Schlumberger

Tieback Connector

Collet connectors increase tieback installation safety and efficiency

Tieback connectors are the crucial element providing a robust and reliable connection between the subsea well and the top-tensioned riser (TTR) systems, maintaining pressure integrity while transferring the dynamic loads from the riser through the subsea wellheads to the seafloor. The tieback connector has an annular piston design, which limits the maximum OD to 32.50 in. Hydraulic pressure acting on the piston activates collet segments similar to those in a traditional collet connector.

Tieback Connector

In the locked position, the segments close around the 18 3/4-in wellhead mandrel. The Cameron collet connector technology, in a high-capacity and compact envelope, has been proven to deliver best-in-class bending, tensile, and fatigue resistance capabilities in more than 2,000 subsea well applications.

The reduced OD allows installation through standard rotary tables without the need to modify the drill floor setup, speeding up installation time and reducing HSE and risk exposure. The collet design features direct load-transfer paths through high-strength structural members, large misalignment tolerance during installation (or disconnect), and the ability to perform multiple make-break cycles when deployed subsea. These features translate to superior fatigue and operation performance and allow for a large installation and operational window, resulting in faster run times and lower rig and operational downtime.

Design features and advantages

  • ROV operation: Hydraulic functions are operated via an ROV panel mounted above the connector to the stress joint.
  • Metal-to-metal sealing: A metal-to-metal AX/VX gasket seals the connector to the wellhead.
  • High load-bearing capacity: The connector has been tested to withstand bending loads of 2,300,000 ft.lbf at 5,500 psi bore pressure (gauge pressure) and 2,800,000 ft.lbf at 0 psi bore pressure (gauge pressure) while maintaining the metal-to-metal seal interface.
  • Positive unlock: The unlock piston can unlock the connector with up to a 0.30 coefficient of friction. The connector also has a mechanical override that serves as an emergency disconnect.
  • Positive disengagement: A collet disengagement ring grips the bottom of the collets when the connector is unlocked, pulling them back into the shell and retaining them during disengagement.
  • Misalignment protection: The retracted collets form a cone at the connector bottom that permits a 5° misalignment angle relative to the wellhead to prevent damage of the gasket seal area during installation.

Specifications

Connector Bending, ft.lbf OD, in
Slim 2,800,000 32.5
High capacity 5,300,000 59.0

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