Safety Evaluation and Reliability Prediction of J55 Steel Casing in Formation Water Service Environment

A finite element model was established for the anti-extrusion strength and tensile strength of J55 steel casing, and the mechanical properties of uniformly corroded and localized corroded J55 steel casing were analyzed. The mechanical properties and service life of J55 steel casing in produced water from oil and gas wells were compared before and after adding corrosion inhibitors. The results indicate that the established model could be effectively used for the mechanical analysis of J55 steel casing. Localized corrosion could significantly reduce the residual strength of J55 steel casing, and under the same corrosion depth (1 mm) condition, the residual tensile strength of localizedly corroded J55 steel casing was 23.3% lower than that of uniformly corroded J55 steel casing. In the produced water from oil and gas wells without corrosion inhibitors, the mechanical properties of J55 steel casing were significantly reduced, and the average service life was only 2.8 a. After adding corrosion inhibitors, the mechanical properties of J55 steel casing were significantly improved, and the service life was also significantly increased.