GB2263119A

GB2263119A - Wireline release mechanism

Info

Publication number: GB2263119A
Application number: GB9205340A
Authority: GB
Inventors: Mark Buyers
Original assignee: Omega Dev & Eng Ltd
Current assignee: Omega Dev & Eng Ltd
Priority date: 1992-03-12
Filing date: 1992-03-12
Publication date: 1993-07-14
Anticipated expiration: 2012-03-12
Also published as: GB9205340D0; GB2263119B

Abstract

A wireline release mechanism comprises a first lower member (1) in the form of a fishing neck connected to a downhole tool and a second upper member connected to the wireline 6 and having fingers 4 which are held in locking engagement with the lower member 1 by a surrounding sleeve 8. The sleeve 8 is biassed upwards by a spring 9 but is normally held in a lower locking position by a ball detent 10 which is prevented from moving inwardly by a spring-loaded bush 11. In use, to release the mechanism a weight is dropped down the wireline to depress bush 11 (as shown to the right of the figure) which allows ball 10 to move inwards releasing sleeve 8 for upward movement. An upward pull on the wireline will then separate the upper member from the lower member 1. <IMAGE>

Description

Wireline Release Mechanism This invention relates to a release mechanism and more particularly-to a wireline release mechanism for use in a well.

In the petrochemical industry there are many operations that are carried out to a well during its lifetime.

All wells have equipment associated therein which requires regular maintenance. To carry out this maintenance, tools of varying descriptions are lowered into the well attached to the end of a wire. Two main types of wire are used, slickline and electric line.

Electric line has an insulated inner for the operation of electronic type devices and a braided wire outer protection which is load bearing. The wire terminates in a "rope socket" which connects the insulated cable to a connector and strands of the wire to a clamp such that a set weak point may be chosen. This weak point is necessary if the tools become stuck in the well so that the wire may be snapped and retrieved leaving only the rope socket and tools in the well. The rope socket has a profile called a fishing neck which allows pulling tools to be engaged. This facility allows other tools to be connected to the top of the rope socket unimpeded by junk wire. Other operations may then be carried out to retrieve the stuck tools.

In many instances slickline is used in preference to electric line.

Slickline rope sockets have a fishing neck but as the wire is a single strand, no weak point may be set.

When slickline tools are stuck in a well, the wire is cut by attaching a tool called a wire cutter to the wire on surface and dropping it down the well.

Sometimes the wire may be cut prematurely, if the cutter passes through a gas/liquid interface or if the cutter hits a protruding part of the well equipment as the cutters rely on stored inertia to provide the force for cutting the wire. Occasionally the cutter reaches the rope socket but does not have enough force to cut the wire. In this case a heavy bar called a "Go Devil" is dropped onto the cutter. After the wire is cut, the Go Devil and cutter must be retrieved before other operations may be carried out to remove the stuck tools.

It is an object of the present invention to obviate or mitigate these disadvantages of known slickline arrangements.

According to the present invention there is provided a wireline release mechanism comprising, a first member having means for engaging a downhole tool, an intermediate member having lifting means for engaging the first member and means for receiving and retaining a wireline, and an upper member having operating means for selectively pressing the lifting means into lifting engagement with the first member or releasing the lifting means therefrom such that the intermediate member and the upper member may be lifted clear of the first member on application of an upward force to the wireline.

Preferably the lifting means on the intermediate member comprises a plurality of fingers each having an engagement head for engaging a profile on the first member.

Preferably also the operating means on the upper member is provided by a sleeve portion of the upper member which extends over the fingers and is resiliently biased towards the release position of the lifting means but retained in the lifting position by a locking arrangement.

Most preferably the locking arrangement comprises a plurality of locking balls which are held in engagement with the upper member by a resiliently biased retaining member.

The retaining member preferably has a profile such that when it is biased downwardly against the resilient biasing the locking balls release allowing the outer sleeve to disengage from the fingers which may then be disengaged from the first member by pulling upwards on the wireline.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig 1 is a sectional side view of a wireline release mechanism in a closed position.

and Fig 2 is a sectional side view corresponding to Fig 1 illustrating one half of the mechanism in a release position.

Referring to the drawings a wireline release mechanism comprises a first member 1 in the form of a fishing neck having a bottom end 2 for attachment to downhole tools (not shown). The member 1 has a profile 3 which is engaged by a number of fingers 4, eight in the example illustrated, which form part of a mandrel 5 to which a wireline 6 is attached by an end fixing 7. The fingers 4 on the mandrel 5 are normally held in engagement with the profile 3 by an outer sleeve 8 which extends down over an end formation 4a on the fingers 4. The outer sleeve 8 is spring pre-loaded by a series of belleville washers 9 and retained in position by a series of three or more locking balls 10 which lock the sleeve 8 and the mandrel 5 together and are held in position by a retainer 11 which is biased upwardly by a spring 12.The retainer 11 has a profile 13 which allows the balls 10 to release when the retainer 11 is pushed downwards.

During normal operation as seen in Fig 1, the fingers 4 engage the profile 3 and are locked by the outer sleeve 8. The whole device is thus locked together.

If it should become necessary to detach the wireline 6 it is a simple procedure to disengage the mandrel 5 and outer sleeve 8 from the first member 1 and pull them from the well. Thus in the event that a tool becomes stuck in the well a Go Devil or other bar which has an extension which may enter the device is dropped down the well to contact the retainer 11 and push it to the bottom of its stroke against the spring 12. This is illustrated in the section labelled A of Fig 2. The balls 10 are able to enter the profile 13 on the retainer 11 and the outer sleeve is forced upwardly by the belleville washers 9 . The finger mandrel 5 is unlocked and as a result the mandrel 5 may be pulled from the first member 1 by pulling on the wireline 6.

The top part of the device can then be pulled from the well exposing the first member 1 or fishing neck for further operations as required. A stop member 15 limits the movement of the outer sleeve 8.

The upper end of the outer sleeve 8 is shaped so as to easily receive the drop bar which is itself shaped so as to ensure easy entry into the outer sleeve 8. An external profile 14 on the outer sleeve 8 allows for its retrieval in the extreme should it prove impossible to operate the device.

The particular release mechanism described is by way of example only and it is envisaged that other known techniques may be used to effect the locking between the various parts of the device.

Modifications and improvements may be made without departing from the scope of the invention.

Claims

1. A wireline release mechanism comprising, a first member having means for engaging a downhole tool, an intermediate member having lifting means for engaging the first member and means for receiving and retaining a wireline, and an upper member having operating means for selectively pressing the lifting means into lifting engagement with the first member or releasing the lifting means therefrom such that the intermediate member and the upper member may be lifted clear of the first member on application of an upward force to the wireline.

2. A wireline release mechanism according to Claim 1, in which the lifting means on the intermediate member comprises a plurality of fingers each having an engagement head for engaging a profile on the first member.

3. A wireline release mechanism according to Claim 2, in which the operating means on the upper member is provided by a sleeve portion of the upper member which extends over said fingers and which is resiliently biased towards the release position of the lifting means but is retained in the lifting position by a locking arrangement.

4. A wireline release mechanism according to Claim 3, in which the locking arrangement comprises a plurality of locking balls which are held in engagement with the upper member by a resiliently biased retaining member.

5. A wireline release mechanism according to Claim 4, in which the retaining member has a profile such that, when it is biased downwardly against the resilient biasing, the locking balls are releasable to allow the outer sleeve to disengage from the fingers and which are then disengageable from the first member by pulling upwards on the wireline.

6. A wireline release mechanism according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.