Drill pipe is a steel pipe with a threaded end that is used to connect the surface equipment of the drilling rig to the drilling and grinding equipment or bottom hole device located at the bottom of the drilling rig. The purpose of the drill pipe is to transport drilling mud to the bit and to raise, lower, or rotate the bottom hole device with the bit. The drill pipe must be able to withstand tremendous internal and external pressure, distortion, bending and vibration. In the process of oil and gas extraction and refining, drill pipe can be used many times. Drill pipe is divided into three categories: kelly pipe, drill pipe and weighted drill pipe. The connection sequence is kelly pipe (1 piece)+ drill pipe (n pieces, determined by the well depth)+ weighted drill pipe (n pieces, determined by the drill assembly design).
The common components of the drill string are: drill bit, drill collar, drill pipe, stabilizer, special joint and kelly pipe.
API standard E75 to S135 steel grades from 2 3/8 “to 6 5/8” outside diameter series of oil drill pipe as well as high torsional resistance double shoulder joint drill pipe and special steel grade BNK C95S drill pipe for sulfur Wells. It is mainly applied to the construction of deep Wells, horizontal Wells and extended reach Wells in the process of oil and gas exploration and development.
Drill pipe is divided into three categories: kelly pipe, drill pipe and weighted drill pipe. The connection sequence is kelly pipe (1 piece)+ drill pipe (n pieces, determined by the well depth)+ weighted drill pipe (n pieces, determined by the drill assembly design).
The kelly pipe is located at the top of the drill string and has two kinds of square and six square.
1.When drilling, the kelly is matched with the bushing and the turntable bushing to transmit the ground rotating torque to the drill pipe to drive the drill string and bit rotation;
2.Bear the full weight of the drill string;
3.Channel for drilling fluid circulation.
Kelly pipe consists of upper and lower joints and pipe body parts. The pipe body part is of two kinds of structure (most of the oil drilling is of four square structure); The upper connector is the left female thread (reverse button), connected with the faucet, in the rotation process of the left female thread to prevent reverse; The lower joint is right-handed male thread and is connected with the drill pipe. When working, the upper end of the kelly is always above the turntable surface and the lower part is below the turntable surface.
Drill pipe is the basic component of drill string. Its main function is to transfer torque and transport drilling fluid, and by gradually lengthening the drill pipe to deepen the hole. Therefore, drill pipe plays a very important role in oil drilling.
Drill pipe structure Drill pipe is made of random steel pipe, the wall thickness is generally 9 ~ 11mm; The drill pipe body and the drill pipe joint are composed of two parts. The pipe body and the joint are welded together by friction welding.
Weighted drill pipe
The weighted drill pipe is similar to the oil drill pipe, which is also a hollow steel column with a length of about 10 meters. However, the single weight is heavier than the oil drill pipe, the wall thickness is 2 to 3 times that of the drill pipe, and the drill pipe is connected between the drill pipe and the drill collar, the purpose is to prevent the fatigue damage when the drill string cross-section changes, and it can also replace the role of a part of the drill collar, but its suspension is simple, the operation is convenient, and the drilling trip time can be saved.