APPARATUS TO MAKE SLOT PERFORATION OF CASING STRING Russian patent published in 1995 - IPC

FIELD: drilling. SUBSTANCE: apparatus has body with extendable cutting tool, made in the form of rolling roller with one or several cutting disks and form creating surface. Apparatus has spring-loaded cantilever, connected with axis of rolling roller. Cantilever is mounted with capability for axial motion. Supporting rollers are placed on opposite to rolling roller side. Apparatus has hydraulic cylinder, piston of which is spring-loaded and is connected with spring-loaded cantilever, on which hydromonitoring extension piece, that hydraulically connects cavity of pump-compressor string pipes with outer space. Hydromonitoring extension piece is oriented to working zone of form creating surface of rolling roller. Facing hydraulic cylinder body is made with throttling holes, communicating under piston space of hydraulic cylinder with outer space. Body of supporting roller has groove to match axis of rolling roller. EFFECT: prevents destruction of rolling roller during hydraulic hits during lifting-lowering operations. 3 dwg