Corrosion Behavior and Protention Technology for Strings in Oil Well of Y District in Longdong Oilfield

The field situation of strings in oil well of Y district in Longdong oilfield was investigated in detail. Water quality analysis of produced water from field sample wells was conducted. The main characteristics of string corrosion in oil well of Y district were analyzed by observation through scanning electron microscopy, energy spectrum analysis and electrochemical testing in the dynamic/static corrosion test of N80 steel in the produced water. The results show that N80 steel was not only uniformly corroded, but also corroded by CO₂ and H₂S acidic gases and SRB bacteria. In the produced water with a strong scaling tendency, the formed scale was densely attached to the corrosion interface to prevent corrosion. In the produced water with a relatively weak scaling tendency, the corrosion products were loosely attached to the interface to accelerate localized corrosion. These anti-corrosion measures reduced field corrosion well maintenance operations by 56% over a period of three years.