The Electrodialysis Of Oilfield Water And The Application In Chemical Flooding

According to preparing polymer solution by oilfield produced water, the effect of ions and salinity on polymer solution viscosity was explored and discussed. Anions have no contribution to the reduction of polymer solution viscosity. Cations are the main reason of polymer solution viscosity loss. The effects of cation concentrations, charge numbers and cation radii on HPAM molecular configuration deeply explored and discussed by applying the mechanism of electrical double layer. The influencing rule of cations on HAPM molecular configuration was obtained. And the effect of salinity on the rheological characteristics of polymer solution was researched. Through matching rheological curve, the rheology parameters are calculated, the higher the salinity is, the smaller the consistency coefficient is, and the bigger the power law index is. Applying the mechanism of the effect of cation on viscosity , the difference of polymer solution viscosity from oilfield freshwater and produced water is explained. At the same time the effect of oil concentrations,impurity concentrations,bacteria and kinds of treating agents on polymer solution viscosity are researched. Impurity concentrations,demulsifers,anti-scaling additive and paraffin inhibitor have no influence on polymer solution viscosity; oil, bacteria, flocculant and bactericide can reduce the viscosity.The oilfield produced water that is disposed by electrodialysis is researched in the laboratory. The technological parameters are explored and discussed. The current is very important for the running process of electrodialysis. So the operating current must be less than limiting current. The limiting current is different for different concentration water. The optimum operating current is 17A for the oilfield produced water which salinity is 4861.4mg/L, optimum flow rate is 700L/h. i lim = 10.65V0.6994cof the empirical model which describe the experiment machine is gained. The electrodialysis can lower the salinity more, and also can wipe off all ions. The desalting rate is more 80% and the ultimate power consum0ption is only 1.7kWh/m3, the ultimate conduct efficiency is less than 500μs/cm. So it is feasible for the electrodialysis to dispose oilfield water. That the multiple-step processing can save the power consumption is pointed out, and the better desalinization effect is obtained. The low-salinity water can increase the polymer solution viscosity more and can be used in the polymer flooding. The high-salinity water is used in Low-alkali-concentration ASP system and increase oil displacement efficiency.