Macroscopic and Microscopic Studies of Nanoparticles-Stabilized Foam for Carbon Dioxide Gas Flooding

The thesis presents microscopic and macroscopic studies of nanoparticlesstabilized
foam stability for CO₂ gas flooding. CO₂ gas flooding experienced poor
sweep efficiency due to high gas mobility, hence foam was utilized as the gas mobility
control agent. However, previous research mostly restricted to foam stability at macroscale,
while very few studies corroborated pore-scale studies with coreflood studies.
This research aims to examine effects of nanoparticles concentration and varying
salinity on foam static and dynamic stability at micro-scale and macro-scale. Foam
static stability tests were conducted to determine the optimized surfactant-nanoparticles
concentration via Design of Experiments (DOE). Microscopic and macroscopic foam
studies were performed in micromodels and Bentheimer sandstone cores respectively.
Optimized surfactant-nanoparticles concentration with the highest foam stability was
0.3 wt% for both Alpha Olefin Sulfonate (AOS) and silica nanoparticles (SiO₂). Results
indicated AOS-SiO₂ foam generated thicker and more stable foam lamella that travelled
through the pore network without rupturing to provide higher gas mobility control.
AOS-SiO₂ foam flooding in high salinity environment shown significant increase in
average pressure drop. This result implied SiO₂ nanoparticles worked synergistically
with electrolyte mixtures to enhance the foam dynamic stability. Coreflood results
validated optimized AOS-SiO₂ concentration was enough to enhance the foam stability
without causing excessive aggregation and pore throat blockage. Overall, the
microscopic and macroscopic studies justified the optimized AOS-SiO₂ foam has
significantly improved the foam stability and gas mobility reduction, consequently
having immense potential to enhance the overall macroscopic sweep efficiency.