Oil casing is a steel pipe used to support oil and gas wells to ensure the normal operation of the whole well after drilling and completion. Each well should use several layers of casing according to different drilling depth and geological conditions. Cement cementing is used after casing goes down. It is different from tubing and drill pipe. It can not be reused. It belongs to disposable consumable material. Therefore, the consumption of casing accounts for more than 70% of all oil well pipes.
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.