Wells – Expansible anchor or casing – Liner hanger
Patent
1993-11-09
1995-04-25
Britts, Ramon S.
Wells
Expansible anchor or casing
Liner hanger
166217, E21B 2302
Patent
active
054090598
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a lock mandrel for downhole assemblies, i.e. lock mandrels with flow control accessories for use in oil and water/gas well operations.
DESCRIPTION OF THE PRIOR ART
Downhole assemblies are known and are used to anchor and seal the assembly in position in the well tubing string.
The assembly is run in and positioned in the well at the pre-determined setting depth by engaging a restriction in the tubing known as the `no-go`. For this purpose, the assembly has a no-go shoulder. In some constructions the assembly is supported by the no-go shoulder, but in others the engagement of the shoulder in the no-go causes a shear pin to shear and allows lock-out keys or `dogs` to engage a profile in the tubing and lock the assembly in position. In such constructions the no-go shoulder is deformable to provide for initial positive positioning before the keys lock out at which stage the shoulder then `disappears`. After use, a new no-go shoulder has to be located on the assembly.
Disadvantages of the deformable no-go shoulder are not only that they have of necessity to be replaced after use, but also a deformed shoulder can become stuck and therefore difficult to remove.
Other constructions have permanent no-go shoulders or movable no-go rings, but disadvantages of these known constructions are that the permanent no-go shoulders can become stuck in incorrect positions while movable no-go rings can cause misruns by premature shear.
U.S. Pat. Nos. 4,595,054 and 4,254,829 disclose lock mandrels but these have the disadvantage of using separate removable dogs for locking the main cylindrical body and this complicates and adds to the expense of the structure.
An object of this invention is to obviate or mitigate the aforesaid disadvantages.
SUMMARY OF THE INVENTION
The above object is met by the present invention by providing a locking mandrel located in a surrounding casing means of a downhole assembly. The casing means includes a receiving means defining a no-go location, a plurality of radially movable no-go members biased in a radial direction. The inner mandrel means has a profiled external surface for reaction with locking keys disposed on its cylindrical body and the no-go members such that, in an initial primed condition of the mandrel, the inner mandrel means positions the no-go members in an extended condition for engagement with the receiving means while allowing the locking keys to be retained within the outer surface of the body. The cylindrical body is fashioned to provide a plurality of flexible fingers constituting the no-go members which are integral with and permanently attached to said cylindrical body, each of the fingers having one end free and the other end integral with the cylindrical body. The fingers are adapted for controlled movement by the inner mandrel means whereby the free ends of the fingers are moved selectively relative to the outer surface of the cylindrical body between the no-go location and a position free of the receiving means.
Preferably, the inner mandrel is formed of upper and lower parts whereby the lock mandrel can be retrieved by raising the upper part so that the proflethereon allows radially inward withdrawal of the locking keys while the lower part continues to allow the no-go members to remain withdrawn.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a half sectional elevation of a lock mandrel for a downhole assembly according to the invention shown in the primed condition;
FIG. 2 is a similar view of the lock mandrel in the locked condition;
FIG. 3 is a similar view of the lock mandrel in the retrieval condition; and
FIGS. 4 and 5 show similar views to FIGS. 1 and 2 for a further embodiment of the present invention.
Referring to FIGS. 1-3 of the drawings, a lock mandrel is connected at its upper end to a flow control accessory not shown to form a downhole assembly.
DESCRIPTION OF THE PREFERRED E
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Britts Ramon S.
Petroline Wireline Services Limited
Tsay Frank S.
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