Graphene oxide-PEG: An effective anti-wax precipitation nano-agent in crude oil transportation

The main objective of this study is to investigate the effect of Graphene oxide (GO) nanostructures in preventing the formation of waxy sediments, and to assess its impact on some crude oil physical properties. By functionalization of graphene oxide with polyethylene glycol (PEG), the GO-PEG nanostructure was synthesized. The nanostructure was then examined using X-ray diffraction analysis, scanning electron microscope, and infrared spectroscopy. It became clear that polymer was connected to graphene and the graphene platelet structure was maintained after modification with the polymer. Then, GO-PEG nanostructure was added to the crude oil in different concentrations of 100, 200, 400, 800, and 1000 ppm and the oil pour point, appearance temperature of the wax, viscosity, and the rate of oil deposition were examined for each sample. The results revealed that the oil pour point was significantly reduced by adding nanostructure. This temperature was decreased from 17 °C in pure crude oil to -5 °C in GO-PEG concentration of 800 ppm. Moreover, the results of calorimetry indicated that the wax appearance temperature was decreased by increasing the nanostructure concentration, and it was reached to 32.2 °C in the final concentration of 800 ppm from 42.1 °C in crude oil as blind sample. The study of sediment thickness in the oil flow via a loop setup indicated that increasing the nanostructure concentration, decreases the amount of sediment. Finally, based on both viscosity and sediment thickness evaluations, the satisfactory concentration of the anti-wax nano-agent was 400 ppm. Consequently, according to the results, this nanostructure could be used as a preventive for sediment formation instead of conventional and costly methods such as heating of crude oil.