PETROLEUM SCIENCE AND TECHNOLOGY
·
2023
·
IF 1.5
Huili Zhang,Yucui Zhao,Xuyu Chen,Long Dong,Hailin Yu,Jinjun Deng,Yanbin Tong,Lingmin Wu,Liqun Sun,Hongsheng Liu
The waxy crude oil was routinely transported by means of adding pour point depressants (PPD), which can significantly improve the flow behavior of waxy crude oil. In this study, the physical properties of crude oil were first characterized. Subsequently, a novel variety of W/O nanoemulsion was prepared based on water in an EVA/toluene solution at a 3:1 proportion, and evaluated as a viscosity improver. It was found by virtue of the laser particle size analyzer that the EVA emulsion reaches the nano-scale. EVA nanoemulsion can present a behavior similar to nanocomposite PPD, and form a denser and regular structure with wax crystals via heterogeneous nucleation. Compared with conventional EVA, EVA nanoemulsion further reduces the oil viscosity, gel point and yield value by 52.8%, 0.05 °C and 29.6%. In addition, the impact of particle size of EVA nanoemulsion on the rheology of crude oil was discussed. In combination with DSC curve and POM, the action mechanism of EVA nanoemulsion on crude oil was analyzed.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2019
·
IF 3.021
Huiyong Xue,Jinjun Zhang,Shanpeng Han,Mengran Sun,Xiaohan Yan,Hongying Li
Asphaltenes, as the most polar component of crude oils, may interact with wax molecules during the wax crystallization, thus changing wax precipitation characteristics and wax crystal structure and affecting the gelation behavior of crude oils. In the present work, waxy model oils of variable asphaltene contents (0–0.20 wt %) were prepared in order to systematically examine the effect of asphaltenes on the wax precipitation characteristics and the gelation behavior of waxy oils and to look into the structure and the surface electrical properties of wax crystals formed in oils of different asphaltene contents. By means of differential scanning calorimetry and multiple rheometries, it was found that asphaltenes play a significant role in inhibiting the precipitation of wax crystals and delaying the gelation, as well as in weakening the strength of the gel structure. It was observed by polarized optical microscopy that as the asphaltene content increases, the size of wax crystals gradually decreases, and the shape of wax crystals transforms from rodlike into elliptical. Furthermore, both the average aspect ratio and the average perimeter of wax crystals decrease, while the boundary box fractal dimension increases, demonstrating that the morphology of wax crystals becomes more complex. Based on the X-ray diffraction (XRD) pattern, the grain size obtained with the Scherrer equation presents a descending trend with the increase of asphaltenes. It could be inferred that the reduction of grain size is one of the reasons leading to the smaller sizes of wax crystals. The XRD result also showed that with higher asphaltene content, the lattice parameter c of wax crystals obviously increases, indicating that the conformation of wax crystals gets more disordered, which results in the weakening of gel strength, corresponding to the decline of the measured yield stress of the waxy oil gel. With higher asphaltene content, the zeta potential of wax crystals goes up, which indicates that with more negative charges adsorbed on the wax crystal surfaces, stronger electrostatic double layers have formed. The greater electrostatic repulsion among wax crystals would interfere with the growth and aggregation of wax crystals, thus holding up the gelation of waxy oils.
研究领域:
石油工程
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Zuojia Xi,Xubiao Zhang,Chaohe Yang,Jun Xu
In the global energy landscape, the development of desert oil in Africa has increased the diversity of world oil supply and helped maintain the balance of the global energy market. However, wax precipitation and asphaltene deposition cause numerous challenges during the recovery and pipeline transportation of African crude oil. Traditional linear polymer additives often have limited wax-modifying and asphaltene-dispersing efficiency. In this work, linear poly(octadecyl acrylate-styrene) (POA-St) and a series of star POA-St copolymers with different arm numbers (3, 4, and 6) were synthesized through reversibly additive fragment chain transfer polymerization. The effects of the linear and star POA-St on the wax precipitating properties, pour point, rheology, and asphaltene stability of African waxy crude oil were studied in detail. The star POA-St copolymers show superior performance compared with linear polymers in inhibiting wax crystal formation, improving crude oil rheology, and stabilizing asphaltene. Increasing the arm number of star POA-St greatly improves its performance. Star POA-St-6 reduces the wax appearance temperature of the crude oil from 53.7°C to 51.1°C. At 20°C, the addition of the star POA-St-6 reduces the pour point of crude oil from 30°C to 21°C, and the viscosity and yield stress decrease by 74% and 55.2%, respectively. In addition, star POA-St-6 increases the initial precipitation points of asphaltene from 44.3% to 57.1%, showing a splendid asphaltene inhibiting efficiency. We speculate that the star POA-St stabilizes asphaltene aggregates among its arms and changes the wax crystal morphology through co-crystallization and nucleation effects, thereby exhibiting good performance. These findings provide prospective insights and avenues for the structural optimization and innovation of a new type of pour point depressant.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2018
·
IF 1.454
Zhengnan Sun,Guolin Jing,Ziyi Tu
The nano-hybrid pour-point depressant (PPD) was prepared with organically modified nano-silica covering in EVA. The effects of modified nano-silica/EVA on the flow behavior and wax crystallization of model oils with different wax contents were evaluated. Compared with pure EVA and nano-silica/EVA, modified nano-silica/EVA exhibited a better effect, when doped with 500 ppm, the pour point of the model oil containing 20 wt% wax was reduced from 33°C to 0°C. However, it is noteworthy that pour point cannot accurately reflect the effect of YSiO2/EVA as cold flow improver for a high wax content. The crystal morphology and crystallization behavior of the model oils at low temperature were also observed using polarizing optical microscopy (POM). The results indicated that modified nano-silica/EVA can reduce the size of the wax crystals and disperse the wax crystals by heterogeneous nucleation.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2024
·
IF 1.9
Xinyuan Li,Meifei Niu,Junjie Zhang,Zhuoping Yu,Jun Xu,Guangyu Sun
Wax precipitation and deposition are challenging hurdles in pipeline transportation of waxy crude oil. This study focuses on transforming SiO2, Laponite, and montmorillonite particles into hydrophobic particles through polymer grafting. Chemical structure analysis and grafting ratio calculation were performed. Through thermogravimetric analyzer (TGA) test, Laponite showed the highest grafting ratio. The effects of adding nanocomposites, TDA-2024-22, and commercial pour point depressants on the rheological behavior and wax crystallization behavior of African crude oil were compared. Addition of the nanocomposite PDA-22@SiO2 to crude oil, reduced the viscosity by 85.6% at 20 °C and the thixotropy by 60.2%. Wax crystal size decreased in the order of PDA-22@SiO2, PDA-22@Laponite, KS-10, TDA2024-22, and PDA-22@MMT. The pour point decreased by 6 °C with PDA-22@ SiO2 particles but only 3 °C with Laponite and montmorillonite composites. Spherical nanocomposites are promising flow improvers for waxy crude oil.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2024
·
IF 3.7
Limin Wang,Jinrong Duan,Bei Liu,Zhi Li,Guangjin Chen
Ethylene-vinyl acetate copolymer (EVA) as a kind of effective polymeric pour point depressant has been extensively used in the pipeline transportation of crude oil to inhibit wax deposition and improve the low temperature fluidity of crude oil. In this work, molecular dynamics simulations were performed to investigate the effect of EVA on wax-hydrate coexistence system to evaluate the application potentiality of EVA to the flow assurance of deep-sea oil–gas–water multiphase flow system. Our simulation results reveal that wax molecules gradually stretched and stacked from random coiling to a directional and ordered crystalline state during the process of wax solidification. The strong affinity of polar vinyl acetate side chains of EVA to neighboring water molecules made the EVA molecule prefer being in a curly state, which disrupted the ordered crystallization of surrounding wax molecules and delayed the solidification rate of wax cluster. In addition, it is found that EVA cocrystallized with wax molecules to form eutectic when the wax was fully solidified. The simulation results of hydrate nucleation and growth show that the EVA molecule displayed a two-sided effect on gas adsorption of wax crystals, which was the key factor that affected the nucleation and growth of hydrates in the methane-water system. The nonpolar hydrocarbon backbone of EVA increased the diffusion rate of methane and water, allowing more methane to diffuse to the surface of wax crystals, reducing the methane concentration in aqueous solutions and inhibiting the hydrate formation. On the other hand, the nonpolar vinyl acetate chains had a repulsive effect on methane, which reduced the adsorption area of methane on the eutectic surface and decreased the adsorption threshold value of the wax crystal. The excluded methane molecules would continue dissociating in the aqueous phase and participating in the nucleation and growth process of hydrates. Therefore, the probability of hydrate formation would be increased. It was worth noting that the inhibition performance of EVA on hydrate formation mainly played a significant role in the system with small wax crystal, while its hydrate promotion effect played a dominant role in the system with lager wax crystal. In summary, EVA could significantly inhibit both of the wax and hydrate deposition for the wax-gas-water multiphase system with low wax content. When the wax content in the system was high, the role of EVA was mainly played in the alleviation of wax crystallization rather than the gas hydrates. The results of the present work can contribute to a better understanding of EVA on wax deposition and hydrate formation, and provide theoretical support of the potential industrial applications of EVA.
研究领域:
石油工程
·
分子动力学模拟
·
材料科学
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2023
·
IF 7.4
Haopeng Zhang,Qingshan Xie,Haibo Ding,Yanjun Qiu
In cold region, crystalline wax can continuously precipitate from the asphalt binder distilled from the crude oil after cooling, which seriously damages cracking resistance of the asphalt pavement at the low-temperature. Few researchers have developed wax inhibitors (WIs) to inhibit wax crystallization in the asphalt field and existing WIs only focus on direct interaction with wax crystals. Herein, the ionic liquid (IL) modified with different commonly used concentrations of graphene oxide (GO) (0.3 %, 0.6 %, 0.9 %, 1.2 % IL) was synthesized as novel WI through in situ polymerization from the new perspective that the dispersed asphaltenes could inhibit wax crystal network. The successfully synthesized nanocomposites at the optimal content (900 ppm) and component (IL-0.6 %GO) reduced wax precipitation temperature (WPT) of asphalt binders by 14 °C, and the synergistic effect of IL and GO in the nanocomposite has most significant effect on wax inhibition than the existing WIs (IL and Poly(methyl methacrylate) (PMMA)). IL indirectly inhibits wax crystal network by dispersing asphaltenes through π - π interactions and charge transfers from IL to asphaltenes, which is superior to the direct reduction of wax crystals by PMMA. Therefore, it is very effective and promising to synthesize nanocomposites as wax inhibitors from the new perspective of dispersing asphaltenes compared with existing WIs to improve the low-temperature performance of asphalt.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2022
·
IF 4.132
Xuewen Ning,Xin Song,Sheng Zhang,Yong Wang,Yujun Feng
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.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENERGY & FUELS
·
2017
·
IF 3.091
Guolin Jing,Zhengnan Sun,Ziyi Tu,Xudong Bian,Yu Liang
Nanohybrid pour-point depressants (PPDs) were prepared by organically modified nano-SiO2 in copolymers of ethylene and vinyl acetate (EVA) with various vinyl acetate contents. The effects of nanohybrid PPDs on the cold-flow properties of 25 wt % wax model oil were evaluated. The crystallization behavior and crystal morphology of the model oil at low temperatures were also observed using polarized optical microscopy. The results indicated that the co-crystallization and dispersion effects of EVA on wax crystals are the key factors in determining the heterogeneous nucleation effect of the nanohybrid PPDs. The vinyl acetate content in EVA strongly affects the compatibility between the modified nanosilica and EVA. As a result, the selection of an appropriate EVA according to the oils used and the compatibility factor is important. In this work, EVA (VA = 32%)/modified nano-SiO2 composite PPD [N-SiPPD(32)] provided the best cold-flow improvement for the model oil when doped at 500 ppm. The pour point of the model oil was reduced from 34 to 5 °C, which resulted in a regular, diamond-shaped, and uniform arrangement of wax morphologies.
研究领域:
材料科学
·
石油工程
✓ 已验证
产品关联
DOI
高影响因子
Petroleum Science
·
2024
·
IF 6
Xin-Yuan Li,Xu-Biao Zhang,Si-Bei Li,Li-Wei Hui,Xin-Jie Sun,Jun Xu
The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobic-modified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly (octadecyl, docosyl acrylate) and poly (acrylate-α-olefin) onto the surface of nano-sized SiO 2 were synthesized by grafting polymerization method. The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO 2 nanoparticle (PDA@SiO 2 ) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20 °C, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules, thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO 2 hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.
研究领域:
材料科学
·
石油工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2018
·
IF 1.454
Ziyi Tu,Guolin Jing,Zhengnan Sun,Zhiwei Zhen,Wei Li
Nanocomposites 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).
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2024
·Vol. 141
·期 14
·e55198
·
IF 2.7
Junjie Zhang,Shuiliang Yan,Xinyuan Li,Peng Xiao,Meifei Niu,Yanfu Pi,Jun Xu
The precipitation and deposition of waxes in high waxy crude oil often result in the low throughput and clogging of pipeline. Adding polymers is a practical approach to solve these problems. In this study, poly(styrene-co-docosyl maleate)s (PSDMs) were synthesized by reversible addition-fragmentation chain transfer polymerization. The chemical structure and molecular weight of copolymers were characterized using Fourier infrared spectroscopy, 1 H nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The ratio of phenyl to aliphatic branches varies from 10:8 to 25:8. The crystallization and morphology of waxes in model oil were investigated by x-ray diffraction, differential scanning calorimetry, and polarized light microscopy. The cold flow behaviors of crude oil were evaluated by rheological methods. With the increase of the ratio of phenyl to aliphatic branches, the crystallinity, viscosity, and yield stress of crude oil first increase and then decrease. In the presence of PSDM-2, the crystallinity and enthalpy of phase transition (Δ H ) are reduced by 44.2% and 48.9%. Thus, the pour point, viscosity, and yield stress of crude oil are reduced by 6.0°C, 76.8% and 77.4%, respectively. Therefore, well-defined PSDMs are promising to be remarkable flow improvers for waxy crude oils.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）