OCTG, Special pipe for petroleum, is a type of steel pipe used specifically for oil and gas extraction. It consists of drill pipe, casing and tubing.
The drill pipe is a large seamless pipe that drives the drill bit to rotate and circulate the drilling fluid. The drill pipe simultaneously bears the high torque of the drilling process, the axial tension due to the dead weight and the internal pressure due to the circulation of the drilling fluid.
The casing is subjected to axial tension due to dead weight, internal pressure due to fluid flushing, and external pressure from the surrounding rock. The casing in particular is subjected to axial tension and internal pressure from the pumped oil or emulsion.
A pipe is a pipe that carries oil or natural gas from a well and has a threaded connection at each end.
