The interfacial tension (IFT) of a crude oil/CO 2 system is recognized as the main property affecting the efficiency of CO 2 flooding during an enhanced oil recovery (EOR) process. The addition of a paraffin group hydrocarbon to asphaltenic crude oils as an asphaltene precipitant component is aimed to mimic the asphaltene precipitation process during crude oil production and transportation. Asphaltene precipitation would critically affect the interfacial behavior of crude oil/CO 2 systems. In the first part of this study, the equilibrium densities of oil samples which contain nheptane at different ratios were measured over varying pressures at 323 K. Then, the equilibrium IFT between CO 2 and the crude oil samples was measured using the axisymmetric drop shape analysis (ADSA) technique. This investigation was followed by measuring the minimum miscibility pressure (MMP) of the oil/CO 2 systems using the vanishing interfacial tension (VIT) technique. The results showed that the density of oil sample increases linearly with pressure. Moreover at a constant pressure and temperature, the density was linearly decreased with nheptane content of the crude oil sample. Linear correlations between density, n-heptane content, and pressure at the temperature of 323 K for each oil sample were also noticed. The results of IFT tests indicated that asphaltenic crude oil samples have two slope IFT-pressure behavior. It was found that for oil samples with high asphaltene content (9 wt %), the higher the n-heptane content of the oil sample is, the lower is the pressure of the IFT's slope change, while for low asphaltenic oil sample (0.56 wt %) an increase of n-heptane has little effect on the point of the slope change of the IFT. Consequently, it was found that asphaltenes increase the rate and magnitude of the light component extraction in oil/CO 2 systems. The experimental results showed that the MMP of the oil samples decreased linearly with the n-heptane content of the oil sample. The linear relation between the MMP and n-heptane content revealed the crucial role of the paraffinic group as the controlling miscibility component of the crude oils.

Interfacial tension (IFT) is known as the critical parameter affecting the efficiency of CO 2 flooding during the enhanced oil recovery (EOR) process. Besides, the asphaltene precipitation phenomenon is reported as the most significant problem during CO 2 injection into asphaltenic oil reservoirs. Accordingly, it is important to examine the effect of asphaltene precipitation on the IFT behavior of the oil−CO 2 system at reservoir conditions. The main objective of this research work is to study of the effect of asphaltene and its type on the IFT behavior of the oil−CO 2 system. The IFT between pure CO 2 and a model oil both with and without asphaltene was measured using an axisymmetric drop shape analysis (ADSA) technique over a wide range of pressures and a constant temperature of 323 K. The asphaltene particles used for the work were precipitated and separated from three different crude oil samples, each having different physical properties. The model oil, consisted of 50 vol % nheptane and 50 vol % toluene ("heptol50") and was doped with asphaltene particles at a concentration of 4 wt % to ensure that the particles remained suspended in the model oil over the range of pressures studied. The results showed that the IFT between CO 2 and the model oil is inversely proportional to the pressure and that the constant proportionality is affected by the presence of asphaltene particles. In fact, the asphaltene aggregates formed in the model oil lead to a reduction in the magnitude of this constant. This, in turn, could result in lower CO 2 solubility. Also, the effect of the asphaltene molecular structure on IFT of CO 2 −model oil was investigated in this work. It was shown that the hydrogen deficiency and aromaticity of asphaltene molecules were important parameters that could significantly affect the IFT for CO 2 −model oil.

Corrugated sheets with optimized mechanical properties are crucial for lightweight design in industrial applications. This study considered and optimized a corrugated sheet with a sinusoidal profile to enhance elastic modulus, tensile-bending coupling, and weight reduction. For this aim, first, flat specimens consisting of E-glass woven fiber and epoxy resin were made by hand lay-up method, following ASTM D3039. The tensile test determined young’s modulus of flat samples. Afterward, two molds with supports were fabricated. The corrugated specimens were constructed and exposed to a standard tensile test. The finite element analysis was used to simulate the tensile test of corrugated samples. The numerical force-displacement curve is derived from numerical analysis and verified by experimental results. After that, two multi-objective optimization problems, mass-constraint and global optimization, were implemented. Analytical formulations were verified by numerical and experimental results and utilized for optimization purposes. The genetic algorithm was used to examine and confirm trade-off behavior between objective functions. The Pareto fronts diagrams for mentioned two multi-objective optimization problem were obtained. Finally, the optimum parameters are calculated by using the LINMAP (Linear Programming Technique for Multi-dimensional Analysis of Preference) method.

The stabilization of nanoparticles is a main concern to produce an efficient nanofluid.