Research on Residual Strength of Corroded Tubing of Gas Well With Sustained Casing Pressure

Abstract

Corrosion and sustained casing pressure have serious threats to the integrity of tubing of gas well. Researching the residual strength of corroded tubing has great significance to ensure the safety of gas well. The finite element method was used to study the relationships between residual strength and corrosion defects size, internal pressure, external pressure, axial load. The results show that, for tubing with uniform corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, and the defect width and defect length have little effects on it. For tubing with pitting corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, while the defect radius has little effect on it. These simulation data were fitted into the functions of residual strength of corroded tubing according to different corrosion morphology types. Both of the verifications of the fitting results show that most of the error between the original calculation data and the fitting calculation data is less than 4%. The fitting formulas can be used conveniently to evaluate the safety of the tubing of gas well with sustained casing pressure.

Finite element study on residual internal pressure strength of corroded oil pipes and prediction method for remaining life

“…However, these methods have some limitations in describing the precise failure pressure, and each has its specific scope of application (Fu and Batte, 1999;Choi et al, 2016). The finite element method can consider the nonlinearity, elasticity and plasticity of the corrosion damaged pipeline (Sun et al, 2015;Yang et al, 2011;Abdalla Filho et al, 2010;Mohd et al, 2015;Chen et al, 2015a), and it can get better evaluation results. Chouchaoui and Pick (1996), Chouchaoui and Pick (1996), Bin and Kirkwood (1995) and Bin and Kirkwood (1995) in Canada have all performed non-linear finite element analysis on corroded pipes and conducted experimental verification.…”