Experimental investigation into the development and evaluation of ionic liquid and its graphene oxide nanocomposite as novel pour point depressants for waxy crude oil

Abstract

Wax deposition in pipelines transporting crude oil is a serious problem as wax tends to precipitate under low temperature conditions observed during pipeline flow. The current research work embarks on the development of novel nanocomposite pour point depressant (PPD) for waxy crude oils. Two additives were synthesized in the laboratory: 1-octyl 3-methylimidazolium chloride [(OMIM)Cl], and a novel class of nanocomposite PPD: PPDR-GO. These additives were tested on an Indian waxy crude oil and proved to be acting as PPDs and flow improvers. Pour point reduction occurred from 39 °C to 21 °C with [(OMIM)Cl], while the depression occurred from 39 °C up to 9 °C with nanocomposite PPDR-1%GO, suggesting significant improvement in the flow ability of the crude oil. The PPDs also induced reduction in the apparent viscosities of crude oil significantly from 7 Pa s down to 0.04 Pa s by (OMIM)Cl and 0.02 Pa s (at higher shear rates and temperatures) by PPDR-1%GO respectively. Apart from the pour point and viscosity tests, the effectiveness of the additives were tested by cold finger, gelation point and aging tests and they produced encouraging set of results. The characterization of the two PPDs performed using spectroscopic analytical techniques FTIR, Proton NMR, XRD and Raman helped identifying the presence of different components and confirm their structure. The purpose of this work is to develop new pour point depressants which are highly effective for providing flow assurance of waxy crude oils. This research also aimed at improving the synthesized PPDs in important areas such as improving dispersion of VGO nanosheets in nanocomposite matrix, enhanced pour point depression ability, low dosage requirement of PPDs, eliminating the need of solvent for PPDs. The action mechanism of the PPDs develops theoretical insights on interactions of ionic liquids, graphene oxide sheets and asphaltenes with the wax structures, which would be highly beneficial for future research.