The present disclosure relates to devices and methods for perforating a subterranean formation.
Hydrocarbons, such as oil and gas, are produced from cased wellbores intersecting one or more hydrocarbon reservoirs in a formation. These hydrocarbons flow into the wellbore through perforations in the cased wellbore. Perforations are usually made using a perforating gun that is generally comprised of a steel tube “carrier,” a charge tube riding on the inside of the carrier, and with shaped charges positioned in the charge tube. The gun is lowered into the wellbore on electric wireline, slickline, tubing, coiled tubing, or other conveyance device until it is adjacent to the hydrocarbon producing formation. Thereafter, a surface signal actuates a firing head associated with the perforating gun, which then detonates the shaped charges. Projectiles or jets formed by the explosion of the shaped charges penetrate the casing to thereby allow formation fluids to flow through the perforations and into a production string.
The present disclosure addresses the continuing need for enhancing the operation of perforating tools.
In aspects, the present disclosure provides a perforating tool for use in a wellbore. The perforating tool may include a conveyance device, a carrier, a plurality of encapsulated shaped charges, a detonating cord, and plates. The carrier is connected to the conveyance device and has a plurality of encapsulated shaped charges positioned thereon. Each encapsulated shaped charge may include a bulkhead having a reduced wall thickness section. The detonating cord has a sheath surrounding an energetic core and is energetically coupled to the plurality of encapsulated shaped charges. The plates have a shallow recess. One plate is positioned between the detonating cord and the reduced wall thickness section of each encapsulated shaped charge. The energetic core forms the plate into a explosively formed perforator when detonated. The encapsulated shaped charge and detonating cord may be in contact with a borehole liquid in the wellbore.
In another aspect, a perforating tool for use in a wellbore may include an encapsulated shaped charge, a plate, and a detonating cord. The encapsulated shaped charge includes a bulkhead having a reduced wall thickness section. The plate has a shallow recess. The detonating cord has an energetic core that forms the plate into a explosively formed perforator when detonated. The plate is positioned between the energetic core and the reduced wall thickness section.
In further aspects, the present disclosure provides a method of perforating a subterranean formation. The method includes connecting a carrier to a conveyance device. The carrier includes a perforating arrangement as described above. The method further includes conveying the carrier into a wellbore intersecting the subterranean formation using the conveyance device, wherein the encapsulated shaped charges and detonating cord are in contact with a borehole liquid in the wellbore; rotating the encapsulated shaped charges from a compact position to a firing position, wherein the compact position and the firing position have at least a forty five degree offset; and detonating the encapsulated shaped charges using the detonating cord.
It should be understood that certain features of the invention have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will in some cases form the subject of the claims appended thereto.
For detailed understanding of the present disclosure, references should be made to the following detailed description taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:
The present disclosure relates to devices and methods for perforating a formation intersected by a wellbore. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure 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.
Referring now to
The case 12 may be formed as a cylindrical body 22 having a mouth 24 at one end and a bulkhead 26 at the other end. The mouth 22 provides the only access into an interior space 28. The liner 14 covers the mouth 22 and secures the explosives 16, 18 in the interior space 28. The bulkhead 26 is a portion of the body 24 that includes an external slot 30 and one or more internal recesses 32. The external slot 30 may have a “U” shape for receiving a detonating cord 50, which will be discussed in greater detail below. The internal recess 32 may be a groove, indentation, channel, or other feature that forms a reduced thickness portion 34 at the bulkhead 26. Because the wall of the bulkhead 26 is thinner at the reduced thickness portion 34 relative to the immediately adjacent areas, the bulkhead 26 is structurally weakened at the reduced thickness portion 34.
When detonated, the primary and secondary explosives 16, 18 cooperate to form a perforating jet from the liner 14. The primary explosive 16 is positioned next to the liner 14 and the secondary explosive 18 is positioned between the primary explosive 16 and the bulkhead 26. The primary explosive 16 may include a high explosive, such as RDX, HMX and HNS, which is formulated to generate the heat, pressure, and shock waves for forming a perforating jet from the liner 14. The secondary explosive 18 may be include one or more explosive materials that enable the secondary explosive 18 to detonate the primary explosive 16. For convenience, the secondary explosive 18 will be referred to as a “booster.”
Pressure isolation for the interior of the shaped charge 10 is created by attaching the cap 20 to the case 12. In embodiments, sealing elements 21 may be used to form a fluid-tight barrier between the cap 20 and the case 12. This fluid-tight barrier provides a sealed space for the internal components such as the liner 14 and explosives 16, 18. It should be noted that the case 12 is perforation-free: i.e., the case 12 does not have any passages or openings that penetrate completely through the case 12 to provide access to the booster 16. Thus, the booster 16 must be detonated by transmitting a suitable shockwave through the bulkhead 28. In embodiments according to the present disclosure, the detonating cord 50 is configured to detonate the booster 18 by puncturing the reduced wall section 34 and directing shock waves and thermal energy to the booster 18.
Referring now to
In one arrangement, the concave recess 56 may be formed as a linear groove that runs axially along an external surface 57 of the sheath 54 of the detonating cord 50. As shown, the groove may have a cross-sectional profile that conforms to an arc. In other embodiments, the groove may have a “V” shape (triangular cross-sectional shape). The concave recess 56 is not necessarily a straight axially elongated depression. For instance, the recess 56 may be a spherical, shallow curved hollow, a shallow pyramid indentation, or a shallow concave arcuate shaped cavity.
Referring to
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The devices, systems, and methods of the present disclosure may be advantageously applied to any number of perforating guns used to perforate a well.
The perforating gun 100 includes a firing connection assembly 104 and a carrier 106. The carrier 106 is a frame-like structure on which the shaped charges 10 are connected. The detonating cord 50 energetically connects the firing connection assembly 104 to the shaped charges 50. It should be noted that the carrier 106 does not enclose the shaped charges 10 and detonating cord 50. Thus, the shaped charges 10 and detonating cord 50 are exposed to surrounding borehole liquids such as drilling mud and formation fluids. However, as described above, the shaped charges 10 and detonating cord 50 are configured to be liquid tight and protected from harmful contact with ambient fluids and pressure.
In the illustrated embodiment, the shaped charges 10 of the perforating 100 rotate from a compact position to a firing position. As shown in
The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.
This application claims priority from U.S. Provisional Application Ser. No. 62/209,717, filed on Aug. 25, 2015, the entire disclosure of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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62209717 | Aug 2015 | US |