Investigation into mechanisms and kinetics of asphaltene aggregation in toluene/n-hexane mixtures

Abstract

Determining the rate of asphaltene particle growth is one of the main problems in modeling of asphaltene precipitation and deposition. In this paper, the kinetics of asphaltene aggregation under different precipitant concentrations have been studied. The image processing method was performed on the digital photographs that were taken by a microscope as a function of time to determine the asphaltene aggregation growth mechanisms. The results of image processing by MATLAB software revealed that the growth of asphaltene aggregates is strongly a function of time. Different regions could be recognized during asphaltene particle growth including reaction-and diffusion-limited aggregation followed by reaching the maximum asphaltene aggregate size and start of asphaltene settling and the final equilibrium. Modeling has been carried out to predict the growth of asphaltene particle size based on the fractal theory. General equations have been developed for kinetics of asphaltene aggregation for reaction-limited aggregation and diffusion-limited aggregation. The maximum size of asphaltene aggregates and settling time were modeled by using force balance, acting on asphaltene particles. Results of modeling show a good agreement between laboratory measurements and model calculations.

Combined experimental and molecular dynamics investigation of 1D rod-like asphaltene aggregation in toluene-hexane mixture

“…Starting from the base solution, the asphaltene at every concentration of titrant is thoroughly mixed to ensure that the asphaltene particles are uniformly distributed. The aggregation phenomenon at different concentrations of titrant has been investigated using two methods, the filter paper method [34] and the microscopic method [17,32]. In the filter paper method, Whatman grade 41 filter paper is used to observe the aggregation phenomenon.…”

“…Tirjoo et al [31] studied asphaltene aggregation for two different asphaltene models with one containing two lateral side chains and the other containing two methyl groups. Recently, Soulgani et al [32] studied asphaltene aggregation in toluene and n-hexane mixture by performing experiments and theoretical investigation using hydrodynamic modeling. The aggregate sizes in solution are investigated using optical microscopy and the settling time of the aggregates is calculated.…”

Effect of Sulfate-Based Scales on Calcite Mineral Surface Chemistry: Insights from Zeta-Potential Experiments and Their Implications on Wettability

“…This could be because the different studies used varying experimental conditions and models which failed to account for the effect of brine and rock–fluid interactions. 45 − 47 …”

“…Furthermore, the rate of asphaltene adsorption is linearly correlated with the change in wettability. ,− Regarding the relationship between the crude oil, asphaltene content, and adsorption, opposing views have been voiced. This could be because the different studies used varying experimental conditions and models which failed to account for the effect of brine and rock–fluid interactions. − …”

Evaluación del aceite de Anacardium occidentale como inhibidor de floculación de asfaltenos

“…El sistema coloidal formado por la unión de los asfaltenos y las resinas (micelas) y los componentes líquidos del petróleo crudo, se encuentra en un estado de pseudo equilibrio termodinámico (Li et al, 2020) por lo que cambios en las condiciones de temperatura, presión, composición y régimen de flujo causan la desestabilización del sistema, propiciando la separación y agregación de las partículas de asfaltenos, formando depósitos que producen taponamiento de tuberías y equipos de procesos (Soltani, Reisi & Norouzi, 2019).…”