FIELD: mining.
SUBSTANCE: invention relates to a method and a system for reducing vibrations of a drill string. Method and a system for reducing or preventing at least axial or torsional vibrations in a drill string with a drill bit attached to its bottom end and controlled by a lifting mechanism and a rotating mechanism attached to its top end, herewith the controlled variables are vertical speed and rotation speed, and the variable of response are axial tension force and torque related to the top of the drill string, herewith, this method includes the following steps: i) selected is at least one oscillation mode of the drill string to be controlled; ii) performed is monitoring of the controlled variable and the variable of response relevant for the said oscillation mode; iii) defined is a period of oscillation of the said mode; iv) evaluated is dynamic rate of the drill bit basing on the relevant variables of response of the said mode; v) determined is the rate pulse able to generate vibrations with an amplitude, in fact, equal to the amplitude of the said evaluation rate of the drill bit; and vi) initiated is an adjustable without a feedback speed change by adding the said rate pulse to a setting the rate operator command, when the amplitude of the said evaluation of the bit rate exceeds certain threshold level, while counterphase of the said evaluation of the bit rate corresponds to the oscillation phase generated by the pulse.
EFFECT: technical result is elimination or considerable reduction of sudden oscillations in the drill string.
7 cl, 9 dwg
