The generation of semi-solid emulsion gels was observed in crude oil with low asphaltene, resin, and wax contents. The semi-solid emulsion gels were very stable and could not be effectively demulsified by conventional demulsifiers. To solve the problem of demulsification, crude oil component analysis, high-temperature gas chromatography, element analysis, Fourier transform infrared spectroscopy, oil–water interfacial tension measurement, and viscoelastic analysis of interface film were used to conduct a detailed study on the stability mechanism of the emulsion gels. The results show that crude oil has a low resin/asphaltene mass ratio and poor asphaltene solvation; thus, resin and asphaltene mainly exist as colloids at the oil–water interface. Meanwhile, the resin and asphaltene in the crude oil have high oxygen content and low acid number, indicating the existence of many phenolic hydroxyl groups. Therefore, strong hydrogen bonding between phenolic hydroxyl groups further enhances the structural strength of resin/asphaltene aggregates. In addition, the long carbon-chain wax in crude oil has poor solubility and is easy to precipitate when the temperature decreases. The long carbon chains easily form a three-dimensional network structure. Resin/asphaltene aggregates are adsorbed on the surface of water droplets, and their alkyl parts interact with the wax in crude oil to form a tight, three-dimensional network structure, which binds the water droplets. The water droplets aggregate without coalescing, resulting in crude oil emulsion gels and causing difficulties in demulsification.
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