Impact of Polymers on Sand Sedimentation Characteristics of Shale Oil-Produced Fluid.

The introduction of polymers has significantly altered the properties of sand particles in shale oil production fluids, leading to a more complex sedimentation mechanism. However, the specific ways in which polymers influence sand sedimentation dynamics remain poorly understood. In this study, Soxhlet extraction and supercritical water oxidation techniques were employed to compare the particle size distribution of polymer-containing sand with that of actual sand. The results show that sand sedimentation in polymer-containing shale oil production fluids involves two mechanisms: gravity-dominated single-particle sedimentation and polymer-induced multi-particle flocculation-sedimentation. Additionally, polymers induce both flocculation-sedimentation and hindering effects. Specifically, the water content and temperature can promote single-particle sedimentation and flocculation-sedimentation of the sand particle group by adjusting the rheology, polymer content, and stability of the production fluid. In this experimental study, the sedimentation rates of the two processes were increased by 38.05% and 54.76%, respectively. Based on these findings, the sedimentation characteristics of sand particles in production fluids under the influence of polymers were obtained, offering valuable insights for the management and control of sand in polymer-containing shale oil production fluids.