Joints and connections – Interfitted members – Peripheral enlargement – depression – or slot on one member is...
Patent
1998-03-09
1999-11-16
Kim, Harry C.
Joints and connections
Interfitted members
Peripheral enlargement, depression, or slot on one member is...
403297, 403335, 166207, F16B 204
Patent
active
059845686
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a connector assembly for use in connecting sections of an expandable tubing string, and in particular but not exclusively for use in the connection of sections of an expandable slotted tubing (EST) string as utilised in downhole applications in the oil and gas exploration and extraction industries.
Expandable slotted tubing (EST) is used in various downhole applications. The tubing comprises lengths of tube which have been machined to create a large number of longitudinal slots. Thus, it is relatively easy to expand the tube radially outwardly by, for example, running a mandrel through the tubing. The expansion causes the slots to extend to create diamond-shaped apertures. The tubing is useful where it is desired to, for example, line a bore below a restriction without further reducing the diameter of the bore. Using conventional tubing, the outer diameter of the tubing must, by necessity, be of smaller diameter than the restriction, to permit the tubing to be passed through the restriction. This reduction in the bore diameter has a number of significant effects, primarily in reducing the production capabilities of the bore. Using EST, the tubing may pass through a restriction into a reamed section of bore below the restriction. The tubing may then be expanded to a diameter larger than the restriction.
EST is supplied in lengths which are, at present, made up into a string by welding the lengths to one another. This is relatively time consuming and expensive and in many situations, for example in an off-shore operation in bad weather, it may be difficult to maintain consistent weld quality. Safety problems may also arise due to the high temperatures and exposed flames or sparks created by a welding operation. Further, in the event of a "mis-run", requiring the welded lengths of tubing forming the EST string to be separated, the tubing must be cut, and the cut tubing cannot be reused.
It is among the objects of the present invention to provide a means of connecting sections of EST which obviates or mitigates these difficulties.
According to the present invention there is provided a connector assembly for interconnecting sections of an expandable slotted tubing string, the assembly comprising a male part and a female part formed integrally with the ends of respective tubing sections, each part being slotted and being adapted to co-axially engage the other part to permit expansion of the coupled parts in a corresponding manner to the tubing string, wherein the male and female part are interconnectable by one series of circumferentially spaced mechanical fasteners.
Preferably, the male part is formed by an end of one of the interconnected tubing sections of which the outer surface has been machined away over a selected distance and the female part is formed by an end of the other of the interconnected tubing sections of which the inner surface has been machined away over a similar distance.
In such case it is preferred that the free end of the male and female part fits within an annular groove formed at the other end of the corresponding part such that if the parts co-axially engage each other said free ends are locked in a radial sense inside said grooves to prevent flaring of said free ends when the tubing string is expanded.
This minimizes the possibility of the free ends flaring on expansion of the tube. Such flaring of the male end would create an irregularity in the tubing bore on which tools could become snagged.
The slotted free ends of the parts will define fingers and in a preferred arrangement mechanical fasteners are provided for coupling the respective overlapping fingers to one another. This prevents the ends of the parts from separating when the connected tubing is expanded. Preferably, each fastener is located substantially in the middle of a node and halfway between a pair of adjacent slots. The fasteners may be releasable, for example short screws for location in appropriate holes provided in the parts, such that the tubing may be separated in the event of a mis-run.
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Kim Harry C.
Shell Oil Company
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