Experimental Investigation on the Effect of Asphaltene Types on the Interfacial Tension of CO₂–Hydrocarbon Systems

Abstract

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.

Investigation of Low-Density CO2 Injection for Enhanced Oil Recovery

“…Another possible reason for the abovementioned observation could be the precipitation and deposition of asphaltene of the oil which have been reported in various CO 2 EOR studies. 18,29,30 However, several results presented in previous investigations using the same crude oil used in this study and under conditions similar to those of the experiments reported here have shown that the contact of CO 2 and the oil did not result in the precipation or deposition of the asphaltene fraction of the oil in porous media. 26 Therefore, it appears that the precipitation or deposition of asphaltene would have not been the case in our experiments.…”

Nanoparticles for Inhibition of Asphaltenes Deposition during CO2 Flooding

“…The particles tend to accumulate at the interfaces, which can increase the interfacial activity of colloidal solutions. This particles accumulation can occur at the oil–CO 2 interface, which leads to IFT alteration. , Therefore, it is concluded that large molecules of asphaltenes begin to aggregate at the CO 2 –oil interface, which causes the IFT to slightly increase in the high pressure range. Because of the asphaltene agglomeration, the asphaltene film is formed at the oil–CO 2 interface and modifies the IFT–pressure trend by compensation of the effect of CO 2 solubility, as shown in Figure .…”

Development and Applications of CO2-Responsive Gels in CO2 Flooding and Geological Storage

“…There is a lack of a systematic quantitative characterization method of gel CO 2 responsiveness in order to screen out the ideal CO 2 responsive gel. Moreover, CO 2 -responsive groups can be used not only in the preparation of CO 2 -responsive gels, but also in the preparation of CO 2 -responsive ionic solutions, which have broad application prospects in the field of CO 2 capture [128,129]. (3) The current CO 2 -responsive gels are based on the mechanism of protonation of the CO 2 responsive groups, which causes the volume expansion of the gels, and thus seal the CO 2 migration channel of the formation.…”