Evaluation Method and Screening Application of FeS Scale Inhibitor

The produced water in the ground processing system of an oilfield in the west of the South China Sea became black due to FeS scaling. New methods were established to evaluate scale inhibitors of FeS both in lab and in situ. Five basic scale inhibitors were used as raw materials, and the scale inhibition effects of single scale inhibitors and compound scale inhibitors were estimated to screen the special scale inhibitor for FeS. The results showed that the compound scale inhibitor based on organic phosphonate (A), polymer phosphonate (B), EDTA (C) and organic acid chelating agent (E) had the best scale effect, which could effectively inhibit the production of FeS. When the dosage of the compound scale inhibitor was 20 mg/L (5 mg/L A+5 mg/L B+5 mg/L C+5 mg/L E), the scale inhibition efficiency reached 92.17% and 91.25% in lab test and in situ test respectively.