Drill pipe is a kind of 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 bit is to transport and lower the drill bit to the bottom hole. 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. Drill pipe is divided into three types: Kelly, drill pipe and weighted drill pipe. The connection sequence is Kelly (1 piece) + drill pipe (n, determined by well depth) + weighted drill pipe (n, determined by BHA design). The classification, joint, specification, steel grade and strength of drill pipe are introduced in detail.
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.
