Properties Of Nanoparticle-Stabilized Foam And Its Flow Behavior In Porous Media

With the increasing demand and consumption of energy global,the resudial oil after waterflooding is an important goal for oil development.In order to enhance oil recovery,a serious of new technologies and new processes?such as surfactant flooding,polymer flooding,foam flooding?have been proposed all over the world.Of all the technologies,foam flooding has been developed as a kind of mature oil displacement technique.But the bubble is unstable both thermodynamically and kinetically.So the unstability of foam restricts its application in oil field.Given this,partially hydrophobic SiO₂ nanoparticles and surfactant were used to prepared aqueous foam.And the flow behaviors of foam in sandpack were studied by experiment.The foam properties prepared by SiO₂ nanoparticles and different surfactants were studied using the Warning Blender method.The results showed that the SiO₂/CTAB foam system can not increase the foam stability obviously.Although the SiO₂/C₁₂E₄ foam system can increase the foam stability,the synergy mainly came from the enhanced viscosity of system.The synergy might happen between hydrophobic SiO₂ and SDS,so the SiO₂/SDS foam system can increase the foam stability obviously.The oil/liquid interface of different hydrophobic nanoparticles and surfactant were analysised by a drop shape tensiometer?Tracker-H?.The surface tension and interfacial dilational viscoelasticity were measured and related to that of foam stability.The result data showed that SiO₂ nanoparticles did not reduce surface tension obviously,and the surface tension of SiO₂/SDS dispersion was higher than that of pure SDS solution because of the adsorption of SDS moleculers on particle surface.When the SDS concentration was proper,the SDS moleculers adsorped on the nanoparticles could increase the surface activity of particles,and this might help the particles adsorp on the air/liquid interface more easily.So the surface structure of air/liquid was changed and enhanced the dilational viscoelasticity.But the SDS concentration being too high or too low was bad to foam stability.Besides,the more hydrophibic of the nanoparticles,the more stable of the foam.The micromodel fooding experiments showed that SiO2/SDS foam flooding could displace more oil than waterflooding,SDS solution flooding,or SDS foam flooding,and it had been observed to have greater utility for flushing oil from dead end pores.The improvement was attributed to the enahcned foam stability and viscoelasticity caused by the attached particles.The sandpack flooding tests indicated that SiO₂/SDS foam had good properties for oil displacement in both homogeneous and heterogeneous formation.The increases in differential pressure and profile control effect have a good correspondence with the increase of SiO₂ concentration,and the test with higher SiO₂ concnetration led to a higher oil recovery.When the SiO₂ concentration was above 1.5wt%,the increase was minor.The retention of nanoparticles and the damages for sandpack decreased with increasing the sandpack permeabilities.The foam volume changed little before and after injection,while the half life time is lower than that of original SiO₂/SDS dispersion.But the gap narrowed with increasing the permeability of sandpack.