Formulation Of Polymer Solutions By Using Domestic Sewage And Their Application In Tertiary Oil Recovery

Polymer flooding is a widely used technology to enhance oil recovery. It hasbecoming one important strategy to maintain the oil output of Daqing oil field, whichenhance10million tons of oil each year. In the process of tertiary oil recovery, wateris often mixed with polymer to tune the viscosity and save the consumption ofpolymer. Each year in Daqing, the consumption of water on making polymer solutionfor oil recovery is about30million tons. The water consumption is way too much forDaqing, a water-lacking city. In recent years, along with the application of China’s"the most strict water resources management system", the increasing of industrialwater price intensified the conflict between water supply and oil production.There is70million tons of sewage in Daqing city each year, which were drainedwithout recirculation. This thesis aimed to investigate the possibility of using citysewage in polymer solutions for tertiary oil recovery process. The composition ofsewage which could affect the viscosity of polymer solutions was investigated. Theoil recovery performance of the polymer solutions made by sewage was compare withthat made by drink water.The sewage from Daqing Chengfengzhuang sewage treatment plant wasinvestigated. Several factors in sewage, such as cation, anion, salinity, organic species,oxygen content, bacteria etc, were investigated to evaluate their impact on theviscosity of polymer solutions. Multi-valence cations were found to have the mosteffect. The effect of different multi-valence cations was also compared.We also evaluated the performance of sewage after removing the multi-valencecations. The polymer solutions made by treated sewage have similar viscosity, shearresistance and stability to the polymer solution made by water. The treated sewage canbe used as a low cost replacement for water in making polymer solutions for tertiaryoil recovery.