How to judge whether the roller cone bit is normal in the downhole?

What should be paid attention to when drilling with a roller cone bit?


(1) After the drill bit reaches the bottom of the well, it should run with light pressure for about 0.5h, and then gradually increase the pressure to the specified drilling pressure. It is strictly forbidden to pressurize and start the turntable.

(2) When operating the brake lever, the mind should be concentrated, the drill should be sent evenly, and the accidents of slipping and stopping the drill should be strictly prevented.

(3) During drilling, analyze at any time according to the change of drilling time and the operation of the drill bit, grasp the change of lithology, and adjust the parameters to meet the needs of the drilled formation.

(4) Master the drilling time. Under normal circumstances, the working time of the drill bit depends on the life of the teeth and bearings.

How to judge whether the roller cone bit is normal in the downhole?

1. Collect as much information as possible to make a comprehensive judgment.

2. Judgment of cutting the borehole wall by reducing the diameter of the drill bit

The torque of the turntable increases, the downhole drilling is poor, and the rotation speed of the turntable changes greatly. The rotation speed of the turntable changes uniformly in a wave shape on the curve, and the torque does not increase and decreases slowly without drilling. Drilling with small drilling pressure and low speed can not alleviate the downhole poor drilling. The lithology remains unchanged, and the drilling time doubles. After stopping the pump, there is no jamming when lifting and lowering the drilling tool, and there is no large debris on the vibrating screen. It can be analyzed that the diameter of the drill bit shrinks and the screw helps to cut the well wall.

3. Judgment of bearing damage of roller cone bit

When repressurizing, the torque and the rotating speed of the turntable are different, sometimes it is very stable, and sometimes the torque fluctuates abnormally; when repressurizing, the pointer of the weight gauge swings (not a jumping drill).

4. In most cases, tooth loss is in the first 40 hours.

5. The torque of sandstone formation is larger than that of mudstone formation and changes frequently within a small range, while that of mudstone formation is relatively stable.

6. Judgment of large cuttings that cannot be returned in the wellbore

During drilling, the torque amplitude of the turntable changes greatly, large pieces of cuttings come back, the screw centralizers that are pulled out are worn to varying degrees, the drill gets stuck, and the pump is lame.

7. When lost circulation or well collapse occurs, the torque of the rotary table increases, and the downhole drilling is poor.

8. Most of the roller cone bits can be used in normal life.

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