GB2175674A - An explosive cutting device - Google Patents
An explosive cutting device Download PDFInfo
- Publication number
- GB2175674A GB2175674A GB08610175A GB8610175A GB2175674A GB 2175674 A GB2175674 A GB 2175674A GB 08610175 A GB08610175 A GB 08610175A GB 8610175 A GB8610175 A GB 8610175A GB 2175674 A GB2175674 A GB 2175674A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pipe
- charge
- charges
- lined cavity
- lined
- 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- Withdrawn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 title claims abstract description 19
- 238000005520 cutting process Methods 0.000 title claims abstract description 13
- 239000011159 matrix material Substances 0.000 claims abstract description 20
- 238000005474 detonation Methods 0.000 claims abstract description 17
- 230000000977 initiatory effect Effects 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims description 9
- 238000005553 drilling Methods 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 7
- 239000002184 metal Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 230000035939 shock Effects 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000004880 explosion Methods 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 230000004323 axial length Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B1/00—Explosive charges characterised by form or shape but not dependent on shape of container
- F42B1/02—Shaped or hollow charges
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Physics & Mathematics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
Abstract
An explosive cutting device for removing sections of a well casing pipe within a borehole comprises, in one embodiment, a plurality of lined cavity charges 2 defining a tubular shaped matrix of criss-crossing explosive charge lines. The charge 2 terminate in a ring 6 of lined cavity charge-on each end of the tubular matrix. Between the rings 6 the lined cavity charges define spaced crossover points 7. Spaced initiation points 3 around the ring 6 at one end of the tubular matrix provide for detonation to simultaneously begin from each initiation point. The casing is severed at 6 and portions opposite the lined charges are fragmented and dislodged to the middle of the well where they can drop downhole and do not interfere with the drilling head during side-tracking. in another embodiment separate cavity charges (as shown-in Figs. 4-7) can be used sequentially to cut the casing, first along one set of parallel lines and then along a second transverse set, when the geological formation does not permit casing expansion. <IMAGE>
Description
SPECIFICATION
An explosive cutting device
The present invention relates to a device for removing sections of a pipe or tube, and, in particular, sections of a well casing, by means of an explosive charge.
In the oil industry it is known to remove sections of pipe forming the well casing within a bore hole. The sections of pipe must be removed cleanly without leaving any debris behind as it is possible for the drilling head to be damaged by any fragments of the pipe left within the bore hole. Conventional practice in this respect is to insert into the pipe a specialised machine tool with a cutting head which is adapted to cut the section of pipe to be removed into pieces small enough to be circulated back to the surface. From here they can be withdrawn through the pipe casing.
The machine tool can be required to work at quite considerable depths below the head of the bore hole and for this reason the machine tool is a very expensive and complex item of equipment.
It is an object of the present invention to provide a device for removing sections of a pipe or tube by means of an explosive charge.
According to one aspect of the present invention there is provided a device for removing sections of pipe or tube comprising a first lined cavity charge for cutting pipe in a plurality of spaced parallel first directions around the periphery of the pipe, a second lined cavity charge for cutting pipe in a plurality of spaced parallel second directions around the periphery of said pipe, said second directions being transverse to said first directions, the arrangement being such that, in use, said first and said second cavity charges when disposed in a section of pipe to be removed define a plurality of cross-over points and a plurality of areas defined by said cross-over points to generate respective cut pieces of said pipe from locations of said pipe disposed adjacent said discrete areas.
Preferably said device for removing sections of a pipe or tube comprises a plurality of lined cavity charges which are arranged to define a tubular shaped matrix of criss-crossing explosive charge lines and fuse means connected to one end of the said tubular matrix.
Preferably, said plurality of lined cavity charges are comprised of a plurality of pairs of helically shaped lined cavity charges, one of which runs clockwise and the other anticlockwise.
Preferably, a ring of lined cavity charge is provided at each end of the said tubular shaped matrix.
Preferably, each pair of helically shaped lined cavity charges begins at a single initiation point provided on the circumference of one of said rings, and the fuse means is connected to each initiation point so as to cause detonation to begin simultaneously from each initiation point.
Preferably, the initiation points are equally spaced around the circumference of the said ring, and the diameter and pitch of each of the helically shaped line charges is the same.
Preferably, the explosive charge of each of the said rings of lined cavity charge is greater than that of the individual lined cavity charges defining the said tubular shaped matrix.
Accordingly in another aspect of the present invention there is provided a method of removing sections of pipe or tube from a pipe comprising the steps of;
providing a first lined cavity charge for cutting pipe in a plurality of spaced parallel first directions around the periphery of the pipe, disposing said first line cavity charge adjacent a section of pipe to be cut and detonating said charge to create a pattern of cut sections of pipe in said pipe corresponding to said first lined cavity charge, providing a second lined cavity charge for cutting pipe in a plurality of spaced parallel second directions around the periphery of said pipe, said second parallel direction being transverse to said first parallel direction, disposing said second lined cavity charge into said pipe adjacent the section of pipe to be cut and detonating said charge to create a pattern of cuts in said pipe corresponding to the first lined cavity charge, and to divide said first cut sections of pipe into a plurality of discrete pieces small enough to be removed.
Although not essential to the operation of the device of the present invention there will always be drilling fluid or sea water inside the well casing. This has the effect of amplifying the shock wave which follows the detonation wave caused by explosion of the lined cavity charge.
An embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which:
Fig. 1 shows a schematic representation of a device embodying the present invention;
Fig. 2 shows a schematic diagram of a cross-section through a lined cavity charge and illustrates the travelling jet developed within a well casing as a result of detonation of the charge;
Fig. 3 shows a schematic diagram of the shock front which follows penetration of the well casing.
Figs. 4 and 5 illustrate examples of charge configuration for use with an alternative method of removing sections of pipe, and
Figs. 6 and 7 depict alternative charge configurations for use with the alternative method.
Referring to Fig. 1 of the accompanying drawings there is shown a tubular shaped matrix 1 of lined cavity charge which is defined by six pairs 2 of helically shaped lined cavity charges,each of equal diameter and pitch.
Each pair of helically shaped lined cavity charge 2 begins at one of six equally spaced initiation points 3 provided around the circumference of one end of the tubular shaped matrix 1, with one 4 running clockwise and the other 5 anti-clockwise from the initiation point 3. Each end of the tubular shaped matrix 1 is terminated by a ring 6 of lined cavity charge of equal diameter to the six pairs 2 of helically shaped lined cavity charges. Between the rings 6, the helically shaped lined cavity charges 4,5 define a plurality of equally spaced crossover points 7. Detonation of the lined cavity charge is caused by fuse means (not shown) connected to each of the initiation points 3 and begins simultaneously at each initiation point.The lined cavity charge comprising the rings 6 and the helixes 4,5 is such that upon detonation it provided a highly localised jet of molten metal which cuts through any adjacent surface. This explosive material is commonly referred to as a linear cutter.
The diameter of the tubular matrix 1 is slightly smaller than the internal diameter of the well casing from which it is intended to remove a section so that the tubular matrix 1 can be lowered into the casing and is spaced from the internal surface of the casing about its entire circumference. The rings 6 and helixes 4,5 are comprised of sufficient explosive material to cut through the wall of the casing.
Referring to Fig. 2 the lined cavity charge comprises in section a substantially V-shaped channel of copper liner 7, the open end of which faces outward from the centre of the tubular matrix 1 and towards the surface to be cut. The back of the V-shaped liner is coated with a layer of explosive RDX 8. Detonation of the lined cavity charge takes place linearly along its length and results in the production of a highly localised metal jet in the direction of arrow Vj which penetrates any adjacent surface which depth of penetration depends on the explosive loading. In water the jet is followed by a shock wave which facilitates cracking of any uncut metal, particularly at the crossover points.
Operation of the device according to the present invention will now be described with reference to Figs 1,2 and 3. As described the well casing is filled with water or drilling mud which may enhance the cutting abilities of the charges due to containment of the charges caused by the hydrostatic head, but it is not essential to the operation of the device.
The effect of detonation is best understood if we consider a small section of the matrix of
Fig. 1 between points A, B, C, D and E. Detonation occurs simultaneously at each of the six initiation points 3 and spreads outwardly therefrom at an even rate around the uppermost ring 6 and along each of th helically shaped lined cavity charges 4,5. Around the ring 6 the explosive material cuts through the well casing and severs the section to be cut away from the well casing above it. Along lines AD, AC, BC and BE the explosive material scribes a line in the well casing.
The detonation waves originating at A and
B meet at junction C and the superposition of the detonation waves gives rise to high localised dynamic stresses at this crossover point which will facilitate complete fracture of the casing by forced crack potential origin from which cracks can spread propagation at the roots of any uncut metal regions. The gases generated by the detonation of the lined cavity charges along sides AC and BC dynamically compress the water between the lined cavity charges and the well casing, and give rise to compressive loading of the well casing along a line bisecting the angles between sides AC and BC. The cylindrical nature of the casing ensures that the loading on the wall of the well casing is even at each of the six points of intersection around the tubular matrix 1.
The shock waves generated by the detonation waves within the water are amplified within the water and tend to bend the wall of the well casing along the line bisecting the angle between sides AC and BC with the result of slight expansion of the casing which facilitates fracture. The action of the shock waves is aided by the gases generated by the explosion which meet at the centre of the casing and expand radially outwards to shock and subsequently expand the casing, thus forcing the cut sections of casing apart. At the same time the detonation waves meeting at point C also act to provide a booster for the detonation of the next pair of lined cavity charges.
Because of the low impedance of the material outside the well casing, the compressive stress wave will be reflected back as though from a free surface. This action tends to dislodge the cut-out sections of the well casing into the middle of the well casing from where they can be removed.
Reference is now made to Figs. 4,5 of the drawings which depicts separate circumferential and axial cavity charges which are used where geological formations allow no radial expansion of the casing to take place, and therefore no fracture of uncut metal. In such cases complete severance of the casing is required. The charges are used with a method in which two runs of the separate explosive charges are required.
As can be seen in Fig. 4 the first charge is a series of coaxial circular ring lined cavity explosive charges 10 disposed on a PVC or foam pipe charge holder 12 or any other suitable frangible material. The charges 10 are coupled by boosters 14 and fuses 16 to a detonator 18 which is fed to the surface by wires 20. The charges 10 have associated inflation collars 22 and casing cutter lines 24.
The second charge 25 as seen in Fig. 5 con sists of straight axial lengths 26 of copper linear cavity charge.
In the use, either charge 10 or charge 25 can be run first into the pipe. If charge 10 is run in first the explosive charge cuts the pipe into rings and the second charge cuts the rings into squares which are small enough to fall downhole. This technique minimises the possibiltiy of having linear metal at crossover points which could prevent the casing from facturing into single pieces (which can occur if the surrounding formation does not permit expansion of the casing).
Reference is now made to Figs. 6 and 7 which illustrate sets of clockwise and anticlockwise helical charges 28, 30 mounted on charge holders 32,34 respectively. Using charges 28,30 sequentially cuts the casing firstly into spiral sections and then into diamond shaped pieces. Either helical charge can be used with the charge pattern of cavity charges 10 or 25. The charges can be run in any order desired.
It will be appreciated that the device of the present invention provides a highly localised and controlled explosion which progresses the length of the device removing portions of the section of well casing to be removed. Due to the controlled nature of the explosion, small portions can be partially cut away from the main section and then with the superposition of the detonation waves at each crossover point can be dislodged into the middle of the well casing from where it can be easily removed. This technique ensures that portions of the pipe are not blasted into the material surrounding the well casing where it could later represent a threat to a drill head.
Claims (12)
1. A device for removing sections of pipe or tube comprising a first lined cavity charge for cutting pipe in a plurality of spaced parallel first directions around the periphery of the pipe, a second lined cavity charge for cutting pipe in a plurality of spaced parallel second directions around the periphery of said pipe, said second directions being transverse to said first directions, the arrangement being such that, in use, said first and said second cavity charges when disposed in a section of pipe to be removed define a plurality of crossover points and a plurality of areas defined by said crossover points to generate respective cut pieces of said pipe from locations of said pipe disposed adjacent said discrete areas.
2. A device for removing sections of a pipe or tube as claimed in claim 1 wherein said first and said second lined cavity charges which arranged to define a tubular shaped matrix of criss-crossing explosive charge lines and fuse means connected to one end of the said tubular matrix.
3. A device as claimed in claim 1 or claim 2 wherein said plurality of lined cavity charges are comprised of a plurality of pairs of helically shaped lined cavity charges, one of which runs clockwise and the other anticlockwise.
4. A device as claimed in claim 2 or claim 3 wherein a ring of lined cavity charge is provided at each end of the said tubular shaped matrix.
5. A device as claimed in claim 4 wherein each pair of helically shaped lined cavity charges begins at a single initiation point provided on the circumference of one of said rings, and the fuse means is connected to each initiation point so as to cause detonation to begin simultaneously from each initiation point.
6. A device as claimed in claim 5 wherein the initiation points are equally spaced around the circumference of the said ring, and the diameter and pitch of each of the helically shaped line charges is the same.
7. A device as claimed in claim 5 or claim 6 wherein the explosive charge of each of said rings of lined cavity charge is greater than that of the individual lined cavity charges defining said tubular shaped matrix.
8. A device as claimed in claim 1 wherein said first lined cavity charge is comprised of a plurality of spaced parallel circumferentially shaped lined cavity charges, and said second lined cavity charge is comprised of a plurality of spaced parallel axially disposed shaped lined cavity charges.
9. A method of removing sections of pipe or tube from a pipe comprising the steps of;
providing a first lined cavity charge for cutting pipe in a plurality of spaced parallel first directions around the periphery of the pipe, disposing said first line cavity charge adjacent a section of pipe to be cut and detonating said charge to create a pattern of cut sections of pipe in said pipe corresponding to said first lined cavity charge, providing a second lined cavity charge for cutting pipe in a plurality of spaced parallel second directions around the periphery of said pipe, said second parallel direction being transverse to said first parallel direction, disposing said second lined cavity into said pipe adjacent the section of pipe to be cut and detonating said charges to create a pattern of cuts in said pipe corresponding to the first lined cavity charge, and to divide said first cut sections of pipe into a plurality of discrete pieces small enough to be removed.
10. A method as claimed in claim 9 wherein said first and second lined cavity charges are combined into a single cavity charge arranged in a tubular matrix and said single cavity charge is detonated to cut said pipe into discrete pieces small enough to be removed.
11. A device substantially as hereinbefore described with reference wo Figs. 1-3 or to
Figs. 4-7 of the accompanying drawings.
12. A method substantially hereinbefore de scribed with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858510891A GB8510891D0 (en) | 1985-04-30 | 1985-04-30 | Explosive cutting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8610175D0 GB8610175D0 (en) | 1986-05-29 |
| GB2175674A true GB2175674A (en) | 1986-12-03 |
Family
ID=10578402
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858510891A Pending GB8510891D0 (en) | 1985-04-30 | 1985-04-30 | Explosive cutting device |
| GB08610175A Withdrawn GB2175674A (en) | 1985-04-30 | 1986-04-25 | An explosive cutting device |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB858510891A Pending GB8510891D0 (en) | 1985-04-30 | 1985-04-30 | Explosive cutting device |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8510891D0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4207828C1 (en) * | 1992-03-12 | 1993-08-26 | Deutsche Aerospace Ag, 8000 Muenchen, De | |
| DE19919041A1 (en) * | 1999-04-27 | 2000-11-09 | Daimler Chrysler Ag | Device for penetrating brickwork comprises housing containing two or more even-symmetrical hollow charges of explosive which produce cutting effect |
| WO2002063132A1 (en) * | 2001-02-06 | 2002-08-15 | Qinetiq Limited | Oil well perforator |
| WO2016067020A1 (en) * | 2014-10-28 | 2016-05-06 | Spex Engineering (Uk) Limited | Cutting tool |
| WO2017125745A1 (en) * | 2016-01-19 | 2017-07-27 | Spex Engineering (Uk) Limited | Tool with propellant sections |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB657763A (en) * | 1948-05-24 | 1951-09-26 | Du Pont | Improvements in explosive charges and methods of blasting |
| GB1046655A (en) * | 1963-02-21 | 1966-10-26 | Asahi Chemical Ind | Line welding metals by explosives |
| US3838643A (en) * | 1971-10-04 | 1974-10-01 | Us Navy | Explosive device for scuttling ships |
-
1985
- 1985-04-30 GB GB858510891A patent/GB8510891D0/en active Pending
-
1986
- 1986-04-25 GB GB08610175A patent/GB2175674A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB657763A (en) * | 1948-05-24 | 1951-09-26 | Du Pont | Improvements in explosive charges and methods of blasting |
| GB1046655A (en) * | 1963-02-21 | 1966-10-26 | Asahi Chemical Ind | Line welding metals by explosives |
| US3838643A (en) * | 1971-10-04 | 1974-10-01 | Us Navy | Explosive device for scuttling ships |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4207828C1 (en) * | 1992-03-12 | 1993-08-26 | Deutsche Aerospace Ag, 8000 Muenchen, De | |
| DE19919041A1 (en) * | 1999-04-27 | 2000-11-09 | Daimler Chrysler Ag | Device for penetrating brickwork comprises housing containing two or more even-symmetrical hollow charges of explosive which produce cutting effect |
| WO2002063132A1 (en) * | 2001-02-06 | 2002-08-15 | Qinetiq Limited | Oil well perforator |
| WO2016067020A1 (en) * | 2014-10-28 | 2016-05-06 | Spex Engineering (Uk) Limited | Cutting tool |
| GB2533844B (en) * | 2014-10-28 | 2017-03-01 | Spex Eng (Uk) Ltd | Cutting tool |
| US10550656B2 (en) | 2014-10-28 | 2020-02-04 | Spex Corporate Holdings Limited | Cutting tool |
| AU2015340369B2 (en) * | 2014-10-28 | 2020-03-19 | Spex Corporate Holdings Limited | Cutting tool |
| AU2015340369B9 (en) * | 2014-10-28 | 2020-07-30 | Spex Corporate Holdings Limited | Cutting tool |
| US11332993B2 (en) | 2014-10-28 | 2022-05-17 | Spex Corporate Holdings Limited | Cutting tool |
| WO2017125745A1 (en) * | 2016-01-19 | 2017-07-27 | Spex Engineering (Uk) Limited | Tool with propellant sections |
| US11215024B2 (en) | 2016-01-19 | 2022-01-04 | Spex Corporate Holdings Ltd. | Tool with propellant sections |
| AU2017209990B2 (en) * | 2016-01-19 | 2022-06-30 | Spex Corporate Holdings Ltd | Tool with propellant sections |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8610175D0 (en) | 1986-05-29 |
| GB8510891D0 (en) | 1985-06-05 |
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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) |