Patent Application
20210222525
Generally, when completing a subterranean well for the production of fluids, minerals, or gases from underground reservoirs, several types of tubulars are placed downhole as part of the drilling, exploration, and completions process. These tubulars can include casing, tubing, pipes, liners, and devices conveyed downhole by tubulars of various types. Each well is unique, so combinations of different tubulars may be lowered into a well for a multitude of purposes.
A subsurface or subterranean well transits one or more formations. The formation is a body of rock or strata that contains one or more compositions. The formation is treated as a continuous body. Within the formation hydrocarbon deposits may exist. Typically, a wellbore will be drilled from a surface location, placing a hole into a formation of interest. Completion equipment will be put into place, including casing, tubing, and other downhole equipment as needed. Perforating the casing and the formation with a perforating gun is a well-known method in the art for accessing hydrocarbon deposits within a formation from a wellbore.
Explosively perforating the formation using a shaped charge is a widely known method for completing an oil well. A shaped charge is a term of art for a device that when detonated generates a focused output, high energy output, and/or high velocity jet. This is achieved in part by the geometry of the explosive in conjunction with an adjacent liner. Generally, a shaped charge includes a metal case that contains an explosive material with a concave shape, which has a thin metal liner on the inner surface. Many materials are used for the liner; some of the more common metals include brass, copper, tungsten, and lead. When the explosive detonates, the liner metal is compressed into a super-heated, super pressurized jet that can penetrate metal, concrete, and rock. Perforating charges are typically used in groups. These groups of perforating charges are typically held together in an assembly called a perforating gun. Perforating guns come in many styles, such as strip guns, capsule guns, port plug guns, and expendable hollow carrier guns.
Perforating charges are typically detonated by detonating cord in proximity to a priming hole at the apex of each charge case. Typically, the detonating cord terminates proximate to the ends of the perforating gun. In this arrangement, an initiator at one end of the perforating gun can detonate all of the perforating charges in the gun and continue a ballistic transfer to the opposite end of the gun. In this fashion, numerous perforating guns can be connected end to end with a single initiator detonating all of them.
The detonating cord is typically detonated by an initiator triggered by a firing head. The firing head can be actuated in many ways, including but not limited to electronically, hydraulically, and mechanically.
Expendable hollow carrier perforating guns are typically manufactured from standard sizes of steel pipe with a box end having internal/female threads at each end. Pin ended adapters, or subs, having male/external threads are threaded one or both ends of the gun. These subs can connect perforating guns together, connect perforating guns to other tools such as setting tools and collar locators, and connect firing heads to perforating guns. Subs often house electronic, mechanical, or ballistic components used to activate or otherwise control perforating guns and other components.
Perforating guns typically have a cylindrical gun body and a charge tube, or loading tube that holds the perforating charges. The gun body typically is composed of metal and is cylindrical in shape. Charge tubes can be formed as tubes, strips, or chains. The charge tubes will contain cutouts called charge holes to house the shaped charges.
It is generally preferable to reduce the total length of any tools to be introduced into a wellbore. Among other potential benefits, reduced tool length reduces the length of the lubricator necessary to introduce the tools into a wellbore under pressure. Additionally, reduced tool length is also desirable to accommodate turns in a highly deviated or horizontal well. It is also generally preferable to reduce the tool assembly that must be performed at the well site because the well site is often a harsh environment with numerous distractions and demands on the workers on site.
Electric initiators are commonly used in the oil and gas industry for initiating different energetic devices down hole. Most commonly, 50-ohm resistor initiators are used. Other initiators and electronic switch configurations are common.
An example embodiment may include a tandem sub for connecting one or more perforating guns comprising a cylindrical body with a first end, a second end, and a hollow inner bore, wherein the first end is a pinned end adapted to couple to a box end of a First perforating gun housing, wherein the second end is a pinned end adapted to couple to a box end of a second perforating gun housing, wherein the inner bore is adapted to contain a plug and play cartridge detonator assembly that can detonate a detonating cord upon receiving an electrical command from a wire.
A variation of the example embodiment may include the tandem sub further comprising a cartridge detonator assembly disposed within the hollow inner bore, the cartridge detonator further comprising a cylindrical body housing an electrical switch and circuit board, a distal end having a detonator, and a contact spring for electrically coupling the detonator assembly to a signal wire. It may include a feed thru puck coupled to a feed thru body, disposed within the hollow inner core. It may include the feed thru puck having a thru hole for an electrical wire. The feed thru body may have a means for coupling the electrical wire to the puck, thereby electrically coupling the electrical wire with the feed thru body. The contact spring may be coupled to the feed thru body. The feed thru body may have a hollow thru bore adapted for containing a booster and the detonator adjacent to each other. The means for electrically coupling the electrical wire with the feed thru body may be a radial wire groove on the feed thru body that an exposed end of the wire is wrapped around. The means for electrically coupling the electrical wire with the feed thru body may be a tangential thru hole that an exposed end of the wire is wrapped through and around. The means for electrically coupling the electrical wire with the feed thru body may be a metal screw that clamps an exposed end of the wire against a metal insert that is further coupled to the contact spring.
An example embodiment further may include a perforating gun string comprising a first perforating gun with an uphole box end, a downhole box end, a plurality of shaped charges connected together with a detonating cord, and a wire disposed therein, traveling from the uphole end to the downhole end, a first tandem sub for connecting one or more perforating guns coupled to the downhole end of the first perforating gun further comprising a cylindrical body with a first end, a second end, and a hollow inner bore, wherein the first end is a pinned end adapted to couple to a box end of the first perforating gun housing, wherein the second end is a pinned end adapted to couple to a box end of a second perforating gun housing, and wherein the inner bore is adapted to contain a plug and play cartridge detonator assembly that can detonate the detonating cord of the first perforating gun upon receiving an electrical command from the wire.
A variation of the example embodiment may include the tandem sub having a cartridge detonator assembly disposed within the hollow inner bore, the cartridge detonator further comprising a cylindrical body housing, an electrical switch and circuit board, a distal end having a detonator, and a contact spring for electrically coupling the detonator assembly to a signal wire. It may include a feed thru puck coupled to a feed thru body, disposed within the hollow inner core. The feed thru puck may have a thru hole for an electrical wire. The feed thru body may have a means for coupling the electrical wire to the puck, thereby electrically coupling the electrical wire with the feed thru body. The contact spring may be coupled to the feed thru body. The feed thru body may have a hollow thru bore adapted for containing a booster and the detonator adjacent to each other. The means for electrically coupling the electrical wire with the feed thru body may be a radial wire groove on the feed thru body that an exposed end of the wire wraps around. The means for electrically coupling the electrical wire with the feed thru body may be a tangential thru hole that an exposed end of the wire is wrapped through and around. The means for electrically coupling the electrical wire with the feed thru body may be a metal screw that clamps an exposed end of the wire against a metal insert that is further coupled to the contact spring. The perforating gun string may include a second perforating gun having an uphole box end, a downhole box end, a plurality of shaped charges connected together with a second detonating cord, and a second wire disposed therein, traveling from the uphole end to the downhole end. It may include a second tandem sub coupled to the downhole end of the second perforating gun, the second tandem sub further comprising a cylindrical body with a first end, a second end, and a hollow inner bore, wherein the first end is a pinned end adapted to couple to the box end of the second perforating gun housing, wherein the second end is a pinned end adapted to couple to a box end of a third perforating gun housing, and wherein the inner bore is adapted to contain a plug and play cartridge detonator assembly that can detonate a detonating cord upon receiving an electrical command from the second wire.
An example embodiment may include a method for detonating a perforating gun including coupling a first perforating gun to a tandem sub, wherein the tandem sub contains a plug and play cartridge detonator, connecting a signal wire from the first perforating gun to the tandem sub, placing the first perforating gun at a predetermined location downhole to perforate a desired location of a wellbore, detonating the first perforating gun by sending a firing command to the tandem sub, and removing the first perforating gun from the wellbore.
It may include coupling a second perforating gun to the tandem sub. It may include coupling a second tandem sub to the second perforating gun and connecting a second signal wire from the second perforating gun to the second tandem sub. It may include placing the second perforating gun at a second predetermined location downhole in the wellbore. It may include detonating the second perforating gun by sending a firing command to the second tandem sub.
For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings in which reference numbers designate like or similar elements throughout the several figures of the drawing. Briefly:
In the following description, certain terms have been used for brevity, clarity, and examples. No unnecessary limitations are to be implied therefrom and such terms are used for descriptive purposes only and are intended to be broadly construed. The different apparatus, systems and method steps described herein may be used alone or in combination with other apparatus, systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.
An example embodiment is shown in
The first perforating gun assembly 122 includes a detonating cord 121 coupled to shaped charges and a pass thru electrical wire 120. The second perforating gun assembly 123 includes a feed thru assembly 124 coupled to the charge tube and in proximate contact with the tandem sub 110.
Tandem sub 110 has a pin-by-pin connection, meaning it has male threads on both connection ends. The tandem sub 110 includes an inner bore containing a cartridge detonator assembly 130 disposed therein. The cartridge detonator assembly 130 includes the detonator 131 disposed within the contact spring 132. The distal end of the detonator 131 is located within the feed thru body 111. The feed thru body 111 is threaded into and engaged with the feed thru puck body 115. The feed thru body 111 includes a radial wire groove 112 where the exposed end 113 of wire 120 wraps around. The wire 120 is fed through the puck body 115 via wire thru hole 114. As the feed thru body 111 is threaded into the puck body 115 the exposed end of the wire is caught and secured. Detonating cord retention grommet 116 is coupled to the booster on the end of detonating cord 121 and disposed within the feed thru puck body 115 and located proximate to the feed thru body 111. The puck body 115 may include a keyed broach 125 for aligning the puck body 115 correctly with the adjacent end fitting coupled to the charge tube of the gun assembly 122.
An example embodiment is shown in
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Terms such as booster may include a small metal tube containing secondary high explosives that are crimped onto the end of detonating cord. The explosive component is designed to provide reliable detonation transfer between perforating guns or other explosive devices, and often serves as an auxiliary explosive charge to ensure detonation.
Detonating cord is a cord containing high-explosive material sheathed in a flexible outer case, which is used to connect the detonator to the main high explosive, such as a shaped charge. This provides an extremely rapid initiation sequence that can be used to fire several shaped charges simultaneously.
A detonator or initiation device may include a device containing primary high-explosive material that is used to initiate an explosive sequence, including one or more shaped charges. Two common types may include electrical detonators and percussion detonators. Detonators may be referred to as initiators. Electrical detonators have a fuse material that burns when high voltage is applied to initiate the primary high explosive. Percussion detonators contain abrasive grit and primary high explosive in a sealed container that is activated by a firing pin. The impact of the firing pin is sufficient to initiate the ballistic sequence that is then transmitted to the detonating cord.
Although the invention has been described in terms of embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto. For example, terms such as upper and lower or top and bottom can be substituted with uphole and downhole, respectfully. Top and bottom could be left and right, respectively. Uphole and downhole could be shown in figures as left and right, respectively, or top and bottom, respectively. Generally downhole tools initially enter the borehole in a vertical orientation, but since some boreholes end up horizontal, the orientation of the tool may change. In that case downhole, lower, or bottom is generally a component in the tool string that enters the borehole before a component referred to as uphole, upper, or top, relatively speaking. The first housing and second housing may be top housing and bottom housing, respectfully. In a gun string such as described herein, the first gun may be the uphole gun or the downhole gun, same for the second gun, and the uphole or downhole references can be swapped as they are merely used to describe the location relationship of the various components. Terms like wellbore, borehole, well, bore, oil well, and other alternatives may be used synonymously. Terms like tool string, tool, perforating gun string, gun string, or downhole tools, and other alternatives may be used synonymously. The alternative embodiments and operating techniques will become apparent to those of ordinary skill in the art in view of the present disclosure. Accordingly, modifications of the invention are contemplated which may be made without departing from the spirit of the claimed invention.
This application claims priority to U.S. Provisional Application No. 62/773,044, filed Nov. 29, 2018.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US19/63584 | 11/27/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62773044 | Nov 2018 | US |
