Analysis of Gelling Characteristics and Mesoscopic Factors of Water-in-Oil Waxy Crude Oil Emulsions

High Resolution Image Download MS PowerPoint Slide In this study, the simultaneous rheology and in situ microscopy measurements, as well as the microfluidic technique, were employed to investigate the dynamic formation law of the gelled system in waxy crude oil emulsions, the mesoscopic influencing factors of gel strength, and their corresponding mechanisms under different water cuts, stirring rates, and temperature conditions. The results show that the mesoscopic structural evolution of the emulsion follows a distinct three-stage pathway: wax crystal/water droplet monomers → homogeneous/heterogeneous aggregates → wax crystal-water droplet floc structure, and each evolutionary stage corresponds to the variation of the macroscopic storage modulus. During the structural evolution, emulsified water droplets act as filling units that strengthen the interfacial connection, and their specific surface area is the primary mesoscopic parameter affecting the structural strength of the gelled system, which directly determines the scale of the oil–water interface and the interfacial interaction between wax crystals and water droplets. Wax crystals constitute the continuous network skeleton of the gelled system, and their quantity governs the compactness and continuity of the three-dimensional floc structure, playing a more dominant role in the macroscopic gel strength. Individual regulation of either the specific surface area of water droplets or the quantity of wax crystals can significantly alter the gel strength of the system. The simultaneous optimization of the two parameters produces an obvious synergistic strengthening effect, leading to an exponential rise in gel strength; conversely, the rheological properties of the emulsion can be remarkably improved. The dual-phase synergistic enhancement and weakening model proposed from a topological perspective clarifies that the “small and abundant” mesoscopic morphology featured by high-specific-surface-area water droplets and a large number of wax crystals is the core cause for the strengthened gel structure and deteriorated rheological properties of the emulsion. This model can systematically explain the influence mechanisms of various working conditions on the gel strength of water-in-oil (W/O) waxy crude oil emulsions. The conclusions of this research are well applicable to waxy crude oil emulsions characterized by high saturates, low aromatics, and low heavy polar components, and can provide theoretical references for the rheological regulation and pipeline transportation optimization of waxy crude oil emulsions.