Wax Inhibitors Research Articles

Molecular dynamics approach on intermolecular interaction between n-icosane and gemini surfactant assisted nanoparticles

Wax molecules tend to aggregate, and form wax solid at low temperature and result in a wax deposition. Chemical wax inhibitors are introduced to prevent wax deposition. However, the performance of chemical wax inhibitors is temperature dependent. Computational method using Molecular Dynamics (MD) simulation is used in this research to investigate how temperature affects wax inhibition using 2,5,8,11 Tetramethyl 6 dodecyn-5,8 Diol Ethoxylate Gemini surfactant (GS) and nanoparticles silicon dioxide (NP1), tin oxide (NP2), and nickel oxide (NP3). Wax-wax interaction of H58⋯H61of n-icosane and wax-solute interaction of hydrogen atom from n-icosane wax and carbonyl oxygen atoms from GS and NPs was investigated via radial distribution function analysis (rdf). The findings revealed that GS/NPs blends have a better chance of wax inhibition than corresponding individuals. Besides that, wax-wax interaction was strongest at 288K, indicating the higher chances of wax formation at low temperature. MD simulation is a promising tool for identifying atoms responsible for the wax formation and inhibition and can be used for chemical wax inhibitor screening for different temperature.

Paraffin wax deposition and its remediation methods on crude oil pipelines: A systematic review

Due to low-temperature circumstances, precipitation and paraffin wax deposition in manufacturing pipes and transportation tubes from offshore to onshore are significant challenges in the oil and gas sector. It may cause a reduction in output, a shutdown, pipeline blockage, and increased fluid viscosity. The most often used method for resolving this problem is to inject a wax inhibitor into the channel. Most current studies about paraffin wax are disseminated in literary works or exist as tacit knowledge in professional crania. This review research aims to exchange information and fulfil the deficits caused by providing a complete overview of the chemistry of paraffin wax precipitation and accumulation and causes, processes, and detection. It also discusses the overall impacts of paraffin wax deposition, how to deal with it, and several cleaning options. It also includes a conclusion and beneficial tips.

The influence of palm oil additives on the pour point and wax deposition tendencies of Chenor crude oil

One of the major concerns during the production of crude oil especially in tropical waters is the deposition of wax on to the walls of the pipeline. This is due to the low seabed temperatures which can be below the wax appearance temperature (WAT) which leads to wax depositing out through molecular diffusion. Currently, there are many methods to prevent and remedy wax deposition but most of these solutions pose a serious environmental threat and are expensive to produce. Hence, this research investigated the use of an organic and cheaper alternative by utilizing synthetic fatty acid esters such as oleic acid which has shown promising results in reducing the pour point of waxy crude oils. The solution that was used was of palm oil origin, crude palm oil (CPO) and crude palm kernel oil (CPKO) and was subsequently compared with the pour point depressant and wax inhibition efficiency of the current industry used inhibitors utilizing the SETA Pour Point and Cloud Point as well as the cold finger apparatus. It was observed that the palm oil inhibitors were highly effective at 1 wt.% due to the high composition of oleic acid present portraying a similar result to Triethanolamine (TEA) while Ethylene Vinyl Acetate (EVA) performed best at low concentration of 0.1 wt.% but deteriorates significantly as the concentration increases due to the polar end agglomerating among itself.

Inhibiting wax deposition using palm oil additives

Among the flow assurance problems that the petroleum industry faces, the deposition of paraffin waxes on to the wall of the pipeline is the most challenging. The challenge arises when the crude oil temperature decreases below the wax appearance temperature which prompts wax crystallization in the crude oil. An efficient method in remedying paraffin wax deposition is the utilization of chemical inhibitors. However, currently used chemical inhibitors are costly and environmentally harmful if a spillage occurs. Therefore, the use of biodegradable or environmentally friendly inhibitors as potential chemical inhibitors is being studied by various researchers. This study investigated oleic acid, poly (ethylene-co-vinyl acetate) (EVA) and triethanolamine (TEA) as inhibitors that perform based on the van der Waals intermolecular interaction between the main wax component molecule eicosane C20H42 using molecular dynamics simulations Material Studio 8.0 software package. In order to analyse the desired structural property which is the radial distribution function (RDF), COMPASS force field was used. The RDF and g(r) function portrayed the functional atoms which aid in inhibiting the agglomeration and crystallization of the wax crystal formation. The presence of a carbonyl oxygen in oleic acid plays a vital role to inhibit the wax formation through the van der Waals interaction between active hydrogen atoms in eicosane molecule. Therefore, the chances of wax inhibition in eicosane are higher by introducing oleic acid as an inhibitor as compared to EVA and TEA. The results were then validated experimentally utilizing a cold finger technique under static condition.

A critical review on the development of wax inhibiting agent in facilitating remediation process of contaminated groundwater.

Transportation of crude oil and refined petroleum is the main function of pipeline system in petroleum industry. Unfortunately, wax precipitation has become a serious problem for the petroleum industry where it causes pipeline blockage and eventually results in operational catastrophe. Up-to-date, the technique used to mitigate wax deposition by injecting chemical wax inhibiting agent remains a debate amongst researchers. This review addresses the evolution of chemical wax inhibitor generations started from polymer-based in the early 1980s, followed by biosurfactant-based in the late 1990s and finally plant-based or agricultural-based in recent years. Pivoting to environmental impact, petroleum industry is amidst finding a green wax inhibiting agent to solve wax deposition problem that occurs during the transportation of crude oil whilst facilitating the remediation process of contaminated groundwater.

Effect of wax inhibitor and sodium cloisite, Na+ nanoparticle on wax deposition of Malaysian crude oil through cold finger analysis

Wax deposits are undesirable as they affect crude oil production. Wax inhibitor which changes crude oil properties like pour point, viscosity and wax appearance temperature (WAT) are used by oil industries. The efficiency of wax inhibitor poly (ethylene-co-vinyl acetate) (EVA), poly (maleic anhydride-alt-1-octadecene) (MA) and sodium cloisite Na + nanoparticle (NP) is assessed in this research to determine their effects on the wax deposition of Malaysian crude oil. Cold finger analysis was used to identify the best inhibitor to prevent the wax formation. The highest paraffin inhibition efficiency (PIE) obtained was at 80.91% when the crude oil was treated with EVA/NP blend of 1000 ppm EVA and NP of 600 ppm. The minimum amount of wax formed was at 25 °C proving that cold finger temperature plays a crucial role in altering the wax deposition. The van der Waals (vdW) molecular interaction between wax molecules and wax inhibitor was studied with molecular dynamics simulation (MD). The radial distribution function (rdf) value shifted from 2.75 Å to 3.25 Å when EVA/NP blend was used as the inhibitor, supporting the experimental data. The EVA/NP blend offers significant effect in reduction of wax deposit amount.

Molecular interaction study on Gemini surfactant and nanoparticles in wax inhibition of Malaysian crude oil

AbstractWax deposition can cause a slowdown in operation by restricting crude oil flow in the pipeline. Chemical inhibitors interact with the wax molecule in crude oil and prevent wax aggregation. The molecular dynamics (MD) simulation was used to analyze the intermolecular interaction between a wax molecule of n‐icosane and a Gemini surfactant 2,5,8,11 tetramethyl 6 dodecyn‐5,8 diol ethoxylate (GS) with three distinct nanoparticles: silicon dioxide (SiO2)(NP1), tin oxide (SnO)(NP2), and nickel oxide (Ni2O3)(NP3). The desired structural feature of the radial distribution function (rdf) was analyzed using the COMPASS force field. Weakest intermolecular interaction between n‐icosane (highest rdf value of 5.25 Å), indicating high wax solubility, was achieved in the presence of GS/NP3 blend. In addition, GS/NP3 blend gave the strongest van der Waals (vdW) interaction with a hydrogen atom in n‐icosane. The presence of the O carbonyl group in both GS and NP3 establishes a higher number of hydrogen bonds. Thus, the GS/NP3 blend acts as the best inhibitor compared to the individual GS and NP3. The simulation analysis on the degree of wax formation reduction using GS/NP3 blend correlated well with cold finger experiment that showed a wax formation reduction of 61.6%.

Evaluation of the effect of nanoparticle addition into Gemini surfactant on rheology and wax deposition of Malaysian crude oil

Crude oil is fossil fuel formed from the decomposition of decaying plants and animals in the ground. In crude oil, there is a high percentage of asphaltene that leads to wax deposition along the transport pipeline. The objective of this research is to study the effect of temperature, shear rate and nanoparticle loadings towards viscosity, interfacial tension, surface tension as well as the weight of wax deposit form. Two types of nanoparticles were used in this study, which were GOHSENX Anionic PVOH L-3266 and NICHIGO G-polymer AZF8035W. Whereas, Gemini YND1233 was used as a surfactant. Nanoparticle with different amount of loading (2 mg, 3 mg, 4 mg and 5 mg) was prepared using cyclohexane as the solvent. The nanofluid was prepared according to the load ratio of Gemini surfactant to nanoparticles of 3:1. With 5 mg of nanoparticle, L-3266 loading in Gemini surfactant showed the best performance where it resulted in the lowest viscosity, interfacial tension, surface tension and wax deposition as compared to the 2 mg of nanoparticle AZF8035W loading in Gemini surfactant. This is due to the carboxylic acid group present in AZF8035W. The optimum temperature and shear rate in reducing the crude oil viscosity was obtained at 35 °C and 80 rpm. In order to investigate the effect of nanoparticle loading and the stirring rate of impeller on the formation of wax deposit, the cold finger test had been conducted. From the cold finger analysis, the lowest weight of wax deposit was obtained at the cold finger temperature of 20 °C and the stirring rate of 500 rpm by adding 5 mg of nanoparticles L-3266 in Gemini surfactant. In conclusion, the best performance of wax inhibitor from this research was obtained by adding 5 mg of nanoparticles GOHSENX Anionic PVOH L-3266 in Gemini surfactant in order to improve the rheology of the crude oil and decrease the formation of wax deposition.

Bioinspired Hybrid Nanostructures for Wax Inhibition Coatings with Superhydrophilicity

Bioinspired Hybrid Nanostructures for Wax Inhibition Coatings with Superhydrophilicity

The rheological behavior of crude oil in the presence of palm oil additives

Wax precipitation has become a serious problem for the petroleum industry. The problem occurs when there is equilibrium disturbance on the pressure and temperature as well as crude oil composition. Wax deposits will eventually result in restriction of the fluid flow inside the pipeline, and severe deposition will cause blockage. The chemical additives currently being implemented in the industry have various limitations including the high cost and the irreversible impact it has on the environment. Therefore, the use of cheaper organic wax inhibitor obtained from crude palm oil (CPO) and crude palm kernel oil (CPKO) on the rheology and deposition of wax was investigated by using Chenor waxy crude oil from the Penyu basin, Pahang, Malaysia. To compare the efficiency of palm oil additives in inhibiting wax deposition, currently utilized chemical additives such as triethanolamine (TEA) and ethylene vinyl acetate (EVA) were also examined. The pour point of the crude oil was determined using SETA cloud & cryostat, while the rheological behavior of the crude was determined using a rotational Fann viscometer. The results obtained from this study reveal that CPO and CPKO could be used to improve the flow of crude oil, especially when 1 wt.% CPO or when 0.5 wt. % CPKO is used. It was also noted that the palm-based additives were much more effective at reducing the viscosity of the Chenor crude oil than the commercial wax inhibitor tested (TEA and EVA).

Influence of Wax Inhibitor Molecular Weight on Solution Crystallization and Rheology of Monodisperse Waxes

Molecular weight fractionation via stepwise precipitation or chain scission is performed on four pour point depressant polymers to study the pour point reduction mechanism. An homologous series of model oils is prepared by dissolving 5 wt % of a single-component paraffin wax (n-C24, n-C28, n-C32, or n-C36) in n-C12. The polymers are dosed at 500 ppm in the model oils and moderately reduce crystallization temperatures by elevating the nucleation barrier. Polymers containing carboxylate or acrylate moieties also modestly enhance equilibrium wax solubility. Reduction in crystallization temperature is largely independent of polymer molecular weight, except for carboxylate polymers where low molecular weight fractions are largely ineffective. In general, model fluids containing shorter wax chains show a larger reduction in crystallization temperature than model fluids containing longer wax chains. However, yield stress reduction often shows a distinct dependence on polymer molar mass. Low molecular weight fractions of carboxylate and acrylate polymers provide smaller reductions in yield stress than the overall parent fraction. Cross-polarized microscopy reveals that polymers reduce the crystal size, alter the crystal morphology from platelet to needle-like, and induce branching. Crystal branching and formation of dendrite-like structures result from strong polymer binding at the wax crystal interfaces. Hence, single-component wax crystal branching occurs phenomenologically along with yield stress reduction.

Study on waxy crudes characterisation and chemical inhibitor assessment

Wax deposition brings severe challenges to the production, transportation, and storage of crude oils. Accumulation of wax can block the pipeline, lead to equipment failure, and lose production. The use of chemical inhibitors has been reported as one of the most effective measures to mitigate wax deposition in the pipeline. The inhibition efficiency depends on the effects of the inhibitor molecules on the formation, growth, agglomeration and morphology of wax crystals. The chemicals and their compositions in the inhibitor together with the crude composition determine wax inhibition performance. Many different types of chemical inhibitors have been developed. Oil industry benefits significantly from high-efficiency inhibitors. This paper reported a simple method to optimise the inhibition performance by blending different inhibitors. Firstly, a comprehensive characterisation of two naturally waxy crude oils (KSG#49 and Ex Mwambe) and a synthetic crude oil was presented. The synthetic crude oil was prepared by mixing a dead oil of 3% wt wax content with a solid wax sample obtained from the North Sea field. The variation in properties of the three oils was evaluated through cloud point measurements, pour point, wax content, SARA fractions, colloidal instability index, American Petroleum Institute gravity (APIg), and the n-Paraffin distribution. Then, the influence of four Polymer-based pour point depressants (PPDs) on wax crystallization were critically assessed. The PPDs induced morphological changes to wax crystals transformed the needle-shaped crystals into an agglomerate. The small particles dispersed in the oil matrix reduced the apparent viscosity and wax gelling properties, and the efficiency of PPDs could be affected by the SARA fraction. A higher fraction of flocculated asphaltenes provides active sites for wax crystallization. Hence it increases cloud point and interferes with the crystal inhibition mechanism. Finally, a blended PPD produces a synergistic effect on inhibition performance that effectively reduces apparent viscosity, wax appearance temperature (WAT) and pour point (PP). The improvement can be attributed to the interactions between the molecules of wax inhibitors with wax crystals. This works sheds light on new inhibitor development by blending different inhibitors to promote performance synergies. • The properties of three waxy crude oil were thoroughly characterised by defined methods. • The effectiveness of polymer based chemical inhibitors on wax crystallization was investigated through viscometric analysis and morphological characterisation. • The synergistic effect as a result of blending different inhibitors leads to the improved efficiency of a new inhibitor.

Investigation on the mechanism of wax deposition inhibition induced by asphaltenes and wax inhibitors

This study is specifically concerned with the effect and mechanism of asphaltenes and wax inhibitors on the wax deposition characteristics of model waxy oil. According to the rheological and wax deposition test, the pure model waxy oil has a pour point higher than the pipe wall temperature, and the formed wax deposit exhibits the slowest aging rate and homogeneous wax deposit structure. Based on the DSC and rheological experiments, the solubility of wax crystals is hardly influenced by asphaltenes or wax inhibitors, but the decrease of oil viscosity and the weakened low-temperature gel structure induced by asphaltenes and wax inhibitors would increase the wax molecular diffusion coefficient and wax content in the wax deposit, which ultimately leads to a thinner and harder wax deposit. Moreover, based on the molecular dynamic simulation, the EVA molecules can be adsorbed on the asphaltene surface thus forming EVA-asphaltene composite particles, which can change the crystallization habit of wax molecules and the wax crystal micromorphology, thereby dramatically improving the crude oil rheology at low temperatures and inhibiting wax deposition. This work provides a comprehensive understanding of the wax deposition mechanism induced by asphaltenes and wax inhibitors, which helps to the well or pipeline operation safety and efficiency. • The solubility of wax crystals is hardly influenced by the asphaltenes. • Asphaltenes decrease the oil apparent viscosity thus increasing the molecular diffusion coefficient of wax molecules. • Asphaltenes decrease the gel structure strength thus increasing the wax content of the formed wax deposit. • EVA molecules can adsorb on the asphaltene surface to form EVA-asphaltene composite particles.

Influence of pour point depressants (PPDs) on wax deposition: A study on wax deposit characteristics and pipeline pigging

Pour point depressant (PPD) is widely used for wax prevention in crude oil production and transportation. This paper aims to investigate the compositional and rheological properties of wax deposits formed from crude oils with and without PPDs. To this end, an in-house cylindrical Taylor-Couette cold finger device was constructed to conduct wax deposition experiments. Tests on wax deposits show that wax deposit properties are dramatically changed by addition of PPDs. It was observed that PPDs lower wax deposition rate and increase wax appearance temperature (WAT) and wax content of the deposits. Moreover, the enriched heavy components of n-alkanes and the diluted light ones indicate an accelerated aging process caused by PPDs, and the critical carbon number (CCN) and average carbon number of the deposits accordingly increase. The contents of asphaltenes and resins entrained in wax deposits get lowered when PPD was added into the crude oil. In addition, PPDs would weaken the mechanical strength of wax deposits, thus the wax resistive force decreases and therefore the risk of pig stalling accordingly gets lowered. Above all, among the evaluated PPDs, NPPD (which contains nanocomposites) presents the best wax inhibition performance.

Wax inhibitor performance comparison for waxy crude oil from Fang oilfield

In petroleum chemistry, waxy oil from paraffins can cause operating problems for oil production. The chemical method is used to remove by using chemicals or additives to prevent the wax problem. In this study, the performance of wax inhibitor are evaluated by the measurement of pour-point reduction and wax deposition of crude oil from Mae Soon area, Fang oilfield. Wax deposition is determined by cold finger technique. Wax inhibitors, hexane, Poly(maleic anhydride-alt-1-octadecene) (PMAO) and monoethanolamine (MEA) are mixed in oil sample at various concentrations. From the experiment, it is presented that hexane is used to reduce pour-point temperature up to 19.55 % and to reduce wax deposit up to 92.56 %. Moreover, MEA and PMAO have less effect on pour-point reduction. However, they have high efficiency to prevent wax deposition. PMAO provide the better wax deposition performance than MEA. The amount of wax deposit is lower at the same conditions. The percentage of wax deposit is from 39.19 % to 83.02 % for MEA and from 58.54 % to 88.51 % for PMAO. Furthermore, from the results, the preferred concentration of hexane can be at 10 % and PMAO can be 7500 ppm at low temperature or 5000 ppm for higher temperature. The results of this research can be applied to the practical way for wax deposition prevention operation in Mae Soon area in Fang oilfield to reduce the wax problem in the future.

New apparatus for evaluating the performance of wax inhibitors under flowing conditions

New apparatus for evaluating the performance of wax inhibitors under flowing conditions

Investigation on Hydrate Growth at the Oil-Water Interface: In the Presence of Wax and Kinetic Hydrate Inhibitor.

In oil industry, the coexistence of hydrate and wax can result in a severe challenge to subsea flow assurance. In order to study the effects of wax on hydrate growth at the oil-water interface, a series of microexperiments were conducted in a self-made reactor, where hydrates gradually nucleated and grew on the surface of a water droplet immersed in wax-containing oil. According to the micro-observations, hydrate shells formed at the oil-water interface in the absence of kinetic hydrate inhibitor (KHI). The roughness and growth rate of hydrate shells were analyzed, and the effects of wax were investigated. In addition, vertical growth of the hydrate shell was observed in the presence of wax, and a mechanism was proposed for illustration. In the presence of KHI, small hydrate crystals formed separately at the oil-water interface instead of hydrate shells. The presence of KHI reduced the growth rate of hydrates and changed the wettability of hydrates. Moreover, the presence of wax showed no obvious effect on the effectiveness of KHI under experimental conditions.

Modeling apparent viscosity of waxy crude oils doped with polymeric wax inhibitors

Wax precipitation which frequently occurs throughout transportation and production of waxy crude oils results in various pitfalls including wax deposition, gel formation, and flow reduction, thus exacerbating pipeline performance. To mitigate such issues, polymeric flow improvers are mainly utilized in petroleum industry to improve the rheological behavior, and thus mobility and flowability of waxy crude oil. In the current paper, least squares support vector machine optimized with three algorithms including coupled simulated annealing, particle swarm optimization, and genetic algorithm is employed to develop intelligent models for the prediction of apparent viscosity of waxy crude oils doped with polymeric additives based on experimental data from previously published literature. A dataset with 526 datapoints is implemented to train and test the intelligent models. The forecasted values are compared against the laboratory data with the aid of graphical and statistical approaches. The findings illustrate that an acceptable correlation exists between the experimental and predicted values with coefficients of determination equal to 0.999136, 0.998848, and 0.998827 for the developed models optimized with particle swarm optimization, genetic algorithm, and coupled simulated annealing, respectively, based on total datapoints. The constructed models could be made use of to predict the apparent viscosity of waxy crude oils doped with polymeric additives without requiring experimental methods which are inherently expensive, tedious and time-consuming.

Application of Pineapple Skin Waste as a Source of Biosolvent for Use as Wax Inhibitor

Wax paraffin deposition is a problem faced in the pipeline for petroleum industries that they blockage the partial or full inside the pipe, which will decrease the production rate. One of the treatments is to use the preventive methods called wax inhibitors which are expected to inhibit the crystallization of paraffin wax, and bio-solvent is included. Hydrolysis and fermentation technique are used to produced bio-solvent. Hydrolysis aims to break lignin and hemicellulose, damage the crystal structure, and increase the porosity of the material. At the same time, the occurrence of pentose changes and some glucose into ethanol is present in the fermentation process. Then, purified by the distillation process to obtain bio solvent products that are applied with waxy crude oil can reduce the pour point value of crude oil. From the hydrolysis process with five variations of acid percentage, the amount of reducing sugars increase. By increasing temperature from 50 ° C to 100 ° C, the reducing sugars continues to increase until it reaches the optimal point of 18.2 ° Brix. The amount of inoculant also affects the level of bio-solvent where the optimum results using inoculants are 0.015 g/mL, which produces 6% levels of bioethanol. The high ethanol content of 2% had a density value of 0.979 g/mL. The best °API at 5% is 13.901, and the average value is about 13.0945, where the best viscosity values for ethanol content of 6% are 0.814. Bioethanol testing using waxy crude oil is carried out with the bioethanol content of 6%. The addition of the ethanol contents only decreased the pour point 2-3℃. At sample, #LGK19 experienced a 3°C drop in pour point from 45°C to 42°C. Therefore, it can be concluded that bioethanol used as a solvent can potentially inhibit paraffin deposition.

Effects of Crude Palm Oil and Crude Palm Kernel Oil Upon Wax Inhibition.

The ever-increasing demand for the finite source of oil has led oil production companies to produce and transport the produced crude oil as efficiently and economically as possible. One of the major concerns especially in waters like the South China Sea is the deposition of wax on the walls of the pipeline or wellbore, constricting and hindering the hydrocarbon flow. This is due to the low seabed temperatures, which can be below the wax appearance temperature (WAT), leading to the deposition of wax out of waxy crude oil through the molecular dispersion mechanism. Currently, many prevention and remedy methods are in place to overcome the problem, but most of the additives possess environmental threat, as most of the chemical solutions used are toxic, nonorganic, and costly. Hence, this paper aims to provide some insights into the effect of palm oil derivatives such as crude palm oil (CPO) and crude palm kernel oil (CPKO) on wax inhibition. The effect of aging time (i.e., immersion time) was also evaluated. A comparison was made between paraffin inhibition efficiency results (PIE %) obtained by CPO, CPKO, poly(ethylene-co-vinyl acetate) (EVA), and triethanolamine (TEA). It was observed that the average efficiency of 81.67% was obtained when 1% CPO was added to heavy crude oil. The wax inhibition performance reached a plateau after 1.5 h of aging time for all of the investigated samples.