DEVICE FOR DEMAGNETISATION OF DRILLING TOOL Russian patent published in 2016 - IPC H01F13/00 E21B12/00 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and is intended for demagnetisation of drilling tool directly in drill string. Demagnetisation device comprises a coil for passage of degaussed drilling string, rotor for rotating drill string, placed at wellhead above coils, electric drive control system of draw works intended for lifting of drilling string in casing string. Coil is installed on external surface of well casing string. On rotor there is magnetic field sensor. Signal of presence or absence of magnetic field on drill string from magnetic field sensor is supplied to input of excitation current regulator with indication unit, output of which is connected to input of timer and to input of lowering - raising speed limitation unit. Signal from output of lowering - raising speed limitation unit is transmitted to drill winch electric drive control system speed controller. Output of timer is connected to input of controlled power source, which output is connected with coil in form of solenoid with ferromagnetic core with winding from isolated copper wire. Solenoid and winding consist of two identical parts, joined from one side by hinge and on other side is by latch.

EFFECT: technical result consists in improvement of quality of demagnetising control value of magnetisation of drilling string and reduction of metal consumption and speed of their assembly and disassembly.

1 cl, 2 dwg