Synthesis, evaluation and characterization of vinyl acetate/octadecyl acrylate copolymer as an energy-saving liquid pour point depressant for waxy crude oil

Liquid pour point depressants provide safety, cost savings, and ease of handling for waxy crude oil treatment to reduce wax deposition and improve its rheological behavior. Therefore, we prepared three liquid pour point depressants (LPPDs) using vinyl acetate, acrylic acid, and octadecyl alcohol. The molar ratio of VA:ODA is 1:1, and the prepared pour point depressants, namely PPD-H1, PPD-H2, and PPD-H3, vary in their solid content, which is 20, 30, and 40 %, respectively. The structure of the prepared copolymer was confirmed via 1H NMR analysis, Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). Evaluation of PPD-H1, PPD-H2, and PPD-H3 as pour point depressants, flow improvers, and yield stress reducing agents was performed by pour point temperature measurement, viscosity-temperature curve, and shear stress-shear rate relationship. Experiments revealed that the prepared PPDs exhibit an obvious pour point depressing effect, flow-improving property, and an effective yield stress decreasing on Egyptian waxy crude oil. Among the three LPPDs, PPD-H3 with a solid content of 40 % showed the best results by decreasing the pour point temperature of Well-X1 crude oil from 75 °F to 45 °F and that of Well-X2 crude oil from 65 °F to 25 °F using a 2000 ppm treatment dose. It also reduced the apparent viscosity of Well-X3 significantly, where the 30 cP viscosity of an untreated crude oil sample was reached at 70 °F, while the same viscosity of a 1000 ppm treated sample was reached at 32 °F. All LPPDs showed significant yield stress reduction, with the best results obtained by PPD-H3, where it minimized the yield stress of Well-X4 crude oil by 85 % at 70 °F using a 1000 ppm treatment dose. © 2024 Elsevier B.V.