GEAR FOR TERMINATION OF BOREHOLES Russian patent published in 1994 - IPC

FIELD: drilling. SUBSTANCE: gear for termination of boreholes has casing string. In radial holes of its side walls there are installed guiding bushings with extensible members placed in them. The latter are manufactured in the form of sleeves mounted with ring edges outside casing string. Tool to cut parts of gear entering casing string is mounted in it. Ring edges of extensible members are conically sharpened from outside and are manufactured from soft or flexible material for hard rocks or from hard material for soft rocks. Gear includes cutting tool fabricated in the form of sharpened bushing which common length with grouting plug is bigger than length of perforated section of string. Blind holes of extensible members are filled with highly viscous medium with coarsely divided filler and flexible bushings produced from non-acid-resistant rubber are put into them. EFFECT: enhanced operational reliability. 6 dwg