The Research On The Optimization Of Oil-bearing Wastewater Agents In Extra-low Permeable Reservoirs

The wastewater quality of Qingyilian and the fresh water quality of Qingyizhu in Changqing Oilfield was monitored,analyzed and researched.In addition,the compatibleness of wastewater and fresh water was studied.The results indicated that the wastewater after treatment in Qingyilian still had high total salinity and contained more suspended solids and residual oil.The corrosion rate of wastewater was much higher,the average was 0.1925mm/a,far more than the reinjection water standards of oil industry required.The fresh water of Qingyizhu had high salinity,and the total salinity was above 10600 mg/L.When the fresh water and wastewater mixed in different ratios,scaling phenomenon in different degrees would happen.So the two kinds of water should be treated separately in the production process.Based on the conditions of local corrosion,scaling and bacteria,three kinds of corrosion inhibitors,eight kinds of scale inhibitors and six kinds of bactericides could be selected and evaluated in Qingyilian and Qingyizhu through laboratory evaluation and field test.The results showed that the application effect of different agents was different.When the concentration of HSJ-03 was 100mg/L,its average corrosion rate was 0.010mm/a,which was less than the oil industry standards required;when the concentration of ZG-03 and ZG-04 was 40mg/L,the inhibition rate was more than 90%in Qingyilian,meeting the use requirements;when the dosage of ZG-03 was 40mg/L and ZG-08 was 80mg/L,the inhibition rate was more than 90%in Qingyizhu;when the dosage of SJ-02,SJ-04 and SJ-06 was 100 mg/L,the bactericidal rate of the three agents was almost 100%.The results of mixed agents in field test showed that it would get excellent application effect in Qingyilian with ZG-03:HSJ-03:SJ-04=40:100:100 mg/L;furthermore,it would get the same effect in Qingyizhu with ZG-03:SJ-04=40:100 mg/L.