PERFORATOR CHARGE HAVING AN ENERGETIC MATERIAL
A perforator charge includes a case, an explosive inside the case, and a liner to be collapsed by detonation of the explosive to form a perforating jet. The perforator charge also includes an energetic material to be activated in response to the detonation of the explosive.
To complete a well for purposes of producing fluids (such as hydrocarbons or other fluids) from a reservoir, or injecting fluids into the reservoir, one or more zones in the well are perforated to allow for fluid communication between a wellbore and the reservoir. Perforation is accomplished by lowering a perforating gun to a target interval within the well. Activation of the perforating gun creates openings in any surrounding casing or liner and extends perforation tunnels into the surrounding subterranean formation.
SUMMARYIn general, according to some implementations, a perforator charge includes a case, an explosive inside the case, and a liner to be collapsed by detonation of the explosive to form a perforating jet. The perforator charge also includes an energetic material to be activated in response to the detonation of the explosive.
Other or alternative features will become apparent from the following descriptions, from the drawings, and from the claims.
Some embodiments are described with respect to the following figures:
A perforating gun that is used for creating perforation tunnels in the surrounding subterranean formation can include a carrier structure and a number of perforator charges mounted to the carrier structure. In some examples, the carrier structure can be a loading tube that contains perforator charges. Alternatively, the carrier structure can be a strip carrier that is generally shaped as a strip, onto which perforator charges can be mounted.
The explosive nature of creating perforation tunnels in the subterranean formation can create a crushed zone in the formation. A “crushed zone” refers to a damaged zone that surrounds a perforation tunnel, where the perforating action has altered the formation structure and its permeability. Also, the perforating action can cause debris to fill perforation tunnels. The crushed zone damage can result in reduced ability to perform production or injection.
In accordance with some embodiments, a perforator charge is provided with an energetic material (in addition to a main explosive in the perforator charge) to produce a relatively high energy wave (such as in the form of a relatively high pressure pulse or an explosive blast) that can result in creating fractures in the subterranean formation, enlargement of a perforation tunnel, and/or removal or reduction of crushed zone damage in the formation. The energetic material is activated in response to detonation of the main explosive in the perforator charge.
In the ensuing discussion, reference is made to implementations where the carrier structure 110 is a loading tube. Note that techniques or mechanisms according to some embodiments can be applied to other types of carrier structures.
The perforator charges 112 are ballistically connected to a detonating cord 114. Initiation of the detonating cord 114 causes detonation of the perforator charges 112.
The detonating cord 114 can be connected to a firing head 116, which can be activated from an earth surface 118, such as by use of equipment at the earth surface 118. The activation of the firing head 116 can be in response to electrical commands, acoustic commands, pressure commands, optical commands, and so forth, that can be sent from the equipment at the earth surface 118 to the firing head 116. Alternatively, the activation of the firing head 116 can be performed mechanically.
In some examples, the liner 206 is generally conically shaped. As a result of the general conical shape of the liner 206, the main explosive 204 is also generally conically shaped between an inner wall of the outer case 202 and the liner 206. In other examples, the liner 206 can be generally bowl-shaped or have a parabolic shape.
In examples according to
In some examples, a retaining element 212 is attached (e.g. glued, welded, or otherwise attached) to the outer case 202. The retaining element 212 can be a retaining wire, for example, which is bendable for holding the detonating cord 114 against the rear portion 210 of the main explosive 204. In other examples, the retaining element 212 can be another type of retaining element, or alternatively, the retaining element 212 can be omitted.
According to some embodiments, the perforator charge 112 further has an energetic material 214, which is placed at a front portion of the perforator charge 112. The “front portion” of the perforator charge 112 is the portion of the perforator charge 112 through which the perforating jet extends upon detonation of the perforator charge 112. Stated differently, the “front portion” of the perforator charge 112 is at the front opening of the outer case 202, through which the perforating jet passes.
The energetic material 214 is a material that when activated causes production of an energy wave, such as a pressure pulse, an explosive blast, and so forth. In some implementations, examples of the energetic material 214 include a propellant, a high explosive, gun powder, a combustible metallic powder (e.g. aluminum powder, magnesium powder, manganese powder, copper powder, zinc powder, titanium powder, iron powder, sodium powder, potassium powder, nickel powder, chromium powder, etc.), thermite (a mixture of aluminum powder and a metal oxide, for example), or any combination of the foregoing. In more specific implementations, examples of the energetic material 214 include a high explosive, gun powder, thermite, or any combination of the foregoing. In other implementations, other types of energetic materials can be used.
The energetic material 214 is generally a discrete segment formed of the energetic material that is placed at the front portion of the perforator charge 112. A “discrete segment” of energetic material can refer to any layer, piece, or other amount of the energetic material that has a predefined extent such that the energetic material does not surround an outer surface 203 of the outer cover 202. In some examples, the discrete segment of energetic material 214 does not contact any part of the outer surface 203 of the outer cover 202.
The energetic material 214 is retained to the outer case 202 of the perforator charge 112 using a retaining structure that is attached to the outer case 202. In some implementations, the retaining structure can be a retaining shell (or retaining cap) 216 that covers the discrete segment of energetic material 214. The retaining shell 216 has a receiving chamber 218 in which the energetic material 214 is positioned. The retaining shell 216 is attached to the outer case 202 (at 217). The attachment can be a threaded connection between the retaining shell 216 and the outer case 202. Alternatively, the retaining shell 216 can be attached to the outer case 202 using another type of attachment mechanism, such as by use of a screw, a rivet, glue, and so forth.
In examples according to
In different implementations, rather than providing the generally ring-shaped energetic material 214 that has the inner opening 215, a generally disk-shaped energetic material can be provided, which does not include the inner opening 215 in an inner portion (e.g. center) of the energetic material. In other examples, instead of providing an energetic material that is generally circular in cross section, energetic materials having other shapes can be employed.
As further shown in
In other implementations, the shock attenuator 222 can be omitted.
In operation, the detonating cord 114 of
The collapse of the liner 206 under the detonation force starts near an apex portion 224 of the liner 206, and proceeds to near the base portion 226 of the liner 206. The tip of the perforating jet produced from collapse of the liner 206 is formed by the apex portion 224 of the liner 206, while the tail of the perforating jet is formed by the base portion 226 of the liner 206.
In implementations where the energetic material 214 is generally ring-shaped, the perforating jet extends through the opening 215 (
As noted above, in different implementations, the energetic material 214 is not ring-shaped as shown in FIG. 3—rather, the energetic material can be generally disk-shaped (without the opening 215 of
In
In
The process then activates (at 504) the perforating gun, which causes detonation of the perforator charges. Detonation of the perforator charges causes respective perforating jets to be produced by the perforator charges, which extend perforation tunnels in the surrounding subterranean formation. The energetic material in the at least one perforator charge configured according to
In some examples, by using the perforator charge 112, 112A, or 112B according to some implementations, both the perforating operations and the post-perforating operations of creating fractures, enlarging a perforation tunnel, and/or reducing crushed zone damage can be performed in a single run using the same tool string (e.g. 100 in
In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some or all of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.
Claims
1. A perforator charge comprising:
- a case;
- an explosive inside the case;
- a liner to be collapsed by detonation of the explosive to form a perforating jet;
- an energetic material to be activated in response to the detonation of the explosive;
- a shock attenuator between the explosive and the energetic material; and
- a retaining structure attached to the case to retain the energetic material to the case.
2. The perforator charge of claim 1, wherein the energetic material includes a discrete segment of the energetic material positioned at an opening of the case through which the perforating jet is to pass.
3. The perforator charge of claim 2, wherein the discrete segment is generally ring-shaped.
4. The perforating charge of claim 2, wherein the discrete segment is generally disk-shaped without an opening in an inner portion of the energetic material.
5. The perforator charge of claim 1, wherein the energetic material is selected from the group consisting of a propellant, a high explosive, gun powder, a combustible metallic powder, thermite, or any combination thereof.
6. The perforator charge of claim 1, wherein the energetic material is selected from the group consisting of a high explosive, gun powder, thermite, or any combination thereof.
7. The perforator charge of claim 1, wherein the shock attenuator is generally ring-shaped or generally disk-shaped.
8. The perforator charge of claim 1, wherein the shock attenuator is to cause a delay between the detonation of the explosive and activation of the energetic material.
9. The perforator charge of claim 1, wherein the energetic material is positioned at an opening of the case without contacting any part of an outer surface of the case.
10. The perforator charge of claim 1, wherein the energetic material has an opening through which the perforating jet is to pass, and wherein the energetic material is to be activated after the perforating jet has passed through the opening.
11. The perforator charge of claim 1, wherein the perforating jet is to pass through the energetic material.
12. A perforating gun comprising:
- a carrier structure; and
- perforator charges attached to the carrier structure, wherein at least one of the perforator charges includes: a case; an explosive inside the case; a liner to be collapsed by detonation of the explosive to form a perforating jet; and a discrete segment of energetic material retained to the case and to be activated in response to the detonation of the explosive, wherein the energetic material is selected from the group consisting of a high explosive, gun powder, thermite, or any combination thereof.
13. The perforating gun of claim 12, wherein the discrete segment of energetic material is retained to the case without contacting any part of an outer surface of the case.
14. The perforating gun of claim 12, further comprising a retaining shell that is attached to the case and that receives the discrete segment of the energetic material.
15. The perforating gun of claim 12, wherein the discrete segment of the energetic material is without any opening in an inner portion of the discrete segment.
16. The perforating gun of claim 12, wherein the at least one perforator charge further comprises a shock attenuator between the explosive and the discrete segment of energetic material.
17. A method for use in a well, comprising:
- lowering a perforator charge into the well, wherein the perforator charge includes: a case; an explosive inside the case; a liner to be collapsed by detonation of the explosive to form a perforating jet; an energetic material to be activated in response to the detonation of the explosive; a shock attenuator between the explosive and the energetic material; and a retaining structure attached to the case to retain the energetic material to the case; and
- activating the perforator charge to create a perforation tunnel.
18. The method of claim 17, wherein activating the perforator charge causes detonation of the explosive and collapse of the liner to form a perforating jet for creating the perforation tunnel, where the energetic material is activated after formation of the perforating jet.
19. The method of claim 18, wherein the energetic material is activated a delay after detonation of the explosive, the delay being caused by the shock attenuator.
20. The method of claim 17, wherein activating the energetic material causes generation of an energy wave into the perforation tunnel.
Type: Application
Filed: Nov 3, 2011
Publication Date: May 9, 2013
Inventors: JIAN SHI (Shaanxi), HongJun GUO (Shaanxi), Feng WANG (Shaanxi), Senyuan LI (Shaanxi), Qiang GAO (Shaanxi)
Application Number: 13/288,128
International Classification: E21B 43/11 (20060101); F42B 1/02 (20060101);