Hydraulic lockdown

Patent metadata

Field	Value
Publication number	US-2016177651-A1
Application number	US-201414578028-A
Country	US
Kind code	A1
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

A subsea well connector for connecting a tubular member to a subsea wellhead assembly includes a tieback connector having an annular stationary connector body that circumscribes a portion of an annular moveable connector body. A tie rod with a tie rod profile extends axially from the stationary connector body. A dog ring circumscribes the tie rod and is moveable between a lockdown open position where the dog ring is spaced from the tie rod, and a lockdown engaged position where a dog ring inner diameter profile engages the tie rod profile, to axially couple the stationary connector body and the moveable connector body. An annular piston circumscribes the dog ring and has a region with a reduced inner diameter that engages an outer diameter of the dog ring to retain the dog ring in the lockdown engaged position. A cylinder circumscribes the annular piston, defining a lockdown piston cavity.

First claim

What is claimed is:

1 . A subsea well connector for connecting a tubular member to a subsea wellhead assembly, comprising:
a tieback connector having a stationary connector body and a moveable connector body, the stationary connector body and the moveable connector body being annular members and the stationary connector body circumscribing a portion of the moveable connector body; a tie rod extending in an axial direction from the stationary connector body, the tie rod having a tie rod profile on a tie rod outer diameter; a dog ring with an inner diameter profile circumscribing the tie rod, the dog ring being moveable between a lockdown open position where the dog ring is spaced radially outward from the tie rod, and a lockdown engaged position where the inner diameter profile engages the tie rod profile, to axially couple the stationary connector body and the moveable connector body, wherein the tie rod profile extends an axial height along the tie rod that is greater than an axial height of the inner diameter profile such that the in the lockdown engaged position, the inner diameter profile is operable to engage the tie rod profile at one of a plurality of axial locations along the tie rod profile; an annular piston circumscribing the dog ring, the annular piston having a region with a reduced inner diameter that engages a dog ring outer diameter of the dog ring to retain the dog ring in the lockdown engaged position; and a cylinder that circumscribes the annular piston, defining a lockdown piston cavity.

2 . The subsea well connector according to claim 1 , further comprising an annular ring secured to an upper end of the moveable connector body, wherein the tie rod passes through a hole that extends axially through the annular ring, and wherein the dog ring is supported by an upper surface of the annular ring.

3 . The subsea well connector according to claim 1 , further comprising a biasing member, the biasing member having a first end engaging a top surface of the annular piston, urging the annular piston downward to retain the dog ring in the lockdown engaged position.

4 . The subsea well connector according to claim 1 , wherein the dog ring is biased to move to the lockdown open position when the annular piston is in an axially upper location and wherein the dog ring is in the lockdown engaged position when the annular piston is in an axially lower location.

5 . The subsea well connector according to claim 1 , further comprising an injection port extending through the cylinder and into the lockdown piston cavity, selectively receiving a pressure media for moving the annular piston upward to allow the dog ring to move to the lockdown open position.

6 . The subsea well connector according to claim 1 , the tieback connector further comprising a locking system, the locking system being moveable between a connector engaged position where the tieback connector is secured to a lock housing of the subsea well connector and a connector unengaged position where the tieback connector is moveable relative to the lock housing, the locking system being moveable between the connector engaged position and the connector unengaged position by relative axial movement between the stationary connector body and the moveable connector body.

7 . The subsea well connector according to claim 6 , wherein the dog ring can be in the lockdown engaged position when the tieback connector is in the connector engaged position and when the tieback connector is in the connector unengaged position.

8 . The subsea well connector according to claim 1 , wherein the subsea well connector has a plurality of tie rods spaced around a circumference of the stationary connector body.

9 . A subsea well connector for connecting a tubular member to a subsea wellhead assembly, comprising:
a tieback connector moveable between a connector engaged position where the connector assembly is secured to the subsea wellhead assembly, and a connector unengaged position where the connector assembly is moveable relative to the subsea wellhead assembly; a tie rod extending in an axial direction from the tieback connector, the tie rod having a tie rod profile on a tie rod outer diameter; a dog ring with an inner diameter profile circumscribing the tie rod, the dog ring being moveable between a lockdown open position where the tie rod can move axially relative to the dog ring, and a lockdown engaged position where the inner diameter profile engages the tie rod profile and restricts the tieback connector from moving between the connector engaged position and the connector unengaged position, the dog ring being biased towards the lockdown open position, wherein the tie rod profile extends an axial height along the tie rod that is greater than an axial height of the inner diameter profile such that the in the lockdown engaged position, the inner diameter profile is operable to engage the tie rod profile at one of a plurality of axial locations along the tie rod profile; an annular piston circumscribing the dog ring, the annular piston having a region with a reduced inner diameter that engages a dog ring outer diameter of the dog ring to retain the dog ring in the lockdown engaged position and a region with an enlarged inner diameter that allows the dog ring to move to the lockdown open position; and a cylinder that circumscribes the annular piston, defining a lockdown piston cavity.

10 . The subsea well connector according to claim 9 , wherein the tieback connector includes a stationary connector body and a moveable connector body, the stationary connector body and the moveable connector body being annular and the stationary connector body circumscribing a portion of the moveable connector body, and wherein relative axial movement between the stationary connector body and the moveable connector body moves the tieback connector between the connector engaged position where the connector assembly is secured to the subsea wellhead assembly and the connector unengaged position where the connector assembly is moveable relative to the subsea wellhead assembly.

11 . The subsea well connector according to claim 9 , further comprising a cylinder cap located on an upper end of the cylinder and a biasing member, the biasing member having a first end engaging a top surface of the annular piston, and a second end engaging the cylinder cap, the biasing member urging the annular piston downward to retain the dog ring in the lockdown engaged position.

12 . The subsea well connector according to claim 9 , wherein the cylinder has an inner diameter that sealingly engages an outer diameter of a radially extending flange of the annular piston, the cylinder further comprising an injection port extending through the cylinder and into the lockdown piston cavity, the lockdown piston cavity selectively receiving a pressure media for moving the annular piston upward to allow the dog ring to move to the lockdown open position.

13 . The subsea well connector according to claim 9 , wherein the dog ring alternately selectively engages the tie rod profile and restricts the tieback connector in the connector engaged position and selectively engages the tie rod profile and restricts the tieback connector in the connector unengaged position.

14 . The subsea well connector according to claim 9 , wherein the subsea well connector has a plurality of tie rods and dog rings spaced around a circumference of the tieback connector each of the dog rings being simultaneously moved between the lockdown open position and the lockdown engaged position.

15 . A method of connecting a tubular member to a subs

Assignees

• Vetco Gray Inc

Inventors

• Lyle Rockford Dee

Classifications

• E21B19/002

  specially adapted for underwater drilling (E21B19/09, E21B19/143 take precedence) · CPC title

• E21B33/038 Primary

  Connectors used on well heads, e.g. for connecting blow-out preventer and riser · CPC title