Role of a Nanocomposite Pour Point Depressant on Wax Deposition in Different Flow Patterns from the Perspective of Crystallization Kinetics

Abstract

Wax deposition is one of the core issues affecting flow assurance studies of crude oil pipelines, particularly with deep and ultradeep water conditions. Nanocomposite pour point depressants (NPPDs) provide a novel and effective strategy for inhibiting wax deposition and have recently attracted increasing research attention. Although recent advances have been made in understanding the performance and mechanism of NPPDs, the effect of flow pattern remains an open question. In this paper, deposition thicknesses of waxy oils with different flow patterns and NPPD dosages were obtained using a flow loop experimental device. It was found that the NPPD used in the current work can effectively inhibit the formation of wax deposition layers in different flow patterns. The Avrami model-focused beam reflectance measurement and polarizing microscope experiment method were used to characterize crystallization kinetics parameters and mesoscopic structure parameters of wax crystals. The consistency of results from Avrami equation fitting parameters, wax crystal morphology, and particle number supported the validity of crystallization kinetics analysis. The mechanisms of NPPD in different flow regimes were discussed. The inhibition of laminar and turbulent deposition layers by NPPD was attributed to the improvement of wax crystal morphology and the reduction of wax crystal number, respectively. This has important consequences for our understanding of the utilization and mechanism of nanocomposite pour point depressants.

Experimental study of the effects of a magnetic field/magnetic field-ferromagnetic nanocomposite pour point depressant on wax deposition

“…For details on the experimental devices, we suggest the readers to refer to our previous articles. 30 …”

Wax Deposition during the Transportation of Waxy Crude Oil: Mechanisms, Influencing Factors, Modeling, and Outlook

“…Wang et al 101 delved into the wax inhibition mechanism of nanocomposite pour point depressants under laminar and turbulent flow regimes. They highlighted the enhancement of wax crystal morphology and the reduction in wax crystal numbers were key factors contributing to the decreased wax deposition rate (see Figure 19).…”

“…Wax inhibition mechanism of nanocomposite pour point depressants under different flow states. Reproduced with permission from ref . Copyright 2022 American Chemical Society.…”

Dynamic Behavior Analysis of Wax Crystals during Crude Oil Gelation

“…Many scholars have interpreted the macroscopic rheology from the perspective of micromechanisms of waxy crude oil in order to find the core factors affecting the gelling of waxy crude oil. These studies focus on the rheological properties of waxy crude oil, such as gel point, − viscosity and viscosity–temperature properties, − thixotropy, − and yield properties. − The complex mechanical properties of waxy crude oil systems have been enriched by exploring the gelling process and law of waxy crude oil with small amplitude oscillatory shear experiment − and the destruction process of gelling structure under large amplitude oscillatory shear. − At the microscopic level, many studies focus on the microscopic morphology of wax crystals and try to describe the microscopic morphology of wax crystals and their aggregates by polarizing microscopy, − electron microscopy, − confocal microscopy, , X-ray diffraction, , and computerized tomography (CT) scanning techniques. , In addition, stereology and fractal geometry theory were used as guides to characterize the microscopic morphological characteristics of wax crystals quantitatively. Further, the quantitative relationship between wax crystals and the macroscopic rheological properties of waxy crude oil was constructed to explain the rheological and gelling properties. − Although the research on the rheological mechanism of waxy crude oil has made continuous progress, in recent years, with the deepening of research work, some scholars have found that there is insufficient evidence to explain the complex rheological properties and gelling mechanism of waxy crude oil solely based on the morphological changes of wax crystals .…”