Study On Reutilization Technology Of Wastewater Produced From Polymer Flooding In United Station

With the expansion of the polymer injection scale,a large amount of wastewater is produced from polymer flooding.It is important to treat the wastewater economically and environmentally.In this paper,based on the basic properties analysis of the wastewater,a reutilization technology was studied,which provided a new way for the treatment of the wastewater.The reutilization of the wastewater was determined by the basic properties analysis.The residual concentration of HPAM is beyond 100mg/L,this characteristic makes it possible to reuse for preparation of polymer solution.However,the oil content of the wastewater is range from 100mg/L to 400mg/L and the suspended matter content is above 30mg/L.Therefore,it need to remove oil and suspended matter before preparation of polymer solution.The gel exist in the wastewater is different from the conventional polymer gel,the PAM content is beyond 7%,also,it has high strength,temperature resistance,salt tolerance and an obvious layered structure.It can be used as a particle profile control agent determined by this properties.The process and origin of the gel was explored.The layered structure and gel-like morphological characteristics illustrated that the gel was generated by the crosslinking of HPAM and grew by retention and accumulation.The results of SEM and the difference properties between the individual confirmed that the origin of the gel is a result of multiple factors.Through the analysis of the polymerization process and materials,the imperfection of polymerization process,the quality of confecting polymer water and the quality of HPAM powder were not the main reason for the gel generation.Simulation experiments showed that aldehydes and inorganic metal ions were two important factors for the origin of the gel.Screen,oil removal and suspended matter removal were applied to pretreat the wastewater.Polymer solution was prepared by the wastewater after pretreatment.The property of the polymer solution reached in-site injection demand.As a particle profile control agent,the gel was added to polymer solution after clean,dry,grind and sieving.The suspension could form an effective plugging for the super high permeability formation.Based on the in-site formula of phenolic resin gel,the crosslinking agent was added into the suspension to manufacture the compound profile control agent.The gelation time of the agent is similar to the original gel.For the super high permeability formation,the agent has good injection and plugging performance.Under the permeability ratio is 5,due to the addition of the gel,the agent has better selective plugging ability than the original gel.