TYPES OF OCTG PIPE
First, OCTG is the acronym of “Oil Country Tubular Goods” – i.e. pipes for oil (and gas) extraction from the soil. The three main OCTG pipe types are:
Casing pipes are used to stabilize the wellbore. A casing pipe is subject to axial tensions and to internal pressures generated by the pumped oil or gas, by their heavyweight and the external pressures coming from the surrounding rocks.
Tubing pipes are tubular goods through which the oil or gas is transported from the wellbore to the surface. Tubing segments are generally around 30′ long with a threaded connection on each end (standard or premium connections are available).
Drill pipes are heavyweight seamless tubular that rotates the drill bit and circulates the drilling fluid. Pipe segments of 30′ are coupled with tool joints. Drill pipe is subject to high torque by drilling, axial tension by their weight, and internal pressure due to the purging of the drilling fluid. Additionally, alternating bending loads due to non-vertical or deflected drilling may be superimposed on these basic loading patterns.