CA2196385C - Shaped charge assembly system - Google Patents
Shaped charge assembly system Download PDFInfo
- Publication number
- CA2196385C CA2196385C CA 2196385 CA2196385A CA2196385C CA 2196385 C CA2196385 C CA 2196385C CA 2196385 CA2196385 CA 2196385 CA 2196385 A CA2196385 A CA 2196385A CA 2196385 C CA2196385 C CA 2196385C
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- CA
- Canada
- Prior art keywords
- shaped charge
- assembly
- base
- shaped
- liner
- 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.)
- Expired - Fee Related
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- 239000002184 metal Substances 0.000 claims description 36
- 229910052751 metal Inorganic materials 0.000 claims description 36
- 239000000463 material Substances 0.000 claims description 35
- 230000000712 assembly Effects 0.000 claims description 31
- 238000000429 assembly Methods 0.000 claims description 31
- 238000004880 explosion Methods 0.000 claims description 18
- 230000015572 biosynthetic process Effects 0.000 claims description 16
- 239000011888 foil Substances 0.000 claims description 16
- 238000007789 sealing Methods 0.000 claims description 13
- 238000005474 detonation Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 229910000831 Steel Inorganic materials 0.000 claims description 10
- 239000010959 steel Substances 0.000 claims description 10
- 238000010276 construction Methods 0.000 claims description 7
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 229930195733 hydrocarbon Natural products 0.000 claims description 4
- 125000001183 hydrocarbyl group Chemical group 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 3
- 239000002360 explosive Substances 0.000 description 28
- 239000000843 powder Substances 0.000 description 7
- 239000004568 cement Substances 0.000 description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- 229910052725 zinc Inorganic materials 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 239000011133 lead Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000001802 infusion Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- -1 zinc Chemical class 0.000 description 2
- TZRXHJWUDPFEEY-UHFFFAOYSA-N Pentaerythritol Tetranitrate Chemical compound [O-][N+](=O)OCC(CO[N+]([O-])=O)(CO[N+]([O-])=O)CO[N+]([O-])=O TZRXHJWUDPFEEY-UHFFFAOYSA-N 0.000 description 1
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 1
- 229910000581 Yellow brass Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 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
- 239000010953 base metal Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000003698 laser cutting Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000012255 powdered metal Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- E21B43/11—Perforators; Permeators
- E21B43/116—Gun or shaped-charge perforators
- E21B43/117—Shaped-charge perforators
-
- 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
- F42B1/028—Shaped or hollow charges characterised by the form of the liner
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- General Engineering & Computer Science (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
- Toys (AREA)
Abstract
Shaped charge assembly for use as part of a perforating gun, particularly, channel finder gun. The shaped charge assembly includes a charge configured to produce a jet which is substantially non-circular in cross section (in relation to the axial direction of travel of the jet) in which the assembly includes a base that is relatively rigid with respect to the liner of the assembly.
Description
SHAPED CHARGE ASSEMBLY SYSTEM
This invention is in the field of shaped charges for use in perforating gun systems.
Installation of an oil or gas well involves fixing a tubular steel casing in cement in an underground bore. Holes are subsequently created in the steel casing and cement in order to gain access to the surrounding formation, i.e., oil or gas deposit. Such holes are generally created through a process known as perforation using a perforating gun. A well may also need to be re-perforated for time to time, for example, if the flow of oil or gas into the well becomes impeded by debris. It is also common practice to re-perforate a depleted well which is to be abandoned. Such wells are often sealed by introduction of cement between the casing and well bore to minimize leakage of remaining oil or gas. Re-perforation is carried out to open existing channels in order to improve infusion of the cement. Such specialized perforating guns are sometimes referred to in the industry as "channel finder guns".
In general, a perforating gun includes an elongate member having several explosive charges spaced along the member. There is a detonation cord running between and connected to the charges. The charges are generally arranged along the length of the gun to explode radially outwardly in different directions into the formation. Such a charge, known as a "shaped charge", includes a case, often conically shaped, which contains explosive material sealed in the case interior by a liner. When detonated, the charge delivers explosive forces to penetrate into the formation.
Efforts continue to be made to improve various aspects of the perforation process. For example, Renfro describes in United States Patent No. 5,509,356 (April 23, 1996) a shaped charge with an improved liner. The charge includes a housing made of a pulverable material such as a ceramic.
The shaped charge includes explosive powder and a binder and the powder is pre-compressed to at least 95% of its total maximum density. The liner is generally hemispherical, but decreases in thickness from the central area to its perimeter, or skirt.
This invention is in the field of shaped charges for use in perforating gun systems.
Installation of an oil or gas well involves fixing a tubular steel casing in cement in an underground bore. Holes are subsequently created in the steel casing and cement in order to gain access to the surrounding formation, i.e., oil or gas deposit. Such holes are generally created through a process known as perforation using a perforating gun. A well may also need to be re-perforated for time to time, for example, if the flow of oil or gas into the well becomes impeded by debris. It is also common practice to re-perforate a depleted well which is to be abandoned. Such wells are often sealed by introduction of cement between the casing and well bore to minimize leakage of remaining oil or gas. Re-perforation is carried out to open existing channels in order to improve infusion of the cement. Such specialized perforating guns are sometimes referred to in the industry as "channel finder guns".
In general, a perforating gun includes an elongate member having several explosive charges spaced along the member. There is a detonation cord running between and connected to the charges. The charges are generally arranged along the length of the gun to explode radially outwardly in different directions into the formation. Such a charge, known as a "shaped charge", includes a case, often conically shaped, which contains explosive material sealed in the case interior by a liner. When detonated, the charge delivers explosive forces to penetrate into the formation.
Efforts continue to be made to improve various aspects of the perforation process. For example, Renfro describes in United States Patent No. 5,509,356 (April 23, 1996) a shaped charge with an improved liner. The charge includes a housing made of a pulverable material such as a ceramic.
The shaped charge includes explosive powder and a binder and the powder is pre-compressed to at least 95% of its total maximum density. The liner is generally hemispherical, but decreases in thickness from the central area to its perimeter, or skirt.
Hasselman describes in United States Patent No. 5,522,319 (June 4, 1996) another effort to provide an improved shaped charge for oil well perforation in which a generally hemispherically shaped liner is thicker at its central region than towards its edge. This apparently improves the coherence, stability and mass distribution of the jet produced such that a tip velocity comparable to that of a conical shaped charge is obtained. The case housing of the charge is not described in detail, but is illustrated to be of uniform thickness and, being of thickness of the same order of the liner, is presumably metal. Hasselman states that the case material and configuration are of little importance to the overall design optimization, although they do have an effect and need to be included in any detailed design.
Willis et aL describe in United States Patent No. 5,564,499 (October 15, 1996) a method and device for slotting well casing and scoring surrounding rock to facilitate hydraulic fractures. The device shown includes linear charges arranges lengthwise in the gun and concentrically about the center axis of the gun. This arrangement is described as creating a linear aperture in the well casing in which the charges are exploded.
Conventional perforating guns, however, have been found not to be entirely satisfactory when used to perforate a well in preparation for introduction of cementitious material to seal the casing to the well bore, i.e., when used as channel finder guns. The degree of perforation by such guns is sometimes insufficient to adequately open channels which can lead to insufficient infusion of the material into areas surrounding the casing. This can lead to an inadequate seal which permits leakage of formation contents, typically water, gas, or oil from between the casing and the formation. The invention disclosed herein has been found to be particularly useful in the context of this situation, although its application is not limited to such.
The present invention involves a shaped charge assembly which produces a superior performance when used as part of a perforating gun to be -3_ 2 i '%~~3~~
used as a channel finder gun. The improved performance stems from the use of a shaped charge assembly in which the charge is configured to produce a jet which is substantially non-circular in cross section (in relation to the axial direction of travel of the jet) in which the assembly includes a base that is relatively rigid with respect to the liner of the assembly.
According to a preferred embodiment, the shaped charge assembly includes a linear shaped charge.
Thus, in one broad aspect, the invention is a shaped charge assembly having: a relatively rigid base that has a cavity; a relatively flexible liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
The cavity of the base can have an opening at a top end of the base and preferably at least a portion of the liner is located in the opening of the base and the charge is shaped such that, upon explosion thereof, the jet travels along a major axis through the opening of the base.
Preferably, the shaped charge is a linear charge.
The base can be of milled steel, stamped metal, or cast metal, etc.
The exposed, or outer surface part of the liner can be concave.
The liner (or the portion of the liner in the opening of the base) can be "V"-shaped and inwardly concave with respect to the top end of the base, or the liner can be "W'-shaped and be generally inwardly directed with respect to the top end of the base.
Particularly, interior surfaces of the base can define a longitudinal trough extending between first and second ends of the base, there can be first and second walls extending between the first and second ends, respectively, third and fourth walls extending between the first ends of the first and second walls, and the second ends of the first and second walls, 2l X5385 respectively, and the base can include a pair of apertures therethrough for contacting detonator wires with the charge.
In a particular embodiment, illustrated below, the floor of the cavity has a central ridge extending upwardly toward the liner.
In certain embodiments, there are substantially upright interior side walls extending between the first and second ends of the base.
It is possible for the interior floor surface of the base to be generally concave upward.
In particular embodiments, interior surfaces of the base define a longitudinal trough extending between first and second ends of the base and the liner is concave inward with respect to the cavity such that the shaped material within the cavity has a substantially constant transverse cross section between the first and second ends.
There can be metal foil at the respective first and second ends, to seal the charge in the assembly.
Usually, the base and liner are each of metal.
Usually, the base has a floor having a thickness at least twice that of the liner. The base can have a floor having a thickness at least three times the thickness of the liner. The base can have a floor having a thickness at least four times the thickness of the liner. The base can have a floor having a thickness at least five times the thickness of the liner. The base can have a floor having a thickness at least six times the thickness of the liner.
Preferably, the base has walls having interior surfaces which define the cavity and the walls are relatively thick with respect to the thickness of the liner.
The explosive charge material can be compressed directly against inner surfaces of the base. The liner and base can be formed separate from each other.
The charge can be pressed into the cavity by forced abutment with the liner.
The base can be of unitary construction.
Z 1 ~h385 In certain embodiments, the base has an interior floor and walls having interior surfaces which extend upwardly of the floor in which the average thickness of the floor and walls is between about 2 and 10 that of the liner; or the average thickness of the floor and walls is between about 3 and that of the liner; or the average thickness of the floor and walls is between about 4 and 6 that of the liner; or the average thickness of the floor and walls is between about 5 times that of the liner.
The thickness of the liner can be between about 1/32" and 1/4".
More preferably, the thickness of the liner is about 1116".
In particular embodiments, the invention is a shaped charge assembly in which the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open the cavity and the liner extends between the first and second walls, and the charge is compressed in the cavity such that the shape of the charge is defined by interior surfaces of the floor, walls and liner. Further, there can be first and second means for sealing the charge within the cavity, extending between first ends of the first and second walls, the liner, and the base floor, and between second ends of the first and second walls, the liner and the base floor, respectively. Such means for sealing the charge within the cavity can be a piece of foil.
Usually, interior surfaces of the first and second walls face each other and are symmetrically shaped with respect to a center line of the assembly. The interior floor surface can define an upwardly concave trough which is symmetrical with respect to the center line. In a preferred embodiment, interior surfaces of the floor, first and second walls and liner define the shape of the charge such that the charge has a generally "V"-shaped cross section. The cross section of the charge can be relatively constant and of a defined thickness.
In particular embodiments, the interior surface of the floor has an upwardly protruding ridge which is generally symmetrical with respect to the center line. The liner can be shaped and oriented so as to be parallel to the 21 ~~63°5 center line and be concave upward. In certain preferred embodiments, the liner has a generally "V"-shaped cross section. Alternatively, the liner can be generally "W'-shaped in cross section.
Typically, the inner surfaces of the first and second walls are generally parallel to the center line. Additionally, the inner surfaces of the first and second walls can be generally parallel to each other. In a preferred embodiment, the shaped charge is relatively shallow near the center of the cavity and relatively deep near the first and second walls of the base.
In particular embodiments, a shaped charge assembly of the invention includes a base of metal. The base includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity. The sheath can be held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath. The shaped charge can be oriented to explode in a direction away from the floor of the base.
Preferably, there is means for sealing exposed ends of the charge against the environment. The means can be foil. Typically, the foil is a thin metal sheet, such as aluminum foil, and includes a pressure sensitive adhesive for adherence to the charge and base surfaces. Again, the shaped charge can be a linear shaped charge. The shaped charge can have a generally "V"-shaped cross section, which is relatively constant from end to end of the charge. The shaped charge can have a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
In particular embodiments, a shaped charge assembly of the invention includes a base that is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open cavity and the liner is secured and extends between the first, second, third and fourth _,_ walls so as to seal the charge within the cavity. Preferably, the base is of unitary construction, i.e., is formed of a single piece of material such as cast metal, for example.
In such an embodiment, it is possible to have an arrangement in which interior surfaces of the floor, first, second, third, and fourth walls, and the liner define the shape of the charge. The interior surfaces of the first and second walls can be spaced from each other a distance greater than the distance between the interior surfaces of the third and fourth walls. The interior surfaces of the third and fourth walls can slope upwardly and outwardly. The third and fourth walls preferably are symmetrically shaped with respect to a center line of the assembly.
It is possible for interior surfaces of the walls to be generally upright with respect to the interior surface of the floor. In certain illustrated embodiments, there is a ridge extending upwardly of the floor running parallel to a center line of the assembly running between the first and second walls.
The liner can be generally concave inward. The liner can be generally parallel to a center line of the assembly running between the first and second walls. The liner can have a generally "V"-shaped cross section. The liner can have a generally "W'-shaped cross section.
Preferably, the charge is compressed directly against the inner surfaces and the liner and base are formed separate from each other.
The base can include a pair of apertures therethrough for contacting detonator wires with the charge located in the cavity of the base.
In particular embodiments, a shaped charge assembly of the invention has a base that is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
In such embodiments, it is preferred that the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base 2I~~~~~
_8_ and exterior surfaces of the sheath. Often, the shaped charge is oriented to explode in a direction away from the floor of the base. The shaped charge can be a linear shaped charge. The shaped charge can have a generally "V"-shaped cross section, and can be of relatively constant thickness from end to end of the charge. The shaped charge can have a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
In a particular embodiment, the invention is a shaped charge assembly for mounting to a charge holder of an underground perforating gun including: a rigid base which defines a cavity open at a top end of the base;
charge material received within the cavity; and a liner, relatively flexible with respect to the base, mounted at the top end of the cavity to seal the material within the cavity; and wherein, interior surfaces of the base and the liner together define the shape of the charge material, which shape is such that, upon detonation, a jet with a non-circular cross-section travels along a major axis through the open end of the cavity of the base.
In another particular aspect, the invention is a combination of a shaped charge assembly and a holder therefor, for use in a longitudinal housing of a perforating gun. The holder defines a slot for receipt of the assembly therein to orient the shaped charge assembly within the housing such that, upon explosion of the charge, the axial direction of thrust is in a direction generally orthogonal to a longitudinal axis of the housing.
The holder usually defines a plurality of slots. Often, each respective shaped charge assembly received in a slot is oriented such that, upon explosion of the charge, the jet has a major planar component through a central thrust axis of the jet, which planar component is non-parallel with the longitudinal axis of the housing. In a particular illustrated embodiment, the planar component is generally orthogonal to the longitudinal axis of the housing.
In such a combination in which there is a plurality of shaped charge assemblies, neighboring shaped charge assemblies can be oriented with respect to each other such that their central thrust axes form an angle of 2~9~~~~
_g_ between 10° and 90° with each other, or an angle of between about 20° and 70° with each other, or an angle of between about 30° and 60° with each other, or an angle of about 45° with each other. It possible for assemblies to be dimensioned to permit a density of up to about 16 shaped charge assemblies per meter in a holder, or a density of up to about 14 shaped charge assemblies per meter in a holder, or a density of up to about 12 shaped charge assemblies per meter in a holder, or a density of up to about 10 shaped charge assemblies per meter in a holder.
Such a combination can further include a gun housing.
In another aspect, the invention is a method for perforating a casing of a well bore and a surrounding hydrocarbon-bearing formation. The method includes:
locating at least one shaped charge assembly in the bore, the assembly having a relatively rigid base, a shaped charge in a cavity of the base, and a relatively flexible liner; and exploding the charge, wherein the charge is shaped and oriented within the bore, to produce upon explosion thereof, a jet having an axial direction of thrust in a plane generally orthogonal to the bore and wherein the cross sectional shape of the jet is non-circular.
In another aspect, the present invention is a method for perforating a casing of a bore of a well and a surrounding hydrocarbon-bearing formation which includes:
locating at least one shaped charge assembly of the invention in the bore;
and exploding the charge.
The shaped charge can include:
a relatively rigid base having a cavity;
a relatively flexible liner; in which there is:
a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust, located in a plane generally 219~~85 orthogonal to the bore, in the formation of a jet having a cross sectional shape which is non-circular.
A particular method is one in which the perforating is conducted in preparation for sealing the well.
In the drawings, which illustrate embodiments of the invention, Figure 1 is an elevational view, in partial section, of a perforating gun, with a plurality of shaped charge assemblies of the present invention mounted to a holder within an elongated gun housing;
Figure 2 is an isometric exploded view of a first embodiment shaped charge assembly of the present invention;
Figure 3 is an isometric view of a shaped charge assembly of the Figure 2 embodiment;
Figure 4 is an isometric exploded view of a second embodiment shaped charge assembly of the present invention;
Figure 5 is an isometric view of the Figure 4 embodiment, fully assembled;
Figure 6 is an end view of the Figure 4 embodiment shaped charge assembly;
Figure 7 is an end view representation of the present invention, illustrating the cross sectional profile of a shaped charge a of a third embodiment;
Figure 8 is an end view representation of the present invention, illustrating the cross sectional profile of a shaped charge a of a fourth embodiment;
Figure 9(a) is a side elevation of a charge holder of the present invention having slots for receipt of preferred embodiment shaped charge assemblies. Figure 9(b) is an end view of the charge holder of Figure 9(a), radii thereof indicating the placement of charge assemblies therein;
Figures 10(a), 10(b) and 10(c) each show an outer housing of a perforating gun of the present invention, having thinned areas corresponding to the shaped charge assemblies of the preferred embodiments, in which ~ ~ y~~~~
longitudinal axes of the shaped charges are angled at 90°, 45°
and 0°, respectively, with respect to the lengthwise (i.e., longitudinal) axis of a charge holder in which the assemblies are mounted;
Figure 11 is a cross sectional view of a gun outer housing within a well hole casing;
Figure 12 is a representational view of a shaped charge assembly, as viewed along the longitudinal axis of a holder in which it is mounted showing the general shape of a jet which would be formed upon explosion of the charge; and Figure 13 is a representational view of the jet of Figure 12 taken along line 13-13 of Figure 12.
Turning to the drawings, a description of the preferred mode of implementing the invention, as currently understood by the inventors is described below.
Charge assemblies of the illustrated embodiments are for use as part of a pertorating gun 10, illustrated in Figure 1, but may equally well be incorporated into other pertorating gun systems, appropriately modified as necessary. Gun 10 includes linear shaped charge assemblies 12 mounted on charge holder 14 which is sealed and secured within gun outer housing 16.
A first embodiment charge assembly 112 is illustrated in greater detail in Figures 2 and 3. Device 112 includes rigid base 114 having linear shaped charge 116 (with liner 119) received therein. Charge 116 is a linear shaped charge, cut to the same length as the base 112, the charge containing explosive material 117 compressed within metal sheath 119. Such a linear charge is a continuous core of explosive enclosed in a seamless metal sheath, commercially available from Accurate Arms Company, Inc. of McEewen, Tennessee. Exposed ends of the charge are capped with adhesive foil 118 (omitted in Figure2).
Charge assembly 112 is appropriately dimensioned to be mounted in a holder so as to fit into the a selected gun housing. In the illustrated embodiment, the outer housing of the gun has an outer diameter of 86 mm (3 3/8") and an inner diameter of 68 mm (2 5/8"). Charge holder 14 has an outer diameter of 51 mm (2") and is a tube of thin walled extruded steel, being of substantially constant cross section and substantially constant thickness, having a thickness of about 0.17 cm (0.065"). The overall dimensions of charge assembly base 114 are about 38 mm (1 1/2") 120 (height) x 38 mm (1 1/2") 122 (width) x 51 mm (2") 124 (length). The product of Accurate Arms Company incorporated as part of assembly 112 bears product number Y230-2000. It is a linear shaped charge having a copper sheath containing core, i.e., explosive material, RDX with a grain load of per foot. The outerwidth of the linear shaped charge is 1.15" (about 29 mm).
Similar linear shaped charge products are commercially available from other sources, for example, Teledyne Ryan Aeronautical of Hollister, California.
The base includes cavity 125 having defined by interior surface 126 of floor 127 and interior surfaces 128 of side walls 129, which surfaces match the outer contour of the bottom of the sheath of the shaped charge. A
friction fit holds the shaped charge within the cavity of the base. That is, the sheath fits snugly against the walls defining the cavity. It is possible that an adhesive could be used to secure the liner charge within the base, alone, or in addition to a friction fit.
Base 114, which houses the linear shaped charge, is of milled steel. As would be appreciated be a person skilled in the art, the base can be of other metals, such as zinc, for instance and it can be manufactured by methods other than milling, such as stamping (cold formed) or by casting. The base can be ceramic.
A second embodiment charge assembly 212 is illustrated in Figures 4 to 6. In this embodiment, the charge assembly includes base 214, explosive material 216, and liner 218. Base 214 is formed of one piece, i.e., is of unitary construction, the illustrated housing being milled, pressed or stamped, or cast, as with base 114. Again the base metal can be steel or zinc, etc. Base 214 includes a bottom floor 220 with four upwardly extending side walls 222, 224, 226, 228. The interior surface 230 of the floor of the housing 21 ~~~5~5 base is shaped to be generally congruent with the corresponding interior portion of sheath 119 of the first embodiment.
A third embodiment shape charged device 250 is illustrated in Figure 7, in which the cross sectional shape of the shaped charge 252 is shown. As with other embodiments, base 254 of the assembly might or might not have end walls connecting side walls 256, 258. Interior surfaces of liner 260, the side walls and floor 262 of the base define the shape of the charge, which is compressed within the cavity. The cross sectional width of the cavity defined between the upright parallel inner surfaces 264, 266 of the base is about 30.7 cm (1.2"). The floor of the base has an upraised ridge 268 running between lengthwise ends of the base. The liner has a cross sectional "V"-shape. The depth of the charge increases from line 270 running through the center of the cavity to the peripheral area 272 of the cavity.
A fourth embodiment shaped charge assembly 280 is illustrated in Figure 8. This is similar to the third embodiment assembly, but the cross section of liner 282 is "W"-shaped.
Located within base 214 (or 254) is compacted or compressed explosive material 216. The material is compressed during installation of the liner, in the case of the second embodiment, liner 218. A liner of the present invention is of any metal from which conventional sheaths of linear shaped charges are manufactured: steel, copper, zinc, lead and combinations or alloys of these metals, particularly copper and zinc, or of a suitable powdered metal. A yellow brass liner might be found to be particularly suitable. The liner is installed as part of the assembly by an operation similar to that used in the manufacture of conical charges. The explosive powder is added to the cavity and the base tapped, if necessary, to level the powder. The powder can be preshaped by insertion of an appropriately shaped die into the cavity. A
preshaped liner, held in place, for example by vacuum by the punch die, is then pressed into place and any stray powder cleaned away. The explosive material is compressed during this operation to roughly the same degree as it would be within the liner of the linear shaped charge of the first embodiment.
-14- Z! 96335 Explosive material is compressed, as understood by a person skilled in the art, to obtain a desired explosive density of the charge. As illustrated for the second embodiment, interior surfaces of floor 230, and walls 222, 224, together define a "V"-shaped cavity into which the explosive material is received. Surfaces of walls 222, 224 face each other to define a trough running parallel to an axis of the housing. Opposing end walls 226, 228 join first and second ends of walls 222, 224, respectively. Generally, speaking, the arrangement is such that the explosive material is sealed within the charge assembly.
In alternative embodiments, a base similar to that of base 214 (or base 254), for example, is manufactured without end walls 222, 224. In this case the base is located between two walls of a manufacturing apparatus which hold the explosive powder in place during manufacture of the charge assembly. Once the charge and liner are in place, the walls are moved away and metal foil put in place in analogy to foil 118 shown for the first embodiment charge assembly. In the absence of end walls, it is possible to include more explosive charge in a shaped charge assembly, all else being equal.
It may be possible to vary the shape of the explosive material to obtain more optimum explosive impact than that obtained with the shapes described herein. It is certainly known, however, that the chevron configuration shape disclosed can be varied somewhat with retention of satisfactory performance. It is intended that the use of the term "V"-shaped or having a "V"-shaped cross section not be limited to the precise shapes disclosed herein. A satisfactory result can be obtained using a "V"-shape based on a parabola or an ellipse.
Other transverse cross sectional shapes are suitable. Linear "W'-shaped charges are commercially available. A base comparable to base 114 can thus be manufactured with a suitably shaped floor and inner side walls to receive such a charge. Alternatively, a base comparable to that of base 214 can thus be manufactured with a "W'-shaped explosive-receiving cavity and suitable "W"-shaped liner.
2~ 96385 It is not strictly necessary for the shaped charge to be linear. In the case of the second embodiment type of shaped charge device, for example, the interior surfaces of the floor of the base cavity can be slightly curved or arched, i.e., it is not required to be strictly linear running from end-to-end. It is important that the shaped charge have a longitudinal axis (when viewed from the top, i.e., from the side from which the liner is visible) in order that a jet having a non-circular cross section in relation to the major axis 290 of thrust of the jet 292. See Figures 12 and 13. A charge is shaped such that the explosive material produces forces having a longitudinal component (when viewed along the axis of the principle direction of the movement of the jet) when the charge is detonated. If one is to look at vectorial forces emanating radially from a central thrust axis of the explosion, there is a vector 294 in a first direction that is different in length from a vector 296 in a second direction perpendicular to the first direction. This is in contrast to conical or hemispherical shaped charges in which the cross section of forces in an imaginary plane perpendicular to the major thrust of the explosion (the major thrust being along a radial line perpendicular to the longitudinal axis of the charge holder, in the Figure 1 embodiment, for example) are substantially equal, i.e., together define a circle.
The explosive material of the disclosed shaped charge assemblies is RDX, but any suitable explosive can be used, for example, CH-6, HMX, PETN, HNS, PYX, etc. "Shaped charge" is used herein to describe suitable explosive material compressed so as to have a particular shape.
Holder 14 of the illustrated embodiments is illustrated more fully in Figures 9a and 9b. The illustrated holder has a thickness of about 0.17 cm (0.065"). Other thicknesses of metal could possibly be used, say in the range from about 0.010" to about 0.25". The illustrated holder has been used in the field in conjunction with the first embodiment shaped charge assembly described above. The holder is manufactured by laser cutting an extruded steel tube to obtain the illustrated configuration.
2. ~ ~ J~3~5 The holder defines a slot 320 for receipt of a linear shaped charge assembly. The height 321 of each slot (corresponding to the width of the shaped charge assembly as described above) is 38 mm (1 1/2"). The slots are spaced longitudinally along the length of the holder about 76.2 mm (3") center-to-center from each other. The slots serve to orient the shaped charges in the holder such that neighboring shaped charges are phased at 45°
with respect to each other, as illustrated in Figure 11. The slots of holder 14 thus lie on an imaginary spiral with a complete turn around the circumference of the holder being obtained with every ninth slot. Installed shaped charges spaced from each other by 61 mm (2.4") are thus oriented in the same radial direction.
The number of charge assemblies that can be mounted onto a holder for a given length of the holder, usually stated as "shots per meter", is obviously limited by, among other things, the width of the shaped charge assemblies being installed on a holder. For the present invention, it is possible to have up to 14, or more, shots per meter.
For installation of a shaped charge assembly within slot 320, the assembly is inserted so that respective outer side walls 130, 132 of the base of the charge assembly abut respective slot defining edges 323, 325 of the charge holder. Once the charge assembly is located centrally with respect to the center line 322 of the holder, tabs 324 are bent radially inwardly to abut upper (radially outward) surfaces of the shaped charge assembly to securely mount the assembly to the holder. A detonation cord is located in the holder to run from end to end of the tube. In the case of the Figure 1 embodiment charge assembly 112 (or other charge assembly in having foil which seals in charge material), the detonation cord is secured to foil 118 by means of a clip.
In the case of shaped charge assembly 212, end wall 226 has a slot 232 with a clip for receipt of the detonation cord. The clip is inserted through the slot to connect the detonation cord and the explosive material for detonation thereof.
As an alternative arrangement, the slot for receiving the clip might be located at a central location of the floor of the charge assembly base. Once all of the 2 i 9 ~~ ~5 charge assemblies and detonation cord are mounted, the holder-charge assembly is installed in gun housing 16.
Gun housing 16 is illustrated in Figures 1, 10(a) and 11. Each lengthwise end of the holder is secured to the housing in a conventional manner. The detonation cord (not illustrated) extends out of the upper end of the housing to be connected to a detonator (not illustrated), this being a conventional arrangement. The interior of the housing is sealed against ingress of liquid, again in a conventional manner, so that it can be installed in a well for use without exposure of the explosive material to liquid which might diminish its explosive capacity.
Outer surface 36 of gun housing 16 has scalloped areas 38 which are thinned areas bored out of the housing. These areas of reduced thickness are spaced from each other along a spiral corresponding to that of the installed shaped charges. Each thinned area is suitably sized and shaped to accommodate the jet which emanates from the charge to which it is immediately adjacent when the gun is set off. This enhances the explosive capacity of the gun by reducing the amount of force consumed in breaking through the gun housing. Thinned areas in a gun housing are known to those skilled in the art.
Turning to Figure 11, location of charge assemblies (the charge holder has been omitted for clarity) in relation to the gun housing and well casing 44 is illustrated. Casing 44 has an outer diameter of 114 mm (4 1/2") and a thickness of 7.37 mm (0.29"). The outer diameter of the gun housing 16 is 86 mm (3 3/8") while the thickness of the scalloped portions of the gun housing is 15.2 mm (0.60"). The stand off 40 (the distance between the forward edge of a charge assembly and the inner surface of the gun housing) is 21 mm (0.815") and the clearance 42 is 6.9 mm (0.273"). The standoff distance is important since sufficient distance must be provided to permit adequate jet formation to obtain the desired penetration, while the distance should not be too great that the jet expands too greatly (in a radial direction to the axial direction of thrust of the jet), which can result in an oversized hole.
The distances indicated have been found to produce satisfactory results.
In the illustrated embodiment, each linear shaped charge assembly, when viewed from the liner side (when viewed from the top of the charge assembly as oriented in Figure 4) is non-circular. Various shapes of linear shaped charges are described in, for example, on pages 737-8 of High Velocity Impact Dynamics (Ed. Jonas A. Zukas, John Wiley & Sons, Inc., New York 1990), Shaped charge assemblies similar to assembly 112, but having dimensions suitable for use in an outer gun housing of diameter 114 mm (4 112") or 146 mm (5 3l4") are also possible. In the case of a 9.5 mm (31.8") thick gun housing having an outer diameter 114 mm (4 112"), the base of the charge assembly is 66.7 mm (2 518") in length with the height and width being the same as those shown for charge assembly 112. Such a gun is suitable for use in a well casing having an outer diameter of 140 mm (5 1l2") and thickness of 70 mm (0.275") with a stand off distance of 19 mm (314") and clearance of 5.7 mm (0.225"). In the case of a 8.9 mm (0.375") thick gun housing having an outer diameter of 146 mm (5 3/4"), the base of the charge assembly is 76 mm (3.0") in length, again with the height and width being the same as those of charge assembly 112. Such a gun is suitable for use in a well casing having an outer diameter of 178 mm (7.0") and thickness of 9.2 mm (0.362") with a stand off of 19 mm (3/4") and clearance of 6.7 mm (0.263"). Similar dimensional arrangements are obtainable with a second embodiment type of charge assembly in which charge material is pressed directly into base 214.
Perforating guns incorporating shaped charge assemblies of the first embodiment having a 2" diameter charge holder have been used in the field. Although rigorous studies have not been carried out, it appears that the pattern of "ribbon"-shaped jets generated by the slot charges more reliably hit channels, i:e., gain access to channels, than the pattern generated by conical zl X6385 shaped charges in a comparable perforating gun, as indicated by the amount cement pumpable following perforation.
In the embodiments disclosed, the liner has a thickness of about 0.8 mm (1/32"). A liner can have a smaller or greater thickness, possibly up to about 6 mm (1/4") in thickness. The thickness must be sufficient to provide enough material to form the head of a jet upon explosion of the charge material, as understood by those skilled in the art.
Although phasing of 45° has been illustrated in Figure 9, it will be understood that phasing of other angles, such as 15°, 30°, 60°, 90°, etc. are within the scope of this invention.
Turning to Figures 10(b) and 10(c), angling of slot-shaped charge assemblies is illustrated. Scalloped areas of the illustrated gun housings correspond to underlying charge assemblies, not directly illustrated. Thus in Figure 10(c), longitudinal axis 46 of a slot charge assembly is parallel to the center axis 322 of the holder. Put another way, the longitudinal axis of the charge assembly is perpendicular to a cross-sectional plane of the gun.
Figure 10(b) shows an arrangement in which the longitudinal axes of slot-shaped charge assemblies each form an angle of 45° with the center line of the charge holder. Other angles of incidence between the center axis and longitudinal axes of shaped charges are within the scope of this invention.
In all of the illustrated embodiments, charges are oriented such that upon detonation, each jet travels in a direction which is generally radially outwardly along a radius of the center line of the gun and parallel to a plane generally perpendicular to the center axis of the gun. This is the generally preferred arrangement, as it maximizes the jet forces impinging upon the gun housing and well casing, the jet traveling in a direction which is more or less orthogonal to these two metal surfaces through which it must travel to penetrate into a formation. Although there is a limit to the amount of deviation than can be made from this oriention, other orientations are within the scope of this invention. It is most likely that maintaining a jet direction along a radius of the center line of the gun will remain preferable, with a greater variation in the 2.~ 6~~5 deviation of jet thrust out of the cross-sectional plane of the gun being more likely.
Advantages over obtainable through use of a perforating gun of the present invention over conventional guns may extend beyond use as a channel finder. Particularly, a gun of the present invention may find use in gravel pack perforating of a well, or in perforation of a horizontal section of a well.
Particular embodiments of the invention having been described, the scope of the invention for which protection is sought is defined by the following claims.
Willis et aL describe in United States Patent No. 5,564,499 (October 15, 1996) a method and device for slotting well casing and scoring surrounding rock to facilitate hydraulic fractures. The device shown includes linear charges arranges lengthwise in the gun and concentrically about the center axis of the gun. This arrangement is described as creating a linear aperture in the well casing in which the charges are exploded.
Conventional perforating guns, however, have been found not to be entirely satisfactory when used to perforate a well in preparation for introduction of cementitious material to seal the casing to the well bore, i.e., when used as channel finder guns. The degree of perforation by such guns is sometimes insufficient to adequately open channels which can lead to insufficient infusion of the material into areas surrounding the casing. This can lead to an inadequate seal which permits leakage of formation contents, typically water, gas, or oil from between the casing and the formation. The invention disclosed herein has been found to be particularly useful in the context of this situation, although its application is not limited to such.
The present invention involves a shaped charge assembly which produces a superior performance when used as part of a perforating gun to be -3_ 2 i '%~~3~~
used as a channel finder gun. The improved performance stems from the use of a shaped charge assembly in which the charge is configured to produce a jet which is substantially non-circular in cross section (in relation to the axial direction of travel of the jet) in which the assembly includes a base that is relatively rigid with respect to the liner of the assembly.
According to a preferred embodiment, the shaped charge assembly includes a linear shaped charge.
Thus, in one broad aspect, the invention is a shaped charge assembly having: a relatively rigid base that has a cavity; a relatively flexible liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
The cavity of the base can have an opening at a top end of the base and preferably at least a portion of the liner is located in the opening of the base and the charge is shaped such that, upon explosion thereof, the jet travels along a major axis through the opening of the base.
Preferably, the shaped charge is a linear charge.
The base can be of milled steel, stamped metal, or cast metal, etc.
The exposed, or outer surface part of the liner can be concave.
The liner (or the portion of the liner in the opening of the base) can be "V"-shaped and inwardly concave with respect to the top end of the base, or the liner can be "W'-shaped and be generally inwardly directed with respect to the top end of the base.
Particularly, interior surfaces of the base can define a longitudinal trough extending between first and second ends of the base, there can be first and second walls extending between the first and second ends, respectively, third and fourth walls extending between the first ends of the first and second walls, and the second ends of the first and second walls, 2l X5385 respectively, and the base can include a pair of apertures therethrough for contacting detonator wires with the charge.
In a particular embodiment, illustrated below, the floor of the cavity has a central ridge extending upwardly toward the liner.
In certain embodiments, there are substantially upright interior side walls extending between the first and second ends of the base.
It is possible for the interior floor surface of the base to be generally concave upward.
In particular embodiments, interior surfaces of the base define a longitudinal trough extending between first and second ends of the base and the liner is concave inward with respect to the cavity such that the shaped material within the cavity has a substantially constant transverse cross section between the first and second ends.
There can be metal foil at the respective first and second ends, to seal the charge in the assembly.
Usually, the base and liner are each of metal.
Usually, the base has a floor having a thickness at least twice that of the liner. The base can have a floor having a thickness at least three times the thickness of the liner. The base can have a floor having a thickness at least four times the thickness of the liner. The base can have a floor having a thickness at least five times the thickness of the liner. The base can have a floor having a thickness at least six times the thickness of the liner.
Preferably, the base has walls having interior surfaces which define the cavity and the walls are relatively thick with respect to the thickness of the liner.
The explosive charge material can be compressed directly against inner surfaces of the base. The liner and base can be formed separate from each other.
The charge can be pressed into the cavity by forced abutment with the liner.
The base can be of unitary construction.
Z 1 ~h385 In certain embodiments, the base has an interior floor and walls having interior surfaces which extend upwardly of the floor in which the average thickness of the floor and walls is between about 2 and 10 that of the liner; or the average thickness of the floor and walls is between about 3 and that of the liner; or the average thickness of the floor and walls is between about 4 and 6 that of the liner; or the average thickness of the floor and walls is between about 5 times that of the liner.
The thickness of the liner can be between about 1/32" and 1/4".
More preferably, the thickness of the liner is about 1116".
In particular embodiments, the invention is a shaped charge assembly in which the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open the cavity and the liner extends between the first and second walls, and the charge is compressed in the cavity such that the shape of the charge is defined by interior surfaces of the floor, walls and liner. Further, there can be first and second means for sealing the charge within the cavity, extending between first ends of the first and second walls, the liner, and the base floor, and between second ends of the first and second walls, the liner and the base floor, respectively. Such means for sealing the charge within the cavity can be a piece of foil.
Usually, interior surfaces of the first and second walls face each other and are symmetrically shaped with respect to a center line of the assembly. The interior floor surface can define an upwardly concave trough which is symmetrical with respect to the center line. In a preferred embodiment, interior surfaces of the floor, first and second walls and liner define the shape of the charge such that the charge has a generally "V"-shaped cross section. The cross section of the charge can be relatively constant and of a defined thickness.
In particular embodiments, the interior surface of the floor has an upwardly protruding ridge which is generally symmetrical with respect to the center line. The liner can be shaped and oriented so as to be parallel to the 21 ~~63°5 center line and be concave upward. In certain preferred embodiments, the liner has a generally "V"-shaped cross section. Alternatively, the liner can be generally "W'-shaped in cross section.
Typically, the inner surfaces of the first and second walls are generally parallel to the center line. Additionally, the inner surfaces of the first and second walls can be generally parallel to each other. In a preferred embodiment, the shaped charge is relatively shallow near the center of the cavity and relatively deep near the first and second walls of the base.
In particular embodiments, a shaped charge assembly of the invention includes a base of metal. The base includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity. The sheath can be held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath. The shaped charge can be oriented to explode in a direction away from the floor of the base.
Preferably, there is means for sealing exposed ends of the charge against the environment. The means can be foil. Typically, the foil is a thin metal sheet, such as aluminum foil, and includes a pressure sensitive adhesive for adherence to the charge and base surfaces. Again, the shaped charge can be a linear shaped charge. The shaped charge can have a generally "V"-shaped cross section, which is relatively constant from end to end of the charge. The shaped charge can have a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
In particular embodiments, a shaped charge assembly of the invention includes a base that is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open cavity and the liner is secured and extends between the first, second, third and fourth _,_ walls so as to seal the charge within the cavity. Preferably, the base is of unitary construction, i.e., is formed of a single piece of material such as cast metal, for example.
In such an embodiment, it is possible to have an arrangement in which interior surfaces of the floor, first, second, third, and fourth walls, and the liner define the shape of the charge. The interior surfaces of the first and second walls can be spaced from each other a distance greater than the distance between the interior surfaces of the third and fourth walls. The interior surfaces of the third and fourth walls can slope upwardly and outwardly. The third and fourth walls preferably are symmetrically shaped with respect to a center line of the assembly.
It is possible for interior surfaces of the walls to be generally upright with respect to the interior surface of the floor. In certain illustrated embodiments, there is a ridge extending upwardly of the floor running parallel to a center line of the assembly running between the first and second walls.
The liner can be generally concave inward. The liner can be generally parallel to a center line of the assembly running between the first and second walls. The liner can have a generally "V"-shaped cross section. The liner can have a generally "W'-shaped cross section.
Preferably, the charge is compressed directly against the inner surfaces and the liner and base are formed separate from each other.
The base can include a pair of apertures therethrough for contacting detonator wires with the charge located in the cavity of the base.
In particular embodiments, a shaped charge assembly of the invention has a base that is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
In such embodiments, it is preferred that the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base 2I~~~~~
_8_ and exterior surfaces of the sheath. Often, the shaped charge is oriented to explode in a direction away from the floor of the base. The shaped charge can be a linear shaped charge. The shaped charge can have a generally "V"-shaped cross section, and can be of relatively constant thickness from end to end of the charge. The shaped charge can have a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
In a particular embodiment, the invention is a shaped charge assembly for mounting to a charge holder of an underground perforating gun including: a rigid base which defines a cavity open at a top end of the base;
charge material received within the cavity; and a liner, relatively flexible with respect to the base, mounted at the top end of the cavity to seal the material within the cavity; and wherein, interior surfaces of the base and the liner together define the shape of the charge material, which shape is such that, upon detonation, a jet with a non-circular cross-section travels along a major axis through the open end of the cavity of the base.
In another particular aspect, the invention is a combination of a shaped charge assembly and a holder therefor, for use in a longitudinal housing of a perforating gun. The holder defines a slot for receipt of the assembly therein to orient the shaped charge assembly within the housing such that, upon explosion of the charge, the axial direction of thrust is in a direction generally orthogonal to a longitudinal axis of the housing.
The holder usually defines a plurality of slots. Often, each respective shaped charge assembly received in a slot is oriented such that, upon explosion of the charge, the jet has a major planar component through a central thrust axis of the jet, which planar component is non-parallel with the longitudinal axis of the housing. In a particular illustrated embodiment, the planar component is generally orthogonal to the longitudinal axis of the housing.
In such a combination in which there is a plurality of shaped charge assemblies, neighboring shaped charge assemblies can be oriented with respect to each other such that their central thrust axes form an angle of 2~9~~~~
_g_ between 10° and 90° with each other, or an angle of between about 20° and 70° with each other, or an angle of between about 30° and 60° with each other, or an angle of about 45° with each other. It possible for assemblies to be dimensioned to permit a density of up to about 16 shaped charge assemblies per meter in a holder, or a density of up to about 14 shaped charge assemblies per meter in a holder, or a density of up to about 12 shaped charge assemblies per meter in a holder, or a density of up to about 10 shaped charge assemblies per meter in a holder.
Such a combination can further include a gun housing.
In another aspect, the invention is a method for perforating a casing of a well bore and a surrounding hydrocarbon-bearing formation. The method includes:
locating at least one shaped charge assembly in the bore, the assembly having a relatively rigid base, a shaped charge in a cavity of the base, and a relatively flexible liner; and exploding the charge, wherein the charge is shaped and oriented within the bore, to produce upon explosion thereof, a jet having an axial direction of thrust in a plane generally orthogonal to the bore and wherein the cross sectional shape of the jet is non-circular.
In another aspect, the present invention is a method for perforating a casing of a bore of a well and a surrounding hydrocarbon-bearing formation which includes:
locating at least one shaped charge assembly of the invention in the bore;
and exploding the charge.
The shaped charge can include:
a relatively rigid base having a cavity;
a relatively flexible liner; in which there is:
a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust, located in a plane generally 219~~85 orthogonal to the bore, in the formation of a jet having a cross sectional shape which is non-circular.
A particular method is one in which the perforating is conducted in preparation for sealing the well.
In the drawings, which illustrate embodiments of the invention, Figure 1 is an elevational view, in partial section, of a perforating gun, with a plurality of shaped charge assemblies of the present invention mounted to a holder within an elongated gun housing;
Figure 2 is an isometric exploded view of a first embodiment shaped charge assembly of the present invention;
Figure 3 is an isometric view of a shaped charge assembly of the Figure 2 embodiment;
Figure 4 is an isometric exploded view of a second embodiment shaped charge assembly of the present invention;
Figure 5 is an isometric view of the Figure 4 embodiment, fully assembled;
Figure 6 is an end view of the Figure 4 embodiment shaped charge assembly;
Figure 7 is an end view representation of the present invention, illustrating the cross sectional profile of a shaped charge a of a third embodiment;
Figure 8 is an end view representation of the present invention, illustrating the cross sectional profile of a shaped charge a of a fourth embodiment;
Figure 9(a) is a side elevation of a charge holder of the present invention having slots for receipt of preferred embodiment shaped charge assemblies. Figure 9(b) is an end view of the charge holder of Figure 9(a), radii thereof indicating the placement of charge assemblies therein;
Figures 10(a), 10(b) and 10(c) each show an outer housing of a perforating gun of the present invention, having thinned areas corresponding to the shaped charge assemblies of the preferred embodiments, in which ~ ~ y~~~~
longitudinal axes of the shaped charges are angled at 90°, 45°
and 0°, respectively, with respect to the lengthwise (i.e., longitudinal) axis of a charge holder in which the assemblies are mounted;
Figure 11 is a cross sectional view of a gun outer housing within a well hole casing;
Figure 12 is a representational view of a shaped charge assembly, as viewed along the longitudinal axis of a holder in which it is mounted showing the general shape of a jet which would be formed upon explosion of the charge; and Figure 13 is a representational view of the jet of Figure 12 taken along line 13-13 of Figure 12.
Turning to the drawings, a description of the preferred mode of implementing the invention, as currently understood by the inventors is described below.
Charge assemblies of the illustrated embodiments are for use as part of a pertorating gun 10, illustrated in Figure 1, but may equally well be incorporated into other pertorating gun systems, appropriately modified as necessary. Gun 10 includes linear shaped charge assemblies 12 mounted on charge holder 14 which is sealed and secured within gun outer housing 16.
A first embodiment charge assembly 112 is illustrated in greater detail in Figures 2 and 3. Device 112 includes rigid base 114 having linear shaped charge 116 (with liner 119) received therein. Charge 116 is a linear shaped charge, cut to the same length as the base 112, the charge containing explosive material 117 compressed within metal sheath 119. Such a linear charge is a continuous core of explosive enclosed in a seamless metal sheath, commercially available from Accurate Arms Company, Inc. of McEewen, Tennessee. Exposed ends of the charge are capped with adhesive foil 118 (omitted in Figure2).
Charge assembly 112 is appropriately dimensioned to be mounted in a holder so as to fit into the a selected gun housing. In the illustrated embodiment, the outer housing of the gun has an outer diameter of 86 mm (3 3/8") and an inner diameter of 68 mm (2 5/8"). Charge holder 14 has an outer diameter of 51 mm (2") and is a tube of thin walled extruded steel, being of substantially constant cross section and substantially constant thickness, having a thickness of about 0.17 cm (0.065"). The overall dimensions of charge assembly base 114 are about 38 mm (1 1/2") 120 (height) x 38 mm (1 1/2") 122 (width) x 51 mm (2") 124 (length). The product of Accurate Arms Company incorporated as part of assembly 112 bears product number Y230-2000. It is a linear shaped charge having a copper sheath containing core, i.e., explosive material, RDX with a grain load of per foot. The outerwidth of the linear shaped charge is 1.15" (about 29 mm).
Similar linear shaped charge products are commercially available from other sources, for example, Teledyne Ryan Aeronautical of Hollister, California.
The base includes cavity 125 having defined by interior surface 126 of floor 127 and interior surfaces 128 of side walls 129, which surfaces match the outer contour of the bottom of the sheath of the shaped charge. A
friction fit holds the shaped charge within the cavity of the base. That is, the sheath fits snugly against the walls defining the cavity. It is possible that an adhesive could be used to secure the liner charge within the base, alone, or in addition to a friction fit.
Base 114, which houses the linear shaped charge, is of milled steel. As would be appreciated be a person skilled in the art, the base can be of other metals, such as zinc, for instance and it can be manufactured by methods other than milling, such as stamping (cold formed) or by casting. The base can be ceramic.
A second embodiment charge assembly 212 is illustrated in Figures 4 to 6. In this embodiment, the charge assembly includes base 214, explosive material 216, and liner 218. Base 214 is formed of one piece, i.e., is of unitary construction, the illustrated housing being milled, pressed or stamped, or cast, as with base 114. Again the base metal can be steel or zinc, etc. Base 214 includes a bottom floor 220 with four upwardly extending side walls 222, 224, 226, 228. The interior surface 230 of the floor of the housing 21 ~~~5~5 base is shaped to be generally congruent with the corresponding interior portion of sheath 119 of the first embodiment.
A third embodiment shape charged device 250 is illustrated in Figure 7, in which the cross sectional shape of the shaped charge 252 is shown. As with other embodiments, base 254 of the assembly might or might not have end walls connecting side walls 256, 258. Interior surfaces of liner 260, the side walls and floor 262 of the base define the shape of the charge, which is compressed within the cavity. The cross sectional width of the cavity defined between the upright parallel inner surfaces 264, 266 of the base is about 30.7 cm (1.2"). The floor of the base has an upraised ridge 268 running between lengthwise ends of the base. The liner has a cross sectional "V"-shape. The depth of the charge increases from line 270 running through the center of the cavity to the peripheral area 272 of the cavity.
A fourth embodiment shaped charge assembly 280 is illustrated in Figure 8. This is similar to the third embodiment assembly, but the cross section of liner 282 is "W"-shaped.
Located within base 214 (or 254) is compacted or compressed explosive material 216. The material is compressed during installation of the liner, in the case of the second embodiment, liner 218. A liner of the present invention is of any metal from which conventional sheaths of linear shaped charges are manufactured: steel, copper, zinc, lead and combinations or alloys of these metals, particularly copper and zinc, or of a suitable powdered metal. A yellow brass liner might be found to be particularly suitable. The liner is installed as part of the assembly by an operation similar to that used in the manufacture of conical charges. The explosive powder is added to the cavity and the base tapped, if necessary, to level the powder. The powder can be preshaped by insertion of an appropriately shaped die into the cavity. A
preshaped liner, held in place, for example by vacuum by the punch die, is then pressed into place and any stray powder cleaned away. The explosive material is compressed during this operation to roughly the same degree as it would be within the liner of the linear shaped charge of the first embodiment.
-14- Z! 96335 Explosive material is compressed, as understood by a person skilled in the art, to obtain a desired explosive density of the charge. As illustrated for the second embodiment, interior surfaces of floor 230, and walls 222, 224, together define a "V"-shaped cavity into which the explosive material is received. Surfaces of walls 222, 224 face each other to define a trough running parallel to an axis of the housing. Opposing end walls 226, 228 join first and second ends of walls 222, 224, respectively. Generally, speaking, the arrangement is such that the explosive material is sealed within the charge assembly.
In alternative embodiments, a base similar to that of base 214 (or base 254), for example, is manufactured without end walls 222, 224. In this case the base is located between two walls of a manufacturing apparatus which hold the explosive powder in place during manufacture of the charge assembly. Once the charge and liner are in place, the walls are moved away and metal foil put in place in analogy to foil 118 shown for the first embodiment charge assembly. In the absence of end walls, it is possible to include more explosive charge in a shaped charge assembly, all else being equal.
It may be possible to vary the shape of the explosive material to obtain more optimum explosive impact than that obtained with the shapes described herein. It is certainly known, however, that the chevron configuration shape disclosed can be varied somewhat with retention of satisfactory performance. It is intended that the use of the term "V"-shaped or having a "V"-shaped cross section not be limited to the precise shapes disclosed herein. A satisfactory result can be obtained using a "V"-shape based on a parabola or an ellipse.
Other transverse cross sectional shapes are suitable. Linear "W'-shaped charges are commercially available. A base comparable to base 114 can thus be manufactured with a suitably shaped floor and inner side walls to receive such a charge. Alternatively, a base comparable to that of base 214 can thus be manufactured with a "W'-shaped explosive-receiving cavity and suitable "W"-shaped liner.
2~ 96385 It is not strictly necessary for the shaped charge to be linear. In the case of the second embodiment type of shaped charge device, for example, the interior surfaces of the floor of the base cavity can be slightly curved or arched, i.e., it is not required to be strictly linear running from end-to-end. It is important that the shaped charge have a longitudinal axis (when viewed from the top, i.e., from the side from which the liner is visible) in order that a jet having a non-circular cross section in relation to the major axis 290 of thrust of the jet 292. See Figures 12 and 13. A charge is shaped such that the explosive material produces forces having a longitudinal component (when viewed along the axis of the principle direction of the movement of the jet) when the charge is detonated. If one is to look at vectorial forces emanating radially from a central thrust axis of the explosion, there is a vector 294 in a first direction that is different in length from a vector 296 in a second direction perpendicular to the first direction. This is in contrast to conical or hemispherical shaped charges in which the cross section of forces in an imaginary plane perpendicular to the major thrust of the explosion (the major thrust being along a radial line perpendicular to the longitudinal axis of the charge holder, in the Figure 1 embodiment, for example) are substantially equal, i.e., together define a circle.
The explosive material of the disclosed shaped charge assemblies is RDX, but any suitable explosive can be used, for example, CH-6, HMX, PETN, HNS, PYX, etc. "Shaped charge" is used herein to describe suitable explosive material compressed so as to have a particular shape.
Holder 14 of the illustrated embodiments is illustrated more fully in Figures 9a and 9b. The illustrated holder has a thickness of about 0.17 cm (0.065"). Other thicknesses of metal could possibly be used, say in the range from about 0.010" to about 0.25". The illustrated holder has been used in the field in conjunction with the first embodiment shaped charge assembly described above. The holder is manufactured by laser cutting an extruded steel tube to obtain the illustrated configuration.
2. ~ ~ J~3~5 The holder defines a slot 320 for receipt of a linear shaped charge assembly. The height 321 of each slot (corresponding to the width of the shaped charge assembly as described above) is 38 mm (1 1/2"). The slots are spaced longitudinally along the length of the holder about 76.2 mm (3") center-to-center from each other. The slots serve to orient the shaped charges in the holder such that neighboring shaped charges are phased at 45°
with respect to each other, as illustrated in Figure 11. The slots of holder 14 thus lie on an imaginary spiral with a complete turn around the circumference of the holder being obtained with every ninth slot. Installed shaped charges spaced from each other by 61 mm (2.4") are thus oriented in the same radial direction.
The number of charge assemblies that can be mounted onto a holder for a given length of the holder, usually stated as "shots per meter", is obviously limited by, among other things, the width of the shaped charge assemblies being installed on a holder. For the present invention, it is possible to have up to 14, or more, shots per meter.
For installation of a shaped charge assembly within slot 320, the assembly is inserted so that respective outer side walls 130, 132 of the base of the charge assembly abut respective slot defining edges 323, 325 of the charge holder. Once the charge assembly is located centrally with respect to the center line 322 of the holder, tabs 324 are bent radially inwardly to abut upper (radially outward) surfaces of the shaped charge assembly to securely mount the assembly to the holder. A detonation cord is located in the holder to run from end to end of the tube. In the case of the Figure 1 embodiment charge assembly 112 (or other charge assembly in having foil which seals in charge material), the detonation cord is secured to foil 118 by means of a clip.
In the case of shaped charge assembly 212, end wall 226 has a slot 232 with a clip for receipt of the detonation cord. The clip is inserted through the slot to connect the detonation cord and the explosive material for detonation thereof.
As an alternative arrangement, the slot for receiving the clip might be located at a central location of the floor of the charge assembly base. Once all of the 2 i 9 ~~ ~5 charge assemblies and detonation cord are mounted, the holder-charge assembly is installed in gun housing 16.
Gun housing 16 is illustrated in Figures 1, 10(a) and 11. Each lengthwise end of the holder is secured to the housing in a conventional manner. The detonation cord (not illustrated) extends out of the upper end of the housing to be connected to a detonator (not illustrated), this being a conventional arrangement. The interior of the housing is sealed against ingress of liquid, again in a conventional manner, so that it can be installed in a well for use without exposure of the explosive material to liquid which might diminish its explosive capacity.
Outer surface 36 of gun housing 16 has scalloped areas 38 which are thinned areas bored out of the housing. These areas of reduced thickness are spaced from each other along a spiral corresponding to that of the installed shaped charges. Each thinned area is suitably sized and shaped to accommodate the jet which emanates from the charge to which it is immediately adjacent when the gun is set off. This enhances the explosive capacity of the gun by reducing the amount of force consumed in breaking through the gun housing. Thinned areas in a gun housing are known to those skilled in the art.
Turning to Figure 11, location of charge assemblies (the charge holder has been omitted for clarity) in relation to the gun housing and well casing 44 is illustrated. Casing 44 has an outer diameter of 114 mm (4 1/2") and a thickness of 7.37 mm (0.29"). The outer diameter of the gun housing 16 is 86 mm (3 3/8") while the thickness of the scalloped portions of the gun housing is 15.2 mm (0.60"). The stand off 40 (the distance between the forward edge of a charge assembly and the inner surface of the gun housing) is 21 mm (0.815") and the clearance 42 is 6.9 mm (0.273"). The standoff distance is important since sufficient distance must be provided to permit adequate jet formation to obtain the desired penetration, while the distance should not be too great that the jet expands too greatly (in a radial direction to the axial direction of thrust of the jet), which can result in an oversized hole.
The distances indicated have been found to produce satisfactory results.
In the illustrated embodiment, each linear shaped charge assembly, when viewed from the liner side (when viewed from the top of the charge assembly as oriented in Figure 4) is non-circular. Various shapes of linear shaped charges are described in, for example, on pages 737-8 of High Velocity Impact Dynamics (Ed. Jonas A. Zukas, John Wiley & Sons, Inc., New York 1990), Shaped charge assemblies similar to assembly 112, but having dimensions suitable for use in an outer gun housing of diameter 114 mm (4 112") or 146 mm (5 3l4") are also possible. In the case of a 9.5 mm (31.8") thick gun housing having an outer diameter 114 mm (4 112"), the base of the charge assembly is 66.7 mm (2 518") in length with the height and width being the same as those shown for charge assembly 112. Such a gun is suitable for use in a well casing having an outer diameter of 140 mm (5 1l2") and thickness of 70 mm (0.275") with a stand off distance of 19 mm (314") and clearance of 5.7 mm (0.225"). In the case of a 8.9 mm (0.375") thick gun housing having an outer diameter of 146 mm (5 3/4"), the base of the charge assembly is 76 mm (3.0") in length, again with the height and width being the same as those of charge assembly 112. Such a gun is suitable for use in a well casing having an outer diameter of 178 mm (7.0") and thickness of 9.2 mm (0.362") with a stand off of 19 mm (3/4") and clearance of 6.7 mm (0.263"). Similar dimensional arrangements are obtainable with a second embodiment type of charge assembly in which charge material is pressed directly into base 214.
Perforating guns incorporating shaped charge assemblies of the first embodiment having a 2" diameter charge holder have been used in the field. Although rigorous studies have not been carried out, it appears that the pattern of "ribbon"-shaped jets generated by the slot charges more reliably hit channels, i:e., gain access to channels, than the pattern generated by conical zl X6385 shaped charges in a comparable perforating gun, as indicated by the amount cement pumpable following perforation.
In the embodiments disclosed, the liner has a thickness of about 0.8 mm (1/32"). A liner can have a smaller or greater thickness, possibly up to about 6 mm (1/4") in thickness. The thickness must be sufficient to provide enough material to form the head of a jet upon explosion of the charge material, as understood by those skilled in the art.
Although phasing of 45° has been illustrated in Figure 9, it will be understood that phasing of other angles, such as 15°, 30°, 60°, 90°, etc. are within the scope of this invention.
Turning to Figures 10(b) and 10(c), angling of slot-shaped charge assemblies is illustrated. Scalloped areas of the illustrated gun housings correspond to underlying charge assemblies, not directly illustrated. Thus in Figure 10(c), longitudinal axis 46 of a slot charge assembly is parallel to the center axis 322 of the holder. Put another way, the longitudinal axis of the charge assembly is perpendicular to a cross-sectional plane of the gun.
Figure 10(b) shows an arrangement in which the longitudinal axes of slot-shaped charge assemblies each form an angle of 45° with the center line of the charge holder. Other angles of incidence between the center axis and longitudinal axes of shaped charges are within the scope of this invention.
In all of the illustrated embodiments, charges are oriented such that upon detonation, each jet travels in a direction which is generally radially outwardly along a radius of the center line of the gun and parallel to a plane generally perpendicular to the center axis of the gun. This is the generally preferred arrangement, as it maximizes the jet forces impinging upon the gun housing and well casing, the jet traveling in a direction which is more or less orthogonal to these two metal surfaces through which it must travel to penetrate into a formation. Although there is a limit to the amount of deviation than can be made from this oriention, other orientations are within the scope of this invention. It is most likely that maintaining a jet direction along a radius of the center line of the gun will remain preferable, with a greater variation in the 2.~ 6~~5 deviation of jet thrust out of the cross-sectional plane of the gun being more likely.
Advantages over obtainable through use of a perforating gun of the present invention over conventional guns may extend beyond use as a channel finder. Particularly, a gun of the present invention may find use in gravel pack perforating of a well, or in perforation of a horizontal section of a well.
Particular embodiments of the invention having been described, the scope of the invention for which protection is sought is defined by the following claims.
Claims (160)
1. A shaped charge assembly comprising:
a relatively rigid base having a cavity;
a relatively flexible liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
a relatively rigid base having a cavity;
a relatively flexible liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
2. The shaped charge assembly of claim 1 wherein:
the cavity of the base has an opening at a top end of the base;
at least a portion of the liner is located in the opening of the base; and the charge is shaped such that, upon explosion thereof, the jet travels along a major axis through the opening of the base.
the cavity of the base has an opening at a top end of the base;
at least a portion of the liner is located in the opening of the base; and the charge is shaped such that, upon explosion thereof, the jet travels along a major axis through the opening of the base.
3. The shaped charge assembly of claim 2 wherein the shaped charge is a linear charge.
4. The shaped charge assembly of claim 1 wherein the base is of milled steel.
5. The shaped charge assembly of claim 1 wherein the base is of stamped metal.
6. The shaped charge assembly of claim 1 wherein the base is of cast metal.
7. The shaped charge assembly of claim 3 wherein the said portion of the liner is "V"-shaped and is inwardly concave with respect to the top end of the base.
8. The shaped charge assembly of claim 7 wherein the said portion of the liner is "W'-shaped and is generally inwardly directed with respect to the top end of the base.
9. The shaped charge assembly of claim 2 wherein the outer surface of the liner is concave.
10. The shaped charge assembly of claim 9 wherein interior surfaces of the base define a longitudinal trough extending between first and second ends of the base, there are first and second walls extending between the first and second ends, respectively, there are third and fourth walls extending between the first ends of the first and second walls, and the second ends of the first and second walls, respectively, and the base includes a pair of apertures therethrough for contacting detonator wires with the charge.
11. The shaped charge assembly of claim 10 wherein a floor of the cavity has a central ridge extending upwardly toward the liner.
12. The shaped charge assembly of claim 11 wherein there are substantially upright interior side walls extending between the first and second ends.
13. The shaped charge assembly of claim 2 wherein the interior floor surface of the base is generally concave.
14. The shaped charge assembly of claim 2 wherein interior surfaces of the base define a longitudinal trough extending between first and second ends of the base and the liner is concave inward with respect to the cavity such that the shaped material within the cavity has a substantially constant transverse cross section between the first and second ends.
15. The shaped charge assembly of claim 14 further comprising metal foil at the respective first and second ends, to seal the charge in the assembly.
16. The shaped charge assembly of claim 1 wherein the base and liner are each of metal.
17. The shaped charge assembly of claim 16 wherein the base has a floor having a thickness at least twice that of the liner.
18. The shaped charge assembly of claim 16 wherein the base has a floor having a thickness at least three times the thickness of the liner.
19. The shaped charge assembly of claim 16 wherein the base has a floor having a thickness at least four times the thickness of the liner.
20. The shaped charge assembly of claim 16 wherein the base has a floor having a thickness at least five times the thickness of the liner.
21. The shaped charge assembly of claim 16 wherein the base has a floor having a thickness at least six times the thickness of the liner.
22. The shaped charge assembly of claim 16 wherein base has walls having interior surfaces which define the cavity and the walls are relatively thick with respect to the thickness of the liner.
23. The shaped charge assembly of claim 22 wherein the charge is compressed directly against said inner surfaces and the liner and base are formed separate from each other.
24. The shaped charge assembly of claim 23 wherein the charge is pressed into the cavity by forced abutment with the liner.
25. The shaped charge assembly of claim 1 wherein the base is of unitary construction.
26. The shaped charge assembly of claim 2 wherein the base has an interior floor and walls having interior surfaces which extend upwardly of the floor, wherein the average thickness of the floor and walls is between about 2 and 10 that of the liner.
27. The shaped charge assembly of claim 26, wherein the average thickness of the floor and walls is between about 3 and 8 that of the liner.
28. The shaped charge assembly of claim 27, wherein the average thickness of the floor and walls is between about 4 and 6 that of the liner.
29. The shaped charge assembly of claim 28, wherein the average thickness of the floor and walls is between about 5 times that of the liner.
30. The shaped charge assembly of claim 26 wherein the thickness of the liner is between about 1/32" and 1/4".
31. The shaped charge assembly of claim 27 wherein the thickness of the liner is about 1/16".
32. The shaped charge assembly of claim 1 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open said cavity and the liner extends between the first and second walls, and the charge is compressed in the cavity such that the shape of the charge is defined by interior surfaces of the floor, walls and liner.
33. The shaped charge assembly of claim 32 further comprising first and second means for sealing the charge within the cavity, extending between first ends of the first and second walls, the liner, and the base floor, and between second ends of the first and second walls, the liner and the base floor, respectively.
34. The shaped charge assembly of claim 33 wherein each means for sealing the charge within the cavity comprises a piece of foil.
35. The shaped charge assembly of claim 32 wherein the interior surfaces of the first and second walls face each other and are symmetrically shaped with respect to a center line of the assembly.
36. The shaped charge assembly of claim 35 wherein the interior floor surface defines an upwardly concave trough which is symmetrical with respect to said center line.
37. The shaped charge assembly of claim 36 wherein the interior surfaces of the floor, first and second walls and liner define the shape of the charge such that the charge has a generally "V"-shaped cross section.
38. The shaped charge assembly of claim 37 wherein said cross section of the charge is relatively constant and of a defined thickness.
39. The shaped charge assembly of claim 35 wherein the interior surface of the floor has an upwardly protruding ridge which is generally symmetrical with respect to said center line.
40. The shaped charge assembly of claim 39 wherein the liner is parallel to the center line and is concave upward.
41. The shaped charge assembly of claim 40 wherein the liner has a generally "V"-shaped cross section.
42. The shaped charge assembly of claim 40 wherein the liner is generally "W'-shaped in cross section.
43. The shaped charge assembly of claim 35 wherein the inner surfaces of the first and second walls are generally parallel to said center line.
44. The shaped charge assembly of claim 43 wherein the inner surfaces of the first and second walls are generally parallel to each other.
45. The shaped charge assembly of claim 35 wherein the shaped charge is relatively shallow near the center of the cavity and relatively deep near the first and second walls of the base.
46. The shaped charge assembly of claim 1 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
47. The shaped charge assembly of claim 46 wherein the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath.
48. The shaped charge assembly of claim 46 wherein the shaped charge is oriented to explode in a direction away from the floor of the base.
49. The shaped charge assembly of claim 46 further comprising means for sealing exposed ends of the charge against the environment.
50. The shaped charge assembly of claim 49 wherein said means for sealing each end of the charge comprises a piece of foil.
51. The shaped charge assembly of claim 46 wherein said shaped charge is a linear shaped charge.
52. The shaped charge assembly of claim 46 wherein the shaped charge has a generally "V"-shaped cross section, which is relatively constant from end to end of the charge.
53. The shaped charge assembly of claim 46 wherein the shaped charge has a generally "W'-shaped cross section which is relatively constant from end to end of the charge.
54. The shaped charge assembly of claim 1 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open said cavity and the liner is secured and extends between the first, second, third and fourth walls so as to seal the charge within the cavity.
55. The shaped charge assembly of claim 54 wherein the base is of unitary construction.
56. The shaped charge assembly of claim 55 wherein interior surfaces of the floor, first, second, third, and fourth walls, and the liner define the shape of the charge.
57. The shaped charge assembly of claim 56 wherein the interior surfaces of the first and second walls are spaced from each other a distance greater than the distance between the interior surfaces of the third and fourth walls.
58. The shaped charge assembly of claim 57 wherein the interior surfaces of the third and fourth walls slope upwardly and outwardly.
59. The shaped charge assembly of claim 58 wherein the third and fourth walls are symmetrically shaped with respect to a center line of the assembly.
60. The shaped charge assembly of claim 57 wherein the interior surfaces of the walls are generally upright with respect to the interior surface of the floor.
61. The shaped charge assembly of claim 60 wherein there is a ridge extending upwardly of the floor running parallel to a center line of the assembly running between the first and second walls.
62. The shaped charge assembly of claim 60 wherein the liner is generally concave inward.
63. The shaped charge assembly of claim 62 wherein the liner is generally parallel to a center line of the assembly running between the first and second walls.
64.The shaped charge assembly of claim 63 wherein the liner has a generally "V"-shaped cross section.
65. The shaped charge assembly of claim 63 wherein the liner has a generally "W"-shaped cross section.
66. The shaped charge assembly of claim 56 wherein the charge is compressed directly against said inner surfaces and the liner and base are formed separate from each other.
67. The shaped charge assembly of claim 66 wherein the base includes a pair of apertures therethrough for contacting detonator wires with the charge.
68. The shaped charge assembly of claim 1 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open said cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
69. The shaped charge assembly of claim 68 wherein the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath.
70. The shaped charge assembly of claim 68 wherein the shaped charge is oriented to explode in a direction away from the floor of the base.
71. The shaped charge assembly of claim 68 wherein said shaped charge is a linear shaped charge.
72. The shaped charge assembly of claim 68 wherein the shaped charge has a generally "V"-shaped cross section, and is of relatively constant thickness from end to end of the charge.
73. The shaped charge assembly of claim 68 wherein the shaped charge has a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
74. A shaped charge assembly for mounting to a charge holder of an underground perforating gun comprising:
a rigid base which defines a cavity open at a top end of the base;
charge material received within the cavity; and a liner, relatively flexible with respect to the base, mounted at the top end of the cavity to seal the material within the cavity; and wherein, interior surfaces of the base and the liner together define the shape of the charge material, which shape is such that, upon detonation, a jet with a non-circular cross-section travels along a major axis through the open end of the cavity of the base.
a rigid base which defines a cavity open at a top end of the base;
charge material received within the cavity; and a liner, relatively flexible with respect to the base, mounted at the top end of the cavity to seal the material within the cavity; and wherein, interior surfaces of the base and the liner together define the shape of the charge material, which shape is such that, upon detonation, a jet with a non-circular cross-section travels along a major axis through the open end of the cavity of the base.
75. In combination, at least one shaped charge assembly of claim 1 and a holder therefor, for use in a longitudinal housing of a perforating gun, wherein the holder defines a slot for receipt of the assembly therein to orient the shaped charge assembly within the housing such that, upon explosion of the charge, the axial direction of thrust is in a direction generally orthogonal to a longitudinal axis of the housing.
76. The combination of claim 75, wherein the holder defines a plurality of said slots and each respective shaped charge assembly received therein is oriented thereby such that each, upon explosion of the charge, said jet has a major planar component through a central thrust axis thereof, which planar component is non-parallel with the longitudinal axis of the housing.
77. The combination of claim 76, wherein said planar component is generally orthogonal to the longitudinal axis of the housing.
78. The combination of claim 77, wherein neighboring shaped charge assemblies are oriented with respect to each other so that their central thrust axes form an angle of between 10° and 90° with each other.
79. The combination of claim 77, wherein neighboring shaped charge assemblies are oriented with respect to each other so that their central thrust axes form an angle of between about 20° and 70° with each other.
80. The combination of claim 77, wherein neighboring shaped charge assemblies are oriented with respect to each other so that their central thrust axes form an angle of between about 30° and 60° with each other.
81. The combination of claim 77, wherein each assembly is dimensioned to permit a density of up to about 16 shaped charge assemblies per meter in said holder.
82. The combination of claim 77, wherein each assembly is dimensioned to permit a density of up to about 14 shaped charge assemblies per meter in said holder.
83. The combination of claim 77, wherein each assembly is dimensioned to permit a density of up to about 12 shaped charge assemblies per meter in said holder.
84. The combination of claim 77, wherein each assembly is dimensioned to permit a density of up to about 10 shaped charge assemblies per meter in said holder.
85. A method for perforating a casing of a well bore and a surrounding hydrocarbon-bearing formation, comprising: locating at least one shaped charge assembly in the bore, the assembly having a relatively rigid base, a shaped charge in a cavity of the base, and a relatively flexible liner; and exploding the charge, wherein the charge is shaped and oriented within the bore, to produce upon explosion thereof, a jet having an axial direction of thrust in a plane generally orthogonal to the bore and wherein the cross sectional shape of the jet is non-circular.
86. A method for perforating a casing of a bore of a well and a surrounding hydrocarbon-bearing formation, comprising: locating at least one shaped charge assembly in the bore; and exploding the charge, wherein, the shaped charge assembly comprises: a relatively rigid base having a cavity; a relatively flexible liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust, located in a plane generally orthogonal to the bore, in the formation of a jet having a cross sectional shape which is non-circular.
87. The method of claim 86 wherein the perforating is conducted in preparation for sealing the well.
88. A shaped charge assembly comprising:
a rigid metal base having a cavity;
a liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
a rigid metal base having a cavity;
a liner; and a shaped charge located in the cavity, wherein the charge is in a shape and the liner located such that, upon explosion of the charge, the liner is propelled along an axial direction of thrust in the formation of a jet having a cross sectional shape which is non-circular.
89. The shaped charge assembly of claim 88 wherein: the cavity of the base has an opening at a top end of the base; at least a portion of the liner is located in the opening of the base; and the charge is shaped such that, upon explosion thereof, the jet travels along a major axis through the opening of the base.
90. The shaped charge assembly of claim 89 wherein the shaped charge is a linear charge.
91. The shaped charge assembly of claim 88 wherein the base is of milled steel.
92. The shaped charge assembly of claim 88 wherein the base is of stamped metal.
93. The shaped charge assembly of claim 88 wherein the base is of cast metal.
94. The shaped charge assembly of claim 90 wherein the said portion of the liner is "V"-shaped and is inwardly concave with respect to the top end of the base.
95. The shaped charge assembly of claim 94 wherein the said portion of the liner is "W"-shaped and is generally inwardly directed with respect to the top end of the base.
96. The shaped charge assembly of claim 89 wherein the outer surface of the liner is concave.
97. The shaped charge assembly of claim 96 wherein interior surfaces of the base define a longitudinal trough extending between first and second ends of the base, there are first and second walls extending between the first and second ends, respectively, there are third and fourth walls extending between the first ends of the first and second walls, and the second ends of the first and second walls, respectively, and the base includes a pair of apertures therethrough for contacting detonator wires with the charge.
98. The shaped charge assembly of claim 97 wherein a floor of the cavity has a central ridge extending upwardly toward the liner.
99. The shaped charge assembly of claim 98 wherein there are substantially upright interior side walls extending between the first and second ends.
100. The shaped charge assembly of claim 89 wherein the interior floor surface of the base is generally concave.
101. The shaped charge assembly of claim 89 wherein interior surfaces of the base define a longitudinal trough extending between first and second ends of the base and the liner is concave inward with respect to the cavity such that the shaped material within the cavity has a substantially constant transverse cross section between the first and second ends.
102. The shaped charge assembly of claim 101 further comprising metal foil at the respective first and second ends, to seal the charge in the assembly.
103. The shaped charge assembly of claim 88 wherein the base and liner are each of metal.
104. The shaped charge assembly of claim 103 wherein the base has a floor having a thickness at least twice that of the liner.
105. The shaped charge assembly of claim 103 wherein the base has a floor having a thickness at least three times the thickness of the liner.
106. The shaped charge assembly of claim 103 wherein the base has a floor having a thickness at least four times the thickness of the liner.
107. The shaped charge assembly of claim 103 wherein the base has a floor having a thickness at least five times the thickness of the liner.
108. The shaped charge assembly of claim 103 wherein the base has a floor having a thickness at least six times the thickness of the liner.
109. The shaped charge assembly of claim 103 wherein base has walls having interior surfaces which define the cavity and the walls are relatively thick with respect to the thickness of the liner.
110. The shaped charge assembly of claim 109 wherein the charge is compressed directly against said inner surfaces and the liner and base are formed separate from each other.
111. The shaped charge assembly of claim 110 wherein the charge is pressed into the cavity by forced abutment with the liner.
112. The shaped charge assembly of claim 88 wherein the base is of unitary construction.
113. The shaped charge assembly of claim 89 wherein the base has an interior floor and walls having interior surfaces which extend upwardly of the floor, wherein the average thickness of the floor and walls is between about 2 and 10 that of the liner.
114. The shaped charge assembly of claim 113, wherein the average thickness of the floor and walls is between about 3 and 8 that of the liner.
115. The shaped charge assembly of claim 114, wherein the average thickness of the floor and walls is between about 4 and 6 that of the liner.
116. The shaped charge assembly of claim 115, wherein the average thickness of the floor and walls is between about 5 times that of the liner.
117. The shaped charge assembly of claim 113 wherein the thickness of the liner is between about 1/32" and 1/4".
118. The shaped charge assembly of claim 114 wherein the thickness of the liner is about 1/16".
119. The shaped charge assembly of claim 88 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open said cavity and the liner extends between the first and second walls, and the charge is compressed in the cavity such that the shape of the charge is defined by interior surfaces of the floor, walls and liner.
120. The shaped charge assembly of claim 119 further comprising first and second means for sealing the charge within the cavity, extending between first ends of the first and second walls, the liner, and the base floor, and between second ends of the first and second walls, the liner and the base floor, respectively.
121. The shaped charge assembly of claim 120 wherein each means for sealing the charge within the cavity comprises a piece of foil.
122. The shaped charge assembly of claim 119 wherein the interior surfaces of the first and second walls face each other and are symmetrically shaped with respect to a center line of the assembly.
123. The shaped charge assembly of claim 122 wherein the interior floor surface defines an upwardly concave trough which is symmetrical with respect to said center line.
124. The shaped charge assembly of claim 123 wherein the interior surfaces of the floor, first and second walls and liner define the shape of the charge such that the charge has a generally "V"-shaped cross section.
125. The shaped charge assembly of claim 124 wherein said cross section of the charge is relatively constant and of a defined thickness.
126. The shaped charge assembly of claim 122 wherein the interior surface of the floor has an upwardly protruding ridge which is generally symmetrical with respect to said center line.
127. The shaped charge assembly of claim 126 wherein the liner is parallel to the center line and is concave upward.
128. The shaped charge assembly of claim 127 wherein the liner has a generally "V"-shaped cross section.
129. The shaped charge assembly of claim 127 wherein the liner is generally "W"-shaped in cross section.
130. The shaped charge assembly of claim 122 wherein the inner surfaces of the first and second walls are generally parallel to said center line.
131. The shaped charge assembly of claim 130 wherein the inner surfaces of the first and second walls are generally parallel to each other.
132. The shaped charge assembly of claim 122 wherein the shaped charge is relatively shallow near the center of the cavity and relatively deep near the first and second walls of the base.
133. The shaped charge assembly of claim 88 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, to define an upwardly open cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
134. The shaped charge assembly of claim 133 wherein the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath.
135. The shaped charge assembly of claim 133 wherein the shaped charge is oriented to explode in a direction away from the floor of the base.
136. The shaped charge assembly of claim 133 further comprising means for sealing exposed ends of the charge against the environment.
137. The shaped charge assembly of claim 136 wherein said means for sealing each end of the charge comprises a piece of foil.
138. The shaped charge assembly of claim 133 wherein said shaped charge is a linear shaped charge.
139. The shaped charge assembly of claim 133 wherein the shaped charge has a generally "V"-shaped cross section, which is relatively constant from end to end of the charge.
140. The shaped charge assembly of claim 133 wherein the shaped charge has a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
141. The shaped charge assembly of claim 88 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open said cavity and the liner is secured and extends between the first, second, third and fourth walls so as to seal the charge within the cavity.
142. The shaped charge assembly of claim 141 wherein the base is of unitary construction.
143. The shaped charge assembly of claim 142 wherein interior surfaces of the floor, first, second, third, and fourth walls, and the liner define the shape of the charge.
144. The shaped charge assembly of claim 143 wherein the interior surfaces of the first and second walls are spaced from each other a distance greater than the distance between the interior surfaces of the third and fourth walls.
145. The shaped charge assembly of claim 144 wherein the interior surfaces of the third and fourth walls slope upwardly and outwardly.
146. The shaped charge assembly of claim 145 wherein the third and fourth walls are symmetrically shaped with respect to a center line of the assembly.
147. The shaped charge assembly of claim 144 wherein the interior surfaces of the walls are generally upright with respect to the interior surface of the floor.
148. The shaped charge assembly of claim 147 wherein there is a ridge extending upwardly of the floor running parallel to a center line of the assembly running between the first and second walls.
149. The shaped charge assembly of claim 147 wherein the liner is generally concave inward.
150. The shaped charge assembly of claim 149 wherein the liner is generally parallel to a center line of the assembly running between the first and second walls.
151. The shaped charge assembly of claim 150 wherein the liner has a generally "V"-shaped cross section.
152. The shaped charge assembly of claim 150 wherein the liner has a generally "W"-shaped cross section.
153. The shaped charge assembly of claim 143 wherein the charge is compressed directly against said inner surfaces and the liner and base are formed separate from each other.
154. The shaped charge assembly of claim 153 wherein the base includes a pair of apertures therethrough for contacting detonator wires with the charge.
155. The shaped charge assembly of claim 88 wherein the base is of metal and includes a floor and first and second upstanding walls at first and second opposite sides of the base, respectively, and third and fourth upstanding side walls at third and fourth opposite ends of the base, respectively, to define an upwardly open said cavity and the shaped charge is defined within a relatively flexible sheath, secured within the cavity.
156. The shaped charge assembly of claim 155 wherein the sheath is held within the cavity by frictional forces between abutting interior surfaces of the base and exterior surfaces of the sheath.
157. The shaped charge assembly of claim 155 wherein the shaped charge is oriented to explode in a direction away from the floor of the base.
158. The shaped charge assembly of claim 155 wherein said shaped charge is a linear shaped charge.
159. The shaped charge assembly of claim 155 wherein the shaped charge has a generally "V"-shaped cross section, and is of relatively constant thickness from end to end of the charge.
160. The shaped charge assembly of claim 155 wherein the shaped charge has a generally "W"-shaped cross section which is relatively constant from end to end of the charge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2196385 CA2196385C (en) | 1997-01-30 | 1997-01-30 | Shaped charge assembly system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2196385 CA2196385C (en) | 1997-01-30 | 1997-01-30 | Shaped charge assembly system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2196385A1 CA2196385A1 (en) | 1998-07-30 |
| CA2196385C true CA2196385C (en) | 2005-03-29 |
Family
ID=4159788
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2196385 Expired - Fee Related CA2196385C (en) | 1997-01-30 | 1997-01-30 | Shaped charge assembly system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2196385C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD968474S1 (en) | 2020-04-30 | 2022-11-01 | DynaEnergetics Europe GmbH | Gun housing |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB201222474D0 (en) | 2012-12-13 | 2013-01-30 | Qinetiq Ltd | Shaped charge and method of modifying a shaped charge |
| CA2995139C (en) * | 2015-08-18 | 2020-06-30 | Dynaenergetics Gmbh & Co. Kg | Multiple-point initiation for non-axisymmetric shaped charge |
| US11340047B2 (en) | 2017-09-14 | 2022-05-24 | DynaEnergetics Europe GmbH | Shaped charge liner, shaped charge for high temperature wellbore operations and method of perforating a wellbore using same |
| WO2019105721A1 (en) | 2017-11-29 | 2019-06-06 | Dynaenergetics Gmbh & Co .Kg | Closure member and encapsulated slotted shaped charge with closure member |
| CN112313470A (en) | 2018-06-11 | 2021-02-02 | 德力能欧洲有限公司 | Corrugated liner for rectangular slotted shaped charge |
| CN110617037A (en) * | 2019-07-10 | 2019-12-27 | 大庆石油管理局有限公司 | Perforating bullet slope is fixed and is used bullet frame in location |
| CA3206497A1 (en) | 2021-02-04 | 2022-08-11 | Christian EITSCHBERGER | Perforating gun assembly with performance optimized shaped charge load |
| US11499401B2 (en) | 2021-02-04 | 2022-11-15 | DynaEnergetics Europe GmbH | Perforating gun assembly with performance optimized shaped charge load |
-
1997
- 1997-01-30 CA CA 2196385 patent/CA2196385C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD968474S1 (en) | 2020-04-30 | 2022-11-01 | DynaEnergetics Europe GmbH | Gun housing |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2196385A1 (en) | 1998-07-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |