Pitting and Strip Corrosion Influence on Casing Strength of Salt Cavern Compressed Air Energy Storage

Abstract

In response to the localized corrosion generated by underground casing, which seriously affects the safe operation of salt cavern compressed air storage, we used commercial finite element software, ANSYS, to propose a partial model applicable to casings with pitting and strip corrosion. The results show that the pitting depth of the casing is closely related to fracture and collapse pressure. As pitting corrosion depth increases, its effect on fracture and collapse pressure becomes more significant. The greater the number of corrosion pits, the lower the compressive strength of the casing, and the casing tends to be more prone to fracture. The area with large stress is mainly distributed along the long axis of the strip corrosion. In the short axis of the strip corrosion, there is no stress concentration and appears as a low stress region. The effect of strip corrosion depth on failure pressure is greater than the effect of strip corrosion length. In this work, we developed a method to predict residual strength, which is useful to assess not only well integrity but, additionally, safety of the casing used during petroleum and natural gas exploration and production.

Keywords

• pitting corrosion
• strip corrosion
• casing strength
• finite element model
• SCCAES