Synergistic effect of magnetic field and nanocomposite pour point depressant on the yield stress of waxy model oil

Abstract

Yield stress, as the key parameter to characterize the network strength of waxy oil, is important to the petroleum pipeline safety. Reducing the yield stress of waxy oil is of great significance for flow assurance. In this study, the effect of alternating magnetic field (intensity, frequency) on the yield stress of a waxy model oil with nanocomposite pour point depressant (NPPD) is systematically investigated. An optimum magnetic field intensity and frequency is found for the reduction in yield stress. When adding with NPPD, the heterogeneous nucleation of NPPD contributes to the reduction in yield stress for waxy model oil. Interestingly, the magnetic field is helpful for the modification of yield stress at a lower frequency and intensity before the optimal value; however, the modification is found to be weakened when the magnetic field is further increased after the optimal value. Possible explanation is proposed that the aggregation morphology of wax crystal would be altered and results in the release of wrapped oil phase from the network structure under the magnetic field.

Advances in and Perspectives on Strategies for Improving the Flowability of Waxy Oils

“…In recent years, with the development of micro-and nanocomposite pour point depressants (discussed in detail later in this review), Huang 108 and Yu 120 and their co-workers reported that the addition of a composite pour point depressant with magnetic particles as the core to crude oil can substantially change the structure and aggregation state of precipitated wax crystals when a magnetic field is applied (Figure 13).…”

“…A large number of experimental studies have confirmed the viscosity reduction effect in waxy crude oil after magnetic field treatment, and the viscosity reduction rate is generally above 30%. − However, the experimental results obtained from different studies vary greatly in terms of the type of magnetic field, magnetic field strength, treatment time, treatment temperature, and physical and chemical properties of crude oil. The essential reason is that the mechanism of viscosity reduction by magnetization of crude oil is still controversial.…”

“…Schematic diagram of microstructure and mechanism of action of waxy oil before and after treatment with magnetic field and pour point depressant. Reproduced from ref . Copyright 2020 Springer.…”

Effect of the Ethylene Vinyl Acetate Copolymer on the Induction of Cyclopentane Hydrate in a Water-in-Waxy Oil Emulsion System

“…At the same time, the precipitation of wax crystals and related deposition problems are an important flow assurance topic under low-temperature deep-water circumstances. − Wax can precipitate and crystallize from the bulk oil phase and form a network-like structure, which can bring high risks in liquidity deterioration, blockage, , or rupture accidents. Adding pour point depressants is an effective method to improve the rheological behavior of waxy oil.…”

“…Wang et al 51 also investigated the effect of wax on the cohesive force between hydrate particles. Since adding pour point depressants can undermine the structure of wax and improve the flow ability of crude oil, 29,30,32,52 it is a potential method to improve the rheological behavior of the wax−hydrate coexistence system. Until recently, the influence of pour point depressants on the coupling effect of wax and hydrate has rarely been investigated.…”