Corrosion Reason of Polymer Flooding Oil Gathering and Transportation Pipelines

Polymer oil recovery technology has been widely used in Daqing Oilfield. The injection water contains a large number of microorganisms, which promotes the corrosion perforation of polymer drive gathering and transportation pipeline and causes leakage accidents. The corrosion characteristics of pipelines were analyzed using scanning electron microscopy (SEM), EDS, X-ray diffraction, and laser confocal microscopy. rRNA sequencing was used to detect microbial species, and the main types of corrosion and identification characteristics of microbial corrosion in gathering and transportation pipelines were explored. The results show that the mineralization and TDS of the medium transported by the pipeline were relatively high, and the mass concentrations of and exceeded 2 000 mg/L. Microorganisms were enriched in the medium and corrosion products, and a large number of rust nodules were formed on the inner wall of the pipeline. The mass fraction of S on the surface of rust nodules was 16.62%, and the mass fraction of S in the shell of rust nodules was 6.60%, SRB caused severe microbial and subsurface corrosion of polymer flooding pipelines in oil fields.