An Environmentally-Friendly Method for Disposal of the ASP Flooding Produced Water

Abstract In the field practice of alkaline/surfactant/polymer (ASP) flooding, many produced water disposal methods faced the challenges of purifying effect, facilities pollution, healthy and environmental threat, and economical justification with the water cut rising of the benefited oil wells and the appearance of alkali, surfactant and polymer in produced water. Focus on using the physical comprehensive effects to remove the oil and suspended solids in produced water is an environmentally-friendly method development recently to address the challenges. A laboratory investigation of characterizing the properties of ASP flooding produced water was recently carried out. The oil-water separation processes were practiced, including sedimentation with aeration, lateral flow coalescence and dissolved air flotation. The micro-flocculation suspended sludge blanket filtration process disposal ASP flooding produced water was studied. The application effect of the combination disposal process was assessed, and the operation parameters of aeration rate, dissolved-air pressure, reflux ratio and filtering velocity were optimized. The results show that the ASP flooding produced water is characterized by high salinity, high viscosity, small oil droplet size, high oil content, strong electronegativity and stability. There appears to be a nonlinearity relationship between aeration rate, dissolved-air pressure, reflux ratio, filtering velocity and disposal effect. Compared with the previous polymer flooding produced water sedimentation and filtration disposal process, the sludge amount of the ASP flooding produced water was decreased more than 70.0%, power and agent expense was reduced 60.0%, secondary pollution was decreased drastically and running expense was also saved when disposed under the combination disposal process and operation parameters. And the produced water could meet the re-injection standard of high permeability reservoir after disposal. As the matching technology of ASP flooding enhanced oil recovery (EOR), the environmentally-friendly produced water disposal method is worth pursuing.