A mechanistic study toward the effect of single-walled carbon nanotubes on asphaltene precipitation and aggregation in unstable crude oil

Abstract

Despite the numerous works devoted to using of different types of nanoparticles for treatment of asphaltene related issues, the potential applications of carbon nanostructures for controlling of asphaltene precipitation have not been addressed in the literature. Here, single-walled carbon nanotubes (SWCNTs) are synthesized and characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) techniques. The viscometry, asphaltene dispersant tests, and microscopy experiments are performed to investigate the effects of synthesized carbon nanotubes at different dosages on asphaltene precipitation and the size-growth of asphaltene particles in an unstable crude oil. Results of different experiments indicate that the synthesized carbon nanotubes considerably postpone the asphaltene onset of precipitation. In addition, SWCNTs adsorb asphaltenes and lead to a slower asphaltene aggregation process, and hence smaller asphaltene aggregates size distribution. Experiments performed at different concentrations of SWCNTs reveal that the highest performance of SWCNTs can be achieved at concentration of 100 ppm with dispersion efficiency value of 93.5% via asphaltene dispersant tests (ADTs). The large surface area of synthesized carbon nanotubes and strong π − π interactions between carbon nanotubes and asphaltenes are responsible for efficient controlling of asphaltene precipitation/aggregation by SWCNTs. Results of this work demonstrate that the synthesized SWCNTs can be utilized as cost-efficient and environmentally friendly asphaltene inhibitor and dispersant for oilfield applications. Also, using of SWCNTs can eliminate the weaknesses of other types of nanoparticles and tackles the induced problems by asphaltene precipitation and deposition.