Study On Modified Fe3o4 Nanoparticle Stabilized Foam System For Enhanced Oil Recovery

With the demands of petroleum energy growing in the world,developing the technology of foam flooding to exploit low permeability reservoirs has become an important way to expand the global crude oil demands and increase energy reserves.Foam flooding has controllable flow ratio,good plugging effect and high oil displacement efficiency.It has been one of the enhanced oil recovery technologies that is widely applied in oil fields at home and abroad.Therefore,good static stability and high rheology are the keys to improve the efficiency of foam flooding.Based on this,the Fe₃O₄ nanoparticles with an average particle size of 20 nm was carried out to modify surface and then combined with surfactants and polymers.The aim of this article was to reveal the foam stabilization mechanism of modified Fe₃O₄ nanoparticles,and focused on the effect of modified nanoparticles with different hydrophobicity on the stability of the foam system.In this paper,the three modifiers of dimethylsiloxane,glycidyl carbonate,1,2-epoxy dodecane were selected,and the physicochemical properties and stability of the unmodified nanoparticles and modified nanoparticles were evaluated.Then,four kinds of hydrophilic nanoparticles with the contact angles of 12.7°,20.6°,57.5°and 94.3°were prepared by the selected modifier which was suitable for nanoparticle stabilized foam system,and the optimum contact angle and nanoparticle stabilized foam system were obtained by evaluating the foam stabilization and rheological properties,optimizing the formulation.Finally,the physical simulation test of oil displacement was carried out to evaluate the oil displacement effect of the modified nanoparticles.The experimental results showed that the stability of 1,2-epoxy dodecane modified nanoparticles was better than that of dimethylsiloxane,glycidyl carbonate.The best contact angle was 94.3°.The formula was 0.1%MFe₃O₄(?=94.3°)+0.2%SDS+0.1%HPAM,and the foam half-time of the system was 214 min,which was 2.36 times higher than that of the unmodified nanoparticle stabilized foam system.The rheological property test showed that the system was pseudoplastic fluid,maintained high viscosity at high shear rate,and had good foam states.Its elastic modulus was larger than that of the viscous modulus at variable shear frequency.The physical simulation test of oil displacement showed that the oil recovery of 0.1%MFe₃O₄(?=94.3°)+0.2%SDS+0.1%HPAM system,0.1%Fe₃O₄+0.2%SDS+0.1%HPAM system and CO₂ gas drive were increased by 10.64%,9.78%and 7.83%,respectively.The results showed that the modification of 1,2-epoxy dodecane could effectively enhance the foam stability of Fe₃O₄ nanoparticles,and further enhance the oil recovery of low permeability reservoirs.This study provided a reference for the development of subsequent magnetic particle stabilized foam system.