CA2512924A1 - High energy gas fracturing charge device and method of use - Google Patents
High energy gas fracturing charge device and method of use Download PDFInfo
- Publication number
- CA2512924A1 CA2512924A1 CA 2512924 CA2512924A CA2512924A1 CA 2512924 A1 CA2512924 A1 CA 2512924A1 CA 2512924 CA2512924 CA 2512924 CA 2512924 A CA2512924 A CA 2512924A CA 2512924 A1 CA2512924 A1 CA 2512924A1
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- charge
- well
- openings
- closure elements
- sub
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- Abandoned
Links
- 238000000034 method Methods 0.000 title claims description 21
- 239000003380 propellant Substances 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 6
- 239000002360 explosive Substances 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 10
- 238000002485 combustion reaction Methods 0.000 claims description 9
- 239000004576 sand Substances 0.000 claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 239000003129 oil well Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000012856 packing Methods 0.000 claims 2
- 238000007789 sealing Methods 0.000 claims 2
- 239000007789 gas Substances 0.000 description 11
- 230000001965 increasing effect Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000000872 buffer Substances 0.000 description 4
- 239000004020 conductor Substances 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 4
- 239000000020 Nitrocellulose Substances 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 229920001220 nitrocellulos Polymers 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- SNIOPGDIGTZGOP-UHFFFAOYSA-N Nitroglycerin Chemical compound [O-][N+](=O)OCC(O[N+]([O-])=O)CO[N+]([O-])=O SNIOPGDIGTZGOP-UHFFFAOYSA-N 0.000 description 2
- 239000000006 Nitroglycerin Substances 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229960003711 glyceryl trinitrate Drugs 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- UQMRAFJOBWOFNS-UHFFFAOYSA-N butyl 2-(2,4-dichlorophenoxy)acetate Chemical compound CCCCOC(=O)COC1=CC=C(Cl)C=C1Cl UQMRAFJOBWOFNS-UHFFFAOYSA-N 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000011435 rock 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
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/263—Methods for stimulating production by forming crevices or fractures using explosives
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B3/00—Blasting cartridges, i.e. case and explosive
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B3/00—Blasting cartridges, i.e. case and explosive
- F42B3/04—Blasting cartridges, i.e. case and explosive for producing gas under pressure
- F42B3/06—Blasting cartridges, i.e. case and explosive for producing gas under pressure with re-utilisable case
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Geochemistry & Mineralogy (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
A high energy gas fracturing device, adapted to be lowered into a well. The device comprises a closed tube made of strong material, sized to fit into the well and having at least one sidewall, which defines a set of openings. A set of closure elements seal the openings in a water-tight manner. Also, a charge of propellant is located in the closed tube, the charge achieving best performance if kept dry. Finally, an ignition element contacts the charge.
Description
HIGH ENERGY GAS FRACTURING CHARGE DEVICE
AND METHOD OF USE
BACKGROUND OF THE INVENTION
Deposits of valuable fluids, such as crude oil, natural gas and even water, frequently occur in geologic formations having limited permeability. Although the initial perforating of the sides of an oil well typically opens up this type of deposit for initial exploitation, the well may soon experience a drop in production and require further treatment. To address this situation, a number of different fracturing techniques have been developed including explosive fracturing, hydraulic fracturing and high energy gas fracturing (HEGF). Each of these techniques is designed to fracture the underground geologic formation, thereby increasing permeability.
HEGF appears to have an advantage over the other fracturing techniques when certain conditions exist in a well. Test observations have shown that HEGF can create several radially extending fractures, thereby increasing the chance of significantly increasing permeability of nearby rock.
One type of HEGF uses a propellant that must be kept dry and contained during combustion. In this version, a strong container bearing a charge of propellant (i.e. a low explosive) is lowered into a partially liquid filled well and the propellant is ignited. The container keeps the charge dry and constrains it to obtain the full explosive force.
Until recently, the container for the propellant charge has been torn apart in the blast. Unfortunately, this has resulted in debris being left in the well, sometimes in the form of pieces that were large enough to create problems in the further exploitation of the well.
SUMMARY
The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.
In a first separate aspect, the present invention is a high energy gas fracturing device, adapted to be lowered into a well. The device comprises a closed tube made of strong material, sized to fit into the well and having at least one sidewall, which defines a set of openings. A set of closure elements seal the openings in a water-tight manner. Also, a charge of propellant is located in the closed tube, the charge achieving best performance if kept dry. Finally, an ignition element contacts the charge.
In a second separate aspect, the present invention is a method of performing a high energy gas fracturing of a well. The method uses an enclosed charge device that includes a closed tube made of strong material, sized to fit into the well and having at least one sidewall, which defines a set of openings. A set of closure elements seal the openings in a water-tight manner. Also, a charge of propellant is located in the closed tube, the charge achieving best performance if kept dry. In addition, an ignition element contacts the charge. To perform the method, the enclosed charge device is lowered into the well and the charge is ignited. Finally, the closed tube is lifted from the well.
In a third separate aspect, the present invention is a method of obtaining substantially uniform combustion of a charge of propellant, comprising dividing the charge into a set of sub-charges and placing the sub-charges of propellant in close proximity, but separating each sub-charge from any neighboring sub-charge by an isolating baffle. The set of sub-charges are then contemporaneously ignited.
In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut-away perspective view of a high energy gas fracturing device, according to a preferred embodiment of the present invention.
FIG. 2 is a cut-away perspective view of a buffered explosive packet, a part of the device of FIG. 1.
FIG. 3 is a perspective view of a blast aperture and a closure disk, which form part of the device of FIG.
1. FIG. 4 is a perspective view of the device of FIG. 1, being lowered into a well.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS) Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.
AND METHOD OF USE
BACKGROUND OF THE INVENTION
Deposits of valuable fluids, such as crude oil, natural gas and even water, frequently occur in geologic formations having limited permeability. Although the initial perforating of the sides of an oil well typically opens up this type of deposit for initial exploitation, the well may soon experience a drop in production and require further treatment. To address this situation, a number of different fracturing techniques have been developed including explosive fracturing, hydraulic fracturing and high energy gas fracturing (HEGF). Each of these techniques is designed to fracture the underground geologic formation, thereby increasing permeability.
HEGF appears to have an advantage over the other fracturing techniques when certain conditions exist in a well. Test observations have shown that HEGF can create several radially extending fractures, thereby increasing the chance of significantly increasing permeability of nearby rock.
One type of HEGF uses a propellant that must be kept dry and contained during combustion. In this version, a strong container bearing a charge of propellant (i.e. a low explosive) is lowered into a partially liquid filled well and the propellant is ignited. The container keeps the charge dry and constrains it to obtain the full explosive force.
Until recently, the container for the propellant charge has been torn apart in the blast. Unfortunately, this has resulted in debris being left in the well, sometimes in the form of pieces that were large enough to create problems in the further exploitation of the well.
SUMMARY
The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.
In a first separate aspect, the present invention is a high energy gas fracturing device, adapted to be lowered into a well. The device comprises a closed tube made of strong material, sized to fit into the well and having at least one sidewall, which defines a set of openings. A set of closure elements seal the openings in a water-tight manner. Also, a charge of propellant is located in the closed tube, the charge achieving best performance if kept dry. Finally, an ignition element contacts the charge.
In a second separate aspect, the present invention is a method of performing a high energy gas fracturing of a well. The method uses an enclosed charge device that includes a closed tube made of strong material, sized to fit into the well and having at least one sidewall, which defines a set of openings. A set of closure elements seal the openings in a water-tight manner. Also, a charge of propellant is located in the closed tube, the charge achieving best performance if kept dry. In addition, an ignition element contacts the charge. To perform the method, the enclosed charge device is lowered into the well and the charge is ignited. Finally, the closed tube is lifted from the well.
In a third separate aspect, the present invention is a method of obtaining substantially uniform combustion of a charge of propellant, comprising dividing the charge into a set of sub-charges and placing the sub-charges of propellant in close proximity, but separating each sub-charge from any neighboring sub-charge by an isolating baffle. The set of sub-charges are then contemporaneously ignited.
In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut-away perspective view of a high energy gas fracturing device, according to a preferred embodiment of the present invention.
FIG. 2 is a cut-away perspective view of a buffered explosive packet, a part of the device of FIG. 1.
FIG. 3 is a perspective view of a blast aperture and a closure disk, which form part of the device of FIG.
1. FIG. 4 is a perspective view of the device of FIG. 1, being lowered into a well.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS) Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.
In broad overview, referring to FIG. 1, a first embodiment of the present invention is a high energy gas fracturing device 10 that includes a closed steel pipe 12 sized to fit down a well. Pipe 12 defines a set of S apertures 14, shut with closure disks 16, which prevent the entry of liquid into pipe 12. Although only some apertures 14 are shown as being shut with closure disks 16, for ease of presentation, in practice all apertures 14 are shut with closure disks when device 10 is prepared for use.
The pipe 12 encloses a set of baffled charge packets 18, each containing propellant. (A "propellant"
deflagrates or burns very rapidly, rather than detonates virtually instantaneously like a high explosive) A
conductor wire 30 and ground wire 31 are threaded through the annular packets 18, with wire 30 terminating to a blasting cap 32, which in turn is connected with a detonating cord 34, set to detonate packets 18. Wire 30 terminates to bottom plug 50, which is discussed further below.
Device 10 can be used in oil, gas or water wells and in production, injection or disposal wells. The process begins by lowering device 10 into a well. The blasting cap 32 is detonated by the conductor wireline 30, causing detonating cord 34 to ignite the packets 18. The resulting blast forcibly ejects closure disks 16 and causes a rapid gas discharge that creates and/or widens cracks in the local geologic formation. These cracks may permit an increased flow of fluids into or out of the well. Both the device 10 and its method of use are described in greater detail below.
Referring to FIG. 2, baffled charge packets 18 include a shell 40, which may be made of cardboard, and which encompasses a charge pack 42, interposed between a pair of sand packs 44. Sand packs 44 serve the purpose of partially isolating the charge in one charge pack 42 from any adjacent charge packs 42. It has been found that in the 5 absence of baffles, such as sand packs 44, the combustion of the propellant can progress in an unpredictable manner, causing regions of very fast combustion (hot spots) that can result in damage to pipe 12. Sand packs 44, by partially isolating one charge bearing enclosure 42 from its neighbors, prevent this from happening. Packets 18 also serve the purpose of facilitating assembly of a device 10, by reducing the need for handling of uncontained explosives.
A bottom plug 50 is a standard bottom plug from a perforating gun, except that it includes 3 apertures 14, each bearing a closure disk 16. A top sub 52 is threaded into the top of pipe 12. In general a top sub, such as top sub 52, is a standard item of down hole wireline gear, easily connectable with other wireline equipment and familiar to logging crews and other oil well hands. In an alternative preferred embodiment top sub 52 defines 3 apertures 14, each bearing a closure disk 16, and is threaded into the top threads of pipe 12. Top sub 52 can easily be sealed against down hole liquids, while still permitting the conductor wire 30 and ground wire 31 to pass through.
A steel spacer/buffer 60 is placed at either end of the interior of pipe 12. Spacer/buffers protect bottom plug 50 and top sub 52 by absorbing some of the explosive force from the propellant. Spacer/buffers 60 are less expensive than bottom plugs 50 or top subs 52 and if damaged may be discarded. Also, spacer/buffers act to keep packets 18 in position in the longitudinal center of pipe 12, where they are closer to apertures 14.
Pipe 12 has an outer diameter of 8.6 cm (3.38 in), permitting it to be lowered into a typical well, as S noted. The inner diameter of pipe 12 is 5.4 cm (2.13 in).
Accordingly the thickness of the circular sidewall of pipe 12 is 1.6 cm (.63 in). A thickness of this magnitude is necessary to permit pipe 12, which is made of high strength steel, to withstand the explosive force of charges 18.
Referring to FIG. 3, each aperture 14 has a neck 62 that has a 1.9 cm (0.75 in) diameter. This expands out to an outwardly tapering head portion 64, that is about 2.53 cm (0.997 in) closest to neck 62 and about 2.61 cm (1.027 in) at its outermost extent. An annular seat 66 is formed where neck 62 widens out to head portion 64.
A closure disk 16 is set into head portion 64 and defines a circumferential slot 68 for accommodating an O-ring 70, which facilitates the seal created between closure disk 16 and aperture 14. As noted each disk 16 prevents liquid from entering device 10 until the ignition of charges 18.
Disks 16 are made of a polymer designed to withstand moderate temperatures and pressures, such as white acetal. For jobs in which high temperatures are to be encountered, disks 16 are made of a polymer, such as polyethermide. For jobs in which high pressures are to be encountered, disks 16 are made of a metal, such as aluminum. O-rings 70 are made of high temperature polymer, such as nitrile.
Referring to FIG. 4, device 10 is lowered into a well that is at least partially filled with liquid. As the device 10 is lowered into the liquid, to a depth of at least 91 meters (300 ft), pressure increases against disks 16, thereby pressing each disk 16 more firmly against the corresponding annular seat 66 and enhancing the seal provided by disk 16. It should be noted although 91 meters (300 ft) generally serves as the minimum depth to which device 10 must be submerged in order to work effectively, it can be made to work even in a dry well, if steps are taken to block the gas produced from the propellant combustion from leaking upwardly or downwardly, away from device 10, once emitted. Moreover, device 10 may be very deeply submerged, to a depth at least on the order of 3,000 meters.
Next, the blasting cap 32 is detonated by the conductor wire 30, which ignites the detonating cord 34.
This detonating cord ignites all of the charge packs within approximately 1 millisecond. Each charge pack preferably bears mufti-perforated propellant. The multiple perforations, which expand as the combustion continues, creating more surface area, cause the charge to combust at an increasing rate.
The gasses produced are contained by the column of liquid in the well and burst out rapidly toward the sides of the well, where perforations in the well casing are found and transited. The first gas to emerge through the perforations tends to blast debris out of the perforations, while immediately subsequent gas, at an even higher pressure and velocity due to the progressive combustion, opens up new cracks in the geologic formation.
The combustion is completed in about 20 milliseconds.
Propellant 42 may be either single-based (nitrocellulose), double-based (nitrocellulose and nitroglycerin), or triple-based (nitrocellulose, g nitroglycerin, and nitroguanadine). These propellants may be available from Alliant Techsystems, Inc., in Radford, Virginia.
While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
The pipe 12 encloses a set of baffled charge packets 18, each containing propellant. (A "propellant"
deflagrates or burns very rapidly, rather than detonates virtually instantaneously like a high explosive) A
conductor wire 30 and ground wire 31 are threaded through the annular packets 18, with wire 30 terminating to a blasting cap 32, which in turn is connected with a detonating cord 34, set to detonate packets 18. Wire 30 terminates to bottom plug 50, which is discussed further below.
Device 10 can be used in oil, gas or water wells and in production, injection or disposal wells. The process begins by lowering device 10 into a well. The blasting cap 32 is detonated by the conductor wireline 30, causing detonating cord 34 to ignite the packets 18. The resulting blast forcibly ejects closure disks 16 and causes a rapid gas discharge that creates and/or widens cracks in the local geologic formation. These cracks may permit an increased flow of fluids into or out of the well. Both the device 10 and its method of use are described in greater detail below.
Referring to FIG. 2, baffled charge packets 18 include a shell 40, which may be made of cardboard, and which encompasses a charge pack 42, interposed between a pair of sand packs 44. Sand packs 44 serve the purpose of partially isolating the charge in one charge pack 42 from any adjacent charge packs 42. It has been found that in the 5 absence of baffles, such as sand packs 44, the combustion of the propellant can progress in an unpredictable manner, causing regions of very fast combustion (hot spots) that can result in damage to pipe 12. Sand packs 44, by partially isolating one charge bearing enclosure 42 from its neighbors, prevent this from happening. Packets 18 also serve the purpose of facilitating assembly of a device 10, by reducing the need for handling of uncontained explosives.
A bottom plug 50 is a standard bottom plug from a perforating gun, except that it includes 3 apertures 14, each bearing a closure disk 16. A top sub 52 is threaded into the top of pipe 12. In general a top sub, such as top sub 52, is a standard item of down hole wireline gear, easily connectable with other wireline equipment and familiar to logging crews and other oil well hands. In an alternative preferred embodiment top sub 52 defines 3 apertures 14, each bearing a closure disk 16, and is threaded into the top threads of pipe 12. Top sub 52 can easily be sealed against down hole liquids, while still permitting the conductor wire 30 and ground wire 31 to pass through.
A steel spacer/buffer 60 is placed at either end of the interior of pipe 12. Spacer/buffers protect bottom plug 50 and top sub 52 by absorbing some of the explosive force from the propellant. Spacer/buffers 60 are less expensive than bottom plugs 50 or top subs 52 and if damaged may be discarded. Also, spacer/buffers act to keep packets 18 in position in the longitudinal center of pipe 12, where they are closer to apertures 14.
Pipe 12 has an outer diameter of 8.6 cm (3.38 in), permitting it to be lowered into a typical well, as S noted. The inner diameter of pipe 12 is 5.4 cm (2.13 in).
Accordingly the thickness of the circular sidewall of pipe 12 is 1.6 cm (.63 in). A thickness of this magnitude is necessary to permit pipe 12, which is made of high strength steel, to withstand the explosive force of charges 18.
Referring to FIG. 3, each aperture 14 has a neck 62 that has a 1.9 cm (0.75 in) diameter. This expands out to an outwardly tapering head portion 64, that is about 2.53 cm (0.997 in) closest to neck 62 and about 2.61 cm (1.027 in) at its outermost extent. An annular seat 66 is formed where neck 62 widens out to head portion 64.
A closure disk 16 is set into head portion 64 and defines a circumferential slot 68 for accommodating an O-ring 70, which facilitates the seal created between closure disk 16 and aperture 14. As noted each disk 16 prevents liquid from entering device 10 until the ignition of charges 18.
Disks 16 are made of a polymer designed to withstand moderate temperatures and pressures, such as white acetal. For jobs in which high temperatures are to be encountered, disks 16 are made of a polymer, such as polyethermide. For jobs in which high pressures are to be encountered, disks 16 are made of a metal, such as aluminum. O-rings 70 are made of high temperature polymer, such as nitrile.
Referring to FIG. 4, device 10 is lowered into a well that is at least partially filled with liquid. As the device 10 is lowered into the liquid, to a depth of at least 91 meters (300 ft), pressure increases against disks 16, thereby pressing each disk 16 more firmly against the corresponding annular seat 66 and enhancing the seal provided by disk 16. It should be noted although 91 meters (300 ft) generally serves as the minimum depth to which device 10 must be submerged in order to work effectively, it can be made to work even in a dry well, if steps are taken to block the gas produced from the propellant combustion from leaking upwardly or downwardly, away from device 10, once emitted. Moreover, device 10 may be very deeply submerged, to a depth at least on the order of 3,000 meters.
Next, the blasting cap 32 is detonated by the conductor wire 30, which ignites the detonating cord 34.
This detonating cord ignites all of the charge packs within approximately 1 millisecond. Each charge pack preferably bears mufti-perforated propellant. The multiple perforations, which expand as the combustion continues, creating more surface area, cause the charge to combust at an increasing rate.
The gasses produced are contained by the column of liquid in the well and burst out rapidly toward the sides of the well, where perforations in the well casing are found and transited. The first gas to emerge through the perforations tends to blast debris out of the perforations, while immediately subsequent gas, at an even higher pressure and velocity due to the progressive combustion, opens up new cracks in the geologic formation.
The combustion is completed in about 20 milliseconds.
Propellant 42 may be either single-based (nitrocellulose), double-based (nitrocellulose and nitroglycerin), or triple-based (nitrocellulose, g nitroglycerin, and nitroguanadine). These propellants may be available from Alliant Techsystems, Inc., in Radford, Virginia.
While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
Claims (22)
1. A high energy gas fracturing device, adapted to be lowered into a well and comprising:
(a) a closed tube made of strong material, sized to fit into said well and having at least one side wall, which defines a set of openings;
(b) a set of closure elements, sealing said openings in a water-tight manner;
(c) a charge of propellant located in said closed tube, said charge achieving best performance if kept dry; and (d) an ignition element contacting said charge.
(a) a closed tube made of strong material, sized to fit into said well and having at least one side wall, which defines a set of openings;
(b) a set of closure elements, sealing said openings in a water-tight manner;
(c) a charge of propellant located in said closed tube, said charge achieving best performance if kept dry; and (d) an ignition element contacting said charge.
2. The device of claim 1, wherein said sidewall is round and said tube is a round tube.
3. The device of claim 1, wherein said closure elements are set into said openings so as to maintain said watertight seal when said device is lowered into liquid to a depth of 91 meters (300 feet).
4. The device of claim 1, wherein said closure elements are set into said openings so as to maintain said watertight seal when said device is lowered into liquid to a depth of 1,500 meters (4,921 feet).
5. The device of claim 1, wherein said closure elements are set into said openings so as to maintain said watertight seal when said device is lowered into liquid to a depth of 3,000 meters (9,843 feet).
6. The device of claim 1, wherein said charge of explosive is divided into at least partially isolated sections.
7. The device of claim 6, wherein each said section is at least partially isolated from any adjacent section by isolating baffles.
8. The device of claim 7, wherein each said isolating baffle is a container filled with sand.
9. The device of claim 7, wherein each said section comprises a packing tube enclosing propellant.
10. The device of claim 9 wherein said packing tube is made of cardboard.
11. The device of claim 1, wherein said closure elements are less than 1 cm (0.4 in) thick.
12. The method of claim 1, wherein said strong material is steel.
13. The method of claim 11, wherein said steel is greater than 1 cm (0.4 in) thick.
14. A method of performing a high energy gas fracturing of a well, comprising:
(a) providing an enclosed charge device, including:
(i) a closed tube made of strong material, sized to fit into said well and having at least one side wall, which defines a set of openings;
(ii) a set of closure elements, sealing said openings in a water-tight manner;
(iii) a charge of propellant located in said closed tube, said charge achieving best performance if kept dry; and (iv) an ignition element contacting said charge;
(b) lowering said enclosed charge device into said well;
(c) igniting said charge; and (d) lifting said closed tube from said well.
(a) providing an enclosed charge device, including:
(i) a closed tube made of strong material, sized to fit into said well and having at least one side wall, which defines a set of openings;
(ii) a set of closure elements, sealing said openings in a water-tight manner;
(iii) a charge of propellant located in said closed tube, said charge achieving best performance if kept dry; and (iv) an ignition element contacting said charge;
(b) lowering said enclosed charge device into said well;
(c) igniting said charge; and (d) lifting said closed tube from said well.
15. The method of claim 14, wherein said well is an oil well.
16. The method of claim 14, wherein said well is a gas well.
17. The method of claim 14, wherein said well is a water well.
18. The method of claim 14, wherein said well is a storage well.
19. A method of obtaining substantially uniform combustion of a charge of propellant, comprising:
(a) dividing said charge into a set of sub-charges and placing said sub-charges of low explosive in close proximity, but separating each sub-charge from any neighboring sub-charge by an isolating baffle; and (b) contemporaneously detonating said set of sub-charges.
(a) dividing said charge into a set of sub-charges and placing said sub-charges of low explosive in close proximity, but separating each sub-charge from any neighboring sub-charge by an isolating baffle; and (b) contemporaneously detonating said set of sub-charges.
20. The method of claim 19 wherein said isolating baffles are containers filled with sand.
21. A baffled charge packet adapted for use in assembling a charge device and comprising:
(a) a shell;
(b) a pair of baffles, enclosed in said shell;
(c) a charge pack, enclosed in said shell and interposed between said pair of baffles.
(a) a shell;
(b) a pair of baffles, enclosed in said shell;
(c) a charge pack, enclosed in said shell and interposed between said pair of baffles.
22. The baffled charge packet of claim 21 wherein said baffles are in the form of sand packs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2512924 CA2512924A1 (en) | 2005-07-22 | 2005-07-22 | High energy gas fracturing charge device and method of use |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2512924 CA2512924A1 (en) | 2005-07-22 | 2005-07-22 | High energy gas fracturing charge device and method of use |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2512924A1 true CA2512924A1 (en) | 2007-01-22 |
Family
ID=37682417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2512924 Abandoned CA2512924A1 (en) | 2005-07-22 | 2005-07-22 | High energy gas fracturing charge device and method of use |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2512924A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108801090A (en) * | 2018-06-28 | 2018-11-13 | 中国人民解放军陆军工程大学 | Underwater broken development test device based on high-energy combustion agent |
| WO2021094582A1 (en) * | 2019-11-13 | 2021-05-20 | SPEX Group Holdings Limited | Improved tool |
| CN116398106A (en) * | 2023-04-26 | 2023-07-07 | 中国矿业大学 | Shale reservoir in-situ analysis methane high-efficiency utilization and multistage energy-gathering combustion explosion fracturing method |
-
2005
- 2005-07-22 CA CA 2512924 patent/CA2512924A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108801090A (en) * | 2018-06-28 | 2018-11-13 | 中国人民解放军陆军工程大学 | Underwater broken development test device based on high-energy combustion agent |
| CN108801090B (en) * | 2018-06-28 | 2019-11-19 | 中国人民解放军陆军工程大学 | Underwater broken development test device based on high-energy combustion agent |
| WO2021094582A1 (en) * | 2019-11-13 | 2021-05-20 | SPEX Group Holdings Limited | Improved tool |
| CN116398106A (en) * | 2023-04-26 | 2023-07-07 | 中国矿业大学 | Shale reservoir in-situ analysis methane high-efficiency utilization and multistage energy-gathering combustion explosion fracturing method |
| CN116398106B (en) * | 2023-04-26 | 2024-05-07 | 中国矿业大学 | Shale reservoir in-situ analysis methane high-efficiency utilization and multistage energy-gathering combustion explosion fracturing method |
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