A comparative study of density estimation of asphaltene structures using group contribution methods and molecular dynamic simulations for an Australian oil field

Elkahky, Sherif; Lagat, Christopher; Sarmadivaleh, Mohammad; Barifcani, Ahmed

doi:10.1007/s13202-019-0641-x

Cited by 19 publications

(11 citation statements)

References 7 publications

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“…We used well-defined classical intra- and intermolecular potentials of the calculations that incorporated the consistent valence force field (CVFF) to calculate the interatomic force. The force field has been used to demonstrate the resin and asphaltene density and behavior of aggregation. , The non-bonded interactions between the atoms were described by the Lennard-Jones potential, and the interaction parameters are presented in Table . The cross-potential parameters were obtained using the Lorentz–Berthelot mixing rules .…”

Section: Methodsmentioning

confidence: 99%

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Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Zhu

Zhang

et al. 2021

Energy Fuels

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Heavy oil, with high viscosity and complex compositions, often faces a series of challenges in the process of its exploitation and utilization. There are huge amounts of compositions with different molecular structures in heavy oil, and it is a great challenge to clarify the influence of the microstructure of heavy oil on the rheological and viscosity–temperature properties. Based on the experimental data, such as acid value, element content, functional group type of the heavy oil, and so on, we constructed six types of heavy oils from three regions to reveal the unique properties of Karamay heavy oil. Molecular dynamics simulation was used to study the effects of the compositions and the aggregation structure on the rheological and viscosity–temperature properties of heavy oil. The results show that the rheological properties of Karamay heavy oil with low asphaltene concentration are dominated by molecular conformation, and heavy oil with molecules that are not easily stretched has a higher viscosity. When the concentration of asphaltene is high, the nanoaggregates formed by asphaltene molecules and their variation with shear rate affect the viscosity. Compared with the aggregates by the island structure asphaltene molecules, the larger nanoaggregate size of continental structure due to stronger π–π interaction leads to the increase in viscosity. However, the viscosity decreases faster with the increase in shear rate, which is attributed to the more orderly aggregate structure of polycondensed aromatic rings that can be easily pulled along the velocity plane. In addition, we found that metal ions, as a bridge, can interact with molecules containing different heteroatoms, forming larger clusters and increasing the viscosity of Karamay heavy oil. For the viscosity–temperature properties, the more intense thermal movement of molecules with the increased temperature weakens the interaction between the aromatic rings and decreases the viscosity of heavy oils.

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Section: Methodsmentioning

confidence: 99%

“…The force field has been used to demonstrate the resin and asphaltene density and behavior of aggregation. 36,41 The non-bonded interactions between the atoms were described by the Lennard-Jones potential, and the interaction parameters are presented in Table 3.…”

Section: ■ Methodsmentioning

confidence: 99%

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Zhu

Zhang

et al. 2021

Energy Fuels

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“…The increase in the density of asphaltenes due to the inclusion of heteroatoms according to previous studies should be between 4 and 10%. 64 In this case, the density difference between CCC molecules and molecules with heteroatoms is ∼30%.…”

Section: Resultsmentioning

confidence: 93%

Molecular Dynamics Study of the Aggregation Behavior of Polycyclic Aromatic Hydrocarbon Molecules in n-Heptane–Toluene Mixtures: Assessing the Heteroatom Content Effect

et al. 2021

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This study is focused on evaluating the aggregation behavior of four asphaltene molecules (PA3-type) dissolved in three different solvents. Hence, solution models composed of asphaltenes dissolved in toluene, n-heptane, and mixtures of n-heptane and toluene (known as heptol), were evaluated with molecular dynamics (MD) simulations. For MD calculations, four PA3-type structures were chosen to evaluate the effect of the location of one heteroatom in the polyaromatic core on the aggregation behavior. The first structure consists of only a CH structure, the second has sulfur, the third has nitrogen, and the last one contains oxygen. The heteroatom was replaced in the same location in one of the five-membered rings in the center of the molecule to test the different chemical effects induced by these heteroatoms. Molecules with the heteroatoms showed a higher aggregation tendency in n-heptane than in heptol-50 and toluene, with an average size of 12.8, 6.2, and 2.4 molecules per aggregate, respectively, whereas the PA3 molecule with no heteroatom forms less and smaller aggregates. The inclusion of only one heteroatom increases the polarity and the planarity of the molecule, increasing the attractive interaction energies (140−160% in n-heptane) and the overall aggregation tendency. The molecule with the sulfur heteroatom forms bigger and more stable aggregates than molecules with oxygen and nitrogen. In conclusion, the inclusion of heteroatoms in the PA3 structure increases the polarity and planarity of the molecule, improving the aggregation tendency in all solvents, notoriously in n-heptane.

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“…The recent increase in the number of scientific publications [61][62][63][64][65][66][67][68][69] devoted to a detailed analysis of various approaches to modeling RAC by world scientists proves the importance and prospects of developing improved mathematical models for predicting RAC.…”

Section: Association Modelmentioning

confidence: 99%

Analysis of the Modern State of Researches on Deposition of Asphalt-Resin Substances, Paraffin and Modeling Methods Review Part I: Precipitation of Asphaltenes

Manafov¹,

Келбалиев²

2020

AChJ

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Asphaltenes are the heaviest crude oil fraction and tend to self-associate and precipitate. The precipitation and deposition of asphaltenes during the production, refining, transportation of oil is the main for the oil industry, the precipitation of asphaltenes and their subsequent deposition can cause problems at all stages of production. Asphaltenes have different structures and molecular composition, they are a mixture of poorly defined components, they are self-associated even at very low concentrations, what makes them one of the most difficult components of crude oil. Since the deposition mechanism of paraffin wax differs from the deposition mechanism of asphaltenes, mathematical modeling of crystallization of paraffin will be considered separately in another work. Creating accurate asphaltene models that can predict the behavior of asphaltenes in various scenarios should help reduce asphaltene problems. This review is specifically devoted to advances in mathematical modeling of asphaltenes. Several different models have been proposed in the literature for predicting the initial conditions and precipitation of asphaltenes. Existing modeling approaches can be broadly classified into colloidal and thermodynamic models. It should be noted intelligent models, such as a vector machine, an artificial neural network, in recent years are increasingly used for modeling various parameters and properties in the oil and chemical industries. However, these models are a black box and cannot provide a clear link between the output and input parameters of the model. In the past few years, models based on the Cubic Plus EoS Association (CPA EoS) and Statistical associating fluid theory (SAFT) have been recognized as promising one for studying asphaltene sediments. However, in the literature, there exist different opinions. Therefore, a systematic study is important for modeling the deposition of asphaltenes. Over the past decades, several different models have been proposed to predict the onset of asphaltenes and the amount of asphaltenes deposited. This paper examines various models that have been proposed to predict asphaltenes deposition under changing thermobaric conditions. A brief summary of various research approaches is presented.The main focus is on the description of the basic assumptions underlying various models, as well as on the ability of the model to correspond to experimental data. The presented models are compared and current modeling trends for forecasting precipitation are shown. This work will help improve understanding of asphaltenes and provide recommendations for the proper study and modeling of asphaltenes in future research.

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A comparative study of density estimation of asphaltene structures using group contribution methods and molecular dynamic simulations for an Australian oil field

Cited by 19 publications

References 7 publications

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Molecular Dynamics Study of the Aggregation Behavior of Polycyclic Aromatic Hydrocarbon Molecules in n-Heptane–Toluene Mixtures: Assessing the Heteroatom Content Effect

Analysis of the Modern State of Researches on Deposition of Asphalt-Resin Substances, Paraffin and Modeling Methods Review Part I: Precipitation of Asphaltenes

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