Dimensionless analysis of foam stability for application in enhanced oil recovery

The stability of foam during injection into oil reservoirs is critical, especially under high-temperature and high-salinity conditions. This study formulates foam stabilizers using one polymer, two surfactants, and six types of nanoparticles (NPs). Foam stability was assessed with a static setup, examining factors such as interfacial tension (IFT), bubble characteristics, and solution viscosity through dimensionless numbers: Bond number (Bo), Worthington number (We), and Neumann number (Ne). A new formula for dimensionless electrical conductivity was also introduced. Results showed that at optimal concentrations of the four additives, foam stability improved with NPs due to enhanced surface charge from in situ physiochemical reactions, promoting their migration to the fluid interface. Notably, Ne proved more effective than Bo and We in describing foam stability as it accounts for droplet height's impact on IFT. Acidic NPs demonstrated greater electrostatic force than amphoteric NPs, correlating with improved foam stability reflected in a downward trend in the Ne plot. Additionally, we analyzed the coarsening rate of foam bubbles over time and its relationship to stability. Our findings suggest that dimensionless numbers serve as valuable benchmarks for evaluating foam stability across various additive mechanisms.