Polymeric Pour Point Depressants Research Articles

Novel Optical Methodology Unveils the Impact of a Polymeric Pour-Point Depressant on the Phase Morphology of Waxy Crude Oils.

Crude oil, also known as petroleum, plays a crucial role in global economies, politics, and technological advancements due to its widespread applications in industrial organic chemistry. Despite environmental concerns, the dwindling supply of easily accessible oil reservoirs necessitates the exploration of unconventional resources, such as heavy and extra-heavy oils. These oils, characterized by high viscosity and complex composition, pose challenges in extraction, transportation, and refinement. With decreasing temperatures, heavy oils undergo phase changes, with transitions from Newtonian to non-Newtonian fluid behavior, leading to difficulties in transportation. Alternative methods, such as the use of polymeric pour-point depressants, help mitigate flowability issues by preventing wax precipitation. Understanding the properties of waxy crude oil, such as the wax appearance temperature (WAT), is crucial for effective mitigation strategies. The objective of this research is to determine the WATs of different types of waxy crude oils through a comparative analysis using advanced techniques such as cross-polar microscopy (CPM), standard rheology, and differential scanning calorimetry (DSC). Disparities in WAT identified through different analytical methods highlight the potential of microscopy to enhance our understanding of complex fluid dynamics in real time in order to proactively identify and address crystallization issues in oilfields.

Alterations in paraffin wax crystal networks induced by asphaltenes and pour point depressants, investigated by atomic force microscopy

Wax crystallization in pipelines in cold environments is a key factor affecting flow assurance during crude oil production. Polar crude oil components, such as asphaltenes, and polymeric pour point depressants (PPDs) have been demonstrated to interact with wax during gelation and crystallization through complex formation during nucleation or crystal growth alteration which leads to co-crystallization. This study introduces a methodology based on atomic force microscopy (AFM) to characterize features of solid surfaces precipitated from model wax, wax-PPD, wax-asphaltene and asphaltene systems. Height data collected from AFM measurements enabled the quantification of modifications in crystal sizes and shapes induced by the presence of asphaltenes and PPDs. The 2D Fourier transform of the height was used to generate statistics for the frequency of height amplitude, revealing information about the pore size and the height patterns. A stiffness/elasticity analysis was used to calculate the Young Modulus of the upper layers. In wax and wax-asphaltene systems, two nano-scale layers with different Young Modulus profiles emerged. The nano-scale layer on the top was softer and corresponded to more amorphous wax crystal networks with trapped dissolved wax. The nano-scale layer on the bottom was stiffer, comprising of more crystalline structures, corresponding to wax crystals with lower deviations from full crystallinity, with properties independent of asphaltene concentration. A bilayer did not form in the presence of PPD, which prevented the formation of amorphous phases with trapped dissolved wax or gel. After a methodology for model systems was established, the focus moved to systems based on production wax i.e. recovered from deposits. This was complemented by a comparison between model precipitation conditions and precipitation by cold finger, resembling industrial processes. Results highlighted the effect of change in chemical composition on topography, elasticity and adhesion of the surface. AFM provided new insights into wax crystallization patterns in the presence of inhibitors, which can be used to quantify the extent of wax-inhibitor interactions and project it on production systems. The method could be used to explain macro-scale rheological properties of oils during flow assurance in the future.

Synthesis of copolymers based on maleic anhydride and α-olefins and modification with primary amines as pour point depressant (PPD) for waxy crude oils

Polymeric PPDs that reduce the pour point of crude oil are one of the most important chemicals utilized in the petroleum industry, especially when transporting waxy oil. The regulation of the structure of such polymers with different hydrophobic-hydrophilic balance makes it possible to select an effective PPD to improve the low-temperature properties of crude oil. On this basis, the current work presents a series of syntheses of copolymers based on α-olefins and maleic anhydride and their modification by the amidation reaction with primary amines: butylamine, hexylamine, hexadecylamine, octadecylamine, and benzylamine. The structure of the copolymers was determined through FTIR spectroscopy and 1H and 13C NMR spectroscopy. The molecular weight of the copolymers was identified by the method of light scattering. The study of the effect of modified copolymers on rheological behavior and lowering the pour point was performed for waxy crude oil from the Akshabulak field (Kazakhstan). Rheological tests have shown that the synthesized copolymers improve the fluidity of oil and reduce the values ​of the yield stress of oil. Optical micrograph showed that the modified copolymers form fine crystals of paraffins and exhibit dispersing properties.

Modification Effect of Macroporous Comb-Like Polymeric Pour Point Depressants on the Flow Behavior of Model Waxy Oils

Modification Effect of Macroporous Comb-Like Polymeric Pour Point Depressants on the Flow Behavior of Model Waxy Oils

Synthesis of a novel terpolymer of (BA-co-SMA-co-MA) as pour point depressants to improve the flowability of the Malaysian crude oil

During the extraction of crude oil, the reservoir temperature is much higher than the surface temperature especially when the oil is transported cross subsea. Therefore, the flow of virgin oil gets impeded due to the precipitation of wax on the inner wall of pipelines when the temperature decreased below the wax appearance temperature (WAT) and the flow stops if the temperature falls below the pour point. Polymeric pour point depressants (PPD) have received considerable attention as a wax control approach to enhance the flowability of waxy crude oil. The aim of the current study is to synthesize a novel PPD of benhely acrylate-co-stearyl methacrylate-co-maleic anhydride (BA-co-SMA-co-MA) to improve the viscosity of Malaysian crude oil using free radical polymerization. The effect of polymerization parameters, such as reaction temperature, initiator concentration, experimental duration, and monomer concentration on the yield of the synthesized polymer was evaluated statistically with a one-factor-at-a-time (OFAT) approach. The performance of the prepared PPD was evaluated to determine its effects on the viscosity of crude oil using Brookfield DV-III viscometer. The experimental results showed that the optimum conditions to obtain the highest yield were at the reaction time of 8 h, initiator concentration of 1.5 wt%, reaction temperature of 100 °C, and monomers ratio of (BA:SMA: MA) 1:1:1. At the optimum conditions, the prepared terpolymer reduces the viscosity of crude oil from 7.2 mPa.s to 3.2 mPa.s at 30 °C using 1500 ppm. The significant reduction in the apparent viscosity indicated improvement in the low-temperature flow properties of the crude oil after applying the synthesized PPD.

Use of novel pour point depressant synthesized from vegetable oil for waxy crude oil

A synthesized polymeric pour point depressant (PPD) from olive oil (Olea Europaea) was used to reduce the pour point and rheology improvement. A maximum reduction of 8 °C in pour point which was originally 43 °C at ambient temperature after adding 1000 ppm PPD. Rheology was studied at different shear rate with or without mixing of synthesized PPD at different temperature. Viscosity reduction was 89.20% after mixing 1000 ppm PPD at 45 °C. Viscoelastic property was studied, and it helps in reduction of heat treatment cost during crude oil transportation through pipelines at cold climate.

Characterization of a novel terpolymer containing maleic anhydride-co-stearyl methacrylate-co-benhely acrylate for wax inhibition application

Wax deposition in petroleum pipelines is deliberated as one of the most severe operational issues, and extraordinary efforts have been made to remediate and prevent this flow assurance problem. Using, polymeric pour point depressants (PPD) as a wax control strategy to improve the fluidity of waxy crude oil and reduce the pour point have received significant attention. The purpose of the current research is to synthesize novel terpolymers which used as PPD and viscosity improvers. The synthesis process occurred via polymerization of stearyl methacrylate (SMA), benhely acrylate (BA), and maleic anhydride (MA) monomers using free radical polymerization method in toluene as a solvent, and (1 wt%) benzoyl peroxide (BZP) as initiator. The chemical structure of the prepared terpolymer was characterized by FTIR and NMR. Also, the crystallization behavior of paraffin wax was investigated by differential scanning calorimetry (DSC). Experimental investigations furnish that the synthesized PPD showed high yield (87%) at the concentration (1:1:1) of BA-co-SMA-co-MA. From FTIR and 1HNMR characterization results observed that maleic anhydride moiety, alkyl chain moiety, and methacrylate moiety are existing in the prepared terpolymer. Furthermore, DSC analysis showed that the glass transition temperature of the prepared terpolymer is weakly stated over a wide temperature range.

Synergistic effect of asphaltenes and octadecyl acrylate-maleic anhydride copolymers modified by aromatic pendants on the flow behavior of model waxy oils

Asphaltenes in waxy crude oils greatly influence the performance of polymeric pour point depressants (PPDs), and the relevant mechanism needs to be further discovered. In this article, polyoctadecylacrylate (POA), polyoctadecyl-acrylate-maleic anhydride (POA-MA) and its aromatic pendants-modified derivatives, polyoctadecyl-acrylate-maleic anhydride-aniline (POA-MA-AN) and polyoctadecyl-acrylate-maleic anhydride-naphthylamine (POA-MA-NA) were synthesized and characterized. Subsequently, the performance of the four PPDs on the pure model waxy oil (MO-1) and the model waxy oil containing 0.3 wt% asphaltenes (MO-2) were investigated through the rheological test, DSC analysis and micro-observation. The results showed that the four PPDs could improve the flowability of MO-1 to some extent, and adding 500 ppm POA exhibited the best performance: the pour point decreased from the initial 29 °C to 22 °C and the yield stress at 10 °C reduced from the initial 627.20 Pa to 69.58 Pa. Adding comb-like PPDs could observably improve the flowability of MO-2, meaning that a synergistic effect exits between the asphaltenes and comb-like PPDs. Adding 500 ppm POA-MA-AN in MO-2 showed the best performance: the pour point decreased to 3 °C, the yield stress at 10 °C reduced to 1.27 Pa. The quantitative asphaltenes precipitation test and molecular dynamics simulations revealed that adding POA-MA-AN could significantly reduce the percentage of precipitated asphaltenes in the mixed solution and the interaction energy between POA-MA-AN and asphaltenes was the lowest. This indicates that introducing aromatic pendants in comb-like PPDs strengthens the interactions between asphaltenes and PPDs, facilitating the adsorption of PPDs on asphaltenes to form the composite particles and thus greatly improving the flowability of waxy oils.

Ethylene–Vinyl Acetate Copolymer and Resin-Stabilized Asphaltenes Synergistically Improve the Flow Behavior of Model Waxy Oils. 1. Effect of Wax Content and the Synergistic Mechanism

Both polymeric pour point depressants (PPDs) and asphaltenes can improve the flowability of waxy oils. However, the effect of polymeric PPDs together with asphaltenes on the flowability of waxy oils is not clear. In this paper, the synergistic effect of ethylene–vinyl acetate (EVA) PPD (100 ppm) and resin-stabilized asphaltenes (0.75 wt %) on the flow behavior of model waxy oils (10–20 wt % wax content) was investigated through rheological tests, DSC analysis, microscopic observation, and asphaltenes precipitation tests. The results showed that the asphaltenes disperse well in the xylene/mineral oil solvent as small aggregates (around 550 nm) with the aid of resins. The EVA or asphaltenes alone moderately improve the flow behavior of waxy oils by changing the wax crystals’ morphology from long and needlelike to a large, radial pattern or fine particles, respectively. The wax precipitation temperatures (WPTs) of waxy oils are also slightly decreased by adding EVA or asphaltenes, meaning that the cocrystall...

Effect of nanocomposite of attapulgite/EVA on flow behavior and wax crystallization of model oil

ABSTRACTNanocomposites of attapulgite (ATT)/ethylene vinyl acetate copolymer (EVA) were prepared with organically modified ATT covering in EVA. Organically modified ATT was prepared using KH550 and organic acid. The effect of nano-hybrid on the flow behavior of model oil containing 15 wt% wax was evaluated. The wax crystallization and crystal morphology of the model oil at low temperature were observed by polarizing optical microscopy (POM). The results indicated that the nano-hybrid with long-chain organic acid-modified ATT exhibited a better effect compared with the nano-hybrid with short-chain organic acid-modified ATT, pure EVA. In addition, it is interesting to note that EVA (VA = 32%)/stearic acid-modified ATT composite polymeric pour-point depressant (PPD) S-AtPPD(32) provided better cold-flow improvement for the model oil than EVA (VA = 32%)-modified nano-SiO2 composite PPD N-SiPPD (32) with a low dose, which resulted in a regular, bar-shaped, and uniform arrangement of wax morphologies. The pour point of the model oil was reduced from 30°C to −1°C when doped at 200 ppm S-AtPPD(32).

Performance improvement of the ethylene-vinyl acetate copolymer (EVA) pour point depressant by small dosages of the polymethylsilsesquioxane (PMSQ) microsphere: An experimental study

In a previous work, the addition of the polymethylsilsesquioxane (PMSQ) microsphere (50–400ppm) can improve the flow behavior of waxy crude oil through the spacial hindrance effect. However, the flow improving efficiency of the neat PMSQ microsphere is not as good as the traditional polymeric pour point depressants (PPDs). In this paper, the effect of the ethylene-vinyl acetate copolymer (EVA2806) PPD together with the PMSQ microsphere (with the size around 2µm) on the flow behavior of a typical waxy crude oil was investigated. The results show that adding 50ppm EVA PPD can greatly improve the flow behavior of the oil. The neat PMSQ microsphere cannot improve the flow behavior of the oil at small dosages (≤10ppm), but can significantly improve the performance of the EVA PPD. The gelation point, G′, G″, transient apparent viscosity and yield stress of the oil decrease further after adding both 50ppm EVA and a small amount of the PMSQ microsphere (≤10ppm). The best flow improving efficiency is found at 50ppm EVA+2.5ppm PMSQ. The addition of the PMSQ microsphere has little influence on the WAT and precipitated wax crystal amount of the oil doped with EVA, but outstandingly changes the morphology of the precipitated wax crystals into larger and more compact flocs. The adsorption tests show that the EVA molecules can adsorb and concentrate on the PMSQ microsphere, thus causing the formation of the EVA/PMSQ composite particles. The composite particles can act as nucleation templates for the wax precipitation, resulting in larger and more compact wax microstructures and then further improving the flow behavior of the oil. The PMSQ microsphere dosage and the amount of EVA PPD adsorbed on the microsphere obviously influence the performance of the composite particle with the best performance at 50ppm EVA+2.5ppm PMSQ. The findings mentioned above provide a new way to improve the performance of polymeric PPDs efficiently.

Wax-Inhibitor Interactions Studied by Isothermal Titration Calorimetry and Effect of Wax Inhibitor on Wax Crystallization

Isothermal titration calorimetry is applied to investigate the interactions of polymeric pour-point depressants (PPDs) or asphaltenes with macrocrystalline wax in a model oil system. This represents a novel approach to measure and compare the heat of interaction for solid wax crystals with different wax inhibitors (WIs). In addition, the PPDs were characterized via size-exclusion chromatography and differential scanning calorimetry (DSC), and the effect of PPDs or asphaltenes onto the wax appearance temperature (WAT) and the formed wax-oil gel was investigated using DSC, cross-polarized microscopy (CPM), and rheometry. The results show that there is detectable interaction heat with wax crystals for all PPDs and asphaltenes. DSC and viscometry show a decrease in observed WAT for all WIs as compared to the additive-free blank case. CPM imaging shows differences in structure, shape, and size of the wax crystals formed in the presence of particular PPDs or asphaltenes, which is also seen as a decrease in gel-breakage strength. Overall, there is no direct correlation between interaction heat and WI performance characteristics, such as a high decrease in WAT or gel strength. Ethylene-vinyl acetate copolymer (EVA) with 25% vinyl actetate accounts for the highest interaction heat measured but shows effective decrease in wax crystals size for only part of the crystals while acting as a flocculate to others, which resulted in a low effect on gel strength. Commercial PPDs based on polycarboxylate have the best performance for the model oil system used but show only overage interaction heat values. The interaction heat of asphaltenes with wax is measurable but lower than for the PPDs tested. The presence of asphaltenes significantly lowered the gel strength and changed the wax crystal morphology to rounder and dendrite-like shapes. These findings suggest that asphaltene compounds are incorporated into the wax crystals, changing the structure and shape of the crystals.

Effect of the nano-hybrid pour point depressants on the cold flow properties of diesel fuel

The nano-hybrid pour point depressants (PPDs) was prepared by organically modified nano-clay covering in polymeric PPDs, namely, polymethyl acrylate (PMA), ethylene vinyl acetate copolymer and poly-α-olefin. The effects of nano-hybrid PPDs on the cold flow properties of diesel fuel were evaluated. The crystal morphology and crystallization behavior of the diesel fuels in low-temperature were also observed by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The results indicated that the nano-hybrid PPDs always exhibited a better cold filter plugging point, while it had little effect on solidifying point compared to pure PPDs, and PMA hybrid with organically modified nano-clay in mass ratio of 4:1 exerted the best depression effect. Up addition of 0.15wt.% nano-hybrid PMA (4:1) in diesel, the cold filter plugging point and solidifying point were reduced by 16°C and 14°C, respectively. DSC and POM results showed that the nano-hybrid PMA involved heterogeneous nucleation activity. The nano-hybrid PMA modified the crystallization behavior of diesel by transforming the shape of wax crystals and inhibiting the formation of larger crystals, which result in compact, regular, tiny particle-shaped and uniform arrangement wax morphologies.

Effect of Vinyl-Acetate Moiety Molar Fraction on the Performance of Poly(Octadecyl Acrylate-Vinyl Acetate) Pour Point Depressants: Experiments and Mesoscopic Dynamics Simulation

Polar moieties of the conventional polymeric pour point depressants (PPDs) greatly influence the PPDs’ performance on waxy crude oil. However, the influencing mechanism of the polar moieties on the PPD’s performance is not clear. In this paper, four poly(octadecyl acrylate-vinyl acetate) (POA-VA) PPDs with different VA molar fractions were first synthesized; then, the performance of the four PPDs on Dingbian waxy crude oil was investigated by experiments and mesoscopic dynamic simulation. The experimental results show that the crystallization ability of the PPDs deteriorates with increasing VA molar fraction, while the performance of the PPDs first increases and then decreases with the increase of VA molar fraction. At a moderate VA fraction 25 mol %, the PPD-3 shows the best performance in decreasing the WAT, pour point, and viscosity of the crude oil. The simulation results correlate well with the experimental data and confirm that (a) the addition of the PPDs inhibits the transformation of wax molecule...

Organically modified nano-clay facilitates pour point depressing activity of polyoctadecylacrylate

Introduction of nanomaterials constitutes a novel and efficient means to enhance the performance of polymeric pour point depressants (PPDs). Based on the specific layered structure and favorable cationic exchange characteristics of nano-clay particles in the presence of charged organic compounds, an original hydrophilic nano-clay is first modified by octadecyl trimethyl ammonium chloride (OTAC) and then by polyoctadecylacrylate (POA). The modified nano-clay serves as an effective nanocomposite PPD. Compared to an identical content of POA, addition of POA/clay nanocomposite PPD to Changqing waxy crude oil improves the rheological properties while elevating the wax appearance temperature of the oil. Polarized microscope observation shows that POA/clay nanocomposites provide wax nucleation sites upon which wax molecules assemble and precipitate. Addition of POA/clay nanocomposite PPD results in larger and more compact crystal morphology, thus inhibiting the formation of a network structure, and further improving rheological properties of waxy crude oil.

Preparation and Evaluation of Polymeric Pour Point Depressant for Crude Oil

A series of polyacrylate ester (PAE) was prepared by free-radical polymerization. The PAEs were used as pour point depressant for crude oil from Yumen Oil Field. PAE12 and PAE18 showed potent activity for 2# and 4# samples under the concentration of 500 ppm with the highest Δ pour point of 10-13°C. In the further study, the effect of the concentration on the pour point was investigated.

Wax Control by Designing Polymeric Pour Point Depressant Additives for Indian Crude Oil

This study details improvement of flow property of oil by seven different poly(n-cinnamates-co-N-hexadecylmaleimide) synthesized using cinnamic acid, maleic anhydride, and hexadecylamine and their characterization as performed by infrared (IR), 1H-NMR and 13C-NMR spectroscopy, and gel permeation chromatography (GPC). An AR-500 rheometer was used to evaluate the effect of additives on rheology of oil at different temperatures and different concentration of additives. Cn-22 is the most effective depressant, and reduces the pour point of Dahej oil containing 29.09 wt.% waxes from 35°C to 2°C at 1000 ppm concentration.

Evaluation of Effect of Polymeric Pour Point Depressant Additives on Indian Waxy Crude Oil

Wax deposition in oil production constitutes a critical and difficult-to-control problem in terms of productivity and production operation costs going from the reservoir to surface facilities. In the present work, four polymeric additives were prepared and used as pour point depressants (PPD) for Limbodara (Indian) crude oil via polymerization of different undecylenates with maleic anhydride with a further reaction with amine. The results are encouraging and show that prepared additives function both as wax dispersants and flow improvers due to the presence of polar groups in the structure. Cross–polarizing microscopic studies were performed to study changes in morphology of wax crystals in crude oil with and without additive. A zero-friction advanced rheometer AR-500 was used to determine the viscosity by applying Bingham plastic-flow model.

Preparation of Polymeric Pour Point Depressants for Shale Oil

The melt esterification of acrylic acid and higher alcohols without solvent is carried out and the effects of factors on the production efficiency of acrylic higher alcohol ester are investigated. Optimum reaction conditions are obtained at molar ratio of acrylic acid to higher alcohol 1.2:1.0 and reflux time 7 h at 110–140°C in stepwise heating. At this point the acrylic higher alcohol ester will be polymerized with maleic anhydride, phenylethylene, and vinyl acetate, and formed into four components. Copolymer shale oil pour point depressant and the polymerization condition are also studied by orthogonal method. The effect of pour point depressants is best when the monomer molar ratio is 8:1:1:1 at 80°C for 8 h for reflux and the benzoyl peroxide is added. The pour point of Fushun shale oil reduces by 9°C when only 0.5% copolymer is added.

Synthesis and evaluation of poly-?-olefins for improving the flow properties of gas oil

Polymers of individual and mixed normal C12, C14, C16, and C18 α-olefins are synthesized, purified, and then characterized. The performance of poly-α-olefins is assessed for improving the cold flow properties of a local gas oil in terms of cloud-point and pour-point depression. Results show that poly-α-olefins have great potency in decreasing the pour point of the distillate fuel, whereas a slight effect is observed in decreasing the cloud point. Efficiency of the polymeric pour-point depressants is discussed on the basis of their structure and average molecular weight. © 1996 John Wiley & Sons, Inc.