Dailey Oil Tools, Inc.

Edward L Briscoe

A well jar having an elongated body with an axial passageway and threaded connections for assembly into a string of well pipe. The body has a tubular mandrel slideably mounted within a tubular barrel with the annulus therebetween exposed to well fluid. Fluid seals in the annulus provide an isolated chamber containing a latch whereby the mandrel and barrel are selectively released for delivering an impact to the wellpipe. The improvement to the jar comprises a plurality of elongated, resilient vibration snubbers integrally carried by the mandrel and aligned longitudinally in the annulus between the mandrel and the barrel. The snubbers slideably engage the barrel throughout its telescopic movement along the mandrel. The snubbers are circumferentially spaced apart about the mandrel with the intervening spaces forming flow channels in the annulus to accommodate well fluid flows when the jar is mounted in the string of well pipe being rotated in the well bore. In another embodiment, as a subcombination, an elongated, resilient vibration snubber is designed for mounting in a flat bottom groove in a cylindrical metal surface on a well jar. The snubber has a rectangular body of resilient synthetic rubber integrally bonded to a thin metal base. The base and body are provided with one or more transverse apertures to accommodate threaded fasteners. The body has a curved surface on the side opposite to its mounting on the base. Preferably, the snubber is formed of a synthetic rubber with a hardness of about 80 durometer shore-A.

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Sheridan, TX, United States of America

Edward L Briscoe