Study On The Interfacial Microstructure Of The Oil-water-air Three-phase Foam

Foam fluid has attented more and more attention for applications in the exploitation ofoil and gas, such as the chemical flooding and profile control water plugging and fracturing,wash well, drilling and gas drainage. In this paper, we chose the surfactant and modified SiO2nanoparticles to prepare the emulsion and foam, with the characterization of opticalmicroscopy (FM) to reveal the interfacial structure, especially the interfacial configuration ofemulsified oil droplets and the relationship with the foam stability. The conclusion can bedraw from above experiments as following:(1) With the the increase of oil content, the quantity of oil-gas-water three-phase foamwhich is stabilized by surfactant SDS is become more and more small, but the stability of thefoam is more and more strong and the half life get longer gradually. The small oil dropletswich around bubble are more and more dense and uniform. The bubble diameter decreases.(2) Compared to oil-water-gas three-phase foam and pure water phase foam, the plateauborder of pure water phase foam is wider, it can be clearly seen under the microscope. Theplateau border of three-phase foam is thinner, and the liquid flow channel in the plateauboundary layer is not easily observed by microscopy. The oil drops of three-phase enters intothe plateau border, it has an effect on the foam structure.(3) We have carried on the hydrophobic modification to nano SiO2particle surface, andattain three different hydrophobic modified nano SiO2particles, contact angles which are55.4°,90.5°and141.7°. Contact angle of55.4°can be stabilized of O/W type emulsion,90.5°and141.7°can be stabilized W/O type emulsion. As for foaming capacity, only the stableemulsion prepared with contact angle of55.4°can generate foam, but the amount of foam issmall and foam stability is very poor with half-life of only a few minutes.(4) The configuration of modified SiO2nanoparticles and ordinary surfactant moleculeSDS at interface of three-phase foam is obviously different. For the plateau boundary, theformer is wider than the latter. As for modified SiO2nanoparticles, they can be clearly seenunder the microscope. The bubble diameter is larger, nano-SiO2particles arrange on thebubble interface uniformly. Plateau border of stable emulsion bubble with the ordinarysurfactant SDS molecules is thinner, and the liquid flow channel in the plateau boundary layeris not easily observed by microscope. Silica particles come into the plateau boundary and have an effect on foam structure, which result in the reduction of stability of three-phase foam.