How To Demagnetize The Drill Pipe?

Reasons for magnetization of the drill pipe

As an OCTG pipe, the drill pipe is often affected by the geomagnetic field or other electromagnetic interference during exploration operations, resulting in magnetization. If this magnetization is not eliminated in time, it will cause interference in the exploration data, affecting the accuracy and reliability of the exploration results.

Common demagnetization methods

1. Alternating current demagnetization method

Use a high-frequency AC power supply to generate an alternating electromagnetic field, so that the magnetic molecules inside the drill pipe move with the change of the electromagnetic field, disrupting the orderly arrangement of the magnetic domains to achieve demagnetization. During operation, immerse the drill pipe in a demagnetization tank containing demagnetization liquid, connect a high-frequency power supply, and conduct electricity through the demagnetization liquid to allow the drill pipe to be fully affected by the electromagnetic field.

2. DC demagnetization method

With the help of a DC power supply, a magnetic field in the opposite direction of the residual magnetism of the drill pipe is generated in the demagnetization coil, and the current is gradually reduced to make the magnetic domains in the drill pipe tend to be disordered. The drill pipe needs to be placed in a DC demagnetization coil, and the current is slowly adjusted to zero after the power is turned on.

3. Demagnetization method using AC demagnetizer

Use AC demagnetizer to generate alternating magnetic field, place the drill pipe in its effective magnetic field range, such as passing through the center hole or between the magnetic poles, start the demagnetizer and adjust the magnetic field strength and frequency to make the magnetic domain arrangement of the drill pipe disordered, and the magnetism weakened or disappeared.

4. Heating demagnetization method

According to the Curie point characteristics of magnetic material, when the drill pipe is heated to a temperature close to or exceeding its Curie point, the internal magnetic domain structure is destroyed due to the intensification of molecular thermal motion, and the magnetism is weakened or disappeared. The drill pipe can be evenly heated by oxyacetylene flame, medium frequency induction heating equipment, etc., and naturally cooled after reaching the corresponding temperature.

5. Demagnetization by tapping

By using tools such as sledgehammers to tap evenly and moderately along the length of the drill pipe, the orderly arrangement of the magnetic domains inside the drill pipe is disrupted by mechanical impact force, so that the magnetism is weakened or eliminated, but care should be taken to avoid excessive tapping to damage the drill pipe.

6. Vibration demagnetization method

Use equipment such as a vibration table to make the drill pipe vibrate continuously, or use pneumatic or electric vibration tools to vibrate the drill pipe locally in sections, so that the magnetic domains inside the drill pipe are disordered due to energy excitation, and the orderly arrangement of the magnetic domains is destroyed to achieve demagnetization.

Evaluation of demagnetization effect

In order to ensure the accuracy and reliability of the demagnetization effect, it is necessary to test and evaluate the drill pipe after demagnetization. Common evaluation methods include magnetometer testing and data processing. The magnetometer test can obtain the magnetization degree of the drill pipe, and data processing can finely process the exploration data to eliminate potential interference factors, thereby obtaining more accurate and reliable exploration results.

Conclusion

Drill pipe on-site demagnetization is a commonly used demagnetization treatment method in exploration operations, which can effectively eliminate the interference of drill pipe magnetization on exploration data. By understanding the causes of drill pipe magnetization, demagnetization methods and evaluation of demagnetization effects, we can better master the drill pipe demagnetization technology and ensure the accuracy and reliability of exploration data.