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Nanoparticle-stabilized CO2 foams to improve conventional CO2 EOR process at Batı Raman field

Safran, Saibe Esra
Because of the natural fractured characteristic of the B. Raman field which is the largest field of Turkey, already existing CO2 injection system does not work at desired efficiency. Thus, the main purpose of this project is to control CO2 mobility in the reservoir by creating nanoparticle stabilized CO2 foam using the property of nanoparticles to place at the gas-water interface permanently and to achieve additional oil recovery at B. Raman. For this purpose, first nanoparticle dispersion stabilization and foamability were evaluated. Dealing with the nanoparticle due to their high surface energy is not easy as bulk material. They have high tendency to agglomerate and/or flocculate. Different type of nanosilica was considered. Effect of the nanoparticle concentration, salinity, temperature and pH on the foamability and dispersion stabilization were examined. This studies showed that half hydrophobicity, salt addition and increased concentration have positive effect on the foamability but salinity above 1% generated flocculation. Also, even if the 50 % hydrophobic nanosilica called H30 has better foamability, it could not be stabilized. The particle size of the silica in H30 dispersion was not small enough to flow through the B. Raman core sample. The effect of the pressure, phase ratio and flow rate on the foam formation were also studied. Better foam was observed at the observation cell when CO2: nanodispersion phase ratio was 1. Also, it was found that the pressure should be above 1100 psi where CO2 was in the supercritical phase to create foam with current core flooding system. The phase envelop of the Dodan gas was created by using PVTSim program. XRF test results before and after flooding showed that not any adsorption occurred into core sample. Then, the oil recovery test was conducted with suitable nanoparticles which were PEG and CC301. First, CO2 injection and then WAG were applied to the core sample to express B. Raman field case and obtained extra production after CO2 injection with WAG application. NWAG (nanoparticle dispersion alternating gas) at 650 psi and foam at 1200 psi was tested, later. The results indicated that foam application was successful if appropriate conditions existed. On the other hand, not a significant production was obtained with NWAG application. Interfacial measurements were also studied between both nanodispersion-CO2 and nanodispersion-oil. Nanoparticles were not changing IFT markedly even if they were located at the interface of the water and CO2 as the surfactant. However, a significant decrease of the IFT was obtained between water and oil in the presence of nanoparticles.