The L16(45) orthogonal experiment was selected to investigate the effects of polymer A,petroleum sulfonate B,and surfactant C on the interfacial viscosity of model crude oil,when three factors were coexisted in o/w emulsion.The results indicate that the interfacial viscosity between model oil and aqueous phase gradually decreases with the increase of surfactant C concentration but increases with the increase of polymer A concentration.When three factors were coexisted in o/w emulsion,the surfactant C has the effect on interfacial viscosity between model oil and aqueous phase in the complex system.And the effect of polymer A and petroleum sulfonate B on the interfacial viscosity is the weakest among the three factors under the experimental conditions.The interfacial viscosity of polymer-surfactant complex system is due to the surfactant of the system.
The influence of HPAM on interfacial properties and stability of the emulsions formed by formation water and asphaltene, resin, and crude model oils from Gudong crude oil was investigated by measurement of interfacial shear viscosity, interfacial tension, Zeta potential, and emulsion stability. HPAM may be adsorbed at the interface between the model oils and water, but the interfacial tension is not decreased. With increasing HPAM concentration, the interfacial shear viscosity, Zeta potential, and emulsion stability of the model oils system is increased. The o/w emulsion stability was enhanced with the polymer by steric and electrostatic stabilization.
A new microspheres-surfactant flooding system consisting of polymer microspheres and nonionic surfactant has been detailed to enhance oil recovery of Bohai oilfield by increasing the sweep efficiency of water and the oil displacement efficiency of surfactant synchronously. The surface morphology and particle size distribution of polymer microspheres have been investigated through scanning electron microscopy and dynamic lighting scattering. In addition, plugging performance, oil displacement efficiency and the deep profile control process of combination system have been studied by utilizing assembled parallel double cores models and core displacement experiments. The experimental results have shown that the initial appearance of the polymer microspheres was regularly spherical; the particle size distribution was from 200 nm to 6 μm. The particle size of the microspheres after swelling was increased by nearly five times compared with the original particle size. The combination system could exhibit an effective injectivity and plugging effect for cores with different permeability from 0.5 μm2 to 3.0 μm2. This system could significantly reduce fractional flow through high permeability channel, and also present good profile control effect and oil displacement efficiency in parallel double cores. By the injection of the 2.5 PV microspheres solution, the microspheres flooding recovery could improve about 34% more than water flooding. The slug composition, with 400 mg/L polymeric microspheres and 0.3% nonionic surfactant, could obtain a higher oil recovery by 4 wt% original oil than the microspheres system. The combination system could be recommended as a potential combination for profile control in Bohai heterogeneous reservoirs.
To improve the stability and plugging property of low-solubility phenol formaldehyde resin (LPFR) in the injection water from Daqing Oilfield, hydrophobically associating polymers (HAP) as a stabilizing agent were used. The size and zeta potential of LPFR, LPFR/HAP molecule aggregates, and turbidity and plugging properties of LPFR dispersions were measured in deionized water, simulation water, and injection water, respectively. The results show that the hydrophobic grouping on the HAP molecule has a similar molecular structure as LPFR, and HAP and LPFR can form complex molecule aggregates in the injection water. The zeta potential of LPFR/HAP molecule aggregates is larger than that of LPFR molecule aggregates. Therefore, the repulsive force operating between LPFR/HAP complex molecule aggregates is increased. HAP enhances the stability of LPFR in the injection water and plugging property of LPFR dispersion in porous medium.
Although amphiphilic Janus nanosheets have great potential applications in diverse fields to provide improved performance over conventional homogeneous nanoparticles, its aggregation characteristics are still mostly uncovered. Anisotropic shape and chemistry should play a critical role in the interactions between two colloidal particles. Hence, the amphiphilic Janus nanosheets are expected to have unique aggregation behavior different from homogeneous nanoparticles. In this paper, a representative silica-based amphiphilic Janus nanosheets was synthesized, and the influences of temperature, pH, ionic strength, ion valence on their aggregation and stability were probed by batch static multiple light scattering, zeta potential, and electrophoretic mobility measurements. Particularly, the interactions energy between two adjacent amphiphilic Janus nanosheets were calculated based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The aggregation kinetics and colloidal stability of amphiphilic Janus nanosheets were systematically investigated for the first time. The aggregation of amphiphilic Janus nanosheets depends on the ionic strength, pH, and temperature of aqueous. Amphiphilic Janus nanosheets exhibited a stronger tendency to aggregate compared with hydrophilic Janus nanosheets, and the classical DLVO theory was verified to be inaccurate in predicting its aggregation, which was caused by the additional hydrophobic attraction. A reliable extended DLVO model containing hydrophobic interactions was developed to interpret the aggregation behaviors of amphiphilic Janus nanosheets.
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