Molecular dynamics simulation of CO2 dissolution in heavy oil resin-asphaltene

Li, Bingfan; Liu, Gang; Xing, Xiao; Chen, Lei; Lu, Xin; Teng, Honghui; Wang, Jian

doi:10.1016/j.jcou.2019.06.011

Cited by 29 publications

(16 citation statements)

References 43 publications

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“…It has been reported that carbon dioxide is absorbed by the asphaltene aggregates due to the large free volume fraction and surface area of the aggregate structures. 61,62 The gas concentration near the water droplet surface decreased due to the decreased gas supply when carbon dioxides were trapped into the asphaltene aggregates in the bulk phase. A similar behavior was found in the simulation work of Zi et al, 63 that is, the methane hydrate growth was hindered due to the adsorption of gas molecules on the asphaltene aggregates in bulk.…”

Section: Resultssupporting

confidence: 84%

Nucleation and Growth of Gas Hydrates in Emulsions of Water in Asphaltene-Containing Oils

Zhang

Huang

et al. 2021

Energy Fuels

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Asphaltenes in crude oils may affect hydrate formation in water–oil emulsions, complicating flow assurance and hydrate management in subsea oil–gas multiphase pipelines. In this study, the effects of asphaltenes on hydrate nucleation and growth in water-in-oil emulsions were investigated. It was found that the presence of asphaltenes inhibited hydrate nucleation. The inhibiting effect was enhanced with the increase in asphaltene content from 0 to 0.15 wt % and then was lowered with further increase in asphaltene content from 0.15 to 0.30 wt %. The asphaltenes were found to decrease the formed amount of hydrates. In addition, the effects of water cut, stirring rate, and reformation process on hydrate formation in asphaltene-containing emulsions were studied. The results showed that the nucleation rate of hydrates decreased with a reduction in water cut. The hydrate growth rate first increased and then decreased with decrease in the water cut, which could be attributed to the combined effects of gas concentration and water amount. Furthermore, both the nucleation rate and the growth rate of hydrates were observed to increase with an increase in the stirring rate, indicating the promoting effect of a high stirring rate on hydrate formation in asphaltene-containing emulsions. Finally, it was demonstrated that hydrates nucleated more easily during the reformation process. However, the growth rate during the reformation process was lower than that in the first formation. The results from this study have potential flow assurance applications when asphaltenes and hydrates coexist in the subsea pipelines.

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Section: Resultssupporting

confidence: 84%

Nucleation and Growth of Gas Hydrates in Emulsions of Water in Asphaltene-Containing Oils

Zhang

Huang

et al. 2021

Energy Fuels

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“…Interaction energy helps us examine the interaction between surfactant and heavy oi/bitumen fractions, and clarifies the strength of binding between the surfactant and different oil cuts, e.g., resin–asphaltene, resin, and asphaltene. As expressed in the equation below, the higher the absolute value, the stronger the intermolecular interaction 119 . where E Inter stands for the interaction energy between bitumen molecules and the surfactant, kcal/mol; E Total represents the total energy of the surfactant molecules and the bitumen system, kcal/mol; E Bitumen denotes the energy of the bitumen system, kcal/mol; and E Surfactant assembles the energy of the non-anionic surfactant, kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“… where E Inter stands for the interaction energy between bitumen molecules and the surfactant, kcal/mol; E Total represents the total energy of the surfactant molecules and the bitumen system, kcal/mol; E Bitumen denotes the energy of the bitumen system, kcal/mol; and E Surfactant assembles the energy of the non-anionic surfactant, kcal/mol. The workflow for calculating the interaction energy is as follows 119 : (A) first, the total energy of the system, bitumen sample, and surfactant at the given temperature and pressure is calculated; (B) second, the total energy of pure substances is determined, for bitumen molecules, we must remove the surfactant molecules and then calculate the total energy, and the same is true for the surfactant molecules; (C) finally, the total energy of the entire system is deducted by the total energy of the surfactant and the total energy of bitumen molecules. The final value represents the interaction energy between a surfactant solution and oil sands/bitumen droplets.…”

Section: Resultsmentioning

confidence: 99%

Spotlight onto surfactant–steam–bitumen interfacial behavior via molecular dynamics simulation

Ahmadi

Chen

2021

Sci Rep

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Heavy oil and bitumen play a vital role in the global energy supply, and to unlock such resources, thermal methods, e.g., steam injection, are applied. To improve the performance of these methods, different additives, such as air, solvents, and chemicals, can be used. As a subset of chemicals, surfactants are one of the potential additives for steam-based bitumen recovery methods. Molecular interactions between surfactant/steam/bitumen have not been addressed in the literature. This paper investigates molecular interactions between anionic surfactants, steam, and bitumen in high-temperature and high-pressure conditions. For this purpose, a real Athabasca oil sand composition is employed to assess the phase behavior of surfactant/steam/bitumen under in-situ steam-based bitumen recovery. Two different asphaltene architectures, archipelago and Island, are used to examine the effect of asphaltene type on bitumen's interfacial behavior. The influence of having sulfur heteroatoms in a resin structure and a benzene ring's effect in an anionic surfactant structure on surfactant–steam–bitumen interactions are investigated systematically. The outputs are supported by different analyses, including radial distribution functions (RDFs), mean squared displacement (MSD), radius of gyration, self-diffusion coefficient, solvent accessible surface area (SASA), interfacial thickness, and interaction energies. According to MD outputs, adding surfactant molecules to the steam phase improved the interaction energy between steam and bitumen. Moreover, surfactants can significantly improve steam emulsification capability by decreasing the interfacial tension (IFT) between bitumen and the steam phase. Asphaltene architecture has a considerable effect on the interfacial behavior in such systems. This study provides a better and more in-depth understanding of surfactant–steam–bitumen systems and spotlights the interactions between bitumen fractions and surfactant molecules under thermal recovery conditions.

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“…The solubility of a specific molecule into another molecule is defined as the square root of the cohesive energy density (CED) between these two molecules. Based on Hildebrand’s definition, The solubility parameter (δ) of the surfactant molecules into the system can be calculated using eq . − where Δ E v stands for the change of energy of vaporization, Δ H v represents a change in vaporization enthalpy, V m denotes the molar volume of the liquid at the given temperature, R is the gas constant, and T stands for the temperature of the system. − The above-mentioned definition of the Hildebrand solubility parameter was initially developed for pure nonpolar substances. To defeat this constraint, Crowley et al .…”

Section: Methodsmentioning

confidence: 99%

Insight into the Interfacial Behavior of Surfactants and Asphaltenes: Molecular Dynamics Simulation Study

Ahmadi

Chen

2020

Energy Fuels

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Heavy oil and bitumen drive the leading energy supply in Canada. Several techniques, including in situ thermal methods and mining, have been applied to the recovery of these unconventional resources. Nowadays, to improve the efficiency of in situ thermal methods, coinjection of steam and different types of additives, including chemicals, solvents, and noncondensable gases, is being investigated. Adding these additives to steam can reduce the required amount of steam and, as a result, lowers carbon dioxide emissions; meanwhile, the oil production can be improved. Different interaction mechanisms contribute to oil recovery in each type of additives. In this paper, we focused on the investigation of mechanisms using surfactant additives. One of the primary behaviors that needs to be fully understood is the interfacial behavior of surfactant molecules and asphaltene molecules, the key component of heavy oil and bitumen. Four different types of surfactants, including anionic, cationic, nonanionic, and amphoteric, were employed to study the interaction parameters between asphaltene and surfactant molecules. Two different asphaltene molecules with the archipelago and island architectures were extracted from oil sands from the Athabasca oil field in Alberta, Canada. All thermodynamic conditions were chosen based on the operational steam-assisted gravity drainage (SAGD) conditions. For the sake of comparison, different molecular analyses, including the radial distribution functions (RDFs), interfacial thickness, solubility parameter, and hydrogen bond numbers, were used. According to the results of this study, the anionic surfactant has a good interaction with asphaltenes, and it can lessen the aggregation of asphaltenes. The outcomes of this paper provide useful information to have a deeper understanding on how a surfactant interacts with asphaltene under the thermodynamic conditions of a surfactant− steam coinjection process.

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Molecular dynamics simulation of CO2 dissolution in heavy oil resin-asphaltene

Cited by 29 publications

References 43 publications

Nucleation and Growth of Gas Hydrates in Emulsions of Water in Asphaltene-Containing Oils

Nucleation and Growth of Gas Hydrates in Emulsions of Water in Asphaltene-Containing Oils

Spotlight onto surfactant–steam–bitumen interfacial behavior via molecular dynamics simulation

Insight into the Interfacial Behavior of Surfactants and Asphaltenes: Molecular Dynamics Simulation Study

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