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In recent years, with the advancement of nanoscience, many scientists have used nano materials to solve existing problems in various sectors of oil industry. Nanofluids made with these materials can facilitate the separation of oil and gas in a reservoir and increase oil recovery factor compared to current methods. Therefore, in this work, the effect of clay nanoparticles on oil recovery factor was investigated. For this purpose, two different base fluids, water and ethanol, were used to disperse the nanoparticles. The effect of adding clay nanoparticles on viscosity changes and interfacial surface tension was determined. Also, in order to investigate the effect of nanoparticle concentration in the base fluid on the ultimate oil recovery factor, nanofluids with 3 and 5 wt% were prepared. Results show that oil recovery factor increases significantly in these conditions by adding them into the base fluid, though nanofluids included clay nanoparticles have less stability. Also, the effect of these nanoparticles dispersed in water is greater than in ethanol. For example, at 5 wt%, oil recovery factor for water based nanofluid was 49.7% and for ethanol based nanofluid was 46%.

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Research subject: In situ synthesis of nanoparticles due to greater impact on production mechanisms (such as reducing oil viscosity), uniform distribution of nanoparticles in reservoir fluids, no reduction in formation permeability due to no injection of nanofluids into the reservoir and also economic efficiency is more importance than other nanoparticle synthesis methods which are used in enhanced oil recovery (EOR) processes.
Research approach: In this study, the effect of in-situ synthesized of cerium oxide (CeO₂) nanoparticles at low temperature on the oil recovery factor was investigated. For this purpose, water was considered as the based fluid for dispersion of synthesized nanoparticles. Also, in order to study the effect of nanoparticles concentration in the base fluid on the final oil recovery factor, several nanofluids were prepared at different concentrations of 0.01, 0.1, 0.25 and 0.5 wt.%. Finally, the prepared nanofluids were injected at the injection rate of 0.07 ml/h up to 1 PV into the micromodel and the amount of produced oil and the movement of the injected fluid in the porous medium were analyzed.
Main results: The results showed that the synthesized CeO₂ nanoparticles in this study have appropriate performance to improve the oil recovery factor. The presence of small amounts of these nanoparticles (concentration of 0.01 wt. %), causes a significant increment in oil recovery factor (about 7%) compared to water injection alone. Also, the oil extraction coefficient increased by increasing the concentration of nanoparticles in the base fluid. So that for nanofluids with concentrations of 0.01, 0.1, 0.25 and 0.5 wt.%, the oil recovery factor were 25%, 38%, 43% and 45%, respectively. However, by increasing the concentration of nanoparticles in the base fluid, from an optimal amount onwards, the probability of particle deposition in the micromodel increased, the effect of nanoparticles on changing the hydrodynamic properties of the injected fluid and oil production mechanisms decreased.
 

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Research subject: Using microwave and ultrasonic waves is a novel method in the petroleum industry that has been investigated for various purposes. Due to polar elements such as oxygen, nitrogen, and sulfur, oil molecules are affected by the electric field of microwave waves and create dipole moments that generate hotspots, increasing the temperature of the oil and breaking down heavy compounds such as asphaltene. Ultrasonic waves eliminate intermolecular forces by creating tiny bubbles and bursting them. It also leads to the breakdown of heavy molecules such as asphaltene.
Research approach: In this study, crude oil was exposed to microwave and ultrasonic radiation, and changes in its properties were investigated. The effects of changing parameters such as power and time on crude oil properties were also examined. Changes in the specific gravity and API can indicate the extent of the breakdown of heavy molecules such as asphaltene and improvement in crude oil quality.
Main results: Using microwave and ultrasonic waves can reduce the viscosity of crude oil by 12.4% and 6% and increase the API by 2.8 and 1.2 degrees, respectively. Asphaltene reduction due to microwave and ultrasonic waves is 9.3% and 4.3%, respectively, indicating the breakdown of these compounds and the conversion to smaller compounds soluble in oil, resulting in improved crude oil quality. The EDS results show an increase in the weight percentage of carbon and the reduction of elements such as oxygen and sulfur, which confirms this issue. Examining crude oil structure under microwave and ultrasonic radiation showed that microwave waves, in addition to affecting straight-chain hydrocarbons, also reduced aromatic compounds. However, ultrasonic waves had a more significant effect on straight-chain hydrocarbon structure.