Experimental study of asphaltene precipitation and metastable zone in the presence of polythiophene-coated Fe3O4 nanoparticles

• Published in: Journal of molecular liquids 2020-03, Vol.301, p.112254, Article 112254
• Main Authors: Tazikeh, Simin, Sayyad Amin, Javad, Zendehboudi, Sohrab
• Format: Article
• Language: English
• Subjects: Asphaltene adsorption; Asphaltene precipitation; Fe3O4 nanoparticle; Metastable zone width; Polythiophene
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.112254

Asphaltene precipitation is recognized as one of the critical flow assurance related problems in the petroleum industry. Asphaltene precipitates on the rock surface of the reservoir and changes the rock wettability and permeability. Also, this unfavorable phenomenon damages production components such as wellbores and pumps. Therefore, inhibition of asphaltene precipitation seems essential in corresponding industries. To attain this goal, we synthesize Fe3O4 nanoparticles with a new method and coat it with polythiophene where the resulted nanoparticles have an average crystallite size of 40 nm. The synthesized polythiophene-coated Fe3O4 nanoparticles (Fe3O4-PTNPs) are characterized by x-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and Fourier-transform infrared spectroscopy (FTIR). This paper proposes a quick technique (e.g., centrifugation) to extract asphaltene from crude oil. In addition, an indirect method is used for the first time for determination of the metastable zone width (MSZW) of the asphaltene. The variations of the asphaltene MSZW in the presence and absence of nanoparticles are investigated in this research work. The results show that Fe3O4-PTNPs postpone the onset point of asphaltene in light and heavy synthetic oil samples. The optimum concentration of Fe3O4-PTNP is found to be 0.1 wt%. At this concentration of nanoparticles, the onset point of asphaltene precipitation is delayed from 38 to 45 vol% n-heptane and 32 to 45 vol% n-heptane in the light and heavy synthetic oils, respectively. According to the experimental data, Fe3O4-PTNPs postpone the onset point of asphaltene in the heavy synthetic oil with adsorption type III more than that in the light synthetic oil sample with adsorption type I. The MSZW in the presence of Fe3O4-PTNP moves to more anti-solvent in solubility curve; this observation refers to the condition that the asphaltene nucleation in the presence of Fe3O4-PTNPs is postponed. It is also found that asphaltene is adsorbed on the surface of nanoparticles. Hence, less asphaltene precipitates on reservoir rock under non-equilibrium conditions. The outcome of this research work can assist oil and gas industry to better manage asphaltene precipitation through utilizing various nanoparticles, leading to a greater recovery rate as well as a more economical production strategy. Also, this method is more environmentally friendly, compared to other conventional inhibition techniques. •This research st