Kelly, Drill Pipe, Heavy Weight Drill Pipe

Drill PipeKelly, Drill Pipe, Heavy Weight Drill Pipe

Drill pipe is divided into three types: Kelly, drill pipe and heavy weight drill pipe. The connection sequence is a Kelly (1 joint) + drill pipe (number of joints, depends on well depth) + heavy weight drill pipe (number of joints, depends on drill string design).

Kelly

The Kelly is located at the top end of the drill string, with two sides and six sides.

Function：

(1) when drilling, the Kelly is matched with the core and the rotary table for bushing, and the rotary table torque is transmitted to the drill pipe to drive the drill string and the bit to rotate.

(2) bear the full weight of the drill string;

(3) the circulation channel of drilling fluid.

Structure:

The square Kelly is composed of the upper and lower joints and the pipe body part.  The Kelly body part is a four or six party structure (most of the oil drilling is a square shape); the upper joint is the upper joint as the left hand thread (bucked on), and the tap is connected to the faucet. In the process of rotation, the left-hand thread prevents the buckle; the lower joint is the right hand, and the kelly is connected to 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

Function：

The drill pipe is the basic component of the drill string. Its main role is to transfer torque and transport drilling fluid, and gradually increase the drill pipe to further deepen the borehole. Therefore, drill pipe plays a very important role in oil drilling.

Structure:

The drill rod structure drill rod is made from no steel tube, the thickness of the wall is usually 9 ~ 11mm, and the pipe body of the drill pipe and the two part of the drill pipe joint is welded together with the joint by friction welding.

Heavy weight drill pipe:

The heavy weight drill pipe is similar to the oil drill pipe. It is also a hollow steel drill string with a length of about 10 meters. But the single weight is heavier than the oil drill pipe, and the wall thickness is 2~3 times of the drill pipe. The heavy weight drill pipe is connected between the drill pipe and the drill collar. The purpose is to prevent the fatigue damage caused by the variation of the drill string section. It can also replace a part of the drill collar, but its suspension is simple, and the drilling operation can be saved and the drilling time can be saved.