GB2322393A

GB2322393A - Coiled tubing system

Info

Publication number: GB2322393A
Application number: GB9801122A
Authority: GB
Inventors: Philip Head
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-20
Filing date: 1998-01-21
Publication date: 1998-08-26
Anticipated expiration: 2018-01-21
Also published as: GB2322393B; GB9801122D0

Abstract

The invention relates to a conduit/cable and coiled tubing system for deployment in a well, in which the conduit/cable 2 is arranged internally of the coiled tubing 1, and one end of the coiled tubing 1 is attached to a powered device, such as a motor or a drill, which is to be installed in the well, and wherein the conduit/cable 2 is connected at one end to a power supply at the surface and connected at the opposite end to the powered device by a first connection means so that the conduit/cable is prevented from contact with the outside of the coiled tubing, wherein the space between the conduit/cable 2 and the inside wall of the coiled tubing 1 comprises a filling material 13 which has a first viscosity state and at least one second higher viscosity state. The conduit/cable is pre-installed inside the coiled tubing and attached to the powered tool at the surface and the system lowered down the well together to the desired location. The low viscosity fluid state is such that it may be pumped into the space between the conduit/cable and the coiled tubing, and subsequently sets to a higher viscosity, more solid state. The filling material, in the more viscous state, serves to transfer the weight of the conduit/cable to the wall of the coiled tubing thereby supporting the conduit/cable.

Description

CONDUIT AND CONTINUOUS COILED TUBING SYSTEM AND METHOD OF MANUFACTURE This invention relates to a conduit and continuous coiled tubing system for operating and deploying a powered device in a well.

Coiled or continuous reel tubing has been used in the oil industry for the last 20-30 years. The fact that it is a continuous single tube provides several advantages when entering a live oil or gas well which could have anything up to 7,000 psi well head pressure. This means the well does not have to be killed, (i.e. a heavy fluid does not have to be pumped down the production tubing to control the oil or gas producing zone by the effect of its greater hydrostatic pressure). Continuous tubing has the advantage of also being able to pass through the tubing through which the oil and/or gas is being produced, not disturbing the tubing in place.

Since its introduction, the uses and applications for coiled tubing have grown immensely, and now, rather than just being used to circulate various fluids in a well bore, it is not uncommon for coiled tubing to be used for conveying various hydraulically powered tools and more recently electrically powered tools on its end into the well. This has resulted in conventional electrical wireline logging cables or small hydraulic conduits being inserted into the inside of the reel of tubing so that these more sophisticated tools and services can be performed.

A disadvantage which has resulted from this practice is the capstan effect of the smaller diameter wire-line or hydraulic tube tending to be pulled very tightly to the inner surface of the continuous reel of tubing. When considering the effect this has on the geometry, it will be appreciated that the wire-line or small hydraulic conductor will have a slightly smaller pitch circle diameter to that of the larger reeled tubing. The consequence of this is that for each complete 360 degrees the wire-line or hydraulic tube will be slightly shorter in length than the larger reeled tubing, so if this is added up over its total length of 12,000 ft (3657 m) or usually longer the difference in lengths could be as much as 200 ft (61 m).

This problem has been recognised due to the operational problems encountered.

Either one end of the wire-line or hydraulic tube has been pulled out of its connection, or else the reeled tubing itself has started to form a low frequency wave form caused by the tension in the conduit inside the reeled tubing, which prevents the reeled tubing being lowered any deeper into the well without the risk of damaging it.

Another disadvantage with using traditional wire-line inside reeled tubing is that it is not compatible with many of the fluids pumped through the reeled tubing, the more common ones being corrosive stimulation fluids, and cement slurries used generally for zonal isolation. The reason for this, is the wire-line has two outer reinforcing layers of braided wire beneath which is an insulation layer protecting the conductors, which typically number up to eight. The normal insulation material is not compatible with the acid systems, although some expensive materials are available, but the total price becomes prohibitively expensive. Alternatively, when pumping cement slurries, the gaps between the braided wire of the cable form natural traps which collect some deposits of the cement slurry, which, when set, either make it difficult for the wire-line to bend or, more commonly, the particles of set cement break off leaving residue inside the reel.

Consequently and additionally this has the effect of increasing the weight of the conduit and for conduits having a certain length the conduit is prone to stretching or creep when installed in the well in particular when it is considered that the conduit is intended to remain in position for a relatively long period of time for production of the well. The type of conduit for which stretching is a problem depends upon the weight per unit length of the conduit, the material of the conduit and the expected working life of the conduit as well as the nature of the immediate environment surrounding the conduit, although in many applications the invention enables the conduit to be installed in coiled tubing with a dielectric oil between them. Nevertheless stretching of the conduit is frequently a serious problem.

It is an object of the present invention to provide a conduit, coiled tubing system which avoids this problem of stretching and overcomes the other disadvantages of present known systems mentioned above.

According to the invention there is provided a conduit and coiled tubing system for deployment in a well, in which the conduit is arranged internally of the coiled tubing which comprises a wall and an internal bore, and one end of the coiled tubing is attached to a powered device such as a motor or a drill which is to be installed in the well by a first attaching means arranged between the wall of the coiled tubing and the powered device, and wherein the conduit is connected at one end to a power supply at the surface and connected at the opposite end to the powered device by a first connection means which is located within the wall of the coiled tubing, the space between the conduit and the inside wall of the coiled tubing comprising a filling material which occurs in a low viscosity fluid state, in which state it is pumped into the space between the conduit and the coiled tubing, and a higher viscosity, more solid state, in which state the filling material serves to transfer the weight of the conduit to the wall of the coiled tubing thereby supporting the conduit.

The conduit may be pre-installed inside the coiled tubing and attached to the powered tool at the surface and the system lowered down the well together to the desired location. Alternatively the conduit and the powered device may be lowered to the desired location first and then subsequently the conduit is lowered and connected to the powered device by means of a remote interlocking mechanism.

The filling material may be provided in the form of a slurry which sets after a period of time to form a rubber-like solid with a relatively high viscosity such as of the order of 10,000 poise. The filling material preferably sets by means of a curing process. The curing process may be initiated by temperature.

The filling material may be based on a two part liquid silicon product which cures at approximately room temperature or an ambient temperature which can be pre-selected for the chosen application.

The filling material may also be a suitable compounded polyurethane which cures at a selected temperature.

The filling material will be chosen to cure after a pre-determined time and this time will at least be the time taken to pump the filling material into the tubing preferably with an additional amount of time to allow for unforeseen delays.

The filling material will typically be any appropriate material which has delayed curing properties and which may be pumped into the coiled tubing in the uncured state and cured to a sufficiently viscous state when pumping is complete.

According to the invention there is also provided method of providing a conduit internally inside a coiled tubing system for deployment in a well, in which the coiled tubing comprises a wall and an internal bore, and one end of the coiled tubing is attached to a powered device such as a motor or a drill which is to be installed in the well by a first attaching means, and wherein the conduit is connected at one end to a power supply at the surface and connected at the opposite end to the powered device, and wherein the space between the conduit and the inside wall of the coiled tubing is filled with a filling material in a low viscosity fluid state, and wherein the filling material subsequently sets to a higher viscosity, more solid state, in which state the filling material serves to transfer the weight of the conduit to the wall of the coiled tubing thereby supporting the conduit.

The conversion filling material from the low viscous state to the higher viscous state may occur by a curing process which may be initiated by heating the coiled tubing.

The following is a more detailed description of some embodiments of the invention by way of example, reference being made to the accompanying drawings, in which: Fig. 1 shows a side view of a coiled tubing reel showing a pre-installed conduit; Fig. la shows the conduit and coiled tubing system installed in a well; Fig. 2 shows a cross section of the conduit and coiled tubing system of the invention before applying the filler material; Fig. 3 shows a cross section of the system of fig 2 after the introduction of the filling material; Fig 4 shows a longitudinal cross section of the conduit and coiled tubing system of the invention showing a first embodiment of a centralising means; Fig. 5 shows a cross-section taken along the line A-A of Fig. 4, before adding the filler material of an alternative centralising means; Fig. 6 shows a cross-section taken along the line A-A of Fig. 4, through a conduit before adding the filler material; Fig. 7 shows a longitudinal cross section of the coiled tubing system including a multiple cable conduit; Fig. 8 shows a cross section of Fig. 7, after addition of the filler material; Fig. 9 shows a longitudinal cross section of the coiled tubing system including a shielded cable conduit; Fig. 10 shows a cross section of the embodiment of fig. 9 after addition of the filler material; Fig. 11 shows a longitudinal cross section of the coiled tubing system of the invention including an additional tubular conduit; Fig. 12 shows a cross section the embodiment of fig. 11 after the addition of the filler material; Fig. 12a to 12c show cross sections of a further embodiment wherein the filler material surrounds the conduits; Fig. 13 shows a longitudinal cross section of a first stage of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 14 shows a longitudinal cross section of a second stage of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 15 shows a longitudinal cross section of a third stage of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 16 shows a longitudinal cross section of a fourth of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 17 shows a longitudinal cross section of a fifth stage of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 18 shows a longitudinal cross section of a sixth stage of a method of connecting together free ends of the coiled tubing system of the invention; Fig. 19 shows a schematic representation of a method of installing the conduit in the coil tubing and adding the filler material.

Referring first to Fig. 1, there is shown a side cross-sectional view of one wrap of coiled tubing 1, with a conduit 2, lying on the inside wall 3 of the coiled tubing. A dotted line shows the diameter centre line of the coiled tubing 1 while a second dotted line shows the diameter centre line of the conduit 2. It will be appreciated that because they have different centre line diameters, their lengths per wrap will be slightly different with the coiled tubing being slightly longer.

Multiplying this difference in length by the total number of wraps enables the difference in overall length to be determined, which can be in excess of 100 ft (30 m). The conduit is therefore preferably arranged to comprises a wavy profile to accommodate this.

Referring to figure la the general arranged of the conduit 2 and the coiled tubing 1 connected to a powered a device 7 which is deployed in a well, in which the conduit is arranged internally of the coiled tubing which comprises a wall and an internal bore, and one end of the coiled tubing 1 is attached to the powered device by a first attaching means 8 arranged between the wall of the coiled tubing 1 and the powered device 7. The powered device 7 may be a pump or a drill or other down-hole powered machine.

The conduit 2 is connected at one end (the upper end in the installed position shown in figure la) to a power supply at the surface and connected at the opposite end to the powered device 7 by a first connection means 9 which is located within the wall of the coiled tubing 1 and within the first attaching means 8 so that the conduit 2 is prevented from contact with the outside of the coiled tubing 1 at all times.

The conduit may be pre-installed inside the coiled tubing and attached to the powered tool at the surface and the system lowered down the well together to the desired location. Alternatively the conduit and the powered device 7 may be lowered to the desired location first and then subsequently the conduit 2 is lowered and connected to the powered device 7 by means of a remote autolocking mechanism.

Referring to figures 2 and 3 the conduit and coiled tubing system according to the invention comprise a filling material 13 in the form of a cellular foam-like material which provides an adhesive grip on the internal wall of the coiled tubing which aids the support of the conduit to the coiled tubing. The foam like material is of the expandable form which can be provided on the external surface of the conduit 2 or alternatively on the internal wall of the coiled tubing, in the un expanded state before installation of the conduit inside the coiled tubing. After installation the foam-like expandable material is activated to expand and fill the concentric space 14 between the conduit 2 and the coiled tubing 1. The foam-like expandable material may be any suitable material which can be activated to expand. Such materials are likely to be polymeric and activated by the application or a reagent which causes the expansion process and the reagent is pumped through the coiled tubing after the conduit has been installed. Alternatively the expandable material may be activated by temperature or by time in contact with air. When in the expanded state the expandable material acts as the filler material and exerts a supporting force on conduit transmitting the weight of the conduit to the coiled tubing and thus supporting the conduit when in the vertical position in a well.

Thus it is the main feature of the invention that the space between the conduit and the inside wall of the coiled tubing is filled with a filling material 13 and that this filling material 13 acts to support the weight of the conduit in the coiled tubing. In the embodiments of figures 7 to 12 the filling material 13 is a material which occurs in a low viscosity fluid state, in which state it is pumped into the space 14 between the conduit and the coiled tubing, and a higher viscosity, more solid state, in which state the filling material 13 serves to transfer the weight of the conduit 2 to the wall of the coiled tubing 1 thereby supporting the conduit 2.

The filling material 13 may be provided in the form of a slurry which is pumped into the coiled tubing and sets after a period of time to form a rubberlike solid with a viscosity of 10,000 poise. The filling material preferably sets by means of a curing process. The curing process may be initiated by temperature.

Referring now to figure 4 there is shown a coiled tubing system of the invention in which a centraliser 6 is provided on the external wall 4 of the conduit 2 and which acts against the internal wall 3 of the coiled tubing 1 to retain the conduit in an essentially central position inside the coiled tubing.

This is a temporary measure to ensure that the filler material is able to flow completely around the conduit and that when the filling material sets the conduit is maintained in an essentially central position inside the coiled tubing.

The centraliser 6 shown in figure 4 and figure 6 is in the form of a porous foam type structure which is rigid enough to centralise the conduit but which also allows the filling material to flow through it so that the filling material can penetrate the whole length of the coiled tubing. Figure 5 shows an alternative centralising device 7 which is in the form of radially extending arms between the conduit and the coiled tubing which allow the flow of the filling material when in the fluid state between them.

The conduit may be in a variety of forms; in figure 4 the conduit 2 is shown as a plain cable 11. In figure 5 the conduit is shown as a coaxial fibre optic cable 12. In figure 6 the conduit is shown as a multiple cluster of power and signal cables in a protective casing. Figures 7 and 8 show the conduit in the form of three separate cables 16 helically wound. Figures 9 and 10 show the conduit in the form of three separate cables 16 helically wound and in a protective sheath.

figures 11 and 12 show the conduit as a helically wound triple cable 16 with an hydraulic line 15 alongside. In figures 7 to 12 the longitudinal sections are shown without filling material and the transverse cross sections are shown with the space 14 filled with the filling material 13.

In a further preferred embodiment of the invention as shown in figures 12 a to 12c the filler material surrounds the conduits but dies not fill the internal space 14 of the tube. In this embodiment the conduit 2 is in the form of a bundle of three conduits 2 which are installed in a length of coiled tubing lwhich is laid out flat and the filling material 5 is pumped along the tube 1. The filling material will settle in the lower part of the tube 1 surrounding the conduits 2 to a sufficient extent to secure the conduits 2 to the internal wall of the tubing 1 when the filling material is cured. In fig. 12 c the tube is shown rotated through 90 degrees ready for coiling onto a reel so that the conduits 2 share the same or approximately the same means diameter as the tube 3 and fracture of the bond between the conduits 2 and the tubing 1 caused by them having different diameters during coiling is avoided.

Figures 13 to 18 show a means of reconnecting the conduit and coiled tubing system according to the invention. The conduit free end 22 and the coiled tubing free end 21 are shown in figure 13. The coiled tubing free ends 21 are firstly cut back to expose a desired length of the conduit free end 22. Filling material is then removed from each of the exposed ends of the coiled tubings to form voids 23. A cover sleeve 24 is then slid over one ofthe free ends 21 of the coiled tubing. Then dimpled connectors 25 are fitted in the voids 23 of each of the free ends 21 ofthe coiled tubings. The dimpled connectors preferably have stops 26 which act against the free end of the coiled tubing 21 to hold the connector in the desired position with a supporting portion in the void 23 and a free portion extending outwardly. Both portions are provided with dimples 27 for providing a securing means by swaging. The connectors may be fixedly secured to the free ends of the coiled tubing swaging on the outside of the coiled tubing so that the material of the coiled tubing is deformed into the dimples in the supporting portion of the connector.

The free ends of the conduits are then secured together by known splicing means as shown in fig. 16 forming a splice 28.

The cover 24 is then slid over the open section of the conduit and is of a length which corresponds to the original length of the exposed the conduit free ends combined plus the length of the splice so that the cover 24 fits precisely into the space between the stops 26. The cover is then swaged on to the exposed ends of the connectors 25 on each side and the completed join is made.

Referring now to fig. 19 the schematic representation of a method of providing the coiled tubing system of the present invention is shown. The conduit 2 arranged on a wire-line reel 32 and is pulled through the coiled tubing 1 by a wire pulling unit 30. In this embodiment the coiled tubing 1 is laid out flat in a large flat surface such as a disused air field. The conduit may however be installed by other known techniques, such as pumping through whilst on a reel or by injection whilst the coiled tubing is installed in a well.

Referring again to figure 19 the filling material 13 is also pumped into the space 14 between the conduit and the internal wall of the coiled tubing by means of a pumping unit 31. When the filling material reaches the end of the length of coiled tubing the operation is complete and the ends are closed, any excess material is collected in a retrieval sump 33. The filling material then sets into the viscous state and holds the conduit in position with respect to the coiled tubing and supports the weight of the conduit when the coiled tubing is deployed in the vertical. The filling material may also be pumped into the space whilst the coiled tubing is held in the vertical position in a well.

Whatever the embodiment of the chosen filling material of the invention engages the internal bore of the tube and prevents lateral movement of the conduit relative to the tube in the set viscous state.

Claims

1. A conduit and coiled tubing system for deployment in a well, in which the conduit is arranged internally of the coiled tubing, said coiled tubing comprising a wall and an internal bore, and one end of the coiled tubing is attached to a powered device, such as a motor or a drill, which is to be installed in the well by a first attaching means arranged between the wall of the coiled tubing and the powered device, and wherein the conduit is connected at one end to a power supply at the surface and connected at the opposite end to the powered device by a first connection means so that the conduit is prevented from contact with the outside of the coiled tubing, characterised in that the space between the conduit and the inside wall of the coiled tubing comprises a filling material which has a first viscosity state and at least one second higher viscosity state.

2. A conduit and coiled tubing system according to claim 1, characterised in that the conduit is pre-installed inside the coiled tubing and attached to the powered tool at the surface and the system lowered down the well together to the desired location.

3. A conduit and coiled tubing system according to claim 1, characterised in that the low viscosity fluid state is such that it may be pumped into the space between the conduit and the coiled tubing, and subsequently sets to a higher viscosity, more solid state.

4. A conduit and coiled tubing system according to claim 3, characterised in that the filling material, in the more viscous state, serves to transfer the weight of the conduit to the wall of the coiled tubing thereby supporting the conduit.

5. A conduit and coiled tubing system according to claim 4, characterised in that the filling material is in the form of a slurry which sets after a period of time to form a rubber-like solid.

6. A conduit and coiled tubing system according to claim 4, characterised in that the filling material sets by means of a curing process.

7. A conduit and coiled tubing system according to claim 6, characterised in that the curing process may be initiated by temperature.

8. A conduit and coiled tubing system according to claim 4, characterised in that the filling material sets by means of a reaction with a reagent.

9. A conduit and coiled tubing system according to claim 8, characterised in that the reagent is water.

10. A conduit and coiled tubing system according to claim 1, characterised in that centralising means are provided along the length of the coiled tubing and arranged between the outside wall of the conduit and the internal wall of the coiled tubing to retain the coiled tubing in an essentially central, position within the coiled tubing.

11. A conduit and coiled tubing system according to claim 10, characterised in that the centralising means permits the flow of the filler material axially through the length of the coiled tubing.

12. A conduit and coiled tubing system according to claim 11, characterised in that the centraliser is in the form of a porous foam type structure which is rigid enough to centralise the conduit but which also allows the filling material to flow through it.

13. A conduit and coiled tubing system according to claim 11, characterised in that the centralising device comprises radially extending arms between the conduit and the coiled tubing which allow the flow of the filling material when in the fluid state between them.

14. A conduit and coiled tubing system according to claim 1, characterised in that the filling material is based on a two part liquid silicon product.

15. A conduit and coiled tubing system according to claim 1, characterised in that the filling material cures at approximately room temperature or an ambient temperature which can be pre-selected for the chosen application.

16. A conduit and coiled tubing system according to claim 1, characterised in that the filling material will be chosen to cure after a pre-determined time and this time will at least be the time taken to pump the filling material into the tubing.

16. A conduit and coiled tubing system according to claim 1, characterised in that the filling material is a suitable compounded polyurethane which cures at a selected temperature.

17. A conduit and coiled tubing system according to claim 1, characterised in that the filling material will be chosen to cure after a pre-determined time and this time will at least be the time taken to pump the filling material into the tubing.

18. A method of providing a conduit internally inside a coiled tubing system for deployment in a well, in which the coiled tubing comprises a wall and an internal bore, and one end of the coiled tubing is attached to a powered device such as a motor or a drill which is to be installed in the well by a first attaching means, and wherein the conduit is connected at one end to a power supply at the surface and connected at the opposite end to the powered device, and wherein the space between the conduit and the inside wall of the coiled tubing is filled with a filling material in a low viscosity fluid state, and wherein the filling material subsequently sets to a higher viscosity, more solid state, in which state the filling material serves to transfer the weight of the conduit to the wall of the coiled tubing thereby supporting the conduit.

19. A method according to claim 18 characterised in that the conversion of the filling material from the low viscous state to the higher viscous state occurs by a curing process.

20. A method according to claim 19 characterised in that the conversion of the filling is initiated by heating the coiled tubing.

Amendments to the claims have been filed as follows 1. A conduit and coiled tubing system for deployment in a well, in which the conduit is arranged internally of the coiled tubing, said coiled tubing comprising a wall and an internal bore, and one end of the coiled tubing is attached to a powered device, such as a motor or a drill, which is to be installed in the well by a first attaching means arranged between the wall of the coiled tubing and the powered device, and wherein the conduit is connected at one end to a power supply at the surface and connected at the opposite end to the powered device by a first connection means so that the conduit is prevented from contact with the outside of the coiled tubing, characterised in that the annular space between the conduit and the inside wall of the coiled tubing comprises, at least in part, a filling material which has a first viscosity state, in which the filling material may flow into the annular space, and at least one second higher viscosity state in which the filling material provides support for the weight of the conduit.

3. A conduit and coiled tubing system according to claim 1, characterised in that the filling material, in the more viscous state, serves to transfer the weight of the conduit to the wall of the coiled tubing thereby supporting the conduit.

4. A conduit and coiled tubing system according to claim 3, characterised in that the filling material is in the form of a slurry which sets after a period of time to form a rubber-like solid.

5. A conduit and coiled tubing system according to claim 3, characterised in that the filling material sets by means of a curing process.

6. A conduit and coiled tubing system according to claim 5, characterised in that the curing process may be initiated by temperature.

7. A conduit and coiled tubing system according to claim 3, characterised in that the filling material sets by means of a reaction with a reagent.

8. A conduit and coiled tubing system according to claim 7, characterised in that the reagent is water.

9. A conduit and coiled tubing system according to claim 1, characterised in that centralising means are provided along the length of the coiled tubing and arranged between the outside wall of the conduit and the internal wall of the coiled tubing to retain the coiled tubing in an essentially central, position within the coiled tubing.

10. A conduit and coiled tubing system according to claim 9, characterised in that the centralising means permits the flow of the filler material axially through the length of the coiled tubing.

11. A conduit and coiled tubing system according to claim 10, characterised in that the centraliser is in the form of a porous foam type structure which is rigid enough to centralise the conduit but which also allows the filling material to flow through it.

12. A conduit and coiled tubing system according to claim 10, characterised in that the centralising device comprises radially extending arms between the conduit and the coiled tubing which allow the flow of the filling material when in the fluid state between them.

13. A conduit and coiled tubing system according to claim 1, characterised in that the filling material is based on a two part liquid silicon material.

14. A conduit and coiled tubing system according to claim 1, characterised in that the filling material cures at approximately room temperature or an ambient temperature which can be pre-selected for the chosen application.

1 S. A conduit and coiled tubing system according to claim 1, characterised in that the filling material is a suitable compounded polyurethane which cures at a selected temperature.