Treatment Process for High-Polymer Produced Water in Oilfields
In oilfield production, especially after enhanced oil recovery measures such as polymer flooding, large volumes of high-polymer produced water are generated. This wastewater contains not only crude oil and suspended solids but also high concentrations of polymers (e.g. partially hydrolyzed polyacrylamide, HPAM), giving it high viscosity and severe emulsification that make oil-water separation difficult. Its main characteristics are high viscosity, strong emulsion stability and a complex pollutant profile (oil, suspended solids, COD, etc.), and conventional treatment readily produces "aged oil", further increasing the difficulty.
Conventional processes usually rely on combinations such as "inclined-plate settling tank + walnut shell/fiber ball filtration" or "settling tank + centripetal flotation + fiber ball/multi-media filtration + ceramic membrane". Although applicable within a certain range, these methods have clear limitations: poor shock resistance, unstable water quality, a complex flow sheet, high operating costs, and — because they depend on chemicals — secondary pollution and oily sludge. For reinjection into medium- and low-permeability formations, conventional processes often struggle to meet standards reliably, and maintenance is difficult.
To address these pain points, SINOKLE has introduced an innovative new process: an advanced catalytic ozonation unit (CDOF) combined with cyclonic dissolved gas flotation (CDFU) in an integrated technical route.
Process flow diagram of high-polymer produced water treatment
In this process the water first passes through the CDOF unit, where multi-pathway catalytic ozonation rapidly cleaves and degrades the polymer chains, reducing wastewater viscosity and treatment difficulty; it then enters the CDFU unit, where cyclonic dissolved gas flotation achieves purely physical demulsification with micro-bubbles and efficiently separates oil and suspended solids; the water is finally polished through a KFM active filter media filter or a modified inorganic membrane to guarantee effluent quality.
CDOF Advanced catalytic ozonation unit at a project site
CDFU Cyclonic dissolved gas flotation unit at a project site
The new SINOKLE process offers multiple advantages:
High efficiency and stability: CDOF boosts ozonation efficiency by more than 4 times, while CDFU enhances separation, delivering effluent with oil ≤10 mg/L, suspended solids ≤5 mg/L and COD ≤3 mg/L, reliably meeting reinjection standards.
Environmental and economic benefits: purely physical demulsification, no chemicals, no secondary pollution, sludge reduced by more than 90%, plus a short flow sheet, a small footprint and low operating costs.
Smart and compact: highly integrated, skid-mounted equipment that runs fully automatically with strong shock resistance, suitable for offshore platforms and onshore oilfields under all operating conditions.
The process has been successfully applied in several oilfield projects including PetroChina, demonstrating strong technical adaptability and economic and environmental benefits, and providing an efficient and reliable solution for high-polymer produced water treatment.
