The injection of carbon dioxide gas with high microscopic sweep efficiency is one of the preferred methods to remove hydrocarbons from fine pores in enhanced oil recovery. However, gas injection process in hydrocarbon reservoirs due to the low density and viscosity have problems such as undesired mobility and weak macroscopic sweep efficiency in porous media, which will cause the phenomenon of gas fingering and gravity separation. in order to overcome this problem, foam can be used due to its high apparent viscosity and lower mobility compared to gas mobility. One of the most important physical characteristics of the liquid phase is the lower interfacial tension to create foam, which has been used by adding surfactant to stabilize the gas phase in the liquid to produce foam inside hydrocarbon reservoir. In addition to surfactant, the use of chemicals such as: nanoparticles, co-solvents, polymers, alkalis, smart ions, etc. had significant effects on foam performance. in this thesis, foam-based foam is used to improve the efficiency of oil recovery as control agents. even in the most difficult conditions of reservoirs in which only the surfactant, one candidate is not suitable, the presence of nanoparticles not only improves the efficiency of oil recovery, but also reduces the amount of adsorbed chemicals to the reservoir rock .in all step's, deionized water is used. The stability of co-solvents and nanoparticles was eva‎luated by foamability method and half-life measurements. Acrylic micromodel (polymethyl methacrylate) has been used to investigate the effect of carbon dioxide gas injection, aqueous fluid, surfactant foam, co-solvent and nanoparticles in fractured and porous media. The surfactant and nanoparticles used in this thesis are sodium dodecyl sulfate, silica and aluminum oxide nanoparticles respectively, and the silica nanoparticle has been surfacing modified by tri ethoxy vinyl silane. Hydrophilic surface of silica particles became hydrophobic by modification, which finally increased the stability of the foam. By conducting stability tests, the optimal concentration of silica nanoparticles and aluminum oxide was obtained as 0.1 and 1% by weight respectively in the critical micelle concentration. The disintegration time of surfactant foam in the presence of silica was from 103 to 126 minutes and surface modified silica 50, 70 and 80% by weight of 103 was obtained as 144, 166 and 138, respectively, and finally 50% surface modified nano silica is more hydrophobic than the sample. 70 and 80 percent by weight has a greater effect on the stability of the foam. Looking at the performance of foam injection into the micromodel using the optimal concentrations obtained in stability tests, it was determined that in the process of injecting modified silica compared to silica, due to the greater penetration of oil into the foam by creating a link between modified silica particles and oil, the oil exploitation of the foam with the amount of 74.73% has the highest recovery.

روح الله هاشمي، عليرضا خزعلي

حميدرضا شاهوردي، محسن محمدي