US 6,179,053 B2 · Lockdown mechanism for well tools requiring fixed-point packoff

Abstract

An apparatus for securing a mandrel of a well tool in an operative position in which the mandrel is packed off against a fixed-point in the well is described. The apparatus includes a mechanical lockdown mechanism to secure the tool to the wellhead and maintain the mandrel in proximity to the fixed-point for packoff, and a mechanical or a hydraulic mechanism to move the mandrel into the operative position while the mechanical lockdown mechanism is in a lockdown position. A second mechanical locking mechanism is provided to ensure the mandrel is maintained in the operative position in the event that hydraulic pressure is lost. The invention provides a mechanism to lock down well tools requiring fixed-point packoff in a well and advantageously improves the range of adjustment of the lockdown mechanism so that the length of a mandrel may be less precisely matched to a distance from a top of the wellhead to the fixed-point in the well.

Claims27

Dependent claims

An apparatus for securing a mandrel of a well tool in an operative position requiring fixed-point packoff in the well, comprising:

a first and a second lockdown mechanism arranged so that the mandrel is locked in the operative position only when both the first and the second lockdown mechanism are in respective lockdown positions;
the first lockdown mechanism adapted to detachably maintain the mandrel in proximity to the fixed-point packoff when in the lockdown position, the first lockdown mechanism including a base member for connection to a wellhead of the well and a locking member for detachably engaging the base member;
and
the second lockdown mechanism having a range of adjustment adequate to ensure that the mandrel can be moved into the operative position and locked down in the operative position while the first lockdown mechanism is in the lockdown position.

1 more element

A method for lockdown of a mandrel of a well tool in an operative position in which the mandrel is packed off against a fixed-point in the well, comprising steps of:

a) mounting above a wellhead of the well an apparatus for securing the mandrel of the well tool in the operative position, comprising a first and a second lockdown mechanism arranged so that the mandrel is locked in the operative position only when both the first and second lockdown mechanisms are in respective lockdown positions;
the first lockdown mechanism being adapted to detachably maintain the mandrel in proximity to the fixed-point for packoff, and including a base member for connection to a top of a wellhead of the well and a locking member for detachably engaging the base member;
and the second lockdown mechanism having a range of adjustment to ensure that the mandrel can be moved into the operative position and locked down in the operative position while the first lockdown mechanism is in the lockdown position;
b) after inserting the mandrel through the wellhead into proximity to the fixed-point in the well, engaging the locking member of the first lockdown mechanism with the base member so that the mandrel is only moveable within the range of adjustment;
c) moving the mandrel into the operative position if the mandrel is not yet packed off against the fixed-point;
and
d) locking the second lockdown mechanism in the lockdown position.

4 more elements

Dependencies are inferred from the claim text.

Lockdown mechanism for well tools requiring fixed-point packoff

Life of this patent

Lockdown mechanism for well tools requiring fixed-point packoff

Life of this patent

Abstract

Claims27