Modified Maleic Anhydride Co-polymers as Pour-Point Depressants and Their Effects on Waxy Crude Oil Rheology

To investigate the influence of structure variables of polymeric additives on the pour-point depression and rheological behavior of waxy crude oil, maleic anhydride co-polymer and its derivatives with different polar and/or aromatic pendant chains were designed and synthesized. All prepared additives were characterized by Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). The pour-point and rheological properties of Changqing (CQ) crude oil with a low asphaltene content before and after additive beneficiation were studied in detail. Differential scanning calorimetry (DSC) and polarizing light microscopy were employed to gain insight on the interactions between such additives and wax crystals. The results are encouraging and showed that all four polymeric additives exhibited good efficiency as flow improvers in CQ crude oil. The reduction of pour-point and rheological parameters after additive addition largely related to the polymer structure. The polymer containing aromatic units showed the best performance, which could depress the pour point by 19 degrees C and decrease the yield stress as well as viscosity to a large extent.