CENTRALIZER Russian patent published in 1999 - IPC

FIELD: bore-hole drilling accessories. SUBSTANCE: centralizer is intended for centering lower part of string. Centralizer has hollow body and replaceable centering blade rigidly installed on turnable axle which is connected through large-thread trapezoidal or thrust thread with cylinder which is screwed in body. Thread for connecting cylinder with turnable axle is eccentrically displaced relative to thread for coupling with body. Radius of working surface of blade is somewhat larger than radius of bore-hole. Other end of turnable axle located in cylindrical axial passage of body is linked with single-arm lever. Free end of single-arm lever at delivery of liquid into string is displaced by means of spring-biased double-stage differential piston. Aforesaid embodiment of centralizer allows for adjustment of working diameter immediately before lowering it into bore-hole. Diameter can be restored according to degree of wear of centering (calibrating) member. Centering member can be retracted in body at round-trip operations. If necessary, differential pressure brought to bear on bottom hole can be reduced. Realizable is high-frequency hydrodynamic excitation of washing fluid for improving bottom-hole washing conditions. EFFECT: higher efficiency. 5 cl, 3 dwg