A shock absorber, related methods and apparatuses

摘要

A shock absorber 29 for downhole use includes an elongate, hollow member defined by a series of mutually aligned, plastically deformable perforated members having aligned perforations that define the hollowness of the elongate member. The perforations are spaced from one another in the direction of elongation by respective relatively rigid spacer members 39 that are secured to the perforated members. The elements of each pair of annuli 38 of the series are spaced from one another by one or more of the spacer members 39 such that on compression of the shock absorber the perforated members deform plastically to a lesser extent in regions at which the spacer members 39 are secured than at other regions. The arrangement of the perforated members and the spacer members 39 cause compression to occur substantially parallel to the length of the shock absorber. Also claimed is a logging assembly 10 comprising an elongate toolstring 14 inside a drillpipe where the toolstring 14 can impact a landing surface 24 and where there is a shock absorber 29 to attenuate impact energy fig 4.