Study On Demulsification Of SP Flooding Produced Water Under High Oil Displacement Agent Concentration

In order to enhance oil recovery of oilfields, various measures have been adopted to increase the production domestic and overseas in recent years. With the use of Chemical flooding, Steam flooding and other enhanced oil recovery technologies, oil field produced water composition become more complex. As an important oil recovery technology, SP flooding has the significant characteristic of high oil displacement efficiency. However, due to the use of chemicals during SP flooding and the poor quality of crude oil, produced water becomes more difficult to demulsified. The study has great significance because much research have been done to improve the efficiency of demulsification of SP flooding produced water under high oil displacement agent concentration. The influences of polymer and surfactant on the stability of polymer flooding, suifactant flooding and SP flooding produced water were investigated in this study. The demulsification efficiencies of microwave, ultrasonic and flotation methods of enhancing mass transfer of SP flooding produced water were analysised. A new type of flocculants of BH series were synthesized and then the demulsification efficiencies were studied and finally the molecular structure of BH-3 which performed best was obeserved using infrared spectrum.The selection results of different demulsifiers showed that HB-913 and ZU-4 performed better than any other demulsifiers. Using ultrasonic-thermal settlement, microwave-thermal settlement and thermal settlement-flotation combination methods to study the separation characteristics of SP flooding produced water(polymer and surfactant concentration are 800 mg/L). Under the condition that ZU-4 dosage was 100 mg/L, sedimentation time was 120 min, ultrasonic time was 10 min, power was 100 W and frequency was 40 KHz, the oil removal rate of SP flooding produced water can reach 90.7%. And under the condition that microwave time was 60 s, power was 800 W, the removal rate can reach 91.1%.BH series were prepared by introducing inorganic aluminum salt and/or iron salt into polysilic acid.Within all BH series of flocculants, BH-3 performed best. The infrared spectrum showed that Al3+, Fe3+, hydroxyl aluminum ion, hydroxyl ferric ion and polysilicic acid ion can be chelated and produce new polymer. Under the same condition that HB-913 dosage was 100 mg/L, sedimentation time was 120 min,and flotation time was 30 min, change the dosage of BH-3,when the dosage were 100 mg/L and 200 mg/L,the removal rate can come up to 96.4% and 97.2% respectively.SO42- in BH-3 can increase the degree of polymerization by linking the copolymer using hydrogen bonds.