Polymeric Wax Inhibitors and Pour Point Depressants for Waxy Crude Oils: A Critical Review

Preparation and Performance Evaluation of a New Type of Polyethylene-vinyl Acetate/Polystyrene Microsphere Composite Pour Point Depressant for Waxy Crude Oil

Polymer/inorganic nanocomposite pour point depressant (PPD) is a research hotspot in the field of waxy crude oil pipelining. However, the inorganic nanoparticles need to be organically modified to improve their organic compatibility, and the inorganic nanoparticles are harmful to crude oil refining. In this work, organic PSMS with an average size of 1.4 μm was first synthesized by dispersion polymerization. Then, a new type of EVA/PSMS composite PPD was prepared by melt blending. The effects of the PSMS, EVA PPD, and composite PPD on the pour point, rheological properties, and wax precipitating properties of a specific waxy crude oil were investigated. It was found that adding 50-200 ppm of PSMS alone slightly improves the crude oil rheology through a spatial hindrance effect, while adding 20 ppm of EVA PPD greatly improves the crude oil rheology by modifying the wax crystal morphology. Compared with EVA PPD, adding 20 ppm composite PPD improves the crude oil rheology further, and the rheological improving ability first enhances and then weakens with increasing the PSMS content in the composite PPD (0-10 wt %). At the PSMS content in the composite PPD 5 wt %, the EVA/PSMS 5% composite PPD makes the wax crystal aggregates more compact, thus showing the strongest rheological improving ability. The EVA molecules could adsorb on the PSMS and form the composite particles, which further regulate the wax crystal morphology and then improve the crude oil rheology further.

Mechanistic Study on the Influence of Wax on Hydrate Formation Process

To manage the interactions between wax and hydrate formation, a comprehensive understanding of the system's thermodynamics and flow characteristics is essential. Wax and hydrates coexist under low-temperature and high-pressure conditions, mutually influencing each other both thermodynamically and kinetically. This study focused on two main aspects: how wax affects the rate of hydrate formation in the oil-water system and how hydrate formation influences the thermodynamics of wax crystal precipitation. The presence of wax decreased the rate of hydrate formation, especially at higher wax contents. In systems with high wax content, over 70% of wax precipitated before hydrate formation, leading to less precipitation within the hydrate formation temperature range. With low water content, there were more nucleation sites for wax crystals in the oil phase, resulting in a greater difference in precipitation rates among different wax contents. For water content greater than 10%, the differences in precipitation rates were less significant, indicating a diminished effect of water content on wax crystal precipitation rates. Hydrates' hydrophilic nature had a limited impact on wax crystal nucleation and growth. Generally, wax crystals precipitate before hydrate formation, necessitating control measures for wax deposition during production processes.

Gamma radiation-induced grafting of poly(butyl acrylate) onto ethylene vinyl acetate copolymer for improved crude oil flowability

Ethylene vinyl acetate (EVA) copolymers are widely employed as pour point depressants to enhance the flow properties of crude oil. However, EVA copolymers have limitations that necessitate their development. This work investigated the modification of EVA via gamma radiation-induced grafting of butyl acrylate (BuA) monomers and the evaluation of grafted EVA as a pour point depressant for crude oil. The successful grafting of poly(butyl acrylate) p(BuA) onto EVA was verified through grafting parameters, FTIR spectroscopy, and 1H NMR spectroscopy. Treating crude oil with 3000 ppm of (EVA)0kGy, (EVA)50kGy, and (1EVA:3BuA)50kGy yielded substantial reductions in pour point of 24, 21, and 21 °C, respectively. Also, rheological characterization demonstrated improving evidenced by a viscosity reduction of 76.20%, 67.70%, and 71.94% at 25 °C, and 83.16%, 74.98%, and 81.53% at 12 °C. At low dosages of 1000 ppm, the EVA-g-p(BuA) exhibited superior pour point reductions compared to unmodified EVA, highlighting the benefit of incorporating p(BuA) side chains. The grafted EVA copolymers with p(BuA) side chains showed excellent potential as crude oil flow improvers by promoting more effective adsorption and co-crystallization with paraffin wax molecules.

Synthesis and Performance Testing of Maleic Anhydride-Ene Monomers Multicomponent Co-Polymers as Pour Point Depressant for Crude Oil

To address the issue of pipeline blockage caused by the formation of waxy deposits inside pipelines, hindering the flow of petroleum in the Shengli oilfield, eight new-style polyacrylic acid pour point depressants (PPD) for Shengli crude oil were prepared by maleic anhydride and ene monomers with different polar and aromatic pendant chains. The synthesized Pour Point Depressants were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and polarizing optical microscopy (POM). The results were promising and demonstrated that any type of pour point depressant exhibited excellent performance on high-pour-point crude oil. The reduction in pour-point after additive addition was largely dependent on the polymer structure. Notably, polymers containing long alkyl side chains and aromatic units displayed the most impressive performance, capable of depressing the pour point by 12 °C.

Impact of Paraffin Composition on the Interactions between Waxes, Asphaltenes, and Paraffin Inhibitors in a Light Crude Oil

The effect of wax molecular weight distribution on the efficacy of two alpha olefin-maleic anhydride paraffin inhibitors (PIs) having different densities of alkyl side-chains were examined in light West Texas crude in the absence and presence of asphaltenes. Interpretation of the data was aided by cross-polarization microscopy. Primary differences in wax crystal morphology appear to be driven by the composition of the wax, with secondary differences being associated with the choice of PI. In the absence of asphaltenes, the effect of wax composition on PI performance (i.e., reducing oil viscosity and wax appearance temperature) is greater for the PI having the higher chain density, with the one having the lower chain density being generally more effective regardless of the wax composition. These differences are diminished in the presence of asphaltenes such that the PI having the higher chain density is somewhat more effective. Trends in both morphology and viscosity suggest a steric effect associated with wax composition that is lessened on interaction of the PIs with asphaltenes.

Experience of virtual commissioning of a process control system for the production of high-paraffin oil

This work describes the experience in developing and testing software for oil industry automation control systems based on the simulation of technological processes and control systems combined in virtual reality, this approach is called virtual commissioning and is widely used in the world both to create automated process control systems and to simulate interactions between different systems.

Insights into Flow Improving for Waxy Crude Oil Doped with EVA/SiO2 Nanohybrids

Nanohybrid materials can significantly inhibit wax deposition and improve the fluidity of crude oil. However, the mechanisms behind wax resolving, crystal modification, and flow improving are still unclear owing to the complexity of crude oil. Here, we compared the effect of ethylene vinyl acetate (EVA) and nanohybrids composed of EVA and SiO₂ nanoparticles on wax crystallization and rheological behavior of Shengli waxy oil. Differential scanning calorimetry results indicate that SiO₂ nanoparticles boost the efficiency of EVA for reducing the wax appearance temperature of waxy crude oil. Thermo X-ray diffraction characterization demonstrates that EVA/SiO₂ nanohybrids cut down the crystal index of waxes, with the grain size of crystal cells decreased in (006) and (200) but increased in (110) cross sections. Polarized optical microscopy imaging reveals that EVA can modify the morphology of wax crystals to suppress the formation of wax gel, and nanohybrids serve as nucleuses to adsorb asphaltenes and resins, restraining the appearance of wax crystals. The rheological test shows that nanohybrids outperform EVA in decreasing the viscosity, inflection point, and yield stress of waxy crude oil. These findings help the understanding of flow improving by nanohybrid materials and offer guidelines for designing the new generation of wax inhibitors for safe transportation and flow assurance of waxy crude oil.

Synthesis of crystallizable poly(behenyl methacrylate)-based block and statistical copolymers and their performance as wax crystal modifiers

Behenyl methacrylate-based diblock and statistical copolymers are evaluated as additives for the crystal habit modification of a model wax (n-octacosane) in n-dodecane. The statistical copolymers more strongly influence the wax crystal morphology.

Effect of Graphene on Modified Asphalt Microstructures Based on Atomic Force Microscopy

Atomic force microscopy (AFM) was used to explore the effects of graphene modifier on the microstructure of asphalt. The morphologies of the before- and after-aged base asphalt and modified asphalt were performed and compared with analysis. The formation mechanism of asphaltic “bee structures” and the influence mechanism of graphene on asphalt were discussed from the classical theory of material science (phase transformation theory and diffusion theory). The results show that graphene facilitates the nucleation of “bee structures”, resulting in an increasing number and decreasing volume of “bee structures” in modified asphalt. Additionally, the anti-aging performance of the modified asphalt improved significantly because of graphene incorporation.

Polymer Cold-Flow Improvers for Biodiesel

In recent decades, biodiesel has been explored as a prospective comparable fuel to petroleum diesel for compression ignition engines. However, several drawbacks have limited the wide application of biodiesel as motor fuel, and the poor cold-flow property is one of the major problems. This problem is compounded by the diversity of the biodiesel characteristics arising from a variety of chemical compositions of biodiesel from different sources. Among the methods investigated to improve the cold-flow properties of biodiesel, the use of additives seems highly promising. Despite the significant number of publications, the potential of this method is still far from having been completely discovered or exploited. In the present review, we briefly describe the sources, chemical composition, and physico-chemical characteristics of the main types of biodiesel. Next, we discuss the examples of the use of different polymer additives for the improvement of the cold-flow characteristics of biodiesel and biodiesel/petroleum diesel blends. Additionally, we tried to assess the prospects of the polymer additives to enhance biodiesel performance. The main conclusion of this survey is that innovative and high-efficiency cold-flow improvers for biodiesel should be further developed.

Remarkable decrease in the viscosity of waxy crude oil under an electric field

Uninterrupted transport of waxy crude oil through pipelines remains a pressing concern for the petroleum industry. When the ambient temperature falls below the pour point of the crude, deposition of wax particles may lead to complete blockage of the pipeline. We demonstrate that the application of a DC electric field to waxy crude below its pour point can effectively break the wax network and also reduce the viscosity by up to two orders of magnitude. We have studied the dynamics of the change in viscosity during and after application of an electric field. Three regimes are observed. First is the induction regime, where viscous stresses dominate and the viscosity remains unchanged. During the intermediate and final regimes, the decrease in viscosity follows first order kinetics with rate constants proportional to the strength of the electric field and to the square of the strength, respectively. Microscopic evidence shows that some network connections break during the intermediate regime, whereas in the final regime, further fragmentation of the pieces of the broken network occurs. This is accompanied by aggregation of fine wax fragments. After cessation of the field, the viscosity increases gradually. The rate and the extent of recovery of viscosity depend only on the value of viscosity at the point of cessation of the field. That the breakage of the network occurs, even in the absence of shear, has been demonstrated. Through measurement of the dielectric constants and conductivities of the crude oil and its component phases, we have shown that the wax network experiences compressive Maxwell stress, which is dominated by the electric field within the wax particles.

Wax Formation in Linear and Branched Alkanes with Dissipative Particle Dynamics

We present a dissipative particle dynamics (DPD) model for wax formation (i.e., the freezing transition) in linear and branched alkanes at room temperature (298 K) and atmospheric pressure. We parametrize the model using pure liquid phase densities and the onset of wax formation as a function of alkyl chain length. Significant emphasis is placed on building an accurate representation of the underlying molecular architecture by careful consideration of bond lengths and angles, aided by distributions obtained from molecular dynamics simulation. Using the derived model, we observe wax formation in n-alkanes when the alkyl chain length is greater than 18 (n-octadecane), in excellent agreement with experimental observations. Further, we reproduce the behavior of branched alkanes and mixtures including solubilities of heavy alkanes in light alkane solvents.

Ethylene-Vinyl Acetate Copolymer/Crude Gossypol Compositions as Pour Point Depressants for Waxy Oil

Wax deposition from crude oil that blocks the pipeline and increases the viscosity of the fluid is considered as a serious challenge for petroleum transportation. Employment of chemical additives, the so-called pour point depressants (PPDs), is widely used to solve this problem. Among them are the ethylene-vinyl acetate (EVA) copolymers (EVAc), containing a polyethylene segment along the backbone with vinyl acetate. To improve the performance of EVAc as PPD, the compositions of this polymer with crude gossypol (CG), isolated from the refined cottonseed oil soapstock, were prepared by joint milling in a ball mill. Prepared compositions were characterized by Fourier transform infrared (FTIR), ultraviolet (UV), and nuclear magnetic resonance (NMR) spectroscopy. The pour point and viscosity of the crude oil from the Akshabulak oil field (Kazakhstan) were studied. The compositions with 10, 20, and 25 wt% of CG demonstrate better efficiency as PPD for crude oil than EVAc at the dosage of PPD of 50, 100, 250, and 500 ppm. The improved properties of the obtained PPD in comparison with the commercial EVAc is explained by the appearance of additional nonpolar and polar groups caused by the formation of the EVAc/CG composition.

The Impact of Ethylene Glycol on Droplet Growth Inhibition in Ethylene Vinyl Acetate Emulsions

Pour point depressant (PPD) emulsion has been gaining attention in crude oil transportation owing to its potential to solve solidification issues that arise in cold climate environments. An emulsion system provides a wide range of temperature application that combines good shelf life and tunable thermal properties to tackle this problem. These features can be achieved by incorporating an antifreeze agent into the emulsion. One of the most commonly used antifreeze agents is ethylene glycol (EG). Hence, this study focuses on the thermal properties and droplet size growth of PPD emulsions that were aged in variable concentrations of EG solution. EG50 exhibited the lowest freezing temperature of -44 °C, while EG25 demonstrated the lowest vitrification temperature of -68.7 °C. The particle size of the emulsions underwent a significant reduction from 332.3 to 228.9 nm upon the stepwise EG concentration increment to EG50. However, when the concentration was increased to EG75, a slight increase in the emulsion particle size was observed with a recorded value of 237.8 nm. Thus, it is concluded that EG50 represents the optimum concentration for delivering the best freezing protection and producing a smaller droplet particle size.

A critical update of experimental techniques of bulk and interfacial components for fluid characterization with relevance to well fluid processing and transport

The present article reviews techniques to address central flow assurance and separation issues. It is our purpose to update the need for extended information in order to draw adequate conclusions about the reason for irregularities in production and how this is related to individual components or fractions in the crude oil. Our intention is to show that the mass related analysis (such as SARA, MS etc.) are insufficient for a validation of the early stage predictions concerning irregularities. The review introduces a set of new characterization and fractionation techniques such as interfacial rheology, SANS, and NMR, where the central theme is the functionality of the components and not just their mass. Two crude oil-related issues are addressed: Wax precipitation and deposition, and crude oil/water resolution. First, bulk techniques to characterize wax precipitation are reviewed. The influence of the chemistry of other crude oil components (asphaltenes) and wax inhibitor on the precipitation is highlighted. Secondly, in aqueous systems, interfacial w/o conditions are important for the stability of dispersed systems. Asphaltenes have a crucial and important role in the stability of crude oil emulsions. Here special attention is directed to properties like interfacial viscosity and elasticity as well as the adsorbed layer structure determination. Small molecular changes in these properties will have dramatic influence on the stability of the heterogeneous systems. A good example is inhibitor functionality.

The Associations between Leaf Morphology, Phenylalanine Ammonia Lyase Activity, Reactive Oxygen Species, and Fusarium Resistance in Selected Species of Wheat with Different Ploidy Levels

In wheat, resistance to Fusarium is conditioned by anatomical, morphological, and physiological traits. The aim of this study was to evaluate selected elements of constitutive barriers in common wheat, spelt, Polish wheat, emmer, and einkorn. The activity of the phenylalanine ammonia-lyase (PAL) enzyme and rate of reactive oxygen species (ROS) production were evaluated in the tissues of common wheat and spelt inoculated with Fusarium culmorum. Most of the relict wheat species were more abundant in morphological barriers than common wheat. F. culmorum penetrated constitutive barriers, which increased PAL activity and intensified ROS production 24 h after inoculation in wheat tissues. The lowest increase in PAL activity after inoculation was observed in cv. Sumai3, which resistance is based on limiting the spread of F. culmorum within the spike. Spelt line Tas 581 glumes were characterized by the highest concentration of ROS 24 h after inoculation. The ROS content remained high for five days. The results of this study indicate that high trichome density plays a key role in resistance to pathogens. In the resistant spelt line with effective constitutive barriers, PAL activity and ROS content were higher than those observed in susceptible wheats after inoculation with F. culmorum.

Fatty Acid-Based Radically Polymerizable Monomers: From Novel Poly(meth)acrylates to Cutting-Edge Properties

The increasing price of barrels of oil, global warming, and other environmental problems favor the use of renewable resources to replace the petroleum-based polymers used in various applications. Recently, fatty acids (FAs) and their derivatives have appeared among the most promising candidates to afford novel and innovative bio-based (co)polymers because of their ready availability, their low toxicity, and their high versatility. However, the current literature mostly focused on FA-based polymers prepared by condensation polymerization or oxypolymerization, while only a few works have been devoted to radical polymerization due to the low reactivity of FAs through radical process. Thus, the aim of this Review is to give an overview of (i) the most common synthetic pathways reported in the literature to provide suitable monomers from FAs and their derivatives for radical polymerization, (ii) the available radical processes to afford FA-based (co)polymers, and (iii) the different applications in which FA-based (co)polymers have been used since the past few years.

Non-traditional Ziegler-Natta catalysis in α-olefin transformations: reaction mechanisms and product design

This paper describes our recent results in the field of zirconocene-catalyzed α-oltfin transformations, and focuses on questions regarding the reaction mechanism, rational design of zirconocene pre-catalysts, as well as prospective uses of α-olefin products. It has been determined that a wide range of α-olefin-based products, namely vinylidene dimers, oligomers and polymers, can be prepared via catalysis by zirconocene dichlorides, activated by a minimal (10–20 eq.) amount of MAO. We assumed that in the presence of minimal quantities of MAO, various types of zirconocene catalysts form different types of catalytic particles. In the case of bis-cyclopentadienyl complexes, the reactive center is formed under the influence of R2AlCl, which makes the chain termination via β-hydride elimination significantly easier, with α-olefin dimers being formed as the primary product. Bis-indenyl complexes and their heteroanalogues, form stable cationic catalytic particles and effectively catalyze the polymerization. Mono-indenyl and mono-substituted bis-cyclopentadienyl-ansa complexes catalyze α-olefin oligomerization. Effective catalysts of dimerization, oligomerization and polymerization of α-olefins in the presence of minimal MAO quantities are proposed. Prospects of using α-olefin dimers, oligomers and polymers in the synthesis of branched hydrocarbon functional derivatives (dimers), high quality, low viscosity motor oils (oligomers), and thickeners and absorbents (polymers) are examined.