To provide supplementary oil recovery after the primary and secondary processes, enhanced oil recovery (EOR) techniques are introduced. Carbonated water injection (CWI) as an EOR method can improve sweep efficiency and the risk of gas leakage. On the other hand, the interfacial tension (IFT) is one of the key factors which can affect fluid displacement during the process of CWI greatly. Therefore, the analysis of the IFT on an oil-carbonated water-CO2 system is vital. In this paper, the interfacial interactions of binary systems of asphaltenic crude oil (ACO), carbon dioxide (CO2), and carbonated water (CW) at different pressures and at two temperatures of 40 ° C and 50 ° C and their effects on the oil spreading in the water phase in the presence of gas are experimentally investigated. The IFT measurements were performed by axisymmetric drop shape analysis (ADSA) technique for the pendant/rising oil drop case. It is found out that the equilibrium interfacial tension (EIFT) of the two systems of crude oil-CO2 and water-CO2 is reduced almost linearly with pressure but increased with temperature. Moreover, the pressure has an increasing and decreasing effect on the water-oil and CW-oil IFT’ s respectively. However, temperature has a reverse effect for the both systems. Spreading coefficient (SC) concept would help better understand the oil recovery mechanisms and potential. The results show that SC curve has a minimum point value as a specific pressure, which increases with temperature. The presence of CO2 in the water phase could strongly affect the oil spreading phenomenon through which oil recovery could be significantly enhanced.

The viscous fluid boundary layer equations were adopted to characterize the velocity distribution across the vertical section of the oil slick on moving water. The velocity profile was found to be the combination of linear and parabolic distribution. A numerical model including spreading and dispersion was developed to describe the oil slick’s early movement in the open and ice-covered water. The flume test was conducted to determine the dispersion coefficients (Kx) and the effects of velocity and wave height on the slick’s dispersion were also investigated. In the open water, Kx increased from 4.34 cm2/s to 20.08 cm2/s as the velocity changed from 3 cm/s to 12 cm/s. A coefficient b that characterized Kx fluctuated at 1.5 when wave heights were between 20 mm and 70 mm. Under ice, the slick didn’t move until the velocity exceeded 6 cm/s and Kx increased from 2.69 cm2/s to 5.64 cm2/s as the velocity changed from 6 cm/s to 12 cm/s.b remained 0.4 when wave heights were between 20 mm and 60 mm. The model performed very well in predicting the slick’s position and length during the gravitation-inertia phase for the two situations when relevant dispersion coefficients were input.

The main advantages of surfactant flooding, including the reduction of the interfacial tension between the aqueous surfactant solution and the residual oil and wettability alteration, make it a very potential method for the enhanced oil recovery processes. Since the surface activity of surfactants and their critical micelle concentration (CMC) can be improved by mixing them, this study was aimed to evaluate the binary mixture of various surfactants, including cationic quaternary ammonium surfactant (CTAB), anionic surfactant (AOT) and non-ionic (Tween 80) with an imidazolium-based ionic liquid ([C12mim] [Cl]) in the volume ratio of 2:1. Binary surfactant mixtures have been investigated in low and high salt concentrations (650 ppm and 38350 ppm) to see the effect of salt concentration on each of the binary mixtures. After investigation of the interfacial tension of each of these mixtures, the phase behavior of each of them was investigated. In addition, the wettability alteration on dolomitic carbonate rock has been investigated. To simultaneously investigate the two mechanisms including interfacial tension reduction and wettability alteration, the spreading coefficient and capillary number were calculated. The results showed that despite the decrease in the interfacial tension of crude oil from 8.72 mN/m to less than 0.5 mN/m, this improvement has no significant impact on the creation of a favorable microemulsion and change the wettability alteration of dolomitic rock into strongly water wet state, as a result, no significant changes in the capillary number and spreading coefficient were obtained.

Floodwater Spreading (FS) plays an effective role in improving soil fertility, ground water recharge, vegetation cover, and desertification control. The soil fertility might increase as a result of a suitable suspended sediment material transferred to the downstream by flood events. To define a relevant FS method which increases the efficiency of the FS projects, it is necessary to study the quality and quantity of transported sediment material, spatially and temporarily. In this research, this subject was investigated by taking soil samples throughout 13 FS stations for physical and chemical analysis over 5 years. Within each of the 13 selected stations in the three first flooded dikes, soil sampling was carried out using random-systematic method. The total Nitrogen, absorbed Phosphorous and Potassium, and Organic Carbon of each sample were analyzed. Because of the abnormality of data, nonparametric test was adopted to compare means. All stations were classified into three groups using cluster analysis method. Based on the results, the variations of fertility factors are irregular between the dikes and amongst years. This could have been affected by several factors such as the quality and quantity of diverted flood, the characteristic of FS sites, and irregularity of sediment material deposited on the sites. Despite the low quality of soil fertility prior to the construction of these stations, in general, FS has a considerable role in improving the soil fertility. However, desirable objectives may be achieved in long term through occurrence of diverse flood events and suitable maintenance of the stations.