoclays and fly ash, the use of Si and IO NPs as foam stabilizers results in significant improvements in recovery at much smaller pore-volumes injected (~10 PVIs).