Influence of Crude Oil Production Chemicals on the Performance of Commercial Demulsifiers

During oil production, crude oil is commonly recovered as water-in-oil (w/o) emulsions, which require the chemical destabilization of the emulsion for phase separation. Despite the extensive use of production chemicals, their combined effects on emulsion stability and produced water quality in extra-heavy oils are still poorly understood. In this work, the influence of a corrosion inhibitor (I _cor), a scale inhibitor (I _sca), and two enhanced oil recovery (EOR) polymers (SPAM and HPAM) on the performance of three commercial emulsion destabilizers (D ₁, D ₂, and D ₃) was systematically investigated using synthetic emulsions prepared with asphaltic crude oil and synthetic brine (∼90,000 ppm). Bottle tests showed that, in the absence of EOR polymers, D₁, D₂, and D₃ achieved water separation of ∼55%, 58%, and 78%, respectively, at high concentrations. The individual or combined addition of I_cor and I_sca did not induce phase separation (0.0% water separated) and did not significantly affect the demulsifiers' performance. In contrast, the presence of EOR polymers reduced demulsification efficiency, with HPAM showing the most pronounced effect, decreasing the maximum water separation to ∼39%, 45%, and 59% for D ₁, D ₂, and D ₃, respectively. The method of additive addition did not significantly alter the separation efficiency. Interfacial tension measurements decreased from ∼27.6 mN/m (without additives) to ∼13.2-11.6 mN/m in the presence of demulsifiers, while smaller reductions were observed when EOR polymers were present, indicating competitive adsorption at the oil-water interface. Droplet size analysis revealed a direct correlation between increased water separation and larger droplet values, with D90 values reaching ∼1900 μm at high demulsifier concentrations. Although inhibitors did not affect separation efficiency, enhanced oil recovery (EOR) polymers significantly reduced the quality of the produced water, increasing the total oil and grease (TOG) content from ∼36 to ∼410 ppm (HPAM) and ∼600 ppm (SPAM). These results demonstrate that EOR polymers impair both the efficiency of emulsion destabilization and the quality of produced water in extra-heavy oil systems, while inhibitors showed no effect on the emulsion destabilization performance.