The use of shaped-charges for cutting tubular goods such as production tubing, drill pipe, or casings used to line wells such as oil and natural gas wells and the like, is well-known in the art. Generally, shaped-charges utilized as tubing cutters include a circular, also described as annular or ring shaped, explosive element having a concave surface around its outer circumference. The concave surface normally has a V shaped cross section. The concave surface of the explosive is lined with a thin metal liner which, as is well known in the art, is explosively driven to hydrodynamically form a flat disk shaped jet of material with fluid-like properties upon detonation of the explosive. This jet of viscous material exhibits a good penetrating power to cut tubing. The shaped charge is often manufactured in the form of two identical half charges, top and bottom halves, each comprising explosive material pressed onto a half liner. Two such half charges may be assembled to form a complete shaped charge.
Generally, explosive materials such as HMX, RDX, PYX, HNS, or PETN, among others, are coated or blended with binders such as wax or synthetic polymeric reactive binders such as chlorotrifluoroethylene, sold under the registered trademark NEOFLON by Daikin Industries (formerly available from 3M Corporation under the trademark KEL-F) or a fluoroelastomer sold by DuPont Dow Elastomers L.L.C. under the registered trademark VITON. he resultant mixture is cold- or hot-pressed directly into a shaped-charge case or onto a full or half liner. The resulting shaped-charges are initiated by means of a booster or priming charge in the form of a pellet positioned in the center of the circular main charge and located so that a detonating fuse, detonating cord or electrical detonator may be positioned in close proximity to the priming charge.
The shipment of explosives is carefully regulated by various government agencies, primarily for safety purposes. The regulations impose various levels of restrictions depending upon type of explosive, weight of individual explosive components, total weight in an individual package, relative positioning of multiple explosive components in a single package, types of packaging materials and other factors. It is desirable for the explosives used in shaped charges to meet the requirements for the least restrictive shipping rules both because it reduces the expense and time for shipping and means that the risk of accidents has been minimized.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
In the drawings and descriptions that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawn figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of certain elements may not be shown in the interest of clarity and conciseness. The present disclosure may be implemented in embodiments of different forms. Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed herein may be employed separately or in any suitable combination to produce desired results.
Unless otherwise specified, use of the terms “connect,” “engage,” “couple,” “attach,” or any other like term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described.
Unless otherwise specified, use of the terms “up,” “upper,” “upward,” “uphole,” “upstream,” or other like terms shall be construed as generally toward the surface of the formation; likewise, use of the terms “down,” “lower,” “downward,” “downhole,” or other like terms shall be construed as generally toward the bottom, terminal end of a well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms shall not be construed as denoting positions along a perfectly vertical axis. Unless otherwise specified, use of the term “subterranean formation” shall be construed as encompassing both areas below exposed earth and areas below earth covered by water such as ocean or fresh water.
The description and drawings included herein merely illustrate the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its scope.
A tubing string 150 within the wellbore 110 can extend from the surface to the subterranean formation 140. The tubing string 150 can provide a conduit for formation fluids, such as production fluids produced from the subterranean formation 140, to travel from the substantially horizontal section 125 to the surface. Pressure from a bore in a subterranean formation 140 can cause formation fluids, including production fluids such as gas or petroleum, to flow to the surface.
A radial cutter 160 can be deployed into the well system 100. In some aspects, the radial cutter 160 can be detonated to cut a portion of the tubing string 150, for example separating the single portion of the tubing string 150 into two portions. The radial cutter 160 can be deployed into the tubing string 150 on a conveyance mechanism 170, which may include a wireline or other suitable mechanism. In other aspects, the radial cutter 160 can be deployed as part of the tubing string 150 and the conveyance mechanism 170 can be omitted.
Although the well system 100 is depicted with one radial cutter 160, any number of radial cutters 160 can be used in the well system 100. Although
Turning to
The pair of circular half charges 210a, 210b, in the illustrated embodiment, are formed into the predetermined shape. For example, the predetermined shape could be selected to form the concave edge 215 when the pair of circular half charges 210a, 210b are placed proximate one another. In the illustrated embodiment, the concave edge 215 is in the shape of a V, but the concave edge 215 could embody different concave shapes (e.g., shape of a U, etc.) and remain within the purview of the disclosure. The predetermined shape of the circular charge 210, and thus the circular half charges 210a, 210b illustrated in
While not easily illustrated given the section view of the shaped charge 200, each of the pair of circular half charges 210a, 210b, may comprise a plurality of segments. For example, each of the pair of circular half charges 210a, 210b, may comprise two 180 degree segments, which together form each of the circular half charges 210a, 210b. In another example, each of the pair of circular half charges 210a, 210b, may comprise four 90 degree segments, which together form each of the circular half charges 210a, 210b. The number of segments for each circular half charge 210a, 210b may vary, so long as they generally end up being circular in nature. Accordingly, the present disclosure should not be limited to any specific number of segments.
In accordance with the disclosure, the circular charge 210, and thus each of the pair of circular half charges 210a, 210b, is formed from a Triaminotrinitrobenzene based material. The term “Triaminotrinitrobenzene,” as used herein, is synonymous with 1,3,5-Triamino-2,4,6-Trinitrobenzene and/or TATB, which all have the chemical formula C6(NO2)3(NH2)3. For discussion purposes, Triaminotrinitrobenzene may be referred to throughout the present disclosure as TATB. The phrases “Triaminotrinitrobenzene based material” or “TATB based material,” as used herein, include any material having TATB therein. While many different TATB based material may be used for the circular charge 210, certain combinations have been found to be particularly useful.
For example, the circular charge 210 could comprise approximately 95 weight percent TATB and approximately 5 weight percent PolyChloroTriFluoroEthylene, which may exist under the tradename PBX 9502. Alternatively, the circular charge 210 could comprise approximately 80 weight percent TATB, approximately 15 weight percent cyclotetramethylene-tetranitramine, and approximately 5 weight percent PolyChloroTriFluoroEthylene, which may exist under the tradename PBX 9503. Additionally, the circular charge 210 could comprise approximately 92.5 weight percent TATB and approximately 7.5 weight percent PolyChloroTriFluoroEthylene, which may exist under the tradename LX-17. In yet another embodiment, the circular charge 210 could comprise approximately 60 weight percent TATB, approximately 35 weight percent cyclotetramethylene-tetranitramine, and approximately 5 weight percent of a polymer-bonded explosive (e.g., Viton), which may exist under the tradename PBXN-7. Not only may the weight percent of TATB in the TATB based material change, the median particle size of the TATB based material may change. For example, the TATB based material could have a median particle size of 5 μm or less, which may exist under the tradename ufTATB. One or more of the TATB based material examples given above may be purchased from EURENCO Bofors Inc., having a principal place of business of 20130 Lakeview Plaza Center, Suite 400, Ashburn, Va. 20147, or the Holston Army Ammunition Plant, having a principal place of business of 4509 W. Stone Drive, Kingsport, Tenn. 37660. While a number of different TATB based materials have been focused upon, unless otherwise stated, the present disclosure should not be limited to any specific TATB based material.
The shaped charge 200, in the embodiment of
In accordance with one embodiment of the disclosure, a circular booster charge 240 is positioned within the circular openings 220. The circular booster charge 240, as those skilled in the art may appreciate, may be used to assist in the explosive initiation of the circular charge 210. The circular booster charge 240 may comprise a variety of different materials and remain within the purview of the disclosure. Notwithstanding, given the use of the more stable TATB based material for the circular charge 210, certain embodiments may employ non-TATB based materials for the circular booster charge 240. For example, the circular booster charge 240 might comprise explosive materials such as HMX, RDX, PYX, HNS or PETN, among others.
The circular booster charge 240, in the illustrated embodiment, is positioned at a centerpoint axially in the shaped charge 200. For example, booster sleeves 250 may be used to axially position the shaped charge 200. The booster sleeves 250 may comprise many different materials (e.g., steel, aluminum, copper, brass, lead, tungsten, magnesium, powdered metal, plastic, etc.) and remain within the purview of the disclosure.
In accordance with one embodiment of the disclosure, a detonation feature 260 is axially positioned within the openings 220. For example, when used, the circular booster charge 240 and booster sleeves 250 might have openings centered substantially about the centerline C-C thereof. According to this embodiment, the detonation feature 260 could be axially positioned within the openings in the circular booster charge 240 and booster sleeves 250. The detonation feature 260 may comprise a variety of different materials and remain within the scope of the present disclosure. In one embodiment, however, the detonation feature 260 comprises a cylindrical tube filled with a relatively small amount of high explosive in a metal (e.g., aluminum) casing. The detonation feature 260 may or may not comprise a TATB based material.
In the illustrated embodiment, a pair of opposing circular retainer rings 270a, 270b are axially disposed about the pair of circular half charges 210a, 210b. For example, the pair of opposing circular retainer rings 270a, 270b may be used to sandwich the other features of the shaped charge 200 together. The pair of opposing circular retainer rings 270a, 270b may comprise many different materials (e.g., steel, aluminum, copper, brass, lead, tungsten, magnesium, powdered metal, plastic, etc.) and remain within the purview of the disclosure.
The shaped charge 200 illustrated in
Turning briefly to
The flyer plate 345 may comprise a variety of different materials and remain within the scope of the disclosure. In one embodiment, however, the flyer plate 345 comprises a material selected from the group of copper, copper alloy, aluminum, aluminum alloy, tin, tin alloy, lead, lead alloy, powdered metal, powdered metal within a polymeric base and sintered metal, among others. The flyer plate 345 and the second concave edge are illustrated in
A flyer plate, such as the flyer plate 345 of
The embodiment of
Turning briefly to
Turning to
The shaped charge 510, in the illustrated embodiment, is substantially enclosed by a cartridge assembly 520. The cartridge assembly 520 may comprise a variety of different features, shapes and materials and remain within the scope of the disclosure. In the illustrated embodiment of
The relative insensitive nature of TATB based materials allows larger gram weight radial cutters to pass the UN Series 6C test. When this test is passed, such radial cutters may be shipped under the Department of Transportations (DOT) shipping classification 1.4D, instead of the current 1.1D classification. The 1.4D classification provides for a less restrictive and costly shipping class. While radial cutters employing TATB based materials do not exhibit as high of an energy output (performance potential) as the traditional oilfield explosives HMX, RDX, or PETN, they will still function with these new designs discussed above.
Aspects disclosed herein include:
Aspects A, B, and C may have one or more of the following additional elements in combination: Element 1: wherein the Triaminotrinitrobenzene based material comprises approximately 95 weight percent Triaminotrinitrobenzene and approximately 5 weight percent PolyChloroTriFluoroEthylene. Element 2: wherein the Triaminotrinitrobenzene based material comprises approximately 80 weight percent Triaminotrinitrobenzene, approximately 15 weight percent cyclotetramethylene-tetranitramine, and approximately 5 weight percent PolyChloroTriFluoroEthylene. Element 3: wherein the Triaminotrinitrobenzene based material comprises approximately 92.5 weight percent Triaminotrinitrobenzene and approximately 7.5 weight percent PolyChloroTriFluoroEthylene. Element 4: wherein the Triaminotrinitrobenzene based material comprises approximately 60 weight percent Triaminotrinitrobenzene, approximately 35 weight percent cyclotramethylene-tetranitramine, and approximately 5 weight percent of a polymer-bonded explosive. Element 5: wherein the Triaminotrinitrobenzene based material has a median particle size of 5 μm or less. Element 6: wherein the circular charge has a corresponding circular opening centered substantially about a centerline thereof, and further wherein a circular booster charger is positioned within the circular opening. Element 7: wherein the circular booster charge is formed from a non-Triaminotrinitrobenzene based material. Element 8: wherein the circular booster charge is formed into a second predetermined shape having a second concave edge, and further wherein a flyer plate is shaped to extend along the second concave edge. Element 9: wherein the circular booster charge is formed from a Triaminotrinitrobenzene based material. Element 10: wherein the circular charge has a corresponding circular opening centered substantially about a centerline thereof, and further wherein a detonation feature is axially positioned within the circular opening. Element 11: wherein the circular charge is a pair of circular half charges, and further wherein the pair of circular half charges are placed proximate one another to form the concave edge. Element 12: wherein each of the pair of circular half charges comprises a plurality of segments. Element 13: wherein the concave edge is a concave outside edge. Element 14: wherein the concave edge is a concave inside edge. Element 15: wherein the liner is formed of two half liners. Element 16: wherein the liner comprises a material selected from the group of copper, copper alloy, aluminum, aluminum alloy, tin, tin alloy, lead, lead alloy, powdered metal, powdered metal within a polymeric base and sintered metal. Element 17: wherein the circular charge is positioned between a pair of opposing circular retainer rings.
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
Number | Date | Country | Kind |
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PCT/US2018/067610 | Dec 2018 | US | national |
This application claims priority to International Application Serial No. PCT/US2018/067610, filed on Dec. 27, 2018, and entitled “INSENSITIVE HIGH EXPLOSIVE BASED TUBING CUTTER,” is commonly assigned with this application and incorporated herein by reference in its entirety.