GB1426481A - Hydraulic tools for use in drill strings - Google Patents

Abstract

1426481 Boring earth &c LEE-MASON TOOLS LTD 20 March 1973 13212/73 Heading E1F A hydraulic tool for incorporation into a drill string to free the string when stuck by jarring upwardly or bumping downwardly, comprises a barrel 6 and a mandrel 5 received therein in spaced relationship to define a bumper hydraulic chamber 15, Fig. 1b, and a jar hydraulic chamber 16, and abutment means 21, 22, Fig. 1a, and 6a, 19. The mandrel 5 is held from rotating relative to the barrel 6 by means of male and female splined members 2 and 3, respectively. Relative longitudinal movement of the barrel and mandrel is possible between a fully-contracted position (as shown) where impact faces 21, 22 abut to bump the string downwardly, and a fully-extended position (Figs. 3a to 3c not shown) where impact faces 6a, 19 abut to jar the string upwardly. Intermediate the chambers 15, 16 is provided a reduced section 10 having grooves 55 in the wall thereof, and the mandrel is provided with a slidably-mounted valve sleeve 20 having grooves (52), Fig. 8 (not shown), in its upper edge. In order to jar, the drilling string and therefore the mandrel are drawn upwardly until the valve sleeve 20 enters the section 10 whereupon friction forces the sleeve downwardly into sealing contact with a valve seat 18 and fluid flow between the sleeve and mandrel is blocked. As the mandrel continues upwardly a restricted passage exists between the sleeve and section 10 which causes an increase in fluid pressure in jar chamber 16, and when the sleeve moves out of section 10 and into chamber 16 the mandrel jerks forwardly until impact faces 6a, 19 slam together. In order to bump, the drill string is released and the mandrel drops unseating valve sleeve 20 thereby allowing fluid flow between the sleeve and mandrel allowing the sleeve 20 to drop easily through reduced section 10 until impact faces 21, 22 slam together. To remove mud etc. from between the splines of the female member 3 during contraction of the tool a frusto-conical base 28 and inclined ports 27 are provided. The mandrel in the contracted condition of the tool extends into a sub 7, Fig. 1c (not shown), the lower end of the sub being connected to the lower section of drill string. Fixed seals 13 and a floating seal 14 responsive to mud pressure are provided between the barrel 6 and mandrel 5.