Introduction To Classification Of Drill Pipe

Drill pipe is divided into kelly, drill pipe and heavy drill pipe. The connection sequence is kelly (1 piece)+drill pipe (n pieces, determined by the well depth)+weighted drill pipe (n pieces, determined by the drilling tool assembly design).
Kelly
The kelly is located at the top of the drill string. There are two kinds of kelly: square and hexagonal.
effect
① During drilling, the kelly cooperates with the bushing and rotary table bushing to transmit the ground rotation torque to the drill pipe to drive the drill string and bit to rotate;
② Bear the full weight of the drill string;
③ The passage for drilling fluid circulation.
structure
The kelly is composed of upper and lower joints and pipe body. The pipe body is of square or hexagonal structure (most oil drilling is of square structure); The upper joint is a left-handed female thread (reverse thread), which is connected with the faucet. The left-handed female thread prevents reverse thread during rotation; The lower joint is a right-handed male thread, which is connected with the drill pipe. When working, the upper end of the kelly is always above the rotary table surface and the lower part is below the rotary table surface.
drill pipe
effect
Drill pipe is the basic component of drill string. Its main function is to transmit torque and transport drilling fluid, and to deepen the hole by gradually lengthening the drill pipe. Therefore, drill pipe plays a very important role in oil drilling.
structure
Drill pipe structure The drill pipe is made of seamless steel pipe, and the wall thickness is generally 9~11mm; The pipe body is composed of drill pipe body and drill pipe joint. The pipe body and joint are butt welded by friction welding.
Weighted drill pipe
The weighted drill pipe is similar to the oil drill pipe and is also a hollow steel column with a length of about 10 meters. However, the weight of a single drill pipe is heavier than that of the oil drill pipe, and the wall thickness is 2-3 times of that of the drill pipe. The weighted drill pipe is connected between the drill pipe and the drill collar in order to prevent fatigue damage due to the change of the cross section of the drill string. It can also replace the role of some drill collars, but its suspension is simple, and the tripping operation is convenient, which can save the tripping time.