Drill pipe, one kind of OTCG, is a steel pipe with threaded tail, which is used to connect the surface equipment of drilling rig and drilling and grinding equipment or bottom hole device at the bottom of drilling.

The purpose of the drill pipe is to transport drilling mud to the bit and to raise, lower or rotate the bottom hole device together with the bit.

Drill pipe

The drill pipe must be able to withstand huge internal and external pressure, distortion, bending and vibration.

In the process of oil and gas extraction, drill pipe can be used many times.

Smooth pipe and original steel pipe are made into drill pipe after several processing steps.

First of all, through the treatment of steel pipe thickening process, the surface of smooth tube is bent inward, and the wall of steel pipe is thickened.

Next, thread is machined and plated with copper to increase strength.

Then the nondestructive quality control inspection is carried out, and then the welding of steel pipe body joint is carried out.

After that, the pipe will go through welding heat treatment and final welding treatment to eliminate welding residual stress.

Before the finished drill pipe is painted and packed, some other tests should be carried out on the finished pipe, including hardness test, pressure test and non-destructive test.

Drill pipe is heavy seamless tube that circulates drilling fluid and rotates the drill bit.

Pipe segments 30ft long are combined with tool joints. Drill pipe is at the same time subjected to drilling by its dead weight, high torque by axial tension, and internal pressure by the purging of drilling fluid.

Additionally, alternating bending loads due to non-vertical or redirected drilling may be superimposed on these basic loading patterns.

Casing pipe lines the borehole.

It is liable to internal pressure by fluid purging, axial tension by its dead weight, and external pressure by surrounding rock formations.

The casing is especially exposed to axial tension and internal pressure by the pumped oil or gas emulsion.

Tubing is the pipe through which the oil or gas is transported from the wellbore.

Tubing segments are generally around 30ft long with a threaded association on each end.

Corrosion resistance under sour service conditions is a very important OCTG characteristic, especially for casing and tubing.