U.S. patent application number 10/157609 was filed with the patent office on 2002-12-19 for debris free perforating system.
Invention is credited to Behrmann, Lawrence A., Grove, Brenden M., Kneisl, Philip.
Application Number | 20020189482 10/157609 |
Document ID | / |
Family ID | 26854301 |
Filed Date | 2002-12-19 |
United States Patent
Application |
20020189482 |
Kind Code |
A1 |
Kneisl, Philip ; et
al. |
December 19, 2002 |
Debris free perforating system
Abstract
The present invention provides a debris free perforating system.
In one embodiment, the debris free perforating system includes a
caseless shaped charge carried by a solid loading tube, such as
Styrofoam.TM. or paper. The loading tube can additionally be
combustible and can be coated with an oxidizer to ensure
incineration.
Inventors: |
Kneisl, Philip; (Pearland,
TX) ; Behrmann, Lawrence A.; (Houston, TX) ;
Grove, Brenden M.; (Missouri City, TX) |
Correspondence
Address: |
PATENT COUNSEL
SCHLUMBERGER RESERVOIR COMPLETIONS CENTER
14910 AIRLINE ROAD
ROSHARON
TX
77583-1590
US
|
Family ID: |
26854301 |
Appl. No.: |
10/157609 |
Filed: |
May 29, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60294894 |
May 31, 2001 |
|
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|
Current U.S.
Class: |
102/306 |
Current CPC
Class: |
C06B 45/12 20130101;
C06B 45/105 20130101; C06B 45/10 20130101; F42B 3/08 20130101; E21B
43/117 20130101; F42B 1/032 20130101; F42B 12/72 20130101 |
Class at
Publication: |
102/306 |
International
Class: |
F42B 001/02 |
Claims
What is claimed is:
1. A debris free perforating system, comprising: a caseless shaped
charge having explosive material.
2. The debris free perforating system of claim 1, wherein the
caseless shaped charge is housed within a solid loading tube.
3. The debris free perforating system of claim 2, wherein the solid
loading tube is made from low density plastic.
4. The debris free perforating system of claim 2, wherein the solid
loading tube is made from Styrofoam.TM..
5. The debris free perforating system of claim 2, wherein the solid
loading tube is made from paper.
6. The debris free perforating system of claim 1, wherein the
explosive material further comprises inert heavy materials.
7. The debris free perforating system of claim 6, wherein the inert
heavy material is powdered metal.
8. The debris free perforating system of claim 7, wherein the
powdered metal is tungsten.
9. The debris free perforating system of claim 7, wherein the
powdered metal is selected from iron, copper, and lead.
10. The debris free perforating system of claim 1, wherein the
explosive material further comprises a thermoplastic binder.
11. The debris free perforating system of claim 10, wherein the
thermoplastic binder is selected from Viton.TM., Kel-F-800, THV,
Polyethylene, Nylon, and PVC.
12. The debris free perforating system of claim 1, wherein the
explosive material further comprises a thermosetting plastic
binder.
13. The debris free perforating system of claim 12, wherein the
thermosetting plastic binder is selected from polyesters,
polyurethanes, polyamides, polyimides, and epoxies.
14. The debris free perforating system of claim 1, wherein the
explosive material further comprises a thermoplastic-thermosetting
polymer.
15. The debris free perforating system of claim 14, wherein the
thermoplastic-thermosetting polymer is cured from a blend of
Elvamide.TM. 8061 and an epoxy resin.
16. The debris free perforating system of claim 14, wherein the
thermoplastic-thermosetting polymer is cured from a blend of
Elvamide.TM. 8063 and an epoxy resin.
17. The debris free perforating system of claim 15 or 16, wherein
the epoxy resin is Epon.TM. 828.
18. The debris free perforating system of claim 14, wherein the
thermoplastic-thermosetting polymer is a fluoropolymer.
19. The debris free perforating system of claim 18, wherein the
fluoropolymer is selected from Dupont Viton.TM., 3M Fluorel 2175,
and Dyneon THV.
20. A method of forming a thermoplastic-thermosetting polymeric
binder for pressed or extrudable explosives, comprising: blending
Elvamide.TM. 8061 with a stoichiometric amount of epoxy resin;
curing the blend with a latent curing agent; and coating explosive
particles with the uncured blend.
21. The method of claim 20, wherein Elvamide.TM. 8063 is blended
with the epoxy resin.
22. The method of claim 20, wherein the epoxy resin is Epon.TM.
828.
23. The method of claim 20, wherein the latent curing agent is
Dicyandiamide.
24. The method of claim of claim 20, wherein the blend is cured in
an oven.
25. The method of claim 20, wherein the explosive is coated with
the cured blend in an amount of 2 to 10 percent by weight.
26. A method of forming a fluoropolymer binder for pressed or
extrudable explosives, comprising: formulating a plastic bonded
explosive using the water slurry process; pressing the resulting
explosive molding powder to shape; and exposing the molded shape to
electron radiation.
27. A debris free perforating system, comprising: a shaped charge
having a jacket made from a combustible material; and a case made
from a combustible material.
28. The debris free perforating system of claim 27, wherein the
combustible material is plastic.
29. The debris free perforating system of claim 28, wherein the
plastic is selected from Nylon, PEEK, Polyimide, Polysulfone, PVC,
CPVC, Polyethylene, Torlon.TM., PVDF, Teflon.TM., CTFE, CTFE/E,
Polyethylene, Phenolic, and Polypropylene.
30. The debris free perforating system of claim 27, wherein the
combustible material is an energetic material.
31. The debris free perforating system of claim 27, wherein the
jacket comprises paper.
32. The debris free perforating system of claim 27, wherein the
combustible material further contains or is coated with an
oxidizer.
33. The debris free perforating system of claim 32, wherein the
oxidizer is selected from ammonium nitrate, potassium nitrate,
sodium nitrate, strontium nitrate, barium nitrate, ammonium
perchlorate, potassium perchlorate, sodium perchlorate, RDX, and
HMX.
34. The debris free perforating system of claim 27, wherein the
jacket and case is made from thin metal.
35. The debris free perforating system of claim 34, wherein the
thin metal is copper.
36. The debris free perforating system of claim 34, wherein the
thin metal is glass.
37. The debris free perforating system of claim 34, wherein the
thin metal is ceramic material.
38. A debris free perforating system, comprising: a shaped charge;
and a combustible loading tube coated with an oxidizer.
39. The debris free perforating system of claim 38, wherein the
oxidizer is selected from ammonium nitrate, potassium nitrate,
sodium nitrate, strontium nitrate, barium nitrate, ammonium
perchlorate, potassium perchlorate, sodium perchlorate, RDX, and
HMX.
40. A debris free perforating system, comprising: a caseless shaped
charge; and a densified explosive.
41. The debris free perforating system of claim 40, wherein the
densified explosive comprises an explosive blended with inert heavy
materials.
42. The debris free perforating system of claim 41, wherein the
inert heavy materials are powdered tungsten.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/294,894, filed May 31, 2001
FIELD OF THE INVENTION
[0002] The subject matter of the present invention relates to a
debris free perforating system. More specifically, the subject
matter of the present invention relates to reducing the amount of
debris generated during perforating with shaped charges.
BACKGROUND OF THE INVENTION
[0003] In drilling operations, the drilled hole is often lined with
a casing to prevent the earth from filling the hole. In order for
the surrounding fluid to enter the drilled hole, the well casing
must be perforated. Such operation is typically performed by a
perforating gun loaded with one or more shaped charges.
[0004] Conventional perforating guns produce significant debris
upon detonation of the shaped charges. The generated debris can
enter the well fluid and become entrained in the well fluid. As the
debris is carried by the well fluid, it can complicate down stream
processing of the well fluids by clogging filters and jamming
pumps, for example.
[0005] Extensive research on hollow carrier perforating guns
indicates that the majority of gun debris is generated by the
shaped charge cases. In fact, roughly 80% of all gun debris is
attributed to the charge cases. The remaining debris is attributed
to the charge case jackets and the loading tubes.
[0006] There exists, therefore, a need for a debris free
perforating system that reduces or eliminates the debris generated
upon detonation of the shaped charges.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a cross-sectional view of a typical shaped charge,
loading tube, and perforating gun.
[0008] FIG. 2 is a perspective view of a typical shaped charge and
loading tube.
[0009] FIG. 3 is a perspective view of a loading tube being
inserted into a perforating gun.
[0010] FIG. 4 illustrates an embodiment of the debris free
perforating system in which the shaped charge does not have a
case.
[0011] FIG. 5 illustrates a cross-sectional view of an embodiment
of the debris free perforating system having a solid loading
tube.
[0012] FIG. 6 illustrates an embodiment of the debris free
perforating system in which the jacket and/or case is made from a
plastic or energetic material.
[0013] FIGS. 7a and 7b illustrate an embodiment of the debris free
perforating system in which the loading tube is a combustible
cardboard tube.
[0014] FIG. 8 is a sketch of an embodiment of the debris free
perforating system in which the loading tube is a reinforced
plastic tube or rod.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0015] FIG. 1 provides an illustration of a typical shaped charge,
indicated generally as 1, used for perforating a well casing.
Typical shaped charges for use in perforating guns are discussed in
U.S. Pat. No. 4,724,767 to Aseltine issued Feb. 16, 1988; U.S. Pat.
No. 5,413,048 to Werner et al. issued May 9, 1995; U.S. Pat. No.
4,669,384 to Chawla et al. issued Jun. 2, 1987; and again in U.S.
Pat. No. 5,597,974 to Voreck, Jr. et al. issued Jan. 28, 1997. Each
of the above mentioned disclosures are incorporated by reference
into this specification.
[0016] The shaped charge 1 includes a case 10, a main body of
explosive material 12, which in the past has been, for example,
RDX, 1,3,5,7-tetranitro octahydro-1,3,5,7-tetrazocine (HMX),
2,6-bis (Picrylamino)-3,5-dinitropyridine (PYX), or
2,2',4,4',6-hexanitrostilbene (HNS) packed against the inner wall
of the case 10, a primer 13 disposed adjacent the main body of
explosive 12 that is adapted to detonate the main body of explosive
12 when the primer 13 is detonated, and a liner 14 lining the
primer 13 and the main body of explosive material 12. The liner 14
acts to maintain the shape of the explosive to assure proper
propagation of the detonation. A detonating cord 20 contacts the
case 10 of the shaped charge 1 at a point nearest the apex of the
liner 14 of the charge. When a detonation wave propagates within
the detonating cord 20, the detonation wave will detonate the
primer 13. When the primer 13 is detonated, the detonation of the
primer 13 will further detonate the main body of explosive 12 of
the charge 1. In response to the detonation of the main body of
explosive 12, the liner 14 will form a jet that will propagate
along a longitudinal axis of the shaped charge 1. The jet will
perforate a formation penetrated by the wellbore.
[0017] In a typical shaped charge 1, the case 10 greatly
contributes to the penetration performance of the shaped charge 1.
The case 10 (typically steel or similar) provides substantial
inertial confinement, thereby enhancing the proportion of explosive
energy transferred to the collapsing liner 14, and hence the
penetrating jet.
[0018] Several shaped charges 1 may be spatially arranged in a
pattern (a spiral pattern, for example) in a device called a
perforating gun. The shaped charges 1 are ballistically connected
via the detonating cord 20 or some other means. In general,
perforating guns are either capsule guns, which are essentially a
metallic strip or similar device onto which the shaped charges 1
are attached, or hollow carrier guns as shown in FIGS. 1-3.
[0019] For a typical hollow carrier gun, one or more shaped charges
1 are housed within a loading tube 22 for transport. The loading
tube 22 can house the shaped charges 1 at desired orientations, or
in a linear fashion. A jacket 24 is used to both secure the shaped
charges 1 to the loading tube 22 and to maintain the orientation of
the shaped charges 1. Once the loading tube 22 is ready for
delivery downhole, a perforating gun 30 is used to carry the
loading tube 22 and housed shaped charges 1.
[0020] Conventionally, as shown in FIGS. 2 and 3, the shaped
charges 1 and jackets 24 are inserted into the loading tube 22
until the jackets 24 shoulder against the loading tube shoulders
23. Once all of the shaped charges 1 are secured, the loading tube
22 is inserted into the interior of the perforating gun 30. The gun
30 then transports the shaped charges 1 downhole to the desired
depth of perforation.
[0021] FIG. 4 illustrates one embodiment of the debris free
perforating system in which the shaped charge 1 does not have a
case. Because, as discussed above, a typical shaped charge relies
in part on its metal case to aid in perforating the well casing, it
is desirable to use an explosive 12 that compensates for the
elimination of the case. In one embodiment of the present
invention, the caseless shaped charge 1 shown in FIG. 4 contains a
larger amount of explosive 12. For example, the caseless shaped
charge 1 may contain 2 to 3 times the explosive 12 as similarly
sized metallic cased charges to obtain equivalent penetration
performance.
[0022] In another embodiment of the caseless shaped charge 1 shown
in FIG. 4, the explosive 12 comprises a densified explosive 12 that
possesses the beneficial confinement properties usually afforded by
the case. The densified explosive 12 is formulated to not expand as
quickly, therefore increasing the duration of its primary pulse.
The densified explosive 12 delivers more of its energy to the liner
14 during the primary pulse, and therefore relies less on
subsequent sustained impulse.
[0023] In one embodiment, the explosive 12 is densified by blending
it with some inert heavy materials such as powdered metals. The
inserted powdered metals can include tungsten, iron, copper, and
lead, for example. The resulting blend provides more mass at the
detonation front, which delays expansion due to the explosive cloud
mass, and hence increases primary impulse detonation.
[0024] In a typical shaped charge, the case and liner maintain the
shape and the integrity of the explosives. As discussed above, in
the embodiment of the debris free perforating system shown in FIG.
4, the shaped charge 1 does not have a case. During transport, the
liner 14 acting alone is generally unable to maintain the shape of
the explosive 12. Thus, alternative methods of maintaining the
integrity of the explosive 12 must be incorporated.
[0025] One method of maintaining the integrity of the explosive 12
in the caseless shaped charge 1 is to use a solid loading tube 36,
as shown in cross-section in FIG. 5. Hollow cavities 38 formed in
the solid loading tube 36 provide housings and support for the
shaped charges 1. Suitable materials for the solid loading tube 36
include low density plastic materials, Styrofoam.TM. or paper, for
example. Typically, the detonation of the shaped charge 1 will
incinerate the solid loading tube 36.
[0026] Referring back to FIG. 4, yet another method of maintaining
the integrity of the explosive 12 in a caseless charge 1 is to use
a suitable binder that will not melt or slump when exposed to the
desired operating temperature. For lower temperature applications
(generally below 250.degree. F.), suitable binders can be
thermoplastics such as Viton.TM., Kel-F-800, THV, Polyethylene,
Nylon, or PVC, for example. Other suitable binders include any
polymeric material having a service temperature meeting or
exceeding the desired operating temperature of the application.
[0027] For high temperature applications, thermosetting plastic
binders can be used as the explosive binder. Typical thermosetting
plastics do not have a melting point, but do decompose when exposed
to high temperatures. In one embodiment of using a thermosetting
plastic binder, the explosive 12 is of the castible type where the
binder is in a liquid state during production. The explosive 12 is
cast in a mold of the desired shape, and the binder reacts to form
a crosslinked non-melting plastic. Suitable plastic systems for
castible explosives include polyesters, polyurethanes, polyamides,
polyimides, and epoxies, for example. In another embodiment of
using a thermosetting plastic binder, the explosive 12 is of the
pressed type.
[0028] Another embodiment of a suitable binder for the explosive 12
is a thermoplastic-thermosetting polymer useful as a binder for
pressed or extrudable explosive. In this embodiment, the
thermoplastic-thermosetting binder comprises Elvamide.TM. 8061 or
8063 blended with a stoichiometric amount of an epoxy resin, such
as Epon.TM. 828. The blend is then cured with a latent curing agent
such as Dicyandiamide (DICY), for example. The cured blend can then
be coated on to the explosive 12 using the water slurry method.
Usually a 2 to 10 percent by weight coating is applied. When
pressed at 212-250.degree. F., the binder cures to form a
non-melting thermoset polymer stable to 400.degree. F.
Alternatively, the explosive formulation can be pressed at room
temperature and cured in an oven at elevated temperature.
[0029] Another embodiment of a thermoplastic-thermosetting binder
for use in a pressed or extruded explosive is a fluoropolymer such
as Dupont Viton.TM., 3M Fluorel 2175, or Dyneon THV, for example.
These fluoropolymers can be formulated with RDX or HMX using the
water slurry process. The resulting explosive molding powder is
pressed to shape using standard explosive pressing technology. In
their natural state, these materials are thermoplastics and will
soften and slump at temperatures exceeding approximately
250.degree. F. However, exposure to electron radiation (so called
e-beams) causes the polymer to cross-link and cure by well known
mechanisms. E-beam curing increases the glass transition
temperature and melting points of these polymers. Even in instances
where the e-beam only cures the skin of the polymer, the skin is
sufficiently toughened to prevent deformation of the caseless
shaped charge 1 exposed to elevated temperatures.
[0030] FIG. 6 illustrates another embodiment of the debris free
perforating system in which the jacket 24 and/or case 10 is made of
a plastic or energetic material to support the explosive 12 and
attach the shaped charge 1 to the loading tube 22. The plastic or
energetic material is combustible such that upon detonation of the
shaped charge 1, the jacket 24 and/or case 10 does not leave any
debris. Suitable plastics include Nylon, PEEK, Polyimide,
Polysulfone, PVC, CPVC, Polyethylene, Torlon.TM., PVDF, Teflon.TM.,
CTFE, CTFE/E, Polyethylene, Phenolic, Polypropylene, or any other
plastic or filled plastic possessing adequate thermal stability for
use at the desired operating temperatures. In one embodiment, the
jacket 24 is made of paper.
[0031] In this embodiment of the debris free perforating system,
the shape of the explosive 12 is maintained by the case 10 and may
be fabricated with a meltable binder such as wax, for example. The
jacket 24 and/or case 10 is made as thin as possible to enhance its
combustion by the explosive 12 contained in the shaped charge 1.
Typical jacket 24 and/or case 10 thickness in this embodiment is
between 0.010 and 0.060 inches.
[0032] To enhance the consumption of the jacket 24 and/or case 10,
an oxidizer or oxidizer/powdered metal blend is added to the
plastic or energetic material. Such oxidizers can be added during
the forming process by direct addition to the melted polymer in the
cast of a thermoplastic material. Alternatively the oxidizers can
be added to the uncured resins of a thermosetting system. Suitable
oxidizers can be ammonium nitrate, potassium nitrate, sodium
nitrate, strontium nitrate, barium nitrate, ammonium perchlorate,
potassium perchlorate, sodium perchlorate, RDX, or HMX, for
example. Suitable powdered metals can be aluminum, magnesium, boron
or zirconium, for example.
[0033] Another embodiment of the debris free perforating system
uses jackets 24 and/or cases 10 fabricated from very thin metal
that generate small fragments upon detonation of the explosive 12.
The small fragments can embed themselves in the wall of the
perforating gun 30 so as to not be carried by the well fluids. In
the case of the thin metal comprising copper, the metal case may
expand like a balloon without fragmenting and actually paste itself
to the inside of the perforating gun 30 in one piece.
[0034] Similarly, another embodiment of the debris free perforating
system uses jackets 24 and/or cases 10 fabricated from thin,
low-mass glass and ceramic materials. The fragments generated
during detonation would be in the form of fine particulates that
will not compromise the integrity of the flow of the well
fluids.
[0035] FIGS. 7a and 7b illustrate another embodiment of the debris
free perforating system in which the loading tube 22 is a
combustible cardboard tube. FIG. 7a illustrates a spiral wrap
cardboard tube and FIG. 7b illustrates a convoluted cardboard tube.
To ensure incineration in an oxygen deficient environment, the
loading tube 22 may be coated with an oxidizer filled paint 40. One
embodiment of a suitable coating is a polyester or polystyrene
thermosetting resin filled with an oxidizer such as ammonium
nitrate, potassium nitrate, sodium nitrate, strontium nitrate,
barium nitrate, ammonium perchlorate, potassium perchlorate, RDX,
or HMX, for example. Additional energy can be supplied by
incorporating powder metals such as aluminum, magnesium, boron, or
zirconium.
[0036] Another embodiment of the debris free perforating system is
illustrated in FIG. 8. In this embodiment, the loading tube 22 is a
thin-walled plastic tube or rod made of one of the previously
mentioned engineering plastics formulated with reinforcing fibers
42 (such as glass, carbon, or Kevlar.TM.) and a suitable oxidizer
such as ammonium nitrate, potassium nitrate, sodium nitrate,
strontium nitrate, barium nitrate, 0 ammonium perchlorate,
potassium perchlorate, sodium perchlorate, RDX, or HMX.
[0037] Additional energy can be supplied by incorporating powder
metals such as aluminum, magnesium, boron, or zirconium.
EXAMPLE
[0038] The following example details the results of debris tests
run on two embodiments of the present invention. The "caseless"
shaped charges used in the tests were very thin (0.060" thick) 8
gram plastic combustible cases. The results are compared to test
results for a conventional steel-cased charge of equal size.
[0039] Test I:
[0040] In the first test, five (5) of the above-described
"caseless" shaped charges were carried in a 1-foot gun. The charges
were loaded into a Styrofoam.TM. loading tube without the use of a
jacket. The charges were detonated and the debris was collected.
The amount of debris collected was approximately 2.1 grams of
debris per charge. Most of the debris was actually liner powder
that did not jet and therefore remained in the gun. It was
estimated that the non-liner debris remaining in the gun was less
than 1 gram per charge. For reference, the conventional
steel-shaped cased charge yielded approximately 240 grams per
charge.
[0041] Test II.
[0042] In the second test, four (4) of the above-described
"caseless" shaped charges were carried in a 1-foot gun. The charges
were loaded into a cardboard loading tube without the use of a
jacket. The charges were detonated and the debris was collected.
The amount of debris collected was approximately 6.3 grams of
debris per charge. The debris was a combination of liner powder and
small (approx. 1/4") cardboard pieces. Again, for reference, the
conventional steel-shaped cased charge yielded approximately 240
grams per charge.
[0043] The above discussed data is provided in tabular form in
Table I below.
1TABLE I Conventional Shaped Charge v. "Caseless" Shaped Charge
"Caseless" "Caseless" Conventional Charges in Charges in
Steel-Cased Styrofoam Loading Cardboard Loading Charges Tube Tube
Grams of 240 2.1 6.3 Debris Per Charge
[0044] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such are intended to be included within the scope of the
following non-limiting claims.
* * * * *