DRILLING BIT UNIT WITH LEAD BIT FOR ROTARY DRILLING WITH DRILLING DIRECTION CONTROL Russian patent published in 2008 - IPC E21B10/26 

FIELD: well drilling, particularly to drill well bore to underground reservoir.

SUBSTANCE: drilling bit unit comprises drilling bit body including front body surface with annular section, lead bit extending along central longitudinal axis and partly arranged inside drilling bit body and hinge device. Annular section of front body surface has milling members. Lead bit projects from central part of front drilling bit body surface. The hinge device provides rotary connection of lead bit with drilling bit body so that drilling bit body axis and lead bit axis define varying bit deviation angle. Drilling bit unit also has direction control device, which rotates lead bit to change lead bit direction.

EFFECT: simplified directional drilling bit structure.

13 cl, 1 dwg