Apparatus for electromechanically connecting a plurality of guns for well perforation

Abstract

A gun assembly for perforating wells comprising a plurality of guns with shape charges aligned centrically by end caps having insulated connector pins for conducting electrical signals and pressure through the end caps while preventing debris from the blast of one gun from entering and damaging the electrical connections and components of the next gun. The end caps being interconnected physically and electrically by specialized intermediate subs.

Claims

1. A gun assembly for perforating wells comprising: at least one gun body casing, the casing being a hollow cylinder, with a box fitting at each end; a charge carrier, the carrier being a hollow cylinder, with exterior diameter less than the interior diameter of the casing, and a length shorter than the distance between the box fittings of the casing; a plurality of shape charges positioned radially inside the charge carrier and inter connected by a detonator cord; a plurality of end caps affixed to the ends of the carrier and axially aligning the carrier within the casing between the box fitting ends, and secured therein; at least one end cap being of a durable material, electrically conductive and electrically connects the charge carrier of the gun body; an addressable detonation switch electrically connected between an inner side of at least one end cap and the plurality of shape charges within the charge carrier.

2. The assembly of claim 1 wherein at least one end cap comprises a guide pin along the edge of the end cap; the guide pin seating into a groove on the interior of the casing aligning the charge carrier within the gun casing.

3. The assembly of claim 1 wherein the end caps further comprise: a metallic body; the body further comprising: an extended cylindrical ridge protruding from one face, the ridge fitting into the interior diameter of the charge carrier tube, and being secured thereto.

4. The assembly of claim 3 wherein securing the charge carrier tube to the end cap is by pining or screwing through the body of the tube into end cap.

5. The assembly of claim 3 wherein the end caps further comprise: a charge pin passing through a centralized opening, the charge pin comprising: a conductive core, a contact pin and a threaded shaft at one end, and a contact mating surface within an enlarged body on the distal end; an electrically insulating coating; the charge pin being biased to one side by a spring between the cap body and the charge pin's enlarged body, and retained within the centralized opening by a nut, threaded on the threaded shaft on the opposite side of the end cap.

6. The assembly of claim 5 wherein the charge pin nut loosely fits into a shaped void in the end cap to prevent blast pressure from passing through the end cap's centralized opening.

7. The assembly of claim 5 wherein the assembly further comprise: an intermediate sub mated to the gun assembly at a proximal end of the intermediate sub, wherein the intermediate sub comprises: a pin fitting mating with the box fitting of the gun body casing; a pressure switch, the pressure switch being centrally mounted at one end of the intermediate sub; and contacting the contact mating surface of the contact pin in the end cap of the gun.

8. The assembly of claim 7 wherein the intermediate sub further comprises: a detonator.

9. The assembly of claim 8 wherein the assembly further comprises: a second gun assembly mated to a distal end of the intermediate sub: the second gun assembly having an end cap without a contact pin on the mating end, thereby leaving an open end cap; wherein electrical cables of the pressure switch extend though the open end cap of the second gun assembly to electrically connect the gun assemblies together.

10. The assembly of claim 5 wherein the assembly further comprise: an intermediate sub mated to the gun assembly, wherein the intermediate sub comprises: a pin fitting mating with the box fitting of the gun body casing; a feed through pin in the intermediate sub which is electrically insulated from the body of the intermediate sub, the feed through pin being centrally mounted and extending substantially the length of the intermediate sub; and contacting the contact mating surface of the contact pin in the end cap of the gun.

11. The assembly of claim 5 wherein the assembly further comprises: an intermediate sub mated to the gun assembly at a proximal end of the intermediate sub, wherein the intermediate sub comprises: a pin fitting mating with the box fitting of the gun body casing; an addressable detonation switch; a feed through pin in the intermediate sub which is electrically insulated from the body of the intermediate sub, the feed through pin being centrally mounted and extending substantially the length of the intermediate sub; and contacting the contact mating surface of the contact pin in the end cap of the gun.

12. The assembly of claim 11 wherein the assembly further comprises: second gun assembly mated to a distal end of the intermediate sub: the second gun assembly also having an end cap with a contact pin; the feed through pin in the intermediate sub contacting the contact mating surface of the contact pin in the end cap of the second gun assembly to electrically connect the gun assemblies together.

13. The assembly of claim 5 wherein the assembly further comprises: an intermediate sub mated to the gun assembly at a proximal end of the intermediate sub, wherein the intermediate sub comprises: a pin fitting mating with the box fitting of the gun body casing; a feed through pin in the intermediate sub which is electrically insulated from the body of the intermediate sub, the feed through pin being centrally mounted and extending substantially the length of the intermediate sub; and contacting the contact mating surface of the contact pin in the end cap of the gun.

14. The assembly of claim 13 wherein the assembly further comprises: a second gun assembly mated to a distal end of the intermediate sub: the second gun assembly also having an end cap with a contact pin; the feed through pin in the intermediate sub contacting the contact mating surface of the contact pin in the end cap of the second gun assembly to electrically connect the gun assemblies together.

15. The assembly of claim 3 wherein the end caps further comprise: a mounting point for an electrical ground connector.

16. The assembly of claim 15 wherein the mounting point on the end caps is a threaded hole for screwing a wire lug thereto.

17. The assembly of claim 15 wherein the mounting point on the end caps is a snap connector or connecting pin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-section of an assembly of three armed and assembled guns in a manner that is in accordance with this invention.

(2) FIG. 2 shows a cross section of a single gun joined on each end with a tandem sub.

(3) FIG. 2A shows an insulator cap assembly prior to mating with the gun or sub.

(4) FIG. 2B shows a bottom sub assembly containing a detonator attached to a bottom sub and mated with a gun.

(5) FIG. 3A shows the wired retractable contact pin installed into an insulating top end assembly prior to mating with a sub.

(6) FIG. 3B, is another detailed view of a tandem sub, showing the end cap of the gun and pressure switch of the tandem sub in their respective positions in the gun assembly.

(7) FIGS. 4A, 4B, and 4C are views of an end cap in accordance with an exemplary embodiment of the innovation.

(8) FIG. 4D is an exploded view of the end cap and contact pin assembly in accordance with an exemplary embodiment of the innovation.

(9) FIGS. 5A and 5B are views of an alternative embodiment of an end cap in accordance with an exemplary embodiment of the innovation.

(10) FIG. 6 is a cross section of an end cap assembly in gun body, and joined with a sub employing a pressure/diode switch in accordance with an exemplary embodiment of the innovation.

(11) FIG. 7 is a cross section of an end cap assembled in a gun body employing addressable switches in accordance with an exemplary embodiment of the innovation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(12) The following is a detailed description of exemplary embodiments to illustrate the principles of the invention. The embodiments are provided to illustrate aspects of the innovation, but the invention is not limited to any embodiment. As those skilled in the art will appreciate, the scope of the invention encompasses numerous alternatives, modifications, and equivalent; it is limited only by the appended claims.

(13) In relation to FIG. 1, the perf assembly (1) has a firing head (2), three perforating guns (3), each containing a charge carrier, two tandem subs (aka subs) (4), and a bottom sub (5). The mentioned parts are tubular pieces provided at the ends of the elements of the machined joint that will be described briefly, as they are not included within the sphere of protection of this innovation.

(14) One skilled in the art would be aware with the composition of drill strings which comprises one or more of the following: drill pipe, subs, drill collars, stabilizers, shock absorbers, tools, reamers, bits, and other in-hole equipment. One skilled in the art would be aware the overwhelming majority of these items utilize Rotary Shouldered Threaded Connections which are commonly referred to as pin and box connections. One skilled in the art would appreciate that the male (externally threaded) version is commonly referred to as a pin or pin fitting, and the female (internally threaded) version is commonly referred to as a box or box fitting, and they are generally manufactured to specifications developed and approved by the American Petroleum Institute, which includes internal and external diameters, wall thicknesses, upset dimensions, nominal size, weight, and grade as well as tool joint type, to ensure joint mating of similar products manufactured by different companies. All references to drill pipe, subs, collars, bits, etc. are referred to in conformity with API usage unless otherwise specifically designated herein.

(15) FIG. 2, shows a gun (3) which comprises a charge carrier (13) with a plurality of explosive shape charges (16) joined by a detonation cord or fuse (19). The charge carrier (13) is supported, substantially centered, within the gun body casing (12) by an insulating top end (14) and an isolating bottom end (15). More detail of the centralizing end plates will be provided below.

(16) One can see in the interior of the carrier (13) that the shaped charges (16) are shown set in radial fashion, that is to say, perpendicular to the gun wall, to the carrier, and, when the guns are within the well, to the well casing. In the illustration, six shape charges are illustrated, but the actual number and orientation vary.

(17) The shaped charges are explosives set in such a manner that they concentrate the force of the explosion outward, generating a jet of gas (plasma) at high pressure and temperature, that pulls the metal from the interior of the charge and projects it outward until it arrives at the well formation; with this action the charges produce a perforating effect that is variable in proportion to the potency of the charges.

(18) In each intermediate joint or intermediate sub or tandem sub (4) one can see the pressure activated changeover switch (17), from which wires extend to the rest of the assembly. When the detonator is activated, a detonation is propagated by way of a fuseor detonating cord (19)to each of the shaped charges in the carrier (13) that burst in simultaneous fashion within the corresponding gun (3). Although not described in detail herein, the internal details of the assembly are protected by a watertight seal, otherwise the liquids present in the well would enter into the interior of the gun causing problems with the electric and/or ballistic systems.

(19) In FIG. 2A, the insulating end plate is represented as being attached to the lower end of the charge carrier (13), and has a tab for connecting the ground wire (22) from the carrier to the interior of the gun housing; furthermore, it has a hole, or central orifice, (2) that permits the passage of a pair of wires, live or fire (F) and ground (G). These wires are connected to the components in the next tandem immediately below to pass the signal throughout the assembly (1, not illustrated) as required by the electronic configuration thereof. One skilled in the art will appreciate that these wires can be connected by stripping/twisting/taping; by electrical nuts; or by specialized contact connectors. It is important that the wires be connected correctly and securely to ensure they do not become loose during the handling, break during the assembly process, or short against the housing.

(20) In FIG. 2B, the insulating end plate (15) centers the charge carrier (13) and causes the grounding contact (22) to connect with the gun body (12) represented as being attached to the lower end of the charge carrier (13), and has a tab for connecting the ground wire (22) from the carrier to the interior of the gun housing; furthermore, it has a hole, or central orifice, (23) that permits the passage of a pair of wires, live or fire (F) and ground (G). These wires are connected to the components in the next tandem immediately below to pass the signal throughout the assembly (1, not illustrated) as required by the electronic configuration thereof. One skilled in the art will appreciate that these wires can be connected by stripping/twisting/taping; by electrical nuts; or by specialized contact connectors. It is important that the wires be connected correctly and securely to ensure they do not become lose during the handling, break during the assembly process, or short against the housing.

(21) In FIG. 3A the end plate (14) with the retractable contact pin (21) is shown attached on the upper end of the charge carrier (13). From the top of the end plate (14) protrudes a moving contact point that will make contact with the bottom side of a pressure switch (17, not shown) for the next component in the perf assembly (1, not shown), to allow the passage of the live wire towards the bottom. The tension from the spring urges the contact pin outward from the charge carrier (13) to adapt to any movement of parts and/or differences in length.

(22) The end plate (14) is a tubular piece of plastic with peripheral skirt, bearing a groove (25) that allows it to adapt and center the carrier (13) within the tolerances set by the perforating gun tube provider. The end plate (14) possesses a central tubular portion (26) for mounting the retractable contact pin (21), which contains a screw that connects the fire line (F) to the next device.

(23) In FIG. 3B the end plate (14) is shown in the assemble position. The end plate (14) with the retractable contact pin (21) is shown, and is represented on the upper end of the charge carrier (13). From the top of the end plate (14) protrudes a moving contact point (21) that will make contact with the piece above the carrier, shown herein as a pressure switch (17) set in a tandem sub (4). The retractable contact pin (21) is centered by the central tubular portion (26). Flexible grooves (25) anchor the end plate (14) in the charge carrier (13) and the peripheral skirt centralizes the assembly in the gun body casing (12). The signal fire wire (F) has slack to prevent breaking during the threading process of assembling the gun body casing (12) to the tandem sub (4).

(24) FIGS. 4A, 4B, 4C, and 4D show a front, side cross section, back, and exploded view of an improved end cap in accordance with an exemplary embodiment of the innovation. The end cap (400) is manufactured from a durable solid material which is electrically conductive. In the preferred embodiment the end cap is manufactured from aluminum. The end cap (400) comprises an inner face (410) which is installed toward the charge carrier, and an outer face (420) which is directed toward the mating tandem sub during assembly. From the inner face (410) protrudes a circular projection, the charge carrier mating surface (440) which fits into the end of the charge carrier (13, not shown) and is secured by screws via the holes (445) in the charge carrier mating surface (440).

(25) The end cap has a through hole for receiving the insulated contact pin (500). On the inner face (410) there is a void for receiving the nut which secures the contact pin. This void, hex shaped in the preferred embodiment (480), should match the shape of the nut so as to prevent blast pressure from escaping around it easily. The outer face (420) has a round void (490) for receiving a spring (540) and the pin (517). The spring (540) urges the contact pin (500) outward from the outer surface (420), but the pin (500) is retained by the nut (550) secured to the threads (530) at the inner surface (410).

(26) The pin is coated in an insulating coating (520) which allows the fire signal wire (F) connected to the pin's (500) contact head (513) to pass the electrical signal through the pin body (510) to the pin base (517) where it contacts the next component in the assembly (100, not shown) without grounding against the end cap (400) which is in contact with the gun body casing (12, not shown).

(27) In this embodiment, two secondary guide points (470) extend from the end cap edges approximately one hundred and twenty degrees (120) apart from the principle guide pin (460). In addition to ensuring contact with the gun body for grounding of the electrical signal, the guide pin (460) and guide points (470) ensure centering of the contact pin (500) within the gun body so that proper alignment with the subs is achieved.

(28) FIGS. 5A and 5B show an inner side and a side cross sectional view of an alternative embodiment of the end cap. The end cap (400) has a round opening (480) for the locking component of the contact pin. In this embodiment, a washer may be utilized with the nut. The spring opening (490), charger carrier mating surface (440) and screw holes (445) are the same as in the previous embodiment. The guide pin (460) remains the same situated on the edge of the end cap, extending from the inner surface (410) to the outer surface (420) with a bevel (465) on the inner surface side to ease insertion into the gun body casing (12, not shown).

(29) A single secondary guide point (470) extends from the end cap edge to force the guide pin (460) into the slot: to ensure grounding contact, align the charges, and center the end cap within the gun body; and reduce the friction between the end cap/gun body during assembly by reducing the contact surfaces. In this embodiment, the single guide point (470) is positioned counter to the guide pin (460) and is substantially wider than the guide pin (460) to prevent it from mistakenly being assembled into the alignment slot of the gun body.

(30) FIG. 6 shows a cross section of an intermediate sub incorporating a pressure switch with perforating guns mounted at either end. The perforating guns (3) mate to either end of the tandem sub (4) via screwing interface and pass the wiring signals (F & G) throughout the perf assembly (1, not indicated). The end cap (400) may be used at either end of the charge carrier (13). In the bottom end the center of the end cap (400) is left open so the firing wire (F) may pass from the pressure switch (17) to the detonator (18, not shown). In the top end the center of the end cap (400) contains the insulated contact pin (500) which is biased outward by the spring (540) and retained by the nut (550) to remain in contact with the pressure switch (17). The end cap (400) is held in position in the gun body casing (12) with a spring clip (600).

(31) FIG. 7 shows a cross section of an intermediate sub for use with addressable switches with perforating guns mounted at either end. The perforating guns (3, not indicated) mate to either end of the tandem sub (4) via screwing interface and pass the wiring signals (F & G) throughout the perf assembly (l, not indicated). The center of the end caps (400) contains the insulated contact pin (500) which is biased outward by the spring (540) and retained by the nut (550) to remain in contact with the feed through pin (610) which is also insulated to keep the fire signal isolated from the grounded body of the gun body casing (12) and tandem sub (4). The end cap (400) is held in position in the gun body casing (12) with a spring clip (600). This means the length of the charge carrier (13) and end caps (400) will be less than the length of the gun body casing (12) so the pin fittings (650) of the neighboring component, a tandem sub (4) in this embodiment, can properly mate with the box fittings (640) of the gun body casing (12). The firing signal is passed directly between guns (3, not indicated) through the tandem sub (4) to the addressable switch (620), since pressure switches are not required in this embodiment. The wiring for the addressable switch (620) or pressure switch and detonator (17 and 18, not shown) being located internal to the charge carrier and accessible by the wiring port window (630) for installation and wiring, usually done during on-site final assembly, without disassembling and possibly misaligning the charges or damaging the wiring in the charge carrier.

(32) The diagrams in accordance with exemplary embodiments of the present invention are provided as examples and should not be construed to limit other embodiments within the scope of the invention. For instance, heights, widths, and thicknesses may not be to scale and should not be construed to limit the invention to the particular proportions illustrated. Additionally, some elements illustrated in the singularity may actually be implemented in a plurality. Some element illustrated in the plurality could actually vary in count. Some elements illustrated in one form could actually vary in detail. Such specific information is not provided to limit the invention.

(33) The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.