Oil casing is a steel pipe used to support the wellbore of oil and gas wells, ensuring the normal operation of the entire well during drilling and after completion. Each well requires several layers of casing depending on the drilling depth and geological conditions. After the casing is inserted into the well, cement cementing should be used. Unlike oil pipes and drill rods, it cannot be reused and is a disposable consumable material. So, the consumption of casing accounts for over 70% of all oil well pipes.
Casing can be divided into: conduit, surface casing, technical casing, and reservoir casing according to their usage.