Comparative Analysis of the effect of plant-based and petroleum-based wax inhibition additives on heavy crude oil in the Niger-Delta

This study investigates the use of plant-based oils; Soybean Oil (SO), Coconut Oil (CO), and their bio-fuels, and petroleum distillates namely; Automotive Gas Oil (AGO) and Premium Motor Spirit (PMS) as potential wax inhibitors. At various volume concentrations (3%, 5%, 10%), the impact of the additives on the pour point, rheology, and wax deposition of a heavy waxy crude oil sample from the Niger Delta was investigated. The ASTM standard test procedures were utilized, using the cold finger apparatus for wax deposition test and Paraffin Inhibition Efficiency (PIE) determination. It was observed that though all the additives tested could reduce the crude oil viscosity, SO and CO had the least effect compared to their bio-fuels and petroleum distillates (which had the greatest effect). PMS reduced the yield point (YP) significantly at all concentrations, while AGO reduced same only at low concentration (3%). The plant oils and bio-dieselts had a poor effect on YP. Again PMS had the most effect on pour point reduction, followed by AGO. SO and SOBD showed similar trend, raising the pour point at low concentration, while reducing same at higher concentrations. CO and COBD both reduced the pour point at all concentrations. The cold finger wax deposition test finally revealed that SO is a good wax crystal modifier. At high concentration, its paraffin inhibition efficiency is almost comparable to that of AGO and PMS at reduced concentration. Its flow improvement property is however relatively poor, as it could not improve the yield point and pour point of the crude oil significantly. In comparison with CO however, SO shows more potentials in wax inhibition and flow improvement, while AGO and PMS show excellent results. The plant oil bio-diesels (SOBD and COBD) on the other hand, showed more promise than the original plant oils (SO and CO) in flow improvement, but are less attractive in wax inhibition.