Metal fusion bonding – Process – With shaping
Reexamination Certificate
1999-08-06
2001-04-24
Shaw, Clifford C. (Department: 1725)
Metal fusion bonding
Process
With shaping
C228S044500, C228S049300
Reexamination Certificate
active
06220498
ABSTRACT:
Coiled tubing is used in the oil well industry. Coiled tubing (C.T.) is handled using C.T. units.
The C.T. unit (illustrated in
FIG. 1
) is a hydraulically-powered transportable system including the following main components:
Tubing injector head
1
and tubing guide
91
Tubing reel
2
with counter
92
Blow-out preventer stack
3
Hydraulic power skid
4
Control console
5
connected to power pack
90
Such C.T. units are known in the prior art.
The coiled tubing
6
itself is a continuous tube presently available in diameters from 25 mm (1″) up to 168 mm (6 ⅝″) and available in materials ranging from the most common material which is A606 Type 4, modified High Strength Low Alloy Steel to Titanium, which is less commonly used to date.
This continuous length of steel tubing is wrapped onto reels ranging in diameter from 2.3 m (90″) to 5.2 m (204″) or more.
During operation the tubing is fed over the tubing guide
1
, through the hydraulic drive tubing injector
4
, down through the blow out preventer
3
and into the well head.
The flexibility of C.T. operations in terms of application, cost, rig set up time an the ability to remove a tubing string from one well and reuse it in another gives C.T. an unrivalled attraction to platform operators. C.T. is now being used more frequently to drill new wells, both vertical wells and wells which require the C.T. at certain depths to deviate towards the horizontal, otherwise known as directional drilling or deviated wells, at depths of up to 8000 m (25,000 feet) but can also be used in many other applications, such as:
Nitrogen Lifts
Acidising
Well Cleanouts
Cementing
Fishing
Logging
Drilling
Velocity Strings
Production Strings
Pre-perforated Liners
Gas Lifts
Gravel Packing etc
New applications for C.T. are being explored constantly as new down hole tools are designed and new and better
C.T. materials are developed.
C.T. only really began to take off in the 1980s as great improvements were made to the reliability of the technology.
The real catalyst came in the mid 1980s when the oil price crashed to $10 per barrel. C.T. was shown to cut costs by 50-85% over conventional rig operation using a drilling derrick.
During normal operating the C.T. sometimes has to be cut to remove a damaged length of pipe. In the case of very deep wells one length of tubing, say 3000 m (10,000 feet), may have to be joined to another length of 3000 m (10,000 feet) to make a 6000 m (20,000 feet) string of C.T.
The job of cutting and re-welding the C.T. together in a hostile environment is not straightforward and can present practical problems.
At present the normal practice is to refrain from cutting the C.T. unless absolutely necessary and, if welding is required, the welder does the best he can, making sure high quality control standards are used. The reason for this is that C.T. butt welds must be completely defect free. Onshore in a dry, well lit, draught free fabrication shop, with the welder having to be elevated to get at the C.T. it is a complex operation.
However in on-site conditions, such as in the desert at +40° C. with high winds or on an offshore platform at −20° C. in heavy weather it is very much more difficult. It can take as much as 10 days to complete a C.T. welding operation in a hostile environment.
At present the main reason for trying to avoid cutting and re-welding coiled tubing is because the C.T. has a residual bend in it when taken off the reel, i.e. if a piece a metre long is cut and placed on the floor, it forms an arc. If the same is done with another piece and the two pieces are welded together, a dog-leg in the C.T. string can be created, as illustrated in FIG.
2
.
This dog-leg
7
created during the welding operation creates a weak point in the continuous C.T. string which can and does result in the tubing failing at this point. The perfect weld can only be achieved by welding a substantially straight length of tubing to another substantially straight length of tubing, with the operation being carried out in a well lit, dry stable environment, free of draughts, with good ventilation and an ambient temperature of around 20° C.
There exists a requirement for an apparatus which will provide such conditions in any environment in which coiled tubing operations are carried, such that coiled tubing can be welded in a fraction of the time currently taken, at a reduced direct cost and at the highest standard possible.
There exists a requirement that such apparatus will be completely transportable and self contained, such that it can be transported to the site of the C.T. operations, kept there for the duration of the operations, and then removed to another site.
It is an object of the present invention to provide an apparatus and method which will provide controlled conditions for the welding and inspection of coiled tubing joints in any environment in which coiled tubing operations are carried out.
According to a first aspect of the present invention there is provided a portable unit for on-site welding operations comprising a container for carrying out welding operations therein, a tube clamping means and welding apparatus, said container having a roof, two opposing side walls and at least one door therein.
Preferably the container comprises a slot in each of said opposing walls, each of said slots being adapted to allow the passage of a tube extending through said wall and clamped by said clamping means, such that said tube may move relative to said container. Said slots may be substantially horizontal and extend to an opening in an end wall of said container. Alternatively said slots may be substantially vertical and extend to a further slot provided in said roof.
Preferably the unit comprises means for adjusting the height of said container, most preferably height adjustable legs.
Preferably the tube clamping means is adapted to clamp two sections of tubing in abutting end to end relationship. Preferably the tube clamping means comprises a moveable clamp assembly adapted to hold and move a first one of said sections of tubing axially into abutting end to end relationship with a second one of said sections of tubing. Preferably the tube clamping means further comprises a fixed clamp assembly adapted to hold the second section of tubing.
The unit may comprise a first guide means adapted to guide the tube clamping means between a first position outside the container and a second position inside the container.
The unit may further comprise a tube straightening means. The unit may further comprise a second guide means adapted to guide the tube straightening means between a first position outside the container and a second position inside the container. Preferably the first guide means is operable independently from the second guide means.
Preferably the container comprises a door which is retractable over said opening. The door may be a sliding door, a roller shutter door or other door, and may be adapted to seal the container when the tube clamping means is in said second position inside the container.
The tube straightening means may comprise two drive belts arranged such that a first driving surface of the first belt is opposed and parallel to a second driving surface of the second belt and is spaced therefrom, the first driving surface having a convex shape in the drive direction and the second driving surface having a concave shape in the drive direction.
Preferably both the first and second driving surfaces have a concave shape perpendicular to the drive direction.
Preferably each drive belt is arranged on a jaw member, the jaw members being operable between an open position, in which a tube member may be inserted between the first and second driving surfaces, and a closed position, in which the first and second driving surfaces clamp a tubular member positioned therebetween.
Preferably the tube straightening means is pivotally connected to the second guide means and can pivot between an operating position in which the drive direction is aligned with the clamping means and a non-operative
Gordon Alec
Thomson Ashley
Agais Offshore Limited
Edmondson L.
Ratner & Prestia
Shaw Clifford C.
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