Patent ID: 7669665

Claim:
A mandrel for insertion in a borehole in which a fluid circulates, the mandrel comprising: a body having a longitudinal axis; and a radially-expandable annular assembly attached to the body, the radially-expandable annular assembly including: a first peripheral surface for pressing against the borehole; a second peripheral surface for pressing against the body; and a plurality of radial expansion blocks, each radial expansion block of the plurality of radial expansion blocks having a first bearing face defining a portion of the first peripheral surface, a second bearing face defining a portion of the second peripheral surface, and two side surfaces disposed on opposite sides of the radial expansion block, the plurality of radial expansion blocks being disposed about the longitudinal axis of the body so that each side surface of each radial expansion block faces a side surface of an adjacent radial expansion block, wherein radial expansion blocks of the plurality of radial expansion blocks are displaceable relative to one another, and wherein the radially-expandable annular assembly has a radially-expanded, engaged configuration in which each side surface of each radial expansion block is pressed against the side surface of the adjacent block, and the radially-expandable annular assembly has a radially-contracted configuration having a radial size smaller than a radial size of the radially-expandable annular assembly in the radially-expanded, engaged configuration, wherein the body includes a block-bearing surface, wherein the first bearing face of each radial expansion block is substantially cylindrical about the longitudinal axis and the second bearing face of each radial expansion block is inclined relative to the longitudinal axis, wherein, for each radial expansion block, the first bearing face and the second bearing face are interconnected by the two side surfaces, wherein at least one radial expansion block of the plurality of radial expansion blocks is mounted so as to be able to slide longitudinally over the block-bearing surface between a position in which the radially-expandable annular assembly is in the radially-contracted configuration and a position in which the radially-expandable annular assembly is in the radially-expanded, engaged configuration, and wherein the block-bearing surface is inclined relative to the longitudinal axis.