Abstract

Flowing experiments with different water contents in water-in-waxy-crude-oil emulsions were performed in a flow loop apparatus. The real-time variations of rheological properties and microscopic distributions of the emulsions over time during pipe flow were quantitatively analyzed. It was found that the emulsification effect of the emulsion is enhanced due to shear effect, resulting in an increase of gel point and viscosity over time. The average increments in the gel point are approximately 1.5 °C, 1.7 °C and 1.9 °C for the emulsions with water contents of 10%, 20% and 30%, respectively. During the experimental period from 0.5 h to 18 h, the average viscosities measured at the emulsion temperature increase by 31%. Characterization parameters of number-averaged diameter (d_1,0), specific surface area (SA) and polydispersity (PDI) were applied to reflect the microstructure of emulsions from the perspectives of droplet size, dispersity and nonuniformity. The water droplets become smaller and uniformly dispersed as the pipe flow goes on. The Gibbs free energy increases as the emulsion flows through the pipe, which is mainly caused by the shear of the pipe wall. The van der Waals force increases from −0.0678 × 10⁻²¹ J to −1.7657 × 10⁻²¹ J as the emulsion’s water content changes from 10% to 30%. The water droplets can promote crystallization of wax crystals by offering the necessary nucleus surface. Furthermore, the coexistence of water droplets and wax crystals creates a synergistic effect, which can augment the total energy and structural strength of the emulsion system.

摘要

含蜡原油乳液中不同水含量的流动实验在流动回路装置中进行。定量分析了管道流动过程中乳液的流变特性和微观分布随时间的实时变化。发现乳液的乳化效果由于剪切作用而增强，导致凝胶点和粘度随时间增加。对于水含量分别为 10%、20% 和 30% 的乳液，凝胶点的平均增量约为 1.5 °C、1.7 °C 和 1.9 °C。在从 0.5 小时到 18 小时的实验期间，在乳液温度下测得的平均粘度增加了 31%。数均直径的表征参数 ( d _1,0)、比表面积 ( SA ) 和多分散性 ( PDI ) 从液滴大小、分散性和不均匀性的角度来反映乳液的微观结构。随着管道流动的进行，水滴变小并均匀分散。吉布斯自由能随着乳液流过管道而增加，这主要是由管道壁的剪切引起的。范德华力从 -0.0678 × 10 ^-21 J 增加到 -1.7657 × 10 ^-21J 当乳液的含水量从 10% 变为 30% 时。水滴可以通过提供必要的核表面来促进蜡晶体的结晶。此外，水滴和蜡晶体的共存产生协同效应，可以增加乳液体系的总能量和结构强度。