1
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Peng B, Yuan L, Tang X, Wang Y, Li Y, Liu W, Pei Y. Molecular dynamics simulations of aggregation and viscosity properties of model asphaltene molecules containing a polycyclic hydrocarbon nucleus with toluene additive under shear interactions. RSC Adv 2024; 14:2577-2589. [PMID: 38226146 PMCID: PMC10788708 DOI: 10.1039/d3ra06483b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 12/18/2023] [Indexed: 01/17/2024] Open
Abstract
Reducing the viscosity of heavy oil is beneficial to the process of oil recovery, so it is of great significance to explore the influence of different factors on the viscosity of heavy oil. In this study, molecular dynamics (MD) simulations were carried out to study the viscosity properties of 15 structurally homologous model polycyclic molecules under shear conditions and with a toluene additive with different concentrations. Over 50 sets of simulation systems were constructed and simulated in this work. The molecular structure effect including the phenyl ring arrangements, alkyl side chain decorations, and heteroatoms, as well as the solvent effect such as the concentration of the toluene additive was comprehensively studied. It was found that under the shear conditions, the more branched the benzene ring in the polycyclic hydrocarbon nucleus, the greater the molecular steric hindrance generated, resulting in higher viscosity compared to O-shaped polycyclic hydrocarbon nucleus molecules. The introduction of alkyl side chains and heteroatoms leads to increased intermolecular interactions and more face-to-face stacking configurations, resulting in an increase in viscosity. However, in comparison, the heteroatoms effect is more pronounced in intermolecular interactions and increases in viscosity. Molecular trajectory analysis further indicates the molecular aggregates undergo continuous fracture and recombination under shear interaction, which is related to the trend of changes in viscosity properties. The current research provides new atomic-level insights into the molecular motion of heavy oil components under shear interaction in the presence of a toluene additive.
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Affiliation(s)
- Baoliang Peng
- Research Institute of Petroleum Exploration & Development (RIPED), PetroChina, Key Laboratory of Oilfield Chemistry, CNPC Beijing 100083 People's Republic of China
| | - Lingfang Yuan
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University Xiangtan 411100 People's Republic of China
| | - Xianqiong Tang
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University Xiangtan 411100 People's Republic of China
- School of Mechanical Engineering and Mechanics, Xiangtan University Xiangtan 411100 People's Republic of China
| | - Yao Wang
- PetroChina Liaohe Oilfield Company Panjin 124010 People's Republic of China
| | - Yingying Li
- Research Institute of Petroleum Exploration & Development (RIPED), PetroChina, Key Laboratory of Oilfield Chemistry, CNPC Beijing 100083 People's Republic of China
| | - Weidong Liu
- Research Institute of Petroleum Exploration & Development (RIPED), PetroChina, Key Laboratory of Oilfield Chemistry, CNPC Beijing 100083 People's Republic of China
| | - Yong Pei
- Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Xiangtan University Xiangtan 411100 People's Republic of China
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2
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Faraji Chanzab F, Mohammadi S, Alemi Mahmoudi F. Effect of the bare and functionalized single-wall carbon nanotubes on inhibition of asphaltene molecules aggregation: A molecular dynamic simulation. J Mol Graph Model 2024; 126:108659. [PMID: 37925879 DOI: 10.1016/j.jmgm.2023.108659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/09/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023]
Abstract
A comprehensive study has been carried out by utilizing the molecular dynamics technique in order to investigate the behavior of the N-(1-hexylheptyl)-N'-(2-phenylpropanoicacid)-perylene-3,4,9,10-tetracarboxylicbisimide (PAP) molecules in the n-heptane/toluene solution as well as the role of the bare and functionalized single-wall carbon nanotubes (SWCNTs) with the carboxyl groups (-COOH) on the aggregation of PAP molecules. It was found that the CNTs benefit two mechanism of steric hindrance and adsorbing the PAP molecules to suppress the affinity of PAP molecules to association. The results ascertain that the constant amount of the carboxyl groups acts more efficiently in restricting the growth of aggregate size if they are distributed on the surface of a larger CNT. Both of the increased nonbonding interactions between the functionalized CNTs and the PAP molecules, and the number of formed hydrogen bonds between them clearly proved the efficiency of the -COOH groups in improving the stability of PAP molecules. The strength of the adsorption free energies revealed that the PAP molecule shows more tendency to be adsorbed on the surface of CNT modified with carboxyl groups. Increasing the dosage of the -COOH groups on the surface of the CNTs with constant dimension causes an increment in the PAP molecules' solvent accessible surface area (SASA) value, indicating enhanced stability of the PAP molecules. Finally, the results would facilitate future studies on manipulating the asphaltene precipitation in the oil industry.
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Affiliation(s)
| | - Saber Mohammadi
- Amirkabir University of Technology, Tehran, Iran; Research Institute of Petroleum Industry (RIPI), Tehran, Iran.
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3
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Gurtovenko AA, Nazarychev VM, Glova AD, Larin SV, Lyulin SV. Mesoscale computer modeling of asphaltene aggregation in liquid paraffin. J Chem Phys 2023; 158:234902. [PMID: 37318174 DOI: 10.1063/5.0153741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 05/30/2023] [Indexed: 06/16/2023] Open
Abstract
Asphaltenes represent a novel class of carbon nanofillers that are of potential interest for many applications, including polymer nanocomposites, solar cells, and domestic heat storage devices. In this work, we developed a realistic coarse-grained Martini model that was refined against the thermodynamic data extracted from atomistic simulations. This allowed us to explore the aggregation behavior of thousands of asphaltene molecules in liquid paraffin on a microsecond time scale. Our computational findings show that native asphaltenes with aliphatic side groups form small clusters that are uniformly distributed in paraffin. The chemical modification of asphaltenes via cutting off their aliphatic periphery changes their aggregation behavior: modified asphaltenes form extended stacks whose size increases with asphaltene concentration. At a certain large concentration (44 mol. %), the stacks of modified asphaltenes partly overlap, leading to the formation of large, disordered super-aggregates. Importantly, the size of such super-aggregates increases with the simulation box due to phase separation in the paraffin-asphaltene system. The mobility of native asphaltenes is systematically lower than that of their modified counterparts since the aliphatic side groups mix with paraffin chains, slowing down the diffusion of native asphaltenes. We also show that diffusion coefficients of asphaltenes are not very sensitive to the system size: enlarging the simulation box results in some increase in diffusion coefficients, with the effect being less pronounced at high asphaltene concentrations. Overall, our findings provide valuable insight into the aggregation behavior of asphaltenes on spatial and time scales that are normally beyond the scales accessible for atomistic simulations.
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Affiliation(s)
- Andrey A Gurtovenko
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Prospect V.O. 31, St. Petersburg 199004, Russia
| | - Victor M Nazarychev
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Prospect V.O. 31, St. Petersburg 199004, Russia
| | - Artem D Glova
- Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Sergey V Larin
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Prospect V.O. 31, St. Petersburg 199004, Russia
| | - Sergey V Lyulin
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Prospect V.O. 31, St. Petersburg 199004, Russia
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4
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Espinoza Mejia JE, Li X. Phase Behavior and Reversibility Mechanisms of Asphaltene Precipitation for High-Pressure High-Temperature CO 2–Oil Systems. Ind Eng Chem Res 2023. [DOI: 10.1021/acs.iecr.2c04075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Affiliation(s)
- Julia E. Espinoza Mejia
- Chemical & Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, United States
| | - Xiaoli Li
- Chemical & Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045, United States
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5
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Pétuya R, Punase A, Bosoni E, de Oliveira Filho AP, Sarria J, Purkayastha N, Wylde JJ, Mohr S. Molecular Dynamics Simulations of Asphaltene Aggregation: Machine-Learning Identification of Representative Molecules, Molecular Polydispersity, and Inhibitor Performance. ACS OMEGA 2023; 8:4862-4877. [PMID: 36777594 PMCID: PMC9909787 DOI: 10.1021/acsomega.2c07120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Molecular dynamics simulations have been employed to investigate the effect of molecular polydispersity on the aggregation of asphaltene. To make the large combinatorial space of possible asphaltene blends accessible to a systematic study via simulation, an upfront unsupervised machine-learning approach (clustering) was employed to identify a reduced set of model molecules representative of the diversity of asphaltene. For these molecules, single asphaltene model simulations have shown a broad range of aggregation behaviors, driven by their structural features: size of the aromatic core, length of the aliphatic chains, and presence of heteroatoms. Then, the combination of these model molecules in a series of mixtures have highlighted the complex and diverse effects of molecular polydispersity on the aggregation process of asphaltene. Simulations yielded both antagonistic and synergistic effects mediated by the trigger or facilitator action of specific asphaltene model molecules. These findings illustrate the necessity of accounting for molecular polydispersity when studying the asphaltene aggregation process and have permitted establishing a robust protocol for the in silico evaluation of the performance of asphaltene inhibitors, as illustrated for the case of a nonylphenol resin.
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Affiliation(s)
- Rémi Pétuya
- Nextmol
(Bytelab Solutions SL), Barcelona 08018, Spain
| | - Abhishek Punase
- Clariant
Oil Services,Clariant Corporation, Houston, Texas 77258, United States
| | | | | | - Juan Sarria
- Clariant
Produkte (Deutschland) GmbH, Frankfurt 65929, Germany
| | | | - Jonathan J. Wylde
- Clariant
Oil Services,Clariant Corporation, Houston, Texas 77258, United States
- Heriot-Watt
University, Edinburgh EH14 4AS, Scotland, U.K.
| | - Stephan Mohr
- Nextmol
(Bytelab Solutions SL), Barcelona 08018, Spain
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6
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Eftekhari A, Sayyad Amin J, Zendehboudi S. A molecular dynamics approach to investigate effect of pressure on asphaltene self-aggregation. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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7
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Kondori J, Tazikeh S, Sayyad Amin J, Mohammadzadeh O, Zendehboudi S, Khan F. Quantum mechanics and molecular dynamics strategies to investigate self-aggregation of Quinolin-65. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Zhang J, Wei Q, Zhu B, Wang W, Li L, Su Y, Wang P, Yan Y, Li J, Li Z. Asphaltene aggregation and deposition in pipeline: Insight from multiscale simulation. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Ghamartale A, Zendehboudi S, Mohamadi-Baghmolaei M. Control of Asphaltene Deposition by Chemical Inhibitors in Calcite Pore: Molecular Dynamics Approach. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c01713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ali Ghamartale
- Department of Process Engineering, Memorial University, St. John’s A1C 5S7, NL, Canada
| | - Sohrab Zendehboudi
- Department of Process Engineering, Memorial University, St. John’s A1C 5S7, NL, Canada
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10
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Hammond CB, Aghaaminiha M, Sharma S, Shen C, Chen H, Wu L. Mesoscale Aggregation of Sulfur-Rich Asphaltenes: In Situ Microscopy and Coarse-Grained Molecular Simulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6896-6910. [PMID: 35594154 DOI: 10.1021/acs.langmuir.2c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Asphaltene aggregation is critical to many natural and industrial processes, from groundwater contamination and remediation to petroleum utilization. Despite extensive research in the past few decades, the fundamental process of sulfur-rich asphaltene aggregation still remains not fully understood. In this work, we have investigated the particle-by-particle growth of aggregates formed with sulfur-rich asphaltene by a combined approach of in situ microscopy and molecular simulation. The experimental results show that aggregates assembled from sulfur-rich asphaltene have morphologies with time-dependent structural self-similarity, and their growth rates are aligned with a crossover behavior between classic reaction-limited aggregation and diffusion-limited aggregation. Although the particle size distribution predicted using the Smoluchowski equation deviates from the observations at the initial stage, it provides a reasonable prediction of aggregate size distribution at the later stage, even if the observed cluster coalescence has an important effect on the corresponding cluster size distribution. The simulation results show that aliphatic sulfur exerts nonmonotonic effects on asphaltene nanoaggregate formation depending on the asphaltene molecular structure. Specifically, aliphatic sulfur has a profound effect on the structure of rod-like nanoaggregates, especially when asphaltene molecules have small aromatic cores. Interactions between aliphatic sulfur and the side chain of neighboring molecules account for the repulsive forces that largely explain the polydispersity in the nanoaggregates and corresponding colloidal aggregates. These results can improve our current understanding of the complex process of sulfur-rich asphaltene aggregation and sheds light on designing efficient crude oil utilization and remediation technologies.
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Affiliation(s)
- Christian B Hammond
- Department of Civil Engineering, Ohio University, Athens, Ohio 45701, United States
| | - Mohammadreza Aghaaminiha
- Department of Civil Engineering, Ohio University, Athens, Ohio 45701, United States
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, Ohio 45701, United States
| | - Sumit Sharma
- Department of Chemical and Biomolecular Engineering, Ohio University, Athens, Ohio 45701, United States
| | - Chongyang Shen
- Department of Soil and Water Sciences, China Agricultural University, Beijing 100193, China
| | - Hao Chen
- Department of Agriculture, University of Arkansas at Pine Bluff, Pine Bluff, Arkansas 71601, United States
| | - Lei Wu
- Department of Civil Engineering, Ohio University, Athens, Ohio 45701, United States
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11
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Asphaltenes as novel thermal conductivity enhancers for liquid paraffin: Insight from in silico modeling. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.117112] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Practical quality attributes of polymeric microparticles with current understanding and future perspectives. J Drug Deliv Sci Technol 2021. [DOI: 10.1016/j.jddst.2021.102608] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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13
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Ekramipooya A, Valadi FM, Farisabadi A, Gholami MR. Effect of the heteroatom presence in different positions of the model asphaltene structure on the self-aggregation: MD and DFT study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116109] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Molecular dynamics simulation to investigate the effect of polythiophene-coated Fe3O4 nanoparticles on asphaltene precipitation. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2020.116417] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Nguyen DD, Daneshfar R, Dehaghani AHS, Su CH. The effect of shear rate on aggregation and breakage of asphaltenes flocs: Experimental study and model-based analysis. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Shadman MM, Badizad MH, Dehghanizadeh M, Dehaghani AHS. Developing a novel colloidal model for predicting asphaltene precipitation from crude oil by alkane dilution. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Ahmadi M, Hassanzadeh H, Abedi J. A mesoscopic numerical study of shear flow effects on asphaltene self-assembly behavior in organic solvents. Phys Chem Chem Phys 2020; 22:20758-20770. [PMID: 32909554 DOI: 10.1039/d0cp03026k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A significant amount of research work has been conducted to shed light on the asphaltene aggregation behavior under no-flow conditions. However, their aggregation under shear flow conditions is poorly understood mainly due to the lack of research studies performed on this subject. In this work, we employ the Brownian dynamics simulation to examine the shear flow effects on the self-assembly behavior of asphaltenes. Three volume fractions φ of asphaltene nanoaggregates, ranging from 1 to 7%, are used to investigate the asphaltene aggregation behavior in heptane and heptol (i.e., a solvent containing both heptane and toluene) solvents under shear rates of [small gamma, Greek, dot above] = 0.0-2.5 × 108 s-1. The shear is applied parallel to the x-axis and the shear-gradient is along the y-axis. Under shear flow conditions, the formation of the percolating networks of aggregates is triggered at φ = 3% which is lower than that under the no-flow conditions, i.e., φ = 7%. In both solvent systems, the formed networks mainly percolate along the x- or z-axis to experience less shear-gradient. At all volume fractions, an increase in the shear rate from [small gamma, Greek, dot above] = 0.0 to [small gamma, Greek, dot above] = 2.5 × 108 s-1 resulted in two to three orders of magnitude improvement in the self-diffusion coefficients of colloids.
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Affiliation(s)
- Mohammad Ahmadi
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
| | - Hassan Hassanzadeh
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
| | - Jalal Abedi
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
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18
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Ahmadi M, Hou Q, Wang Y, Chen Z. Interfacial and molecular interactions between fractions of heavy oil and surfactants in porous media: Comprehensive review. Adv Colloid Interface Sci 2020; 283:102242. [PMID: 32858410 DOI: 10.1016/j.cis.2020.102242] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 02/02/2023]
Abstract
The oil production by the natural energy in oil reservoirs is decreasing gradually. Only 25-30% of the world's reservoirs can be produced naturally, and different methods are employed to recover the remaining oil. The use of surfactants is one of the promising methods for unlocking the residual oil after natural depletion. In such a method, one of the main challenges is to study how surfactant, oil, and water interact and how porous media affect these interactions. Molecular dynamics (MD) simulation provides an opportunity to gain insights into this challenge. MD simulation can be used to study interactions between surfactant, oil, and water statically and dynamically in porous media. This paper presents a comprehensive review of interactions between surfactants and fractions of oil/heavy oil, including asphaltene, resin, aromatics, and saturates. Also, it explains the probable mechanisms of oil detachment from reservoir rock in the presence of surfactants. A thorough grasp of molecular interactions between surface-active agents and different fractions of oil helps us to develop successful surfactant-based oil recovery methods.
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19
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Glova A, Larin SV, Nazarychev VM, Kenny JM, Lyulin AV, Lyulin SV. Toward Predictive Molecular Dynamics Simulations of Asphaltenes in Toluene and Heptane. ACS OMEGA 2019; 4:20005-20014. [PMID: 31788635 PMCID: PMC6882142 DOI: 10.1021/acsomega.9b02992] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 10/31/2019] [Indexed: 06/10/2023]
Abstract
The conventional definition of asphaltenes is based on their solubility in toluene and their insolubility in heptane. We have utilized this definition to study the influence of partial charge parametrization on the aggregation behavior of asphaltenes using classical atomistic molecular dynamics simulations performed on the microsecond time scale. Under consideration here are toluene- and heptane-based systems with different partial charges parametrized using the general AMBER force field (GAFF). Systems with standard GAFF partial charges calculated by the AM1-BCC and HF/6-31G*(RESP) methods were simulated alongside systems without partial charges. The partial charges implemented differ in terms of the resulting electrical negativity of the asphaltene polyaromatic core, with the AM1-BCC method giving the greatest magnitude of the total core charge. Based on our analysis of the molecular relaxation and orientation, and on the aggregation behavior of asphaltenes in toluene and heptane, we proposed to use the partial charges obtained by the AM1-BCC method for the study of asphaltene aggregates. A good agreement with available experimental data was observed on the sizes of the aggregates, their fractal dimensions, and the solvent entrainment for the model asphaltenes in toluene and heptane. From the results obtained, we conclude that for a better predictive ability, simulation parameters must be carefully chosen, with particular attention paid to the partial charges owing to their influence on the electrical negativity of the asphaltene core and on the asphaltenes aggregation.
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Affiliation(s)
- Artyom
D. Glova
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
| | - Sergey V. Larin
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
| | - Victor M. Nazarychev
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
| | - Josè M. Kenny
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
| | - Alexey V. Lyulin
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
- Theory
of Polymers and Soft Matter Group, Technische
Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Sergey V. Lyulin
- Institute
of Macromolecular Compounds, Russian Academy
of Sciences, Bolshoi
pr. 31 (V.O.), 199004 St. Petersburg, Russia
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20
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Aggregation Behavior of Model Asphaltenes Revealed from Large-Scale Coarse-Grained Molecular Simulations. J Phys Chem B 2019; 123:2380-2396. [PMID: 30735393 DOI: 10.1021/acs.jpcb.8b12295] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fully atomistic simulations of models of asphaltenes in simple solvents have allowed the study of trends in aggregation phenomena to understand the underlying role played by molecular structure. The detail included at this scale of molecular modeling is, however, at odds with the required spatial and temporal resolution needed to fully understand asphaltene aggregation. The computational cost required to explore the relevant scales can be reduced by employing coarse-grained (CG) models, which consist of lumping a few atoms into a single segment that is characterized by effective interactions. In this work, CG force fields developed via the statistical associating fluid theory (SAFT-γ) [ Müller , E. A. ; Jackson , G. Annu. Rev. Chem. Biomol. Eng. 5 , 2014 , 405 - 427 ] equation of state (EoS) provide a reliable pathway to link the molecular description with macroscopic thermophysical data. A recent modification of the SAFT-VR EoS [ Müller , E. A. ; Mejía , A. Langmuir 33 , 2017 , 11518 - 11529 ], which allows for the parameterization of homonuclear rings, is selected as the starting point to develop CG models for polycyclic aromatic hydrocarbons. The new aromatic-core models, along with others published for simpler organic molecules, are adopted for the construction of asphaltene models by combining different chemical moieties in a group-contribution fashion. We apply the procedure to two previously reported asphaltene models and perform molecular dynamics simulations to validate the coarse-grained representation against benchmark systems of 27 asphaltenes in a pure solvent (toluene or heptane) described in a fully atomistic fashion. An excellent match between both levels of description is observed for the cluster size, radii of gyration, and relative-shape-anisotropy-factor distributions. We exploit the advantages of the CG representation by simulating systems containing up to 2000 asphaltene molecules in an explicit solvent investigating the effect of asphaltene concentration, solvent composition, and temperature on aggregation. By studying large systems facilitated by the use of CG models, we observe stable continuous distributions of molecular aggregates at conditions away from the two-phase precipitation point. As a further example application, a widely accepted interpretation of cluster-size distributions in asphaltenic systems is challenged by performing system-size tests, reversibility checks, and a time-dependence analysis. The proposed coarse-graining procedure is seen to be general and predictive and, hence, can be applied to other asphaltenic molecular structures.
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21
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Mohammed S, Gadikota G. The role of calcite and silica interfaces on the aggregation and transport of asphaltenes in confinement. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.10.163] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Ahmadi M, Hassanzadeh H, Abedi J. Asphaltene Mesoscale Aggregation Behavior in Organic Solvents-A Brownian Dynamics Study. J Phys Chem B 2018; 122:8477-8492. [PMID: 30106586 DOI: 10.1021/acs.jpcb.8b06233] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Significant advances have been achieved in understanding the main molecular mechanisms leading to asphaltene aggregation. However, the existing computational deficiency of molecular dynamics simulations did not allow full reproduction of the complex aggregation behavior of asphaltene in the past. In this work, we use the Brownian dynamics simulation to investigate asphaltene aggregation behavior on larger length and time scales that have not been previously accessed by molecular simulations. This enabled us to completely render the formation of clusters of asphaltene nanoaggregates and the resulting fractal or network of aggregates during the aggregation process. Asphaltene aggregation is studied at several volume fractions (ϕ = 1-7%) of asphaltene nanoaggregates in two solvents including heptane and heptol (i.e., a mixture of heptane and toluene). Our simulation results support the aggregation hierarchy proposed in the Yen-Mullins model (Mullins, Annu. Rev. Anal. Chem. 2011, 4, 393-418.) by demonstrating that asphaltene nanoaggregates form small clusters with an aggregation number of 7-8 and an average gyration radius of ∼4.0 nm capable of forming either fractal aggregates with a fractal dimension of 1.93-2.04 at low ϕ or percolating networks of aggregates at high ϕ. Percolating structures are observed at ϕ = 7% in both solvents. In heptol, the structures mainly percolate along two directions, whereas in heptane, they can percolate along three directions (i.e., x, y, and z). The self-diffusion coefficient ( D) significantly decreases as ϕ increases. Generally, D is larger in heptol than in heptane, but this difference diminishes as ϕ increases, approaching to almost the same value at ϕ = 7%.
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Affiliation(s)
- Mohammad Ahmadi
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering , University of Calgary , 2500 University Drive NW , Calgary , Alberta , Canada T2N 1N4
| | - Hassan Hassanzadeh
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering , University of Calgary , 2500 University Drive NW , Calgary , Alberta , Canada T2N 1N4
| | - Jalal Abedi
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering , University of Calgary , 2500 University Drive NW , Calgary , Alberta , Canada T2N 1N4
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