Oil casing pipe is used to support the walls of oil and gas wells to ensure the operation of the entire oil well after the drilling process and completion. Each well uses several layers of casing pipe according to different drilling depths and geological conditions. Unlike oil pipes and drill pipes, oil casing pipe cannot be reused and is a one-time material.

Oil casing pipe is very important to keep oil well running. Due to the different geological conditions, the downhole stress state is complex, and the combined effects of tension, compression, bending and torsional stress act on the pipe body, which puts forward higher requirements on the quality of the casing pipe. Once the casing damaged, it may lead to reduction in production of the entire well, or even scrap.

According to the strength of the steel, the casing can be divided into J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. Different well conditions and depth require different steel grades. In a corrosive environment, the casing required to have corrosion resistance function. Also, it is required to have anti-collapse performance in the complex geological conditions.