Abstract: The invention provides an expanding and/or collapsing apparatus (10) and a method of use. The apparatus comprises a plurality of elements (12) assembled together to form a ring structure oriented in a plane around a longitudinal axis. The ring structure is operable to be moved between an expanded condition and a collapsed condition by movement of the plurality of elements. The plurality of elements is operable to be moved between the expanded and collapsed conditions by sliding with respect to one another in the plane of the ring structure, in a direction tangential to a circle concentric with the ring structure. Applications of the invention include oilfield devices, including anti-extrusion rings, plugs, packers, locks, patching tools, connection systems, and variable diameter tools run in a wellbore.

Abstract: An apparatus for use in a fluid conduit comprises a plurality of segments arranged along a longitudinal axis, each segment comprising an extendable structure configured for extension in a lateral direction relative to the longitudinal axis, wherein the apparatus is configured for the sequential initiation of lateral extension of the extendable structures of at least two segments. At least two segments may be configured to define different maximum extended dimensions in the lateral direction and may include adjacent support surfaces which provide mutual support for one another when the at least two segments are laterally extended. The apparatus may be configured to form a seal, an anchor, a supporting structure and/or a flow restriction in a fluid conduit.