How do non-magnetic drill collars work?

1. Function of non-magnetic drill collar

Since all magnetic measuring instruments sense the geomagnetic field of the wellbore when measuring the orientation of the wellbore, the measuring instrument must be in a non-magnetic environment. However, during the drilling process, drilling tools are often magnetic and have a magnetic field, which affects magnetic measuring instruments and cannot obtain correct wellbore trajectory measurement information. The use of non-magnetic drill collars can provide a non-magnetic environment and have the characteristics of drill collars in drilling. .

The working principle of the non-magnetic drill collar is shown in the figure. Since the interference magnetic field lines above and below the drill collar have no effect on the measuring instrument, a non-magnetic environment is created for the magnetic measuring instrument, ensuring that the data measured by the magnetic measuring instrument is true. geomagnetic field information.

2. Non-magnetic drill collar materials

Non-magnetic drill collar materials include Monel alloy, chromium-nickel steel, austenitic steel based on chromium and manganese, copper-plated alloy, SMFI non-magnetic steel, domestic manganese-chromium-nickel steel, etc.

Landrill supplying drill collars in standard and spiralled from 3-1/8’’OD up to 14’’OD in accordance with API, NS-1 or DS-1 specifications.