What Is a Drill Pipe?

The drill pipe ^[1] is a steel pipe with a thread at the tail, which is used to connect the surface equipment of the drilling rig with the drilling and grinding equipment or bottom hole device at the bottom of the well. The purpose of the drill pipe is to transport drilling mud to the drill bit, and to raise, lower or rotate the bottom hole device with the drill bit. The drill pipe must be able to withstand huge internal and external pressures, twists, bends, and vibrations. During oil and gas extraction and refining, drill pipes can be used multiple times. The drill pipe is divided into three types: square drill pipe, drill pipe and weighted drill pipe. The connection order is square drill pipe (1) + drill pipe (n, determined by the depth of the well) + weighted drill pipe (n, determined by the combination of drilling tools). The classification of drill pipe, drill pipe joints, drill pipe specifications, and steel grade and strength of drill pipe are introduced in detail.

The drill rod is threaded at the tail

The drill pipe is divided into three types: square drill pipe, drill pipe and weighted drill pipe. The connection order is square drill pipe (1) + drill pipe (n, determined by the depth of the well) + weighted drill pipe (n, determined by the combination of drilling tools).

According to the rules of the American Petroleum Institute (API), drill pipes are divided into three types according to length (L): the first type: 5.486-6.706m (18-22ft); the second type (common): 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 rod size (D): 88.9, 114.3, 127mm (conventionally expressed in inch sizes: 3 1/2 4 ½ 5 ) three kinds ^[5]

The steel grade of drill pipe refers to the grade of drill pipe steel ^[5] , which is determined by the yield strength of drill pipe steel. API (American Petroleum Institute) classifies drill pipe steel grades into five grades: D, E, 95 (X), 105 (G), 135 (S). The 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. In the design of the strength of the drill string, it is recommended to increase the strength of the drill string by increasing the steel grade instead of increasing the upset.