GB2475167A - Under reamer - Google Patents

Under reamer Download PDF

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Publication number
GB2475167A
GB2475167A GB201018612A GB201018612A GB2475167A GB 2475167 A GB2475167 A GB 2475167A GB 201018612 A GB201018612 A GB 201018612A GB 201018612 A GB201018612 A GB 201018612A GB 2475167 A GB2475167 A GB 2475167A
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GB
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Application
Patent type
Prior art keywords
piston
underreamer
blade
tubular member
according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB201018612A
Other versions
GB201018612D0 (en )
Inventor
Anthony Laplante
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WELLTONIC Ltd
Original Assignee
Welltonic Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00Drill bits
    • E21B10/26Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers
    • E21B10/32Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers with expansible cutting tools
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B7/00Special methods or apparatus for drilling
    • E21B7/28Enlarging drilled holes, e.g. by counterboring

Abstract

Under-reamer for a wellbore comprising a tubular member (3, fig 5) with a recessed region (4, fig 5) within which a blade (17, fig 5) is pivotably mounted, a piston (32, fig 2) with a cam surface 36 slidably mounted over the tubular member, when actuated the piston slides along the tubular member and the cam surface causes the blade to pivot out of the recessed region to an expanded position where it is held between a load bearing shoulder (15, fig 5) of the tubular member and cam surface of the piston. The piston may be a tubular sleeve which slides over the tubular member. There may be a nozzle (8, fig 1) and apertures (9, fig 1) which direct fluid exiting the tool onto the blades to clean them.

Description

U nd erreamer This invention relates to an underreamer and more specifically to an underreamer for use in subterranean wellbores. Most preferably such tools are used for expanding the borehole for example behind a down hole mill or drill bit to increase the milling area of the whole bottom hole assembly (BHA).

Typically an underreamer has a tubular body with a thread at either end which allows the tool to be connected to other tools in a drill string and introduced into a well bore. A number of blades are mounted on the body of the underreamer, the blades being moveable from a retracted position in which they lie within the outer diameter of the body to an expanded position in which the blades extend outwardly from the outer diameter of the tubular body.

The blades effectively increase the outer diameter of the underreamer which allows the blades to cut material from the wellbore as the tubular body is rotated within the bore.

Typically the blades of the underreamer are pivotally mounted on the body through a pivot pin which extends through corresponding apertures in one end of the blade and the body to retain the blade in position upon the body. The blades are selectively moved from the retracted to the expanded position either by fluid flow within or around the tool or by the actuation of a piston or sleeve which pushes the blades into the expanded position.

When the blades are in the expanded position, the loads carried by the blade are transferred into the retaining pin which can lead to the pin snapping under the high loading as a result of combined set down weight and torque. If the pin snaps or shears, the blade and the pin become detached from the body and may then fall into the wellbore.

Any material falling from the body of the drill string and striking another tool in the string can cause significant damage either by striking or knocking against another tool or by becoming jammed between one of the other tools and the inner surface of the wellbore, which could cause damage to any of the tools of the string which is rotating within the bore.

Additionally in some cases the broken blade may have to be fished out of the well bore which requires withdrawal of the drill string and the use of specialist fishing tools which introduce delays into the drilling operation and add significant costs in terms for man hours and equipment which can run to many millions of pounds.

A further problem which can occur with known underreamers is that the vibration experienced downhole can lead to the pin backing out of the apertures and falling from the tool thereby freeing the blade and causing failure of the tool and potential damage to equipment or delay to the operation.

It is an object of the present invention to provide an improved underreamer which addresses and or overcomes or mitigates these known problems.

According to one aspect of the present invention there is provided an underreamer for use in subterranean wellbores comprising a tubular member, the outer surface of which has a recessed region, the recessed region comprising a load bearing shoulder, a blade pivotally mounted within the recessed region, a piston slidably mounted over the tubular member, said piston comprising a cam surface, wherein upon actuation the piston slides along the tubular member and the cam surface causes the blade to pivot to a radially expanded position out of the recessed region of the tubular member and wherein in the expanded position the blade is held between the load bearing shoulder of the tubular member and the cam surface of the piston such that load on the blade is transferred through the piston and load bearing shoulder.

Preferably, the cam surface of the piston comprises a tapered surface.

Advantageously the piston is a tubular member and most preferably is a sleeve which slides over the tubular member.

Advantageously the angle of the tapered surface of the piston matches the angle of the load bearing shoulder of the tubular member.

Conveniently the piston is provided with an aperture, the tapered surface of the piston being provided at one end of the aperture.

Advantageously, a slot is formed in the other end of the aperture of the piston, remote from the cam surface.

Conveniently the underreamer comprises three blades, most preferably the blades are mounted equidistant around the circumference of the tubular body.

Preferably when the piston is in the unactivated condition and the blade(s) is/are in the retracted position, the blade(s) is/are retained in the slot of the piston aperture against radial expansion.

Advantageously the underreamer further comprises a nozzle and may also comprise flushing apertures to redirect fluid existing from the nozzle along the tool and onto the blade(s) to clean the blade(s) as it/they cut material from the bore.

Preferably the nozzle is provided at the lower end of the tool in use.

Advantageously the piston actuable from the surface and most preferably the piston is pulled up along the tubular member to activate the blade(s) of the underreamer from the retracted to the expanded position.

According to a further aspect of the present invention there is provided a method of removing material from a wellbore, the method comprising deploying an underreamer according to the first aspect of the present invention into the wellbore and activating the piston of the underrearner to cause the blade of the underreamer to pivot to a radially expanded position and holding the blade in the expanded position between the load bearing shoulder of the tubular member and the cam surface of the piston such that load on the blade is transferred through the piston and the load bearing shoulder.

Preferably the piston is activated from the surface and most preferably the piston is pulled up over the tubular body of the underreamer.

An embodiment of the present invention will now be described by way of

example in which:-

Figure 1 is a partial cross-sectional longitudinal view of an underreamer according to one aspect of the present invention in a closed position; Figures 2 and 3 are similar views to Figure 1 with a blade of the underreamer shown in first and second partially extended positions; Figure 4 is a similar view to Figure 1 in a fully open position; Figure 5 is an exploded plan view of the inner mandrel and blade of the underreamer of Figure 1; Figure 6 is an end view of the underreamer of Figure 1 in a closed condition; Figure 7 is an end view of the underreamer of Figure 1 in an open condition, and Figure 8 is an end view of the inner mandrel of Figure 5.

Turning now to the Figures, there is shown in Figure 1 an underrearner 1 according to one aspect of the present invention. The underreamer comprises a hollow tubular housing 2 within which a hollow tubular mandrel 3 is mounted. The tubular housing is threaded at either end 4 to allow the underreamer to be connected into a drill string or down hole motor assembly comprising other tools or equipment with similar threaded connections.

The tubular mandrel 3 of the underreamer is shown in more detail in Figure 5 and comprises a hollow body 5 with an inlet 6 at one end of the body and an outlet 7 at the other. In use the inlet of the body is at the upper end of the body and the outlet is at the lower end.

The diameter of the body 5 increases adjacent the outlet 7 of the tubular mandrel. A nozzle 8 is mounted within the outlet of the mandrel. One or more ports 9 are formed through the wall of the mandrel in the vicinity of the nozzle to provide for fluid communication between the internal bore 10 of the mandrel and the well bore as will be described further below.

The hollow body 5 of the mandrel comprises a first portion 11 and a second portion 12, the second portion having a greater outer diameter than the first. A circumferential groove 13 is formed in the outer diameter of the second portion adjacent each end of the second portion. The grooves are sized to receive a seal (not shown) such as an 0-ring as will be described further below.

Recesses 14 are milled into the outer surface of the second portion 12 of the body. In the illustrated embodiment three recesses are milled in the body, the recesses being axially spaced around the circumference of the body. The recesses are spaced a similar distance from either end of the second portion of the body.

Each recess is substantially rectangular in form with an arcuate shoulder portion provided at one end of the recess. The arcuate shoulder is provided at the upper end (in use) of the recess. An aperture 16 is formed in the body within each recess. The aperture extends radially into the mandrel body and is provided towards the arcuate shoulder of the recess.

A blade 17 is mounted within each recessed area. In this embodiment as there are three recessed areas, the underreamer comprises three blades.

Each blade comprises a substantially planar member the length of which can be wholly received within the recessed area. A first end 18 of the blade has an arcuate profile 19 which matches the curve of the arcuate shoulder 15 of the recessed area. An aperture 20 is formed through the blade in the region of the first end, which aperture corresponds in size and position to the aperture in the recessed area to enable a pivot pin 21 to be passed through the corresponding apertures to mount the blade on the body of the mandrel.

A retaining screw 22 passes through an aperture 23 through the side wall of the blade and lodges in a corresponding aperture (not shown) in the pivot pin.

The other end of the blade 24, remote from the aperture is wider than the first end and wider than the recessed area 14. The second end of the blade has two opposing tapered faces 25, 26 which meet in an apex 27 at the longest point of the blade. The tapered faces are of different lengths with the face mounted internally of the recessed region 25 being longer than the external tapered face 26.

The edge 28 of the blade which is mounted internally of the recessed area is substantially straight and extends from the end of the internal tapered face 25 to the first end 18 of the blade. The other edge 29 of the blade which extends from the recessed area 14 when the blade is mounted in its retracted position, has a first straight portion 30 which extends from the end of the tapered face 26 and a second tapered portion 31 which tapers from the end of the straight portion 30 towards the arcuate end of the blade 18.

The upper part of the edge 28, first and second tapered faces 25, 26 and first straight portion 30 of the edge 29 of the blade comprises milled recesses around the exposed edges. These recesses can accommodate cutting elements such as Carbide inserts, a crushed carbine matrix, a diamond impregnated matrix, PDC inserts or some other type of milling dressing. Alternatively the exposed edges may be dressed with a hard facing so that the blades can be used for stabilising applications.

The underreamer further comprises a piston 32 which is actuable to move the blade 17 from the position shown in Figure 1 in which it is stored within the recessed area 14 of the body to an expanded position shown generally in Figure 4 in which the blade extends radially from the recessed area of the body.

The piston comprises a hollow tubular member 33, the inner diameter of which is larger than the outer diameter of the inner mandrel 3 and the outer diameter of which is smaller than the inner diameter of the hollow housing 2.

The piston is slidably mounted over the inner mandrel 3 and in use slides between the outer surface of the inner mandrel and the inner surface of the outer housing.

A slot 34 is formed in the body of the piston. When the underreamer is in the closed condition as shown in Figure 1, the slot in the piston sits over the recessed area 14 of the inner mandrel. The upper end 35 (in use) of the slot of the piston is generally rectangular and of a width to retain the first end of the blade 18 and prevent the blade from pivoting around the pin 21 to extend radially from the recessed region.

The lower end (in use) of the slot of the piston has a tapered surface 36 which tapers towards the lower end (in use) of the piston. The tapered surface of the piston slot is substantially straight and substantially matches the straight edge 28 of the blade when in the fully extended position.

In the illustrated embodiment, the underreamer has three blades, each mounted within a recessed area of the inner mandrel. Therefore the piston has three slots spaced around the circumference of the piston, each slot acting to hold the respective blade within its recessed area and each providing a tapered surface to cause its respective blade to move from the retracted to the extended position.

The upper end (in use) of the piston has an internal groove 37 to receive a sealing member (not shown) such as an 0-ring to provide a seal between the outer surface of the first portion 11 of the inner mandrel and the inner surface of the piston.

In use, a blade 17 is mounted into each of the recessed areas 14 of the inner mandrel 3 and pivot pins 21 are passed through the apertures in the blades and the recessed areas. Retaining screws 22 are inserted through the apertures in the side of the blade and the pivot pin. The blades are held in the retracted position and the piston 32 is slid over the inner mandrel 3 such that the slots 34 of the piston overlie the recessed areas 14 and the blades 17 are restrained from pivoting by the rectangular end of the slots which overlies the first end 18 of the blade and covers the pivot pins and retaining screws.

A spring 38 is mounted around the first portion 11 of the inner mandrel and the inner mandrel 3, piston 32 and spring 38 are mounted within the housing 2 of the underreamer. The spring extends between an inner surface 39 of the housing at the upper (in use) end of the housing and the upper end (in use) 40 of the piston and acts to bias the piston into the unactivated position within the housing.

The underreamer is then connected into a drill string or downhole motor assembly and introduced into a welibore where it is lowered until it reaches the required position for operation.

When it is required to operate the underreamer, the piston 32 is pulled upwards within the housing 2 against the bias of the spring force 38. Fluid flowing through the tool flows from the inlet 6 to the outlet 7 through the nozzle 8. The nozzle can be adjusted to alter the flow rate of fluid through the too. A pressure drop is produced in the fluid across the nozzle such that pressure up stream of the nozzle is greater than the fluid pressure down stream. This pressure acts on the piston 38 to pull up the piston thereby compressing the spring.

As the piston moves upwardly within the housing, the piston slot 34 moves upwardly and the rectangular end 35 of the piston slot moves out of contact with the blade thereby freeing the first end 18 of the blade such that it can rotate out of the recessed area 14. Further upward movement of the piston brings the tapered surface 36 at the lower end (in use) of the piston slot into engagement with the tapered face 25 on the other end of the blade. Continued upward movement of the piston causes the tapered face 25 of the blade to slide along the tapered surface 36 of the piston slot which in turn causes the blade to rotate about the pivot pin 21 and the blade is pushed out of the recessed area and out of the slot, thereby bringing the blade into engagement with the wall of the wellbore.

When the blade 17 is in the fully extended position, the tapered surface 36 of the slot of the piston lies against the internal straight edge 28 of the blade and the first end of the blade 18 is securely held between the tapered surface 36 of the slot of the piston and the arcuate load shoulder 15 of the recessed area and the blade is effectively clamped and therefore locked in the extended position between the tapered surfaces of the piston slot and the arcuate load bearing shoulder of the recessed area.

Therefore the load on the extended blade is transferred through the tapered surface and the load shoulder rather than through the pivot pin as with know underreamers. This provides protection to the blades and also to the pins and by reducing the load on the pivot pin, reduces the likihood of the pin to break or vibrate out of the aperture thereby causing the blade to become separated from the underreamer body.

Furthermore, the retaining screw 22 is prevented from backing out of the blade when the blade is both fully open and fully retracted as the rectangular end 35 of the piston slot fully covers the retaining screw.

During use of the underreamer, fluid may be pumped down the bore of the inner mandrel from the inlet to the outlet. At the outlet 7 the fluid can flow from the nozzle 8 to the communication ports 9 in the inner mandrel 3 and from there may be jetted onto the blades 17 thereby providing a flushing function to clean debris material from the blades to prevent the blades from becoming fouled by debris material from the wellbore.

When the cutting operation is over, flow is interrupted and the piston is released and moves downwards under the bias of the spring. As the piston moves downwards, the tapered surface 36 of the slot of the piston moves out of contact with the tapered face 25 of the blade freeing the blade from the locked position.

Simultaneously, the rectangular end 35 of the slot of the piston comes into contact with the inwardly tapered portion 31 of the second external edge 29 of the blade and causes the blade to rotate back into the recessed area of the inner mandrel.

The underreamer may be activated at a selected depth within the wellbore to extend the blades to provide for removal of material from the wellbore.

The device may then be deactivated such that the blades are retracted into the housing and the work string lowered to a different depth within the wellbore. The device may then be reactivated to allow for selected removal of material from the wellbore at a new location.

As described above, during use, loading on the blades 17 of the underreamer is transferred to the arcuate load shoulder 15 of the inner mandrel and the tapered surface 36 of the piston slot rather than the pivot pin. Therefore the pivot pin is protected from loading stresses and is less likely to break or back out of the apertures in the blade and the inner mandrel. This represents a significant advantage over known underreamers in which the pivot pin represents the weakest point of the device but is required to carry the significant loads to which the blades of the underreamer are exposed during the cutting operation.

Whilst a specific embodiment of the present invention has been described above, modifications of the present invention are also envisaged. For example, whilst the underreamer has been described as having three blades equispaced around the body of the underreamer, the number of blades may be changed and the spacing between adjacent blades around the underreamer may be altered. For example four blades may be provided. Afternatively only two blades may be used.

The underreamer may be assembled with an inner tubular sleeve 41 shown in Figure 1 provided over a portion of the inner mandrel 3 and specifically over the communication ports 9 of the inner mandrel to block fluid communication between the nozzle and the blades of the underreamer. The inner sleeve is mounted under the piston and does not inhibit sliding of the piston over the inner mandrel or extension or retraction of the blades of the underreamer.

In some applications it may be desirable to have the annulus outside the tool completely isolated from the internal bore of the tool. Also, if a restriction below the tool is to be used to generate the operating pressure rather than fluid flow through the nozzle as described above, then the flushing ports are blocked off to ensure the pressure differential generated by the restriction is transferred to the piston to cause the piston to actuate.

Claims (17)

  1. CLAIMS1. An underreamer for use in subterranean welibores comprising a tubular member, the outer surface of which has a recessed region, the recessed region comprising a load bearing shoulder, a blade pivotally mounted within the recessed region, a piston slidably mounted over the tubular member, said piston comprising a cam surface, wherein upon actuation the piston slides along the tubular member and the cam surface causes the blade to pivot to a radially expanded position out of the recessed region of the tubular member and wherein in the expanded position the blade is held between the load bearing shoulder of the tubular member and the cam surface of the piston such that load on the blade is transferred through the piston and load bearing shoulder.
  2. 2. An underreamer according to claim 1, wherein the cam surface of the piston comprises a tapered surface.
  3. 3. An underreamer according to claim 1 or 2, wherein the piston comprises a tubular member.
  4. 4. An underreamer according to claim 3, wherein the piston comprises a sleeve which slides over the tubular member.
  5. 5. An underreamer according to claim 2, wherein the angle of the tapered surface of the piston matches the angle of the load bearing shoulder of the tubular member.
  6. 6. An underreamer according to claim 2 or 5, wherein the piston is provided with an aperture, the tapered surface of the piston being provided at one end of the aperture.
  7. 7. An underreamer according to claim 6, wherein a slot is formed in the other end of the aperture of the piston, remote from the cam surface.
  8. 8. An underreamer according to any of the preceding claims comprising a plurality of blades.
  9. 9. An underreamer according to claim 8, wherein the underreamer comprises three blades,
  10. 10. An underreamer according to claim 8 or 9, wherein the blades are mounted equidistant around the circumference of the tubular body.
  11. 11. An underreamer according to any of the preceding claims wherein when the piston is in an unactivated condition and the blade(s) is/are in a retracted position, the blade(s) is/are retained in the slot of the piston aperture against radial expansion.
  12. 12. An underreamer according to any of the preceding claims wherein the underreamer further comprises a nozzle.
  13. 13. An underreamer according to claim 12, further comprising flushing apertures to redirect fluid existing from the nozzle along the tool and onto the blade(s) to clean the blade(s) as it/they cut material from the bore.
  14. 14. An underreamer according to claim 12 or 13, wherein the nozzle is provided at the lower end of the tool in use.
  15. 15. An underreamer according to any of the preceding claims wherein the piston is actuable from the surface.
  16. 16. An underreamer according to claim 15, wherein the piston is pulled up along the tubular member to activate the blade(s) of the underreamer from the retracted to the expanded position.
  17. 17. An underreamer substantially as hereinbefore described with reference to and as shown in the accompany drawings.19. A method of removing material from a wellbore, the method comprising deploying an underreamer according any of claims 1-17 into the wellbore and activating the piston of the underreamer to cause the blade of the underreamer to pivot to a radially expanded position and holding the blade in the expanded position between the load bearing shoulder of the tubular member and the cam surface of the piston such that load on the blade is transferred through the piston and the load bearing shoulder.20. A method of removing material from a wellbore substantially as hereinbefore described.
GB201018612A 2009-11-04 2010-11-04 Underreamer Withdrawn GB201018612D0 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0919332A GB0919332D0 (en) 2009-11-04 2009-11-04 Underreamer

Publications (2)

Publication Number Publication Date
GB201018612D0 GB201018612D0 (en) 2010-12-22
GB2475167A true true GB2475167A (en) 2011-05-11

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GB0919332A Ceased GB0919332D0 (en) 2009-11-04 2009-11-04 Underreamer
GB201018612A Withdrawn GB201018612D0 (en) 2009-11-04 2010-11-04 Underreamer

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Application Number Title Priority Date Filing Date
GB0919332A Ceased GB0919332D0 (en) 2009-11-04 2009-11-04 Underreamer

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2612166C1 (en) * 2015-11-10 2017-03-02 Закрытое акционерное общество "ПРОММАШСЕРВИС" Expander

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB540027A (en) * 1940-04-26 1941-10-02 Percy Cox Improvements in and relating to rock boring and like tools
US5060738A (en) * 1990-09-20 1991-10-29 Slimdril International, Inc. Three-blade underreamer
US5402856A (en) * 1993-12-21 1995-04-04 Amoco Corporation Anti-whirl underreamer
GB2308608A (en) * 1994-10-31 1997-07-02 Red Baron The 2-stage underreamer
GB2374100A (en) * 1999-10-21 2002-10-09 Allen Kent Rives Underreamer and method of use
GB2458527A (en) * 2008-03-25 2009-09-30 Tony Laplante A high expansion anchoring or stabalizing device
WO2010054407A1 (en) * 2008-11-10 2010-05-14 Weatherford/Lamb, Inc. Extendable cutting tools for use in a wellbore

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB540027A (en) * 1940-04-26 1941-10-02 Percy Cox Improvements in and relating to rock boring and like tools
US5060738A (en) * 1990-09-20 1991-10-29 Slimdril International, Inc. Three-blade underreamer
US5402856A (en) * 1993-12-21 1995-04-04 Amoco Corporation Anti-whirl underreamer
GB2308608A (en) * 1994-10-31 1997-07-02 Red Baron The 2-stage underreamer
GB2374100A (en) * 1999-10-21 2002-10-09 Allen Kent Rives Underreamer and method of use
GB2458527A (en) * 2008-03-25 2009-09-30 Tony Laplante A high expansion anchoring or stabalizing device
WO2010054407A1 (en) * 2008-11-10 2010-05-14 Weatherford/Lamb, Inc. Extendable cutting tools for use in a wellbore

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2612166C1 (en) * 2015-11-10 2017-03-02 Закрытое акционерное общество "ПРОММАШСЕРВИС" Expander

Also Published As

Publication number Publication date Type
GB0919332D0 (en) 2009-12-23 grant
GB201018612D0 (en) 2010-12-22 grant

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