GB340292A - Improvements in or relating to fishing tools for use in well drilling operations - Google Patents

Abstract

340,292. Borehole apparatus. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.- (Doheny-Stone Drill Co. ; Torrance, California, U.S.A.) July 8, 1929, No. 20909. [Class 85.] A tool for recovering lost drills, casing &c. from wells comprises a barrel adapted to fit over the drill &c. and provided with wedge slips individually movable longitudinally and radially to grip the drill &c., an annular follower of rigid material acting directly on the upper ends of the slips to move them into corresponding positions. The barrel 11 has a spiral lower end, of which the vertical edge 23 may be pressed outwardly to facilitate centring the drill &c. Wedge slips 38 are mounted in inclined ways 37 and have a tongue and groove connection 42 therewith. The slips preferably have thread-like serrations on their gripping faces, whereby, if the drill &c. is immovable, the tool may be released therefrom by rotation. Above the slips is a loose tubular member 46 from which fingers 48 depend one into each way 37, the member 46 containing a rubber &c. ring 52 adapted to be adjusted to the desired diameter by a threaded ring 57a ; in a modification, the rubber &c. ring is arranged in an outer ring separate from, and resting on, the member 46. The ring 52 has a bevelled lower end resting on a corresponding seat and has an annular upper extension 55 engaging a recess in the ring 57a. In use, the tool is lowered over the work, fingers 48 tending to keep the slips level ; the slips are then engaged with the work by an upward pull. As the ring 52 closes the space between the work and the barrel, the pressure of the flushing fluid may then be used to act on the ring 52 as a piston to cause the slips to take a tighter grip. The ring 52 may be omitted, the bore of the member 46 then engaging the work.