Embodiments described herein provide an expanding and collapsing apparatus and methods of use. The apparatus includes a plurality of elements assembled together to form a ring structure about 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. At least one set of structural elements are operable to move between the expanded condition and the collapsed condition by movement of a first end in an axial direction, and by movement of a second end in a radial dimension. In certain embodiments, the plurality of elements includes at least one set of structural elements extending longitudinally on the apparatus and operable to slide with respect to one another. Applications of the embodiments described herein include oilfield devices, including anti-extrusion rings, plugs, packers, locks, patching tools, connection systems, and variable diameter tools run in a wellbore.

A technique facilitates use of a liner hanger in a borehole. A port free hydraulic unibody system including an outer structure having a tubing hanger portion and a packer portion mounted about a mandrel may be constructed so as to avoid the creation of leak paths. A seal system may be employed between the mandrel and the surrounding outer structure to ensure sealing engagement therebetween. The mandrel has a port free section on the downhole side of the seal system, and this port free section is maintained during, for example, actuation of the tubing hanger portion so as to prevent formation of leak paths. An actuator may be located along the mandrel and may be configured to initiate actuation of hanger slips mounted along the tubing hanger portion. An anti-preset mechanism positioned along the mandrel works in cooperation with the actuator to prevent premature actuation of the hanger slips.

A technique facilitates use of a liner hanger in a borehole. A port free hydraulic unibody system including an outer structure having a tubing hanger portion and a packer portion mounted about a mandrel may be constructed so as to avoid the creation of leak paths. A seal system may be employed between the mandrel and the surrounding outer structure to ensure sealing engagement therebetween. The mandrel has a port free section on the downhole side of the seal system, and this port free section is maintained during, for example, actuation of the tubing hanger portion so as to prevent formation of leak paths. An actuator may be located along the mandrel and may be configured to initiate actuation of hanger slips mounted along the tubing hanger portion. An anti-preset mechanism positioned along the mandrel works in cooperation with the actuator to prevent premature actuation of the hanger slips.

A sidetrack window is cut in a cased wellbore by disposing a sidetracking assembly within the cased wellbore. A first ball is deployed into a drill string of the sidetracking assembly. The first ball leaves the drill string and lands on a ball seat of a cement retainer to block fluid outlet of the cement retainer. Then, the cement retainer is set and a second fluid outlet of the cement retainer is exposed. Cement is flowed through the drill string to the portion of the cased wellbore downstream of the cement retainer to plug the portion of the wellbore. The whipstock assembly is separated from the cement retainer. A second ball is deployed inside the drill string to land on the seat of the whipstock assembly to block a fluid outlet of the whipstock assembly. The whipstock assembly is anchored in the cased wellbore and the milling system is actuated to begin cutting the sidetrack window.

Disclosed herein are embodiments of a pressure compensation piston and embodiments of rotary seal assemblies. In one embodiment, a pressure compensation piston for use with a rotary seal assembly includes a stepped piston having an opening extending there through for positioning the stepped piston about a rotatable shaft of a rotary seal assembly. In accordance with this embodiment, the pressure compensation piston further includes a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft.

Disclosed herein are embodiments of a pressure compensation piston and embodiments of rotary seal assemblies. In one embodiment, a pressure compensation piston for use with a rotary seal assembly includes a stepped piston having an opening extending there through for positioning the stepped piston about a rotatable shaft of a rotary seal assembly. In accordance with this embodiment, the pressure compensation piston further includes a rotary seal positioned along a radial surface of the opening for sealing the stepped piston relative to the rotatable shaft.

An isolation plug tool including a mandrel, an anchor assembly disposed on the mandrel, a seal assembly disposed on the mandrel having a seal, and a sleeve removably disposed radially outwardly of the seal.

Disclosed are an expansion tool assembly, comprising: an expandable tubular; a guide shoe partially inserted into and connected to the lower end of the expandable tubular; a sealing sleeve arranged in the expandable tubular and connected to the upper end of the guide shoe; an expansion assembly comprising an expansion cone and expansion seat disposed inside the expandable tubular, wherein the lower end of the expansion seat is connected with hooks, which can be rested on the upper end of the sealing sleeve; an upper joint that is connected to the upper end of the expansion seat and can be connected to a drill string. A force transfer path can be established via connection between the expansion seat and sealing sleeve, so that expandable tubular weight is borne on the drill string. Unintentional expansion of the expandable tubular, caused by interaction between expandable tubular and expansion cone, can be avoided.

Disclosed are an expansion tool assembly, comprising: an expandable tubular; a guide shoe partially inserted into and connected to the lower end of the expandable tubular; a sealing sleeve arranged in the expandable tubular and connected to the upper end of the guide shoe; an expansion assembly comprising an expansion cone and expansion seat disposed inside the expandable tubular, wherein the lower end of the expansion seat is connected with hooks, which can be rested on the upper end of the sealing sleeve; an upper joint that is connected to the upper end of the expansion seat and can be connected to a drill string. A force transfer path can be established via connection between the expansion seat and sealing sleeve, so that expandable tubular weight is borne on the drill string. Unintentional expansion of the expandable tubular, caused by interaction between expandable tubular and expansion cone, can be avoided.

Dissolvable pump down devices, dissolvable pump down assemblies, and methods to propel a bottomhole assembly through a lateral section are presented. A dissolvable pump down device includes an engageable portion, and one or more expandable pieces that are initially in a first position before the dissolvable pump down device is deployed in a wellbore, and configured to expand from the first position to a second position in response to a force generated by fluid flow of fluid through the wellbore. A diameter of the expandable pieces while the expandable pieces are in the first position is less than the diameter of the one or more expandable pieces while the one or more expandable pieces are in the second position. The engageable portion and the one or more expandable pieces are configured to dissolve after the dissolvable pump down device is positioned at the desired wellbore location.