The oil drill pipe is the basic part of the drill string. It is made of seamless steel pipe (the wall thickness is generally 9~11mm).
Its main function is to transmit torque and transport drilling fluid. deepen. Therefore, drill pipe occupies a very important position in oil drilling.
Drill pipe structure and specification
The drill pipe is composed of seamless steel pipes, and the wall thickness is generally 9~11mm.
It consists of two parts: the drill pipe body and the drill pipe joint.
There are two ways to connect the pipe body joint of the drill pipe:
one is to connect with a thin thread button, that is, there are thin male buttons at both ends of the pipe body, which are connected with the female thin button at one end of the joint, which is called a thin thread.
The drill pipe is buckled; the other is that the pipe body and the joint are butt welded together by friction welding, which is called the butt welding drill pipe.
Drill pipes with fine buckles have been basically eliminated at present, and all drill pipes produced or imported in my country are butt welded drill pipes (drill pipes without fine buckles).
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In order to enhance the connection strength between the pipe body and the joint, both ends of the pipe body are thickened.
Commonly used thickening forms are internal thickening, external thickening, and internal and external thickening.
According to the regulations of the American Petroleum Institute (API-American Petroleum Institute), drill pipe is divided into three categories by length:
- R1 ：5.486~6.706m(18~22ft)；
- R2：8.230~9.144m(27~30ft)；
- R3:11.582~13.716m(38~45ft)；
The most commonly used drill pipe sizes are 88.9 (3.5in), 114.3 (4.5in), and 127.0mm (5in).
The outer diameter of the drill pipe joint is larger than the outer diameter of the pipe.
During the drilling process, it is constantly in contact and friction with the well wall or casing, resulting in wear. Equipped with drill pipe joint wear belt.
Grade and strength of drill pipe
The steel grade of the drill pipe refers to the grade of the steel of the drill pipe, which is determined by the minimum yield strength of the steel of the drill pipe.
API stipulates that the steel grades of drill pipe include:
D, E, 95(X), 105(G), and 135(S) grades, of which X, G, and S grades are high-strength drill pipes.
Our productsthe higher the steel grade of the drill pipe, the greater the yield strength of the pipe, and the greater the various strengths of the drill pipe (tensile resistance, torsion resistance, extrusion resistance, etc.).
I have in the strength design of the drill string. it is recommended to increase the strength of the drill string by increasing the steel grade, rather than increasing the wall thickness.