Foams stabilized by in-situ surface activation of silica micro-particles with surfactant

Abstract

Concept of applying gas foam in EOR was first proposed for gas mobility control to alleviate the challenges of gas flooding and WAG process due to its high viscosity and low mobility. Like surfactant, colloidal particles can be employed as surface-active agent to stabilize the foams and can provide better stability due to its irreversible adsorption to the interface. To get ultra-stable particle stabilized foams/emulsions, the surface wettability of commercial raw colloidal particles should be modified (surface activation) from hydrophilic to partially hydrophobic. However, the studies on the insitu surface activation for the micro-particles are yet to be widely performed. Therefore, the in-situ surface activation of unmodified CAB-O-SIL fumed silica micro-particles by using anionic surfactant such as Sodium dodecyl benzene sulfonate (SDBS) and alpha olefin sulfonate (AOS) has been studied. Its effects on the foamability and foam stability of dispersed solution were analyzed. The research methodology involves the characterization of aqueous foams, measurement of adsorption of particles at the airwater interface, and measurement of surface tensions. The independent variables are concentration of anionic surfactants, concentration of silica micro-particles whereas the dependent variables are foam volume, foam quality, surface tension, and percentage of particles adsorbed at interface. The results showed that hydrophilic silica micro-particles can be surface activated by interacting with anionic surfactants resulting to synergistic effect in foamability and foam stability. The positive charges on the silica microparticles interact with negative charges of anionic surfactant to generate electrostatic interaction. This generates adsorption of surfactant at the particle-water interface making the particles to be surface active and bubble more stable. SDBS is more efficient anionic surfactant for the surface activation of silica micro-particles compared to that of AOS.