U.S. patent application number 09/860117 was filed with the patent office on 2003-02-27 for sintered tungsten liners for shaped charges.
Invention is credited to Betancourt, David, Loehr, John D., Reese, James W., Wendt, Clarence W. JR..
Application Number | 20030037693 09/860117 |
Document ID | / |
Family ID | 26901037 |
Filed Date | 2003-02-27 |
United States Patent
Application |
20030037693 |
Kind Code |
A1 |
Wendt, Clarence W. JR. ; et
al. |
February 27, 2003 |
SINTERED TUNGSTEN LINERS FOR SHAPED CHARGES
Abstract
A method of producing a liner for a shaped charge comprising
mixing a composition of powdered metal with plasticizers and
binders to form a paste. The paste is then particulated and
injected into an injection mold. The paste is molded into a molded
liner shape and then chemically treated to remove plasticizers and
binders from the molded liner shape. After being removed from the
injection mold the molded liner shape is sintered inside of a
furnace. The powdered metal composition can be comprised of a
mixture of from 60% to 97% by weight of powdered heavy metal and
from 40% to 3% by weight of cobalt, or the powdered metal
composition can be comprised of a mixture of from 60% to 97% by
weight of powdered heavy metal and from 40% to 3% of copper, the
preferred heavy metal being tungsten.
Inventors: |
Wendt, Clarence W. JR.;
(Bellville, TX) ; Betancourt, David; (Cypress,
TX) ; Loehr, John D.; (Katy, TX) ; Reese,
James W.; (Spring, TX) |
Correspondence
Address: |
DARRYL M. SPRINGS
BAKER ATLAS DIVISION OF BAKER HUGHES INCORPORATED
P.O. BOX 1407
HOUSTON
TX
77251
US
|
Family ID: |
26901037 |
Appl. No.: |
09/860117 |
Filed: |
May 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60206099 |
May 20, 2000 |
|
|
|
Current U.S.
Class: |
102/306 |
Current CPC
Class: |
F42B 1/032 20130101 |
Class at
Publication: |
102/306 |
International
Class: |
F42B 001/02; F42B
012/02; F42B 012/08; F42B 012/20 |
Claims
What is claimed is:
1. A liner for a shaped charge for perforating well formations
comprising: a mixture of powdered heavy metal and powdered metal
binder said liner formed into a liner shape by injection molding
and sintering.
2. The liner for a shaped charge of claim 1, wherein said powdered
heavy metal is comprised of tungsten, and said powdered metal
binder is comprised of cobalt.
3. The liner for a shaped charge of claim 1, wherein said powdered
heavy metal is comprised of tungsten, and said powdered metal
binder is comprised of copper.
4. The liner for a shaped charge of claim 2, wherein said tungsten
comprises from 60% to 97% by weight of said mixture and wherein
said cobalt comprises from 40% to 3% by weight of said mixture.
5. The liner for a shaped charge of claim 3, wherein said tungsten
comprises from 60% to 97% by weight of said mixture and wherein
said copper comprises from 40% to 3% by weight of said mixture.
6. The liner for a shaped charge of claim 2, wherein said tungsten
comprises from 90% to 94% by weight of said mixture and wherein
said cobalt comprises from 10% to 6% by weight of said mixture.
7. The liner for a shaped charge of claim 3, wherein said tungsten
comprises 85% by weight of said mixture and wherein said copper
comprises 15% by weight of said mixture.
8. The liner for a shaped charge of claim 1, wherein said liner
shape is chosen from the group consisting of conical, bi-conical,
tulip, hemispherical, circumferential, linear, and trumpet.
9. A shaped charge comprising: a housing; a quantity of explosive
inserted into said housing; and a liner inserted into said housing
so that said quantity of explosive is positioned between said liner
and said housing, said liner formed into a liner shape by injection
molding and sintering said mixture.
10. The liner for a shaped charge of claim 9, wherein said powdered
heavy metal is comprised of tungsten, and said powdered metal
binder is comprised of cobalt.
11. The liner for a shaped charge of claim 9, wherein said powdered
heavy metal is comprised of tungsten, and said powdered metal
binder is comprised of copper.
12. The liner for a shaped charge of claim 10, wherein said
tungsten comprises from 60% to 97% by weight of said mixture and
wherein said cobalt comprises from 40% to 3% by weight of said
mixture.
13. The liner for a shaped charge of claim 11, wherein said
tungsten comprises from 60% to 97% by weight of said mixture and
wherein said copper comprises from 40% to 3% by weight of said
mixture.
14. The liner for a shaped charge of claim 10, wherein said
tungsten comprises from 90% to 94% by weight of said mixture and
wherein said cobalt comprises from 10% to 6% by weight of said
mixture.
15. The liner for a shaped charge of claim 11, wherein said
tungsten comprises 85% by weight of said mixture and wherein said
copper comprises 15% by weight of said mixture.
16. The liner for a shaped charge of claim 9, wherein said liner
shape is chosen from the group consisting of conical, bi-conical,
tulip, hemispherical, circumferential, linear, and trumpet.
17. A method of producing a liner for a shaped charge comprising
the steps of: mixing a composition of powdered metal with
plasticizers and binders to form a paste; particulating said paste;
injecting said particulated paste into an injection mold; molding
said particulated paste into a molded liner shape; removing
plasticizers and binders from said molded liner shape; sintering
said molded liner shape to produce a shaped charge liner.
18. The method of claim 17, wherein said powdered metal comprises
tungsten and said binder comprises cobalt.
19. The method of claim 17, wherein said powdered metal comprises
tungsten and said binder comprises copper.
20. The method of claim 18, wherein said composition comprises from
60% to 97% by weight of tungsten and 40% to 3% by weight of
cobalt.
21. The method of claim 19, wherein said composition comprises from
60% to 97% by weight of tungsten and 40% to 3% by weight of
copper.
22. The method of claim 18, wherein said composition comprises from
90% to 94% by weight of tungsten and 10% to 6% by weight of
cobalt.
23. The method of claim 19, wherein said composition comprises 85%
by weight of tungsten, and 15% by weight of copper.
24. The method of claim 17, wherein said liner shape is chosen from
the group consisting of conical, bi-conical, tulip, hemispherical,
circumferential, linear, and trumpet.
Description
RELATED APPLICATIONS
[0001] This application claims priority from co-pending U.S.
Provisional Application No. 60/206099, filed May 19, 2000, the full
disclosure of which is hereby incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates generally to the field of explosive
shaped charges. More specifically, the present invention relates to
a composition of matter for use as a liner in a shaped charge and a
method of manufacturing a liner for a shaped charge, where the
shaped charge is used for oil well perforating.
[0004] 2. Description of Related Art
[0005] Shaped charges are used for the purpose, among others, of
making hydraulic communication passages, called perforations, in
wellbores drilled through earth formations so that predetermined
zones of the earth formations can be hydraulically connected to the
wellbore. Perforations are needed because wellbores are typically
completed by coaxially inserting a pipe or casing into the
wellbore, and the casing is retained in the wellbore by pumping
cement into the annular space between the wellbore and the casing.
The cemented casing is provided in the wellbore for the specific
purpose of hydraulically isolating from each other the various
earth formations penetrated by the wellbore.
[0006] Shaped charges known in the art for perforating wellbores
are used in conjunction with a perforation gun and the shaped
charges typically include a housing, a liner, and a quantity of
high explosive inserted between the liner and the housing where the
high explosive is usually HMX, RDX PYX, or HNS. When the high
explosive is detonated, the force of the detonation collapses the
liner and ejects it from one end of the charge at very high
velocity in a pattern called a "jet". The jet penetrates the
casing, the cement and a quantity of the formation. The quantity of
the formation which may be penetrated by the jet can be estimated
for a particular design shaped charge by test detonation of a
similar shaped charge under standardized conditions. The test
includes using a long cement "target" through which the jet
partially penetrates. The depth of jet penetration through the
specification target for any particular type of shaped charge
relates to the depth of jet penetration of the particular
perforation gun system through an earth formation.
[0007] In order to provide perforations which have efficient
hydraulic communication with the formation, it is known in the art
to design shaped charges in various ways to provide a jet which can
penetrate a large quantity of formation, the quantity usually
referred to as the "penetration depth" of the perforation. One
method known in the art for increasing the penetration depth is to
increase the quantity of explosive provided within the housing. A
drawback to increasing the quantity of explosive is that some of
the energy of the detonation is expended in directions other than
the direction in which the jet is expelled from the housing. As the
quantity of explosive is increased, therefore, it is possible to
increase the amount of detonation-caused damage to the wellbore and
to equipment used to transport the shaped charge to the depth
within the wellbore at which the perforation is to be made.
[0008] The sound speed of a shaped charge liner is the theoretical
maximum speed that the liner can travel and still form a coherent
"jet". If the liner is collapsed at a speed that exceeds the sound
speed of the liner material the resulting jet will not be coherent.
A coherent jet is a jet that consists of a continuous stream of
small particles. A non-coherent jet contains large particles or is
a jet comprised of multiple streams of particles. The sound speed
of a liner material is calculated by the following equation, sound
speed =(bulk modulus /density).sup.1/2 (Equation 1.1). Increasing
the collapse speed will in turn increase the jet tip speed.
Increased the jet tip speed is desired since an increase in jet tip
speed increases the kinetic energy of the jet which provides
increased well bore penetration. Therefore, a liner made of a
material having a higher sound speed is preferred because this
provides for increased collapse speeds while maintaining jet
coherency.
[0009] Accordingly, it is important to supply a detonation charge
to the shaped charge liner that does not cause the shaped charge
liner to exceed its sound speed. On the other hand, to maximize
penetration depth, it is desired to operate shaped charge liners at
close to their sound speed and to utilize shaped charge liners
having maximum sound speeds. Furthermore, it is important to
produce a jet stream that is coherent because the penetration depth
of coherent jet streams is greater than the penetration depth of
non-coherent jet streams.
[0010] As per Equation 1.1 adjusting the physical properties of the
shaped charge liner materials can affect the sound speed of the
resulting jet. Furthermore, the physical properties of the shaped
charge liner material can be adjusted to increase the sound speed
of the shaped charge liner, which in turn increases the maximum
allowable speed to form a coherent jet. Knowing the sound speed of
a shaped charge liner is important since theoretically a shaped
charge liner will not form into a coherent jet when the jet speed
well exceeds the sound speed of the shaped charge liner.
[0011] It is also known in the art to design the shape of the liner
in various ways so as to maximize the penetration depth of the
shaped charge for any particular quantity of explosive. Even if the
shape and sound speed of the shaped charge liner is optimized, the
amount of energy which can be transferred to the liner for making
the perforation is necessarily limited by the quantity of
explosive.
[0012] Shaped charge performance is dependent on other properties
of the liner material. Density and ductility are properties that
affect the shaped charge performance. Optimal performance of a
shaped charge liner occurs when the jet formed by the shaped charge
liner is long, coherent and highly dense. The density of the jet
can be increased by utilizing a high density liner material. Jet
length is determined by jet tip velocity and the jet velocity
gradient. The jet velocity gradient is the rate at which the
velocity of the jet changes along the length of the jet whereas the
jet tip velocity is the velocity of the jet tip. The jet tip
velocity and jet velocity gradient are controlled by liner material
and geometry. The higher the jet tip velocity and jet velocity
gradient the longer the jet.
[0013] In solid liners, a ductile material is desired since the
solid liner can stretch into a longer jet before the velocity
gradient causes the liner to begin fragmenting. In porous liners,
it is desirable to have the liner form a long, dense, continuous
stream of small particles (coherent jet). To produce a coherent
jet, either from a solid liner or a porous liner; the liner
material must be such that the liner does not splinter into large
fragments after detonation.
[0014] The solid shaped charge liners are formed by cold working a
metal into the desired shape, others are formed by adding a coating
onto the cold formed liner to produce a composite liner.
Information relevant to cold worked liners is addressed in Winter
et al., U.S. Pat. No. 4,766,813, Ayer U.S. Pat. No. 5,279,228, and
Skolnick et al., U.S. Pat. No. 4,498,367. However, solid liners
suffer from the disadvantage of allowing "carrots" to form and
become lodged in the resulting perforation--which reduces the
hydrocarbon flow from the producing zone into the wellbore. Carrots
are sections of the shaped charge liner that form into solid slugs
after the liner has been detonated and do not become part of the
shaped charge jet. Instead, the carrots can take on an oval shape,
travel at a velocity that is lower than the shaped charge jet
velocity and thus trail the shaped charge jet.
[0015] Porous liners are formed by compressing powdered metal into
a substantially conically shaped rigid body. Typically, the porous
liners that have been formed by compressing powdered metals have
utilized a composite of two or more different metals, where at
least one of the powdered metals is a heavy or higher density
metal, and at least one of the powdered metals acts as a binder or
matrix to bind the heavy or higher density metal. Examples of heavy
or higher density metals used in the past to form liners for shaped
charges have included tungsten, hafnium, copper, or bismuth.
Typically the binders or matrix metals used comprise powdered lead,
however powdered bismuth has been used as a binder or matrix metal.
While lead and bismuth are more typically used as the binder or
matrix material for the powdered metal binder, other metals having
high ductility and malleability can be used for the binder or
matrix metal. Other metals which have high ductility and
malleability and are suitable for use as a binder or matrix metal
comprise zinc, tin, uranium, silver, gold, antimony, cobalt,
copper, zinc alloys, tin alloys, nickel, and palladium. Information
relevant to shaped charge liners formed with powdered metals is
addressed in Werner et al., U.S. Pat. No. 5,221,808, Werner et al.,
U.S. Pat. No. 5,413,048, Leidel, U.S. Pat. No. 5,814,758, Held et
al. U.S. Pat. No. 4,613,370, Reese et al., U.S. Pat. No. 5,656,791,
and Reese et al., U.S. Pat. No. 5,567,906.
[0016] Each one of the aforementioned references relating to
powdered metal liners suffer from the disadvantages of non-uniform
liner density, limited liner geometries, non-repeatability of liner
characteristics, liner creep, and/or a high percentage of binder
material in the material mix. Liner creep involves the shaped
charge liner slightly expanding after the shaped charge has been
assembled and stored. Even slight expansions of the shaped charge
liner reduce shaped charge effectiveness and repeatability.
[0017] Most of the porous shaped charge liners currently are
fabricated by pressing a powdered metal mixture with a rotating
ram. This process limits the shaped charge liners into a conical or
frusto-conical geometry. It is believed that liners having
different geometries, such as flared openings like the bell of a
trumpet, can provide higher jet tip velocities and longer jets.
However, the rotating ram assembly is incapable of producing liners
where the curve of the liner side has a small radius.
[0018] Further, the rotation time and pressure exerted by the
rotating ram varies with each successive liner manufactured. As
such, each shaped charge liners produced has different physical
properties than the next or previously manufactured shaped charge
liner. Therefore, the performance of the shaped charge liners
cannot be accurately predicted and operational results are
difficult to reproduce. The rotating ram also produces liners
having densities that are not uniform throughout the liner. A liner
that has a non-uniform density will not form as coherent a jet as a
liner having a uniform density.
[0019] The binder or matrix material typically has a lower density
than the heavy metal component. Accordingly the overall density of
the shaped charge liner is reduced when a significant percentage
(i.e. 30% or more) of the shaped charge liner is comprised of the
binder or matrix material. Reducing the overall density of the
shaped charge liner reduces the penetration depth produced by the
particular shaped charge.
[0020] Therefore, it is desired to produce shaped charge liners
that have a uniform density, have varied geometric shapes, have an
improved overall density, have a high sound speed, have repeatable
operating results, and are not subject to creep.
BRIEF SUMMARY OF THE INVENTION
[0021] A method is disclosed of producing a liner for a shaped
charge comprising mixing a composition of powdered metal with
plasticizers and binders to form a paste. The paste is then
particulated and injected into a mold where the particles are
compressed into a molded liner shape. Possible liner shapes include
conical, bi-conical, tulip, hemispherical, circumferential, linear,
and trumpet. After being removed from the mold, the molded linear
shape is then chemically treated to remove plasticizers and binders
from the molded liner shape. Following this, the molded liner shape
is introduced into a furnace where it is heated to a temperature
sufficient to sinter the metal particles to form the liner. In the
process of sintering, any remaining organic materials are removed.
The powdered metal composition of this invention is comprised of a
mixture of a heavy metal powder and a metal binder. The preferred
powdered heavy metal is tungsten and the preferred metal binder is
either copper or cobalt. When the binder is copper, the mixture
comprises from 60% to 97% by weight of heavy metal powder and from
40% to 3% by weight of copper. When the binder is cobalt, the
mixture comprises from 60% to 97% by weight of heavy metal binder
and from 40% to 3% by weight of cobalt.
[0022] Further disclosed is a shaped charge comprising a housing, a
quantity of explosive inserted into the housing and a liner
inserted into the housing. The liner is installed so that the
quantity of explosive is positioned between the liner and the
housing. The liner is formed from a mixture of powdered a powdered
heavy metal and powdered metal binder. The metal binder consists of
either copper or cobalt. When the binder is copper the mixture
comprises from 60% to 97% by weight of powdered heavy metal and
from 40% to 3% by weight of copper, when the binder is cobalt the
mixture comprises from 60% to 97% by weight of powdered heavy metal
and from 40% to 3% by weight of cobalt. The liner is formed by
injection molding and sintering the mixture.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING.
[0023] FIG. 1 depicts a cross-sectional view of a shaped charge
with a liner according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] With reference to the drawing herein, a shaped charge 10
according to the invention is shown in FIG. 1. The shaped charge 10
typically includes a generally cylindrically shaped housing 1,
which can be formed from steel, ceramic or other material known in
the art. A quantity of explosive powder, shown generally at 2, is
inserted into the interior of the housing 1. The explosive 2 can be
of a composition known in the art. Explosives known in the art for
use in shaped charges include compositions sold under trade
designations HMX, HNS, RDX, PYX and TNAZ. A recess 4 formed at the
bottom of the housing 1 can contain a booster explosive (not shown)
such as pure RDX. The booster explosive, as is understood by those
skilled in the art, provides efficient transfer to the explosive 2
of a detonating signal provided by a detonating cord (not shown)
which is typically placed in contact with the exterior of the
recess 4. The recess 4 can be externally covered with a seal, shown
generally at 3.
[0025] A liner, shown at 5, is typically inserted on to the
explosive 2 far enough into the housing 1 so that the explosive 2
substantially fills the volume between the housing 1 and the liner
5. The liner 5 in the present invention is typically made from a
mixture of powdered metals which is injection molded and then
sintered into the desired shape. The liner body is typically open
at the base and is hollow. Possible liner shapes include conical
(which includes frusto-conical), bi-conical, tulip, hemispherical,
circumferential, linear, and trumpet.
[0026] As is understood by those skilled in the art, when the
explosive 2 is detonated, either directly by signal transfer from
the detonating cord (not shown) or transfer through the booster
explosive (not shown), the force of the detonation collapses the
liner 5 and causes the liner 5 to be formed into a jet, once formed
the jet is ejected from the housing 1 at very high velocity.
[0027] It is one of the novel features of the present invention
that the shaped charge liners are fabricated by a process that
involves the steps of injection molding and sintering the powdered
metal mixture to produce the shaped charge liner. The powdered
metal mixture comprises powdered heavy metal mixed with a binder.
The preferred powdered heavy metal is tungsten. While the binder
can be selected from the group consisting of lead, bismuth, zinc,
tin, uranium, silver, gold, antimony, cobalt, zinc alloys, tin
alloys, nickel, and palladium; the preferred binders for the
present invention are cobalt or copper. Another novel feature of
the present invention is that the powdered metal mixture ratio
ranges from 60% to 97% powdered heavy metal and from 40% to 3%
cobalt or 40% to 3% of copper. The preferred mix of the powdered
heavy metal and cobalt mixture is 90% to 94% powdered heavy metal
and 10% to 6% cobalt. The preferred mix of the powdered heavy metal
and copper mixture is 85% powdered heavy metal and 15% copper.
[0028] The powdered metal mixture is first mixed with plasticizers
and binders to produce a powdered metal paste that consists of
pasty clumps of material that are 2 to 3 inches in length. The
powdered metal clumps are then particulated into smaller particles
of about 1 cm in length. While the preferred method of
particulation occurs inside of a particulating machine that
transforms the powdered metal clumps into smaller particles,
particulation can be carried out by any appropriate method known in
the art. After being particulated, the paste is injected into a
mold where it is formed by pressure into the desired liner shape.
Once molded the liner is removed from the mold and chemically
treated to remove most of the plasticizers and binders. The shaped
liner is then placed into a furnace where it is heated at
temperature below the melting point of the powdered metal mixture,
but at a high enough temperature to remove the remaining
plasticizers and binders. Since the sintering process removes mass
(the plasticizers and binders) from the liner material, the liner
will shrink in size during sintering. Once the liner has reached
the desired dimension the liner is removed from the furnace. This
process is known as sintering, and as is appreciated by skilled
artisans, the sintering time and furnace temperature will vary
depending on the liner size desired and the amount of plasticizers
and binders remaining in the material. However, without undue
experimentation, one skilled in the art will know the temperature
and the time during which the liner has reached the desired
dimensions.
[0029] In fabricating the shaped charge, the liner 5 can be
retained in the housing 1 by application of adhesive, shown at 6.
The adhesive 6 enables the shaped charge 10 to withstand the shock
and vibration typically encountered during handling and
transportation without movement of the liner 5 or the explosive 2
within the housing 1. It is to be understood that the adhesive 6 is
only used for retaining the liner 5 in position within the housing
1 and is not to be construed as a limitation on the invention.
[0030] The present invention described herein, therefore, is well
adapted to carry out the objects and attain the ends and advantages
mentioned, as well as others inherent therein. While a presently
preferred embodiment of the invention has been given for purposes
of disclosure, numerous changes in the details of procedures for
accomplishing the desired results. For example, binders selected
from the group consisting of lead, bismuth, zinc, tin, uranium,
silver, gold, antimony, zinc alloys, tin alloys, nickel, and
palladium can be implemented. These and other similar modifications
will readily suggest themselves to those skilled in the art, and
are intended to be encompassed within the spirit of the present
invention disclosed herein and the scope of the appended
claims.
* * * * *