Study on emulsification stability of wastewater produced by polymer flooding

In order to improve the oil–water separation of wastewater produced in polymer flooding of oil field, the emulsification stability of wastewater was investigated by using laser particle-size distribution analyzer, potential measurement and flocculation test. The influences of polymer, water treatment agent, solution viscosity and temperature on emulsification stability were analyzed. The experimental results show that the emulsification stability is mainly determined by the size distribution of oil droplets in wastewater. The addition of polymer will enhance steric hindrance among oil droplets and decrease the efficiency of collision of oil droplets, which results in lower size of oil droplet and slower floating speed. The higher the polymer concentration, the more stable the emulsion. Therefore, the key for improving the efficiency of oil–water separation is to decrease the activation energy barrier for oil droplets coalescence, which can promote the coalesce of tiny oil droplets to from large ones.