GB2178831A - Apparatus for severing a wellhead - Google Patents
Apparatus for severing a wellhead Download PDFInfo
- Publication number
- GB2178831A GB2178831A GB08615903A GB8615903A GB2178831A GB 2178831 A GB2178831 A GB 2178831A GB 08615903 A GB08615903 A GB 08615903A GB 8615903 A GB8615903 A GB 8615903A GB 2178831 A GB2178831 A GB 2178831A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fuse
- charge
- explosive
- fuse device
- casing
- 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- Withdrawn
Links
- 239000002360 explosive Substances 0.000 claims abstract description 26
- 239000004568 cement Substances 0.000 claims abstract description 6
- 239000004567 concrete Substances 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 6
- 238000005474 detonation Methods 0.000 claims description 3
- 239000002984 plastic foam Substances 0.000 claims description 3
- 239000006261 foam material Substances 0.000 claims 1
- 239000006260 foam Substances 0.000 abstract description 5
- 239000011152 fibreglass Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
- E21B29/12—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground specially adapted for underwater installations
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
- E21B29/02—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground by explosives or by thermal or chemical means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/04—Arrangements for ignition
Landscapes
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Fluid Mechanics (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical & Material Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Geophysics And Detection Of Objects (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
- Shovels (AREA)
Abstract
Apparatus 1 for severing a wellhead of a sub-sea well system comprises an explosive charge 2 contained within a casing 5 comprising sleeves 11, 12 with brittle foam, concrete or cement in the space 13 therebetween; a standard weight of explosive can therefore be used for different thicknesses of wellhead to be severed. Fuse devices 3 and 4 are bolted to end rings 6 of the casing 5; each comprises inner and outer shells with brittle foam or cement therebetween. Upper device 3 contains a coiled explosive fuse, and an explosive fuse of the same length extends along each hollow column 14 through the space 13, whereby the charge 2 can be detonated at opposite ends simultaneously. Plane wave formers (8) in the fuse devices ensure the coincidence of plane waves at the centre of the apparatus to provide an explosive severing force at right angles to its length. <IMAGE>
Description
1 GB 2 178 831 A 1
SPECIFICATION
Apparatus for severing a wellhead The invention relates to apparatus for severing a wellhead, or other parts of a well system such as a multistring casing, by means of an explosive charge.
In the oil industry it is known to remove wellheads once a well is found to be dry or depleted of recover- able oil or gas reserves. The well is plugged, cemented and all structures above ten feet (3.05 M) beneath the mud] ine removed, as required bylaw. Conventional practice is either to mechanically cut the casings or lower an explosive charge.
Mechanical cutting is a timely and hence costly procedure. Explosive cutting charges currently are large, inefficient and unreliable resulting in a reluct ance to use them.
It is accordingly an object of the present invention to provide apparatus that will reliably cutthe casing, causing less peripheral damage to the casing using smaller quantities of explosives, and reducethe prob lems of secondary blast effects, such as through wa tershock, damaging vessels in close vicinityto the charge.
According to the invention there is provided appar atus for severing a well system atfor example a well head, comprising a casing having an inner and an outersleeve and an explosive charge within the inner sleeve.
There may be a brittle medium in the space be tween the sleeves.
The brittle mediu m may comprise a plastic foam material.
The brittle medium may alternatively comprise 100 concrete.
The respective sleeves may comprise concentric right cylinders whereby to provide an annularspace therebetween.
The apparatus may comprisetwo fuse devices situ ated one at each end of the casing.
The apparatus may comprise means fordetonating the charge substantially simultaneously at each end.
The means for providing substantial simultaneous detonation may comprise an explosive fuse in one fuse device and an explosivefuse running from the one fuse device to the otherfuse device, both fuses being substantially of the same length.
The one fuse device may have guide means extend ing therefrom through the space between the sleeves to the otherfuse device, the guide means receiving and guiding the explosive fuse between thefuse de vices.
The guide means may comprisetwo substantially rigid tubes which extend from the onefuse device through the space between the sleeves to the other fuse device.
The other fuse device may have sockets for receiv ing the ends of the tubes.
Each fuse device may comprise a plane wave former.
Each fuse device may comprise a body having an inner and an outershell, the space between the shells containing a brittle medium.
The brittle medium may comprise a foam plastics material or a cementitious material e.g. cement.
The inner sleeve of the casing and the inner shell of the or each fuse device may be substantially of the same diameter, and the outer sleeve of the casing and the outer shall of the or each fuse device may be substantially of the same diameter.
Afuse detonating cord may be connected to a central point at one end of the explosive charge and to a central point atthe opposite end of the charge.
The detonating cord may comprise four lengths running to two junction boxes atthe base of the charge, a length of fuse detonating cord running from one fuse boxto one end of the charge and from the otherfuse boxto the other end of the charge, thetwo lengths being substantially equal.
The four lengths may be substantially Wapart.
Apparatus for severing a systernJor example ata wellhead, is hereinafter described, byway of example, with reference to the accompanying drawings.
Figure 1 is an exploded perspective view of apparatus according to the invention; Figures2A-Cshow respective side elevational (partly in longitudinal section) top plan and bottom views of a top (in use) fuse device; Figures3anclA show respective side elevational (partly in longitudinal section) and bottom plan views of a bottom (in use) fuse device; Figures4and 4A show similar views to Figures 3 and 3A, of a charge casing; and Figures 5and 5A show respective side elevational (partly in longitudinal section) and top plan views of an insert in each fuse device.
Referring to the drawings, there is shown apparatus 1 forsevering a wellhead of a sub-sea well system using an explosive charge 2, shown in dashed lines in Figure 1. The apparatus 1 comprises two fuse devices 3 and 4 connected to a casing or housing 5for the charge 2.
Housing the charge 2 within the casing 5 means that a standard weight of explosive can be used for different thicknesses of wellhead to be severed,while providing a minimum thickness of explosiveto detonate at a maximum explosive effect. This is in contrastto the prior art, wherethe explosive is wrapped round a central core. In that arrangement, twice as much explosive must be used forcutting a 40 cm diameter wellhead as a 20 cm one. Thus the present invention provides fora standarized charge.
Thefuse devices 3 and 4 are each made of fibreg- lass and are secured one at each end to a respective ring 6 of the casing 5 using suitable securing means such as boltsthrough aligned holes 7.
Each fuel device 3 is a hollow fibreglass shell containing an explosivefuse and a generally conical fib- reglass former or insert 8 which acts as a plane wave former 8, pointing away from the charge and having an apex 9, in the assembled apparatus 1, and the respective fuse devices 3 are supported on respective rings 10 of the casing 5.
The fuse devices 3 and 4 also contain a packing of a foam plastic material or a cementitious material, e.g. cement.
The casing 5 comprises two steel sleeves 11 and 12 which in the embodiment shown are coaxial, the charge being in the inner sleeve 11. The outer sleeve 2 GB 2 178 831 A 2 12 is of a diameterto pass down the inner diameter of the well casing. The space 13 between the sleeves 11 and 12 is annular and contains a plastic foam fi I ling, and there is means in the form of two tubes or col- umns 14 extending from the furse device 4 to the fuse device 3 for detonating the charge substantially simultaneously.
The foam filling in each case is one which has good shock tra nsmitti ng properties, is brittle, and dense so as little energy as possible is absorbed on detonation.
The upper (in use) fuse device 3 contains a coiled explosive fuseterminating atthe charge 2. An explosive fuse of the same length asthe coiled fuse extends along each column 14 in the space 13 to the bottom (in use) fuse device 4where it contacts the charge 2, at a position oppositethe point of contact of the other fuse.
In use, both explosive fuses are detonated simultaneously, and they explode atthe same rate asthey are the same length, so that they both detonate the charge 2 at opposite ends at the same time, or substantiallyso. The charge 2 is thus detonated at both ends and the inserts or plane wave formers 8 ensure thattwo plane waves pass to the centre of the device, where they coincide to provide an explosive force at right angles to the length of the apparatus 1, which severs the wellhead cleanly.
The actual connection of the fuses can vary, but it one arrangemeritthe fuse detonating cord starts ata central point atthe top of the charge. There are four length, 9Wapart running to two junction boxes 180' apart on the perimeter of the base. At the junction box, two lengths collide, and initiate a second run. One run travels backup into the charge. An equal length, contained in the bottom device, affixes in the opposite end. The end travelling backup into the top fuse unit meets the run from the opposite junction box at the apex of a plane wave former or generator centrally situated in the base of the top unit.
Claims (20)
1. Apparatus for severing a well system atfor example a wellhead, comprising a casing having an inner and an outer sleeve and an explosive charge within the inner sleeve.
2. Apparatus according to Claim 1, there being a brittle medium in the space between the sleeves.
3. Apparatus according to Claim 2, the brittle medium comprising a plasticfoam material.
4. Apparatus according to Claim 2, the brittle medium comprising a concrete ora cement.
5. Apparatus according to any preceding claim, the respective sleeves comprising concentric right cylinders whereby to provide an an nu lar space therebetween.
6. Apparatus according to any preceding claim, comprising two fuse devices situated one at each end of the casing.
7. Apparatus according to Claim 6, comprising means for detonating the charge substantially simultaneousiy at each end.
8. Apparatus according to Claim 7, the means for providing substantial simultaneous detonation corn- prising an explosive fuse in one fuse device and an explosive fuse running from the one fuse device to the otherfuse device, both fuses being substantially of the same length.
9. Apparatus according to Claim 8, the one fuse device having guide means extending therefrom through the space between the sleeves to the other fuse device, the guide means receiving and guiding the explosivefuse between thefuse devices.
10. Apparatus according to Claim 9, the guide means comprising two substantially rigid tubes which extend from the one fuse device through the space between the sleeves to the other fuse device.
11. Apparatus according to Claim 10, the other fuse device having sockets for receiving the ends of thetubes.
12. Apparatus according to Claim 4, each fuse device comprising a body having an inner and an outer shell, the space between the shells containing a brittle medium.
13. Apparatus according to Claim 12, the brittle medium comprising a foam material.
14. Apparatus according to Claim 12, the brittle medium comprising a cement.
15. Apparatus according to any of Claims 4to 14, each fuse device comprising a plane waveformer.
16. Apparatus according to any of Claims 13 to 15, the inner sleeve of the casing and the inner surface of the or each fuse device being substantially of the same diameter, and the outer sleeve of the casing and the outer surface of the or each fuse device being substantially of the same diameter.
17. Apparatus according to any of Claims 8to 16, a fuse detonating cord being connected to a central point at one end of the explosive charge and to a central point atthe opposite end of the charge.
18. Apparatus according to Claim 17, the detonating cord comprising four lengths running to twojunction boxes at the base of the charge, a length of fuse detonating cord running from one fuse box to one end of the charge and from the otherfuse box to the other end of the charge, the two lengths being substantially equal.
19. Apparatus according to Claim 18, the four lengths being substantially 90'apart.
20. Apparatus for severing well system atfor ex ample a wellhead, substantially as hereinbefore de scribed with reference to the accompanying draw ings.
Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 12/86, D8817356. Published by The Patent Office, 25 Southampton Buildings, LondonWC2A 1AY, from which copies may be obtained.
z
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858519111A GB8519111D0 (en) | 1985-07-29 | 1985-07-29 | Severing wellhead |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8615903D0 GB8615903D0 (en) | 1986-08-06 |
| GB2178831A true GB2178831A (en) | 1987-02-18 |
Family
ID=10583029
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858519111A Pending GB8519111D0 (en) | 1985-07-29 | 1985-07-29 | Severing wellhead |
| GB08615903A Withdrawn GB2178831A (en) | 1985-07-29 | 1986-06-30 | Apparatus for severing a wellhead |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858519111A Pending GB8519111D0 (en) | 1985-07-29 | 1985-07-29 | Severing wellhead |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0211515A2 (en) |
| CN (1) | CN86105631A (en) |
| DK (1) | DK329086A (en) |
| GB (2) | GB8519111D0 (en) |
| NO (1) | NO863042L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2179124B (en) * | 1985-06-29 | 1989-07-19 | Deepwater Oil Services | Cutting device. |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10145195B2 (en) | 2014-05-12 | 2018-12-04 | Halliburton Energy Services, Inc. | Well-component severing tool with a radially-nonuniform explosive cartridge |
| CN106930723B (en) | 2017-02-15 | 2019-01-18 | 中国石油大学(北京) | Wall device and its application in solution cavity leak stopping are consolidated in the leak stopping of nesting of cumulative binding type |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB707380A (en) * | 1949-11-21 | 1954-04-14 | Arwyn Randall Davies | Improvements in or relating to cartridges for explosive charges |
| GB1367011A (en) * | 1971-11-25 | 1974-09-18 | Ridgeway J J | Linear shaped-charge device |
| US4037536A (en) * | 1975-09-08 | 1977-07-26 | Imc Chemical Group, Inc. | Enclosure for explosive material |
| GB2055663A (en) * | 1979-06-25 | 1981-03-11 | Jet Research Center | Method and apparatus for severing conduits |
| GB1604688A (en) * | 1977-06-29 | 1981-12-16 | Jet Research Center | Method and apparatus for severing tubing |
| EP0057308A1 (en) * | 1981-01-29 | 1982-08-11 | Wang, Shu-Jen | Apparatus and method of blasting undersea rocks |
| US4378844A (en) * | 1979-06-29 | 1983-04-05 | Nl Industries, Inc. | Explosive cutting system |
| GB2134630A (en) * | 1983-01-10 | 1984-08-15 | Wang Su Jen | Apparatus and method of blasting rocks |
| GB2158207A (en) * | 1984-04-26 | 1985-11-06 | Vetco Ltd C E | Explosive cutting device |
-
1985
- 1985-07-29 GB GB858519111A patent/GB8519111D0/en active Pending
-
1986
- 1986-06-30 GB GB08615903A patent/GB2178831A/en not_active Withdrawn
- 1986-06-30 EP EP86305064A patent/EP0211515A2/en not_active Withdrawn
- 1986-07-10 DK DK329086A patent/DK329086A/en not_active Application Discontinuation
- 1986-07-23 CN CN198686105631A patent/CN86105631A/en active Pending
- 1986-07-28 NO NO863042A patent/NO863042L/en unknown
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB707380A (en) * | 1949-11-21 | 1954-04-14 | Arwyn Randall Davies | Improvements in or relating to cartridges for explosive charges |
| GB1367011A (en) * | 1971-11-25 | 1974-09-18 | Ridgeway J J | Linear shaped-charge device |
| US4037536A (en) * | 1975-09-08 | 1977-07-26 | Imc Chemical Group, Inc. | Enclosure for explosive material |
| GB1604688A (en) * | 1977-06-29 | 1981-12-16 | Jet Research Center | Method and apparatus for severing tubing |
| GB2055663A (en) * | 1979-06-25 | 1981-03-11 | Jet Research Center | Method and apparatus for severing conduits |
| US4378844A (en) * | 1979-06-29 | 1983-04-05 | Nl Industries, Inc. | Explosive cutting system |
| EP0057308A1 (en) * | 1981-01-29 | 1982-08-11 | Wang, Shu-Jen | Apparatus and method of blasting undersea rocks |
| GB2134630A (en) * | 1983-01-10 | 1984-08-15 | Wang Su Jen | Apparatus and method of blasting rocks |
| GB2158207A (en) * | 1984-04-26 | 1985-11-06 | Vetco Ltd C E | Explosive cutting device |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2179124B (en) * | 1985-06-29 | 1989-07-19 | Deepwater Oil Services | Cutting device. |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8615903D0 (en) | 1986-08-06 |
| EP0211515A2 (en) | 1987-02-25 |
| DK329086A (en) | 1987-01-30 |
| NO863042L (en) | 1987-01-30 |
| GB8519111D0 (en) | 1985-09-04 |
| CN86105631A (en) | 1987-02-04 |
| NO863042D0 (en) | 1986-07-28 |
| DK329086D0 (en) | 1986-07-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |