U.S. patent application number 11/306121 was filed with the patent office on 2006-09-14 for energy controlling device.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Claude D. Jones, Frederick Sr. Lemme, Haoming Li, Chantal Smitheman.
Application Number | 20060201371 11/306121 |
Document ID | / |
Family ID | 36100882 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060201371 |
Kind Code |
A1 |
Li; Haoming ; et
al. |
September 14, 2006 |
Energy Controlling Device
Abstract
The present invention provides an apparatus capable of
influencing explosive energy during wellbore applications. In one
embodiment, a cap or other interfering element may be arranged
proximate to an explosive charge prior to detonation. The size and
positioning of the element with respect to the explosive charge may
be manipulated to achieve an optimum explosive orientation. A ring
element having a bore therethrough may be utilized for directing
the explosive energy of the charge upon detonation.
Inventors: |
Li; Haoming; (Missouri City,
TX) ; Smitheman; Chantal; (Pearland, TX) ;
Jones; Claude D.; (Sugar Land, TX) ; Lemme; Frederick
Sr.; (Katy, TX) |
Correspondence
Address: |
SCHLUMBERGER RESERVOIR COMPLETIONS
14910 AIRLINE ROAD
ROSHARON
TX
77583
US
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
300 Schlumberger Drive
Sugar Land
TX
77478
|
Family ID: |
36100882 |
Appl. No.: |
11/306121 |
Filed: |
December 16, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60594057 |
Mar 8, 2005 |
|
|
|
Current U.S.
Class: |
102/307 ;
102/310 |
Current CPC
Class: |
F42B 1/024 20130101;
F42D 3/04 20130101; F42B 3/22 20130101 |
Class at
Publication: |
102/307 ;
102/310 |
International
Class: |
F42B 1/02 20060101
F42B001/02 |
Claims
1. An apparatus for use in a wellbore comprising: an explosive
charge; and at least one element capable of influencing the
explosive energy released by said explosive charge upon
detonation.
2. The apparatus of claim 1, wherein said element further comprises
walls defining at least one cavity.
3. The apparatus of claim 2, wherein said cavity is for conducting
explosive energy.
4. The apparatus of claim 2, wherein said cavity has a generally
cylindrical configuration.
5. The apparatus of claim 2, wherein said cavity has a generally
conical configuration.
6. The apparatus of claim 1, wherein said element further comprises
a first portion for absorbing explosive energy.
7. The apparatus of claim 6, wherein said element further comprises
a second portion for directing explosive energy.
8. The apparatus of claim 7, wherein said first portion of said
element has a first thickness and said second portion of said
element has a second thickness.
9. The apparatus of claim 8, wherein said second thickness is
greater than said first thickness.
10. The apparatus of claim 1, wherein at least a portion of said
element is composed of a frangible material.
11. The apparatus of claim 1, wherein at least a portion of said
element is composed of a material selected from the group
consisting of plastic, polymer, metal, cellulose, and rubber.
12. The apparatus of claim 1, wherein said explosive charge is a
shaped charge.
13. The apparatus of claim 1, wherein said element comprises a
charge cap.
14. The apparatus of claim 1, further comprising a jacket for
mounting said explosive charge and said element into a perforating
gun.
15. An apparatus for use in a wellbore comprising: an explosive
charge for insertion into a perforating gun; and at least one
element capable of influencing the explosive energy released by
said explosive charge upon detonation, said element having walls
defining at least one cavity for directing explosive energy, said
element being positioned between said explosive charge and said
perforating gun.
16. The apparatus of claim 14, wherein said cavity has a generally
cylindrical configuration.
17. The apparatus of claim 14, wherein said cavity has a generally
conical configuration.
18. A method of controlling explosive energy in a wellbore
comprising the steps of: providing a perforating gun containing one
or more explosive charges; positioning at least one element between
said explosive charge and said perforating gun, said element being
capable of influencing explosive energy released by said explosive
charge upon detonation; and detonating one or more of said
explosive charges.
19. The method of claim 18, wherein said element comprises walls
defining at least one cavity for directing explosive energy.
20. The method of claim 18, wherein said element comprises a first
portion for absorbing explosive energy and a second portion for
directing explosive energy.
Description
[0001] This patent application claims priority on a U.S.
provisional patent application entitled "Controlling Explosive
Energy of Charges for Perforating Guns", having a Ser. No.
60/594,057 and a filing date of Mar. 8, 2005.
FIELD OF THE INVENTION
[0002] The present invention relates generally to perforating tools
used in downhole applications, and more particularly to a device
for controlling the use of explosive energy of an explosive charge
in a perforating gun in a wellbore.
BACKGROUND OF THE INVENTION
[0003] An apparatus, such as a perforating gun, may be lowered into
a well and detonated to form fractures in the adjacent formation.
After the perforating gun detonates, fluid typically flows into the
well and to the surface via production tubing located inside the
well.
[0004] Typically, perforating guns (which include gun carriers and
shaped charges mounted on or in the gun carriers) are lowered
through tubing or other pipes to the desired well interval. Shaped
charges carried in a perforating gun are often phased to fire in
multiple directions around the circumference of the wellbore. When
fired, shaped charges create perforating jets that form holes in
surrounding casing as well as extend perforations into the
surrounding formation.
[0005] It may be necessary to control the amount of energy (e.g.,
reduce or focus) released by the explosive charge. For example, in
some cases, it may be advantageous to rupture the hollow carrier
(or other hollow chamber or sealed enclosure) without penetrating
the surrounding casing and/or penetrating the well formation.
SUMMARY OF THE INVENTION
[0006] Accordingly, the present invention provides an apparatus
capable of influencing explosive energy during wellbore
applications. In one embodiment, a cap or other interfering element
may be arranged proximate to an explosive charge prior to
detonation. The size and positioning of the element with respect to
the explosive charge may be manipulated to achieve an optimum
explosive orientation.
[0007] The element utilized by the present invention may be a ring
having a bore therethrough for directing the explosive energy of
the charge upon detonation. Further, the charge cap may include an
area having a thinner wall than the rest of the cap. In operation,
the thicker portion of the cap absorbs some of the explosive energy
of the charge and the thinner portion (or opening) conducts/directs
the explosive energy. The exact thickness of the "absorbing" volume
of the cap and the thickness of the "conducting" volume of the cap
may be determined and selected to achieve a particular result.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings; it being understood that the drawings
contained herein are not necessarily drawn to scale; wherein:
[0009] FIG. 1 is an enlarged cross-sectional view of an embodiment
of a shaped charge.
[0010] FIG. 2A is a profile cross-sectional view of an embodiment
of a perforating gun.
[0011] FIG. 2B is a axial cross-sectional view of an embodiment of
the perforating gun of FIG. 2A.
[0012] FIG. 3 is a profile view of an embodiment of a perforating
gun string being run downhole in a cased wellbore.
[0013] FIG. 4A is a profile view of an embodiment of a perforating
gun string being detonated in a cased wellbore.
[0014] FIG. 4B is a profile view of an embodiment of a perforating
gun string being detonated in an open wellbore.
[0015] FIGS. 5A-6B are axial views of multiple embodiments of the
perforating gun of the present invention.
[0016] It is to be noted, however, that the appended drawings
illustrate only typical embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0017] In the following description, numerous details are set forth
to provide an understanding of the present invention. However, it
will be understood by those skilled in the art that the present
invention may be practiced without these details and that numerous
variations or modifications from the described embodiments may be
possible.
[0018] In the specification and appended claims: the terms
"connect", "connection", "connected", "in connection with", and
"connecting" are used to mean "in direct connection with" or "in
connection with via another element"; and the term "set" is used to
mean "one element" or "more than one element". As used herein, the
terms "up" and "down", "upper" and "lower", "upwardly" and
downwardly", "upstream" and "downstream"; "above" and "below"; and
other like terms indicating relative positions above or below a
given point or element are used in this description to more clearly
described some embodiments of the invention. However, when applied
to equipment and methods for use in wells that are deviated or
horizontal, such terms may refer to a left to right, right to left,
or other relationship as appropriate.
[0019] Referring to FIG. 1, a shaped charge (10) includes an outer
case (12) that acts as a containment vessel. Common materials for
the outer case (12) include steel or some other metal. The main
explosive charge (16) is contained inside the outer case (12) and
is sandwiched between the inner wall of the outer case (12) and the
outer retaining surface (20). A primer column (14) is a sensitive
area that provides the detonating link between the main explosive
charge (16) and a detonating cord (15), which is attached to the
rear of the shaped charge (10).
[0020] To detonate the shaped charge (10), a detonation wave
traveling through the detonating cord (15) initiates the primer
column (14) when the detonation wave passes by, which in turn
initiates detonation of the main explosive charge (16) to create a
detonation wave that sweeps through the shaped charge (10).
[0021] Referring to FIG. 2, a plurality of shaped charges (10) may
be conveyed downhole via a hollow carrier gun (30). The shaped
charges (10) may be non-capsule charges since the shaped charges
are protected from the environment by the hollow carrier (30),
which is typically sealed. The hollow carrier (30) may also include
a plurality of recesses (32) formed in the outer wall. The recesses
(32) are typically localized areas where the wall thickness of the
carrier (30) is reduced to optimize overall system function. Within
the hollow carrier (30), a loading tube (40) is positioned. The
loading tube (40) includes a plurality of openings (42) proximal,
for receiving and mounting the shaped charges (10). The openings
(42) of the loading tube (40) are typically aligned with the
recesses (32) of the hollow carrier (30).
[0022] Referring to FIG. 3, a series of hollow carrier guns (50A)
and (50B) may be assembled to form a perforating gun string (50)
having a desired length. An example length of each gun (50A and
50B, respectively), may be about twenty feet. To make a perforating
gun string (50) of a few hundred feet or longer, several guns may
be connected together in series by adapters (52). Each of the
adapters (52) contains a ballistic transfer component, which may be
in the form of donor and receptor booster explosives. Ballistic
transfer takes place from one gun to another as the detonation wave
jumps from the donor to the receptor booster. At the end of the
receptor booster is a detonating cord that carries the wave and
sets off the shaped charges in the next gun. Examples of explosives
that may be used in the various explosive components (e.g., shaped
charges (10), detonating cord (15), and boosters) include RDX, HMX,
HNS, TATB, and others.
[0023] Generally, once assembled, the gun string (50) is positioned
in a wellbore (60) that is lined with casing (62). A tubing or pipe
(64) extends inside the casing (62) to provide a conduit for well
fluids to wellhead equipment (not shown). A portion of the wellbore
(60) is isolated by packers (66) set between the exterior of the
tubing (64) and the interior of the casing (62). The perforating
gun string (50) may be lowered through the tubing or pipe (54) on a
carrier line (70) (e.g., wireline, slickline, or coiled tubing).
Once positioned at a desired wellbore interval, the gun string (50)
is fired to create perforations in the surrounding casing and
formation (as shown in FIG. 4A).
[0024] In another embodiment, as shown in FIG. 4B, the gun string
(50) includes one or more sealed carriers (30). In alternative
embodiments, the gun string (50) may include one or more sealed
chambers (or other sealed enclosures), each chamber housing one or
more explosive charges therein. The pressure within the gun carrier
(30) is lower than the pressure in the target wellbore interval.
The sealed gun string (50) is positioned in an open wellbore (100).
The perforating gun string (50) may be lowered through the open
wellbore (100) on a carrier line (70) (e.g., wireline, slickline,
or coiled tubing). Once positioned at a desired wellbore interval,
the gun string (50) is fired to create holes or ruptures in the
sealed carrier (30) while not substantially damaging the
surrounding. Upon detonation of the one or more explosive charges
and subsequent rupturing of the carrier (30), a fluid surge will be
formed toward the carrier thus generating a transient underbalanced
condition in the wellbore interval. This transient underbalance
condition may be utilized to clean perforation tunnels in the
surrounding formation, to remove filter cake from the walls of the
wellbore, or to otherwise remove debris from the wellbore interval.
Moreover, by rupturing the carrier, trapped pressurized gas in the
sealed bore of the carrier may be released.
[0025] In other embodiments, the sealed perforating gun string (50)
may be deployed in a cased wellbore and may be used to perforate
the sealed carriers and the casing simultaneously to create a
transient underbalanced condition to surge clean the perforation
tunnels in the formation and remove wellbore debris from the target
well interval. This will effectively increase productivity of the
well.
[0026] The explosive energy released and the resulting perforation
achieved by detonating the guns discussed above may be a function
of the physical size and geometrical arrangement of the explosive
charges. An embodiment of the present invention is directed at
controlling this explosive energy release.
[0027] Referring to FIGS. 5A-6B, a cap or other interfering element
(80) may be arranged proximate the charge (10) to absorb a portion
of the energy. The size and particular arrangement of the cap (80)
with respect to the charge (10) may be determined to achieve an
optimum explosive state for a selected result. For example, by
controlling the explosive energy release of a charge, the amount of
debris released into the wellbore and excessive deformation of the
perforating gun may be limited.
[0028] The charge cap (80) of the present invention may also be
used to direct or otherwise focus the explosive energy release to
achieve a particular result. For example, the cap (80) may be sized
and arranged to focus the explosive energy in a charge to break
debris into small enough fragments such that the debris does not
hider productivity of the well.
[0029] The charge cap (80) of the present invention may be used in
various perforating or other explosive well operations. For
example, the charge cap (80) may be used to direct and control
explosive energy released by charges in a conventional perforating
gun (30) used to perforate a formation and/or a casing and a
formation. In another example, the charge cap may be used to direct
and control explosive energy released by charges in a sealed
chamber (e.g., carrier or other sealed enclosure) to rupture the
chamber but not damage the surrounding casing. In this way, the
charges may be used to generate a transient underbalance condition
to clean debris from the perforation tunnel.
[0030] FIGS. 5A and 5B illustrate embodiments of the charge cap
(80) of the present invention connected to a shaped charge (10).
The charge cap or other interfering element may be designed to fit
between the arms (10A) of the explosive charge (10). This
embodiment of the present invention is ideal for use with shaped
charges capable of fitting relatively snugly within the internal
compartment of the loading tube (40).
[0031] In one embodiment, the charge cap of the present invention
has a section designed to absorb explosive energy (88A) and another
section designed to conduct and/or direct explosive energy (88D).
In one embodiment, the section of the charge cap (80) designed to
absorb explosive energy (88A) is designed to engage an inner
surface (101) of one or more arms (10A) of the explosive charge. In
one embodiment, the section of the charge cap (80) designed to
conduct and/or direct explosive energy (88D) forms a central
portion of the charge cap.
[0032] In one embodiment, the section of the charge cap designed to
absorb explosive energy (88A) may be composed of a relatively thick
and/or dense material particularly suited to absorb explosive
energy. Further, the section of the charge cap designed to conduct
and/or direct explosive energy (88D) may be composed of a thinner
and/or less dense material than that used by the absorbing section
(88A). In this manner, the charge cap allows for maximum
effectiveness with regard to the disbursement of explosive energy
upon detonation. The exact thickness and/or density of each section
(88A and 88D, respectively) of the charge cap may be determined and
selected to achieve any number of desirable results.
[0033] In one embodiment, one or more walls (82) of the charge cap
may define one or more cavities (84) capable of directing explosive
energy. Such cavities may have any number of orientations and/or
configurations designed to achieve particular results. For example,
one or more cavities provided by the present invention may have a
generally conical or cylindrical configuration designed to direct
explosive energy in a particular manner. It being understood that
these are example configurations only, not to be taken in a
limiting sense. A ring element having a bore therethrough may also
be utilized for directing the explosive energy of the charge upon
detonation.
[0034] FIGS. 6A and 6B illustrate embodiments of a charge cap (80)
connected to a shaped charge (10). In these embodiments, the shaped
charge and charge cap are mounted in a jacket (86) and for
insertion into a loading tube (40). The loading tube may hold a
plurality of shaped charges (10), each having a charge cap (80).
The loading tube is loaded into a gun carrier (30). The gun carrier
(30) may have a scallop (32) formed on the outer surface for
alignment with each shaped charge (10).
[0035] In one embodiment, the charge cap (80) of the present
invention is designed to engage the outer surfaces (102) of the
charge arms (10A) of the explosive charge (10). Further, the charge
cap may be utilized in conjunction with a jacket (86) in order to
allow the charge cap/charge/jacket combination to be conveniently
mounted within the loading tube. This feature of the present
invention allows smaller explosive charges to be successfully
mounted within loading tubes having larger diameters. As discussed
above, the present invention may utilize any number of charge cap
arrangements and/or configurations as needed to achieve a
particular result. Further the thickness and/or density of the
materials comprising each section of the charge cap may be varied.
A ring element having a bore therethrough may also be utilized for
directing the explosive energy of the charge upon detonation, as
discussed above.
[0036] In some embodiments, the charge cap (80) may be fabricated
from a material that stays together sufficiently such that the cap
does not exit the ruptures in the gun. This way the cap can be
removed from the well with the gun and does not hinder well
productivity. In other embodiments, the charge cap (80) may be
fabricated from a highly-frangible material such that the cap
breaks into sufficiently small fragments so as not to hinder well
productivity even if the fragments exit the gun. For example, the
charge cap may be fabricated from plastic, polymer, metal,
cellulose, rubber, or other suitable material.
[0037] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed
in a limited sense. Various modifications of the disclosed
embodiments, as well as alternative embodiments of the invention,
will become apparent to persons skilled in the art upon reference
to the description of the invention. It is, therefore, contemplated
that the appended claims will cover such modifications that fall
within the scope of the invention.
* * * * *