Investigation into the Flow Assurance of Waxy Crude Oil by Application of Graphene-Based Novel Nanocomposite Pour Point Depressants

Abstract

In this research article, novel polymer nanocomposites poly(2-ethylhexyl acrylate)–graphene oxide [P(2-EHA)–GO] were developed (with 0.5–2 wt % GO concentrations) by in situ free-radical polymerization and were characterized using several analytical techniques to confirm the formation of nanocomposites. Subsequently, when doped in crude oil, beneficiation was observed in pour point and rheological parameters of a selected waxy crude oil, thus evaluating them as potential pour point depressants (PPDs). An optimized amount of GO (1 wt %) in nanocomposite results in improved flow characteristics of crude oil, providing a notable 18 °C depression in the pour point and upto 99% reduction in its apparent viscosity (down to 0.01 Pa s). Comparison of its beneficiation effect with P(2-EHA), the base polymeric PPD, indicated a superior performance using nanocomposite PPDs which was mainly attributed to a proposed pour point depression mechanism, according to which the GO sheets act as nucleation sites upon which wax crystal precipitates, helping polymeric chains to cocrystallize with these wax molecules and thereby avoiding the formation of a wax interlocking network. Additionally, the nanocomposite PPDs improved the restart flowability of crude oil, causing upto a substantial 17.8 °C reduction in its gelation point. Moreover, they exhibited better control over the aging effect in crude oils than P(2-EHA) and even better than the previously synthesized nanocomposite poly(methyl methacrylate)–GO upto 15 and 30 days. Overall, this study provides new insights into the physical nature of graphene–wax interactions and illustrates the resultant wax morphology modifications, which would help in the development and application of numerous graphene-based products for the flow assurance community of the researchers and the petroleum industry.