Abstract: A lifting apparatus for lifting drill string components from a wellbore, the lifting apparatus comprising: upper and lower support elements, each of the support elements having a central aperture passing therethrough; a lifting arrangement which is operable to vary the distance between the upper and lower support elements between a first, relatively short distance and a second, relatively long distance; and selective gripping arrangements held or supported by the upper and lower support elements, respectively, each selective gripping arrangement being operable to apply a gripping force to the exterior of a substantially tubular element passing through the central apertures of the upper and lower support elements, wherein the selective gripping arrangements may be activated or deactivated independently of one another.

Abstract: A lifting apparatus for lifting drill string components from a wellbore, the lifting apparatus comprising: upper and lower support elements, each of the support elements having a central aperture passing therethrough; a lifting arrangement which is operable to vary the distance between the upper and lower support elements between a first, relatively short distance and a second, relatively long distance; and selective gripping arrangements held or supported by the upper and lower support elements, respectively, each selective gripping arrangement being operable to apply a gripping force to the exterior of a substantially tubular element passing through the central apertures of the upper and lower support elements, wherein the selective gripping arrangements may be activated or deactivated independently of one another.

Abstract: A vibrator apparatus for inducing longitudinal vibrations in a well tubing or casing member for various operations, or for removing stuck tubing or casing. The apparatus includes a vibrator section with spaced apart rotatable shafts carrying eccentric weights and interconnected by timing gears. The shafts are driven by respective pressure fluid motors. The vibrator section is mounted on an isolator section including spaced apart pressure fluid cylinder assemblies for isolating vibrations generated by the apparatus from wellhead structure supporting the apparatus. A fluid flow circuit includes a pump, a manifold, flow control devices for generating fluid flow through the cylinder assemblies and accumulators for damping fluid pressure and flow fluctuations in the circuit.