OCTG is the abbreviation of Oil Country Tubular Goods, mainly refers to the pipeline products used for oil and gas production (drilling activities). OCTG tubes are usually manufactured according to API or related standard specifications.


 


There are three main types, including drill pipe, casing and tubing.


 


The drill pipe is a sturdy seamless tube that can rotate the drill bit and circulate the drilling fluid. It allows the drilling fluid to be pushed through the drill bit by the pump and returned to the annulus. The pipeline bears axial tension, extremely high torque and high internal pressure.


 


Casing is used to line the borehole that is drilled underground to obtain oil. Just like drill rods, steel pipe casings also have to withstand axial tension. This is a large-diameter pipe inserted into a borehole and cemented in place. The self-weight of the casing, the axial pressure, the external pressure on the surrounding rocks, and the internal pressure generated by the fluid flush all produce axial tension.


 


Tubing pipe goes inside the casing pipe because it is the pipe through which oil makes its way out. Tubing is the simplest part of OCTG, with threaded connections at both ends. The pipeline can be used to transport natural gas or crude oil from production formations to facilities, which will be processed after drilling.