Shock absorber for a downhole tool, and running gear for downhole surveying

Abstract

A shock absorber (24) for a downhole tool (18) is disclosed. The shock absorber (24) includes a downhole portion (32) defining a bore (34), and an uphole portion (36) configured for direct or indirect connection to the downhole tool (18). The uphole portion (36) has a stanchion (38) extending from one end and which carries a piston (40). The piston (40) is slidably engaged with the bore (34) to allow relative axial movement of the uphole portion (36) and the downhole portion (32). A first resiliently deformable member (42) is arranged between the uphole portion (36) and the downhole portion (32), and arranged to be compressed when the uphole portion (36) and downhole portion (32) move axially relative to each other in a first direction. A second resiliently deformable member (44) is arranged between an end of the bore (34) and the piston (40) to be compressed when the uphole portion (36) and downhole portion (32) move axially relative to each other in a second direction opposite to the first direction.

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