WELL SHAFT CALIBRATOR Russian patent published in 2009 - IPC E21B17/10 

FIELD: mechanics.

SUBSTANCE: invention refers to support and centering devices used in arrangement of drill column bottom at directed drilling of oil and gas wells. Well shaft calibrator includes upper and lower connection thread, internal channel for feeding flushing liquid to bottomhole, three or more blades with reinforced working surfaces separated from each other with flushing slots, and blade length L in it is related to working diametre of calibrator D_c with the following ratio: L/D_c=(0.7÷0.95). As reinforcing material for blades there used are plates made of polycrystalline diamonds (PDC) with flat external surface, which are installed flush with operating surface, and total area of reinforcing plates S₁ is related to operating blade area S₂ with the following ratio: S₁/S₂=(0.34÷0.48). External flushing channels between blades are uniformly extended along sectional area due to inclination of leading cutting edge at an angle α=(18°÷23°) clockwise to generatrix of calibrator cylindrical part, and trailing edge is made along generatrix of cylindrical part; at that, there provided is ratio of areas of space between bottom of channel and overall line of calibrator at channel outlet S₄ and at channel inlet S₃ within the following limits: S₄/S₃=(1.37÷1.52). Curved surface of flushing channels is smooth without passages and protrusions with unevenness Ra=(1.0÷4.0) mcm.

EFFECT: increasing manoeuvrability at drift angle of well, decreasing packing at directed drilling of viscous and sticky rocks.

4 cl, 4 dwg