Oil casing, also called special oil pipe, is mainly used for drilling oil and gas well and transporting oil and gas.It includes oil drilling pipe, oil casing, pumping pipe.The oil drill pipe is used to connect the drill collars to the drill bit and transmit drilling power.

Oil casing is mainly used to support the borehole wall during drilling and after completion to ensure the drilling process and the normal operation of the whole well after completion.The extraction pipe mainly carries the oil and gas from the bottom of the well to the surface.Oil casing is the lifeblood of oil well operation.Due to the different geological conditions, the downhole stress state is complicated, and the comprehensive action of tensile, compressive, bending and torsional stresses on the pipe body puts forward higher requirements for the casing quality.If the casing itself is damaged for some reason, it can result in reduced production or even abandonment of the entire well.According to the strength of the steel itself, the casing can be divided into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, Q125, V150 and so on.The grade of steel used varies with well condition and depth.The casing itself is also required to be corrosion resistant in corrosive environments.In complex geological conditions, casing is also required to have anti-crush performance.