To investigate the effect of alkane molecular structure
on the
volume expansion of CO2 + alkane systems, the solubility
of CO2 in hexane, octane, decane, and cyclohexane and the
volume of CO2 + alkanes at different temperature and pressure
was measured with a PVT apparatus. The results imply
that the dispersion state of CO2 molecules in the alkane
phase under near critical or supercritical condition of CO2 plays a dominate role in increasing the volume of CO2 + alkane systems. The solubility of CO2 in the alkanes,
the volume expansion of the CO2 + alkane systems, and the
London force operating within alkane molecules are strongly influenced
by molecular structure of the alkanes and pressure.
The dilational viscoelasticity behaviors of oil-water interfaces formed by surface active fractions of different average molecular weights and H=C atom ratios, which were distilled by supercritical fluid extraction and fractionation (SFEF) methods from Iranian heavy oil, and influences of pre-equilibrium time on them were investigated. The interfacial relaxation processes were investigated by interfacial tension relaxation methods. The dilational moduli, elasticities and viscosities all increased and phase angles also regularly changed along with increasing number average molecular weights and decreasing H=C atom ratios. Along with increasing pre-equilibrium time, the dilational moduli of samples increased and the phase angles decreased to the equilibrium values, as a result of the enrichment of surface active fractions into the interface. It took longer to reach the equilibrium for relatively high molecular weight samples than for low molecular weights samples. Along with increasing average molecular weights and decreasing H=C atom ratios of the samples, slow relaxation processes gradually appeared and their contribution increased. The characteristic relaxation times of similar processes of different samples also increased. The results of interfacial tension relaxation experiments and dilational viscoelasticity parameters determined by sinusoidal oscillation of interfacial area perfectly coincided with each other. The results for interfacial dilational viscoelasticity measurements, number average molecular weight and H=C atom ratios, and interfacial tension relaxation experiments illustrated that the fractions containing large condensed ring aromatic compounds that have large conjugated structures played a more important role in film-forming and film rigidity than fractions of smaller molecules.
To investigate the effect of polarity of organic liquids
and the
dispersion state of CO2 in organic liquids on the volume
expansion of CO2 + organic liquid systems, the solubility
of CO2 in methylbenzene and ethanol and the volume of CO2 + methylbenzene and ethanol at different temperatures and
pressures were measured with a PVT apparatus. The
results imply that the microscopic dispersion state of CO2 molecules in organic liquids under near-critical or supercritical
conditions play a dominant role for increasing the volume
of the CO2 + organic liquid systems. The microscopic dispersion
state and the solubility of CO2 in the organic liquids
and the volume expansion of the CO2 + organic liquid systems
are affected by the polarity and the structure of the organic liquid
molecule obviously. When pressure and temperature are fixed, the intermolecular
force between CO2 molecule and the organic liquids and
the intermolecular force operating within the organic liquids play
a dominate role in the volume expansion of the CO2 + organic
liquid systems.
The liquid phase of foam systems plays a major role in improving the fluidity of oil, by reducing oil viscosity and stripping oil from rock surfaces during foam-flooding processes. Improving the oil displacement capacity of the foam’s liquid phase could lead to significant improvement in foam-flooding effects. Oil-liquid interfacial tension (IFT) is an important indicator of the oil displacement capacity of a liquid. In this study, several surfactants were used as foaming agents, and polymers were used as foam stabilizers. Foaming was induced using a Waring blender stirring method. Foam with an oil-liquid IFT of less than 10–3 mN/m was prepared after a series of adjustments to the liquid composition. This study verified the possibility of a foam system with both an ultra-low oil-liquid IFT and high foaming properties. Our results provide insight into a means of optimizing foam fluids for enhanced oil recovery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.