Study On Corrosion Factors Of Water Injection Pipeline In Youfangzhuang Joint Station

Yanchang Oilfield is located in northern Shaanxi Province, where water resources is seriously destitute, and the permeability of formation is also lower. With the production of crude oil, formation water and injection water came to the ground, and formed a large quantity of oil water separation sewage. Severe corrosion effect of produced wastewater on the oil pipeline causes perforation,leakage, as well as other damage, which results in huge economic losses every year, and influences production effect of whole oilfield. Youfangzhuang joint station created 700 tons of waste water every year, and with the feature of high sulfur content that is about 250 mg/L. In addition, the average salinity of waste water is 37000 mg / L,chloride ion 20000 mg / L or more, sulfate-reducing bacteria 103-104 / ml, saprophytes 104-105/ ml, iron bacteria 103-105 / ml, pH 5.5-7.0, the average corrosion rate 0.202 mm/a. However,anti-corrosion measures are not taken until now.In this paper, the characteristics of the formation water in Youfangzhuang joint station oilfield were analyzed by SY / T 5523-2000 standard. The corrosion factors of the injection water system were also examined by the dynamic and static experiments. The corrosion fouling problems were solved by the screening of injection drugs. By screening and optimizing inhibitor indoor experiments, composite scale inhibitor dosage can be 50 mg/L, the maximum inhibition rate can reach 98.4%. Novel phosphonate-containing corrosion inhibitor had a good performance. After double quaternary ammonium salts and quaternary ammonium plus glutaraldehyde double(10: 1) oilfield produced water treatment, the SRB sterilization rate was more than 97%, and TGB sterilization rate was more than 85%. It has a good bactericidal effect on Youfangzhuang produced water and injection water. Pipeline corrosion and scaling have been significantly inhibited after dosing treatment.