According to the strength of steel itself, casing can be divided into different grades, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150, 13cr, etc. Wellbore condition and depth are different, and the steel grade used is also different. In corrosive environment, the casing itself is required to have corrosion resistance. Where geological conditions are complex, casing is also required to have collapse resistance.
Casing can be divided into: conduit, surface casing,intermediate casing and production casing.
Implementation criteria: API-5CT API-5L ASTM-A106-Gr.B ASTM-A53 DIN BS JIS EN
Casing end processing: flat end, STC, LTC, BTC, and some special connection.
Petroleum casing specifications: 4-1/2"—20".