Foams stabilized with silica nanoparticles derived from sodium silicate for gas well liquid unloading

In this study, an anionic surfactant sodium lauryl sulfate (SLS) stabilized with silica nanoparticles was prepared for use as liquid foam unloading agent with good foamability and foam stabilizing ability. In the foam, the silica nanoparticles were adsorbed onto the gas–liquid interface to form a silica-SLS aggregates film which prevents bubble coalescence and, thus, the foam stability and liquid unloading efficiency can be improved. The concentration of silica nanoparticles as the stabilizing agent was unnecessarily high if sufficient time was given for the silica to be in contact with the surfactant. The study on the performance of foam unloading agent showed that nanofluid with 0.03% silica nanoparticles had the best performance with a foam stability of 72% at 80 °C and a liquid efficiency of 97.5% at 100 °C. It also had temperature resistance as high as 100 °C, salinity resistance of up to 10% and hydrocarbon content of up to 50%. Using a bubble column, the high production capacity of SLS-silica nanofluid could be realized. The formation of silica nanoparticles in the bubble column was induced by CO₂ gas, which simultaneously they adsorbed SLS. The foam unloading performance of the nanofluid produced was comparable to that of the small-scale preparation. The success of silica nanofluid production as liquid foam unloading agent in bubble column reactor opens an opportunity for large-scale production in the field.