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The drill pipe is a steel pipe with thread on the tail, which is used to connect the surface equipment of the drilling rig and the drilling and grinding equipment or bottom hole device located at the bottom end of the drilling well. The purpose of the drill pipe is to transport the drilling mud to the drill bit, and together with the drill bit to raise, lower or rotate the bottom hole device.
This article contains the following:
The main characteristics of the drill pipe
Classification of drill pipe
Specification of drill pipe
The drill pipe is a steel pipe with a thread at the tail, which is used to connect the surface equipment of the drilling rig and the drilling and grinding equipment or bottom hole device at the bottom of the drilling well. The purpose of the drill pipe is to transport the drilling mud to the drill bit, and together with the drill bit to raise, lower or rotate the bottom hole device. The drill pipe must be able to withstand huge internal and external pressures, twists, bends and vibrations. During the extraction and refining of oil and gas, the drill pipe can be used multiple times.
The smooth tube and the original steel tube material are made into drill rods after several processing steps. First, through the processing of the steel tube thickening step, the outer surface of the smooth tube is bent inward, and the wall of the steel tube is thickened. In the next step, the threads are processed and plated with copper that increases strength. Then carry out non-destructive quality control inspection, followed by welding of steel pipe joints. Then, the tube body will undergo welding heat treatment and welding final treatment to eliminate welding residual stress. Before painting and packaging the finished drill pipe, some other tests should be carried out on the finished steel pipe, including hardness test, pressure test and non-destructive test. The length of the drill pipe is generally about nine meters.
The drill pipe is divided into three types: square drill pipe, drill pipe and weighted drill pipe. The connection sequence is square drill pipe (1 piece) + drill pipe (n pieces, determined by the well depth) + weighted drill pipe (n pieces, determined by the design of the drill tool combination).
Square drill pipe
The square drill pipe is located at the uppermost end of the drill string, and there are two kinds of square and hexagonal.
①When drilling, the square drill pipe cooperates with the core and turntable core to transmit the ground rotation torque to the drill rod to drive the drill string and bit to rotate;
② bear the full weight of the drill string;
③ Channel for drilling fluid circulation.
The square drill pipe is composed of upper and lower joints and pipe body parts. The pipe body part is of square or hexagonal structure (oil drilling is mostly square structure); the upper joint is the left joint of the left-hand female thread (reverse buckle), which is connected to the faucet, and the left-hand female thread is prevented from being reversed during the rotation; It is a right-handed male thread connected with a drill rod. When working, the upper end of the Kelly bar is always above the turntable surface, and the lower part is below the turntable surface.
The drill rod is the basic component of the drill string. Its main function is to transmit torque and deliver drilling fluid, and the borehole is continuously deepened by the gradual lengthening of the drill pipe. Therefore, the drill pipe occupies a very important position in oil drilling.
Drill pipe structure The drill pipe is made of Wufeng steel pipe, and the wall thickness is generally 9 to 11mm; the pipe body and the joint are composed of two parts of the drill pipe body and the joint of the drill pipe, butt welded together by friction welding.
Weighted drill pipe
The weighted drill pipe is similar to an oil drill pipe and is also a hollow steel column with a length of about 10 meters. However, the weight of a single pipe is heavier than that of an oil drill pipe, and the wall thickness is 2 to 3 times that of the drill pipe. The heavier drill pipe is connected between the drill pipe and the drill collar. It can also replace part of the drill collar, but its suspension is simple, the operation of lifting and lowering is convenient, and the time of lifting and lowering can be saved.
According to the regulations of the American Petroleum Institute (API), drill pipes are divided into three categories according to length (L): the first category: 5.486-1.706m (18-2222ft); the second category (commonly used): 8.230 -9.144m (27-30ft); the third category: 11.582 to 13.716m (38 to 45ft). Drill rods can also be classified by outer diameter. Commonly used drill pipe sizes (D): 88.9, 114.3, 127mm (usually expressed in inch sizes: 3 1/2 ″ 4 ½ ″ 5 ″).