Abstract: 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.

Abstract: A drill string in a well bore has a mandrel extending longitudinally thereof adjacent the lower end of the drill string with a drill bit connected to the mandrel. Longitudinally extending helical groove means are provided in the mandrel and roller means are supported on the drill string and engaged with the helical groove means. Spring means is supported by the drill string and abuts the mandrel to tend to urge the mandrel longitudinally out of the drill string whereby the bit is urged into substantially continuous contact with the well bore bottom as the drill string is rotated during drilling operations. Valve means are provided for selectively circulating fluids from the drill string to the well bore above the drill bit, and when desired jar means may be incorporated in the drill string to impart an up or down jar thereto should the drill string become stuck or tend to become stuck during drilling operations.

Abstract: A drill string in a well bore has a mandrel extending longitudinally thereof adjacent the lower end of the drill string with a drill bit connected to the mandrel. Longitudinally extending helical groove means are provided in the mandrel and roller means are supported on the drill string and engaged with the helical groove means. Spring means is supported by the drill string and abuts the mandrel to tend to urge the mandrel longitudinally out of the drill string whereby the bit is urged into substantially continuous contact with the well bore bottom as the drill string is rotated during drilling operations. Valve means are provided for selectively circulating fluids from the drill string to the well bore above the drill bit, and when desired jar means may be incorporated in the drill string to impart an up or down jar thereto should the drill string become stuck or tend to become stuck during drilling operations.

Abstract: A drill string in a well bore has a mandrel extending longitudinally thereof adjacent the lower end of the drill string with a drill bit connected to the mandrel. Longitudinally extending helical groove means are provided in the mandrel and roller means are supported on the drill string and engaged with the helical groove means. Spring means is supported by the drill string and abuts the mandrel to tend to urge the mandrel longitudinally out of the drill string whereby the bit is urged into substantially continuous contact with the well bore bottom as the drill string is rotated during drilling operations. Valve means are provided for selectively circulating fluids from the drill string to the well bore above the drill bit, and when desired jar means may be incorporated in the drill string to impart an up or down jar thereto should the drill string become stuck or tend to become stuck during drilling operations.