Investigation on Physical Properties and Morphologies of Microemulsions formed with Sodium Dodecyl Benzenesulfonate, Isobutanol, Brine, and Decane, Using Several Experimental Techniques

Abstract

In the context of chemical enhanced oil recovery (EOR), there is no well-established way to characterize and understand the physical properties and structures of microemulsions composed of crude oil and industrial surfactants due to their complexity. Making a comparison to a well-studied model system is a simple and effective way to investigate the complex microemulsions. The purpose of this study is to provide and complete experimental characteristic data of model-microemulsions as a basis of analysis of the complex system. Types of microemulsions studied in the present work were oil in water (O/W), bicontinuous, and water in oil (W/O). The system was composed of water, sodium dodecyl benzenesulfonate (SDBS), isobutanol, sodium chloride (NaCl), and decane. We performed several experiments at room temperature such as spinning drop method, differential scanning calorimetry (DSC), Karl Fischer titration, Hyamine titration, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and electron cryomicroscopy (cryo-SEM). The measurements provided a deeper insight into a correlation between physical properties and morphologies of water/oil in the microemulsions.

Characterization of Complex Crude Oil Microemulsions-DSC Contribution

“…It was possible to estimate a value of the salinity by determining the temperature of the end of melting of ice: around 90 g/L (slightly lower than the expected salinity of 98 g/L). The same tendency was observed in the case of the previously studied model system [19].…”

“…Note that in the case of previously studied model microemulsions which exhibited a bicontinuous structure near the optimum salinity, as revealed by cryo-SEM analysis, the DSC heat profiles showed a simultaneous crystallization of water and oil [19]. With the present complex systems, AI-C12 (complex surfactants-model oil) and AI-AL (complex surfactants-complex crude oil), the structure is clearly different from the bicontinuous one.…”

“…Figure 8 shows the images of the AI-C12 middle phase microemulsion at a salinity of 98 g/L. An interesting point is that this phase is different from the classical bicontinuous phase which is generally found in the literature on model systems [16,19,27] but is rather constructed as a brick wall; one phase is surrounded by a layer of another phase, and they seem to make an array. Figure 8 (right) shows a more detailed picture in comparison to (left).…”

“…DLS (Dynamic Light Scattering), MLS (Multiple Light Scattering), SAXS (Small Angle X-ray Scattering), cryo-SEM (Scanning Electron Microscopy by cryo-fracture), DSC (Differential Scanning Calorimetry), interfacial measurements, etc. [19]. This methodology was validated in the case of a model microemulsion system made of SDBS (Sodium Dodecyl Benzenesulfonate), Isobutanol, Brine, and Decane.…”

“…The objective was to be able to address the case of more complex systems such as the one including real oils and formulations of surfactants, which is of prime importance to chemical EOR, especially surfactant flooding. Among the different techniques that can be applied to investigate complex dispersed systems as emulsions or microemulsions, DSC appears as a technique that can be used for physico-chemical characterization as well as for morphological studies [17,[19][20][21][22][23][24]. In this paper, we will show how DSC can be advantageously used in addition to other classical techniques to investigate complex microemulsions made of real crude oil and representative EOR formulations of surfactants.…”