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

Abstract

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.

Investigating the Compatibility of Various Components in Marine Low-Sulfur Fuel Oil by Molecular Dynamics Simulations

“…Figure 5 demonstrates changes of RDF curves between asphaltene and other components before and after adding the light distillate oil, which can be used to figure out the influence of light components on other fractions in the heavy fuel oil. According to previous research, the maximum hydrogen bonds length is 2.5Å, as no peak is found at a distance lower than 2.5Å in heavy fuel oil and low-sulfur fuel oil RDF curves, so hydrogen bond does not exist in both models [53].…”

A Review of High‐Temperature Foam for Improving Steam Flooding Effect: Mechanism and Application of Foam

“…E bond represents the potential energy of the bond length between two bonded atoms due to deformation, E angle represents the potential energy of the formation of two consecutive chemical bonds between three bonded atoms due to angular motion, and E torsion represents the potential energy of four atoms due to torsion. Ahmadi and Chen [24] carried out MD simulations to preliminarily study the interfacial behavior of asphaltene and surfactant in aqueous solution. The results showed that the interaction between anionic surfactant and asphaltene was greater than that of other surfactants.…”

Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

“…Some studies have addressed the interactions of maltenes and asphaltenes by density functional theory [ 39 , 40 , 41 ] and molecular dynamics simulations [ 42 , 43 ], and experimental studies have investigated the aggregation ability of asphaltenes in different solvents [ 44 , 45 , 46 ]. Although some of these studies found evidence of a stronger interaction between asphaltenes and aromatic molecules, the aromatic–aromatic interactions do not appear to be exclusively responsible for the asphaltene–maltene interactions, as strong anionic, polar and acid-base interactions were also found.…”