Corrosion Reason and Protection Methods of Water Injection Pipelines in Heshui Oilfield

For solving the serious corrosion of water injection pipelines of Zhuangliuzhu in Heshui oilfield,the water quality,micro-morphology of steel sheet specimens,composition of corrosion products were tested and analyzed to find out the corrosion reasons. A new complex corrosion inhibitor was developed on the basis of above research. Single factor experiments and multi-target orthogonal design were employed to optimize inhibitor MIQS,scale inhibitor PAAS and bactericide MIT contents. The experimental results demonstrated that some corrosion including oxygen absorption corrosion,acid corrosion and pitting induced by excessive dissolved oxygen,erosive carbon dioxide and chloride ion were the main causes of pipelines corrosion. The fouling corrosion and bacterial corrosion resulted from exceeding standard of calcium ion and bacteria were also related to the damage of water injection pipelines. The optimal ratio were determined as follows: 115 mg/L MIQS，30 mg/L PAAS，55 mg/L MIT. Under the condition of above parameters,steel sheet specimens exhibited good anti-corrosion performance and the inhibition efficiency of general corrosion and pitting corrosion achieved 99.57% and 98.40%,respectively.