Information
-
Patent Grant
-
6497285
-
Patent Number
6,497,285
-
Date Filed
Wednesday, March 21, 200123 years ago
-
Date Issued
Tuesday, December 24, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Herman; Paul I.
- Youst; Lawrence R.
-
CPC
-
US Classifications
Field of Search
US
- 175 45 P
- 175 459
- 175 46
- 175 455
- 102 312
- 102 321
- 166 297
- 166 551
- 166 552
-
International Classifications
-
Abstract
A shaped charge perforating apparatus (50) for perforating a subterranean well is disclosed. The shaped charge perforating apparatus (50) comprises a support member (62) having a plurality of shaped charge mounting locations each having shaped charge (56) positioned therein. Each of the shaped charges (56) has an initiation end and a discharge end. The initiation end of each shaped charge (56) is coupled to a detonator cord (70) The shaped charges (56) are enclosed in a carrier (52) having a plurality of recesses (54) spaced on an exterior surface thereof and having contoured bottom surfaces (80). Each of the recesses (54) is longitudinally and radially aligned with the discharge end of one of the shaped charges (56).
Description
TECHNICAL FIELD OF THE INVENTION
This invention relates, in general, to an apparatus for perforating a subterranean wellbore using shaped charges and, in particular, to a low debris shaped charge perforating apparatus that utilizes contoured recesses in the charge carrier that reduce the size of the holes made in the charge carrier upon detonation of the shaped charges thus enhancing debris containment.
BACKGROUND OF THE INVENTION
Without limiting the scope of the present invention, its background will be described with reference to perforating a subterranean formation with a shape charge perforating apparatus, as an example.
After drilling the section of a subterranean wellbore that traverses a formation, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within the wellbore. This casing string increases the integrity of the wellbore and provides a path for producing fluids from the producing intervals to the surface. Conventionally, the casing string is cemented within the wellbore. To produce fluids into the casing string, hydraulic opening or perforation must be made through the casing string, the cement and a short distance into the formation.
Typically, these perforations are created by detonating a series of shaped charges located within the casing string that are positioned adjacent to the formation. Specifically, one or more charge carriers are loaded with shaped charges that are connected with a detonating device, such as detonating cord. The charge carriers are then connected within a tool string that is lowered into the cased wellbore at the end of a tubing string, wireline, slick line, coil tubing or the like. Once the charge carriers are properly positioned in the wellbore such that shaped charges are adjacent to the formation to be perforated, the shaped charges are detonated. Upon detonation, each shaped charge creates a Jet that blasts through a scallop or recess in the carrier. Each jet creates a hydraulic opening through the casing and the cement and enters the formation forming a perforation.
When the shaped charges are detonated, numerous metal fragments are created due to, among other things, the disintegration of the metal casings of the shaped charges. These fragments often fall out or are blown out of the holes created in the carrier. As such, these fragments become debris that is left behind in the wellbore. It has been found that this debris can obstruct the passage of tools through the casing during subsequent operations. This is particularly problematic in the long production zones that are perforated in horizontal wells as the debris simply piles up on the lower side of such wells.
A need has therefore arisen for an apparatus and method that reduce the likelihood that debris will be left in the well following perforation of the formation. A need has also arisen for such an apparatus and method that will contain the fragments created when the shaped charges are detonated. Further, a need has arisen for such an apparatus and method that will enhance the performance of the shaped charges in perforating the formation.
SUMMARY OF THE INVENTION
The present invention disclosed herein comprises a shaped charge perforating apparatus and a method for perforating a subterranean formation using a shaped charge perforating apparatus that reduce the likelihood that debris will be left in a well following perforation of a formation. The shaped charge perforating apparatus of the present invention achieves this result by containing the fragments created when the shaped charges are detonated. In addition, the shaped charge perforating apparatus of the present invention enhances the performance of the shaped charges in perforating the formation.
The shaped charge perforating apparatus of the present invention comprises a support member having a plurality of shaped charge mounting locations each of which receive a shaped charge therein. The shaped charges each have an initiation end and a discharge end. The initiation ends of the shaped charges are each coupled to a detonator cord. The shaped charges are placed within an elongated and generally tubular carrier. The carrier has a plurality of recesses that are spaced on the exterior surface thereof and have contoured bottom surfaces. Each of the recesses is axially and radially aligned with the discharge end of one of the shaped charges such that the jet formed upon the initiation of each shaped charge will penetrate the carrier through a recess.
In one embodiment of the present invention, the contoured bottom surface of the recesses is formed such that the center depth of the recess in the carrier is greater than a perimeter depth of the recess. For example, the center depth of the recess may be greater than the perimeter depth of the recess at a point on the perimeter of the recess that is displaced from the center of the recess in a longitudinal direction. Alternatively or additionally, the center depth of the recess may be greater than the perimeter depth of the recess at a point on the perimeter of the recess that is displaced from the center of the recess in a circumferential direction.
In another embodiment of the present invention, the contoured bottom surface of the recesses is formed such that the recesses have a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion to the perimeter of the recesses. In this embodiment, the angular bottom portion may have an angle of between about 10 and 40 degrees and may preferably have an angle of between about 15 and 25 degrees.
In one embodiment of the present invention, the contoured bottom surface of the recesses is formed such that the angular bottom portion extends from the flat bottom portion of the recess to the exterior surface of the carrier. In another embodiment of the present invention, the contoured bottom surface of the recesses is formed such that the angular bottom portion of the recess extends from the flat bottom portion of the recess to a sidewall section of the recess at a location offset from the exterior surface of the carrier by a depth.
The method for perforating a subterranean well of the present invention comprises running a shaped charge perforating apparatus of the present invention downhole, operating the shaped charge perforating apparatus and discharging jets formed from the shaped charges through respective contoured bottom surfaces of recesses in the shaped charge carrier. In such a method, the recesses have a center depth that is greater than a perimeter depth, either in the longitudinal direction from the center, the circumferential direction from the center or both. The recesses may have a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion to the perimeter of the recesses. The angular bottom portion of the recesses may extend from the flat bottom portion of the recesses to the exterior surface of the carrier or may intersect the sidewall of the recesses at the perimeter of the recesses. In all such configurations, using the method of the present invention to discharge jets formed from the shaped charges through the respective contoured bottom surfaces minimizes the size of openings created through the carrier by the discharge of the jets and prevents peeling of the recesses in the longitudinal direction.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:
FIG. 1
is a schematic illustration of an offshore oil and gas platform operating a shaped charge perforating apparatus of the present invention;
FIG. 2
is partial cut away view of a shaped charge perforating apparatus of the present invention;
FIG. 3
is a cross sectional view taken in the circumferential direction of a contoured recess of a charge carrier of the present invention taken along line
3
—
3
of
FIG. 2
;
FIG. 4
is a prior art drawing of a recess of a charge carrier show in a circumferential cross sectional view;
FIG. 5
is a cross sectional view taken in the longitudinal direction of a contoured recess of a charge carrier of the present invention taken along line
5
—
5
of
FIG. 2
;
FIG. 6
is a prior art drawing of a recess of a charge carrier show in a longitudinal cross sectional view;
FIG. 7
is a longitudinal cross sectional view of a contoured recess of a charge carrier of the present invention;
FIG. 8
is a longitudinal cross sectional view of a contoured recess of a charge carrier of the present invention; and
FIG. 9
is a longitudinal cross sectional view of a contoured recess of a charge carrier of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.
Referring initially to
FIG. 1
, a low debris shaped charge perforating apparatus operating from an offshore oil and gas platform is schematically illustrated and generally designated
10
. A semi-submersible platform
12
is centered over a submerged oil and gas formation
14
located below sea floor
16
. A subsea conduit
18
extends from deck
20
of platform
12
to wellhead installation
22
including blowout preventers
24
. Platform
12
has a hoisting apparatus
26
and a derrick
28
for raising and lowering pipe strings such as work sting
30
.
A wellbore
32
extends through the various earth strata including formation
14
. A casing
34
is cemented within wellbore
32
by cement
36
. Work string
30
include various tools including shaped charge perforating apparatus
38
. When it is desired to perforate formation
14
, work string
30
is lowered through casing
34
until shaped charge perforating apparatus
38
is positioned adjacent to formation
14
. Thereafter, shaped charge perforating apparatus
38
is fired by detonating the shaped charges that are disposed within charge carrier
40
and aligned with recesses
42
of charge carrier
40
. Upon detonation, the liners of the shaped charges form jets that pass through recesses
42
of charge carrier
40
and form a spaced series of perforations extending outwardly through casing
34
, cement
36
and into formation
14
.
Even though
FIG. 1
depicts a vertical well, it should be noted by one skilled in the art that the low debris shaped charge perforating apparatus of the present invention is equally well-suited for use in deviated wells, inclined wells or horizontal wells. Also, even though
FIG. 1
depicts an offshore operation, it should be noted by one skilled in the art that the low debris shaped charge perforating apparatus of the present invention is equally well-suited for use in onshore operations.
Referring now to
FIG. 2
, therein is depicted a low debris shaped charge perforating apparatus of the present invention that is generally designated
50
. Perforating apparatus
50
includes a carrier
52
made of a cylindrical sleeve having a plurality of recesses, such as recess
54
, defined therein. Radially aligned with each of the recesses is a respective one of a plurality of shaped charges, such as shaped charge
56
. Each of the shaped charges includes an outer housing, such as housing
58
of shaped charge
56
, and a liner, such as liner
60
of shaped charge
56
. Disposed between each housing and liner is a quantity of high explosive.
The shaped charges are retained within carrier
52
by a support member
62
which includes an outer charge holder sleeve
64
, an inner charge holder sleeve
66
. In this configuration, outer tube
64
supports the discharge ends of the shaped charges, while inner tube
66
supports the initiation ends of the shaped charges. Disposed within inner tube
66
is a detonator cord
70
, such as a Primacord, which is used to detonate the shaped charges. In the illustrated embodiment, the initiation ends of the shaped charges extend across the cental longitudinal axis of perforating apparatus
50
allowing detonator cord
70
to connect to the high explosive within the shaped charges through an aperture defined at the apex of the housings of the shaped charges.
Each of the shaped charges is longitudinally and radially aligned with a recess in carrier
52
when perforating apparatus
50
is fully assembled. In the illustrated embodiment, the shaped charges are arranged in a spiral pattern such that each shaped charge is disposed on its own level or height and is to be individually detonated so that only one shaped charge is fired at a time. It should be noted, however, by those skilled in the art that alternate arrangements of shaped charges may be used, including cluster type designs wherein more than one shaped charge is at the same level and is detonated at the same time, without departing from the principles of the present invention.
Referring now to
FIG. 3
, therein is depicted a circumferential cross sectional view of recess
54
of carrier
52
taken along line
3
—
3
of FIG.
2
. Recess
54
has a contoured bottom surface
80
. In the illustrated embodiment, recess
54
has a flat bottom center portion
82
. Radially outwardly extending from flat bottom center portion
82
are angular bottom portions
84
and
86
. Angular bottom portion
84
extends radially outwardly toward sidewall
88
of recess
54
while angular bottom portion
86
extends radially outwardly toward sidewall
90
of recess
54
. As such, the depth of recess
54
at the center is greater than the depth of recess
54
near the circumferential perimeters of recess
54
, i.e., near sidewalls
88
and
90
.
In the illustrated embodiment, the angle of angular bottom portions
84
and
86
relative to flat bottom potion
82
is angle θ. Angle θ may be any angle greater than zero but is preferably between 10 degrees and 40 degrees and most preferably between 15 degrees and 25 degrees. The exact angle θ will depend upon the desired performance characteristics of recess
54
as well as the relative diameters of recess
54
and flat bottom portion
82
. For example, if recess
54
has a diameter of 1.25 inches, the diameter of flat bottom portion
82
may be between about 0.3 inches and 0.7 inches and is preferable between about 0.4 inches and 0.6 inches. As should be understood by those skilled in the art, other diameter recesses having other diameter flat bottom portions are also desirable and considered within the scope of the present invention.
Utilizing a charge carrier having recesses, such as recess
54
with contoured bottom surface
80
, enhances the performance of a shaped charge for which recess
54
is the first target. Specifically, as compared with conventional recesses having a flat bottom surface, see
FIG. 4
, the thickness of the first target is reduced as the depth of recess
54
near the center of recess
54
is greater than the allowable depth for a conventional flat bottom recess due to the required pressure rating for the charge carrier. There must be a sufficient amount of metal remaining behind a recess to withstand the high downhole pressures seen by the charge carrier. Using recess
54
with contoured bottom surface
80
, the required pressure rating can be achieved even though the metal behind flat bottom center portion
82
is thinner than previous allowable due to the extra metal behind angular bottom portions
84
and
86
. As such, since the first target seen by a shaped charge disposed behind recess
54
having contoured bottom surface
80
is thinner than with conventional flat bottom recesses, the performance of such a shaped charge is improved as the depth of penetration into a formation is increased.
Referring now to
FIG. 5
, therein is depicted a longitudinal cross sectional view of recess
54
of carrier
52
taken along line
5
—
5
of FIG.
2
. Recess
54
has a contoured bottom surface
80
. In the illustrated embodiment, recess
54
has a flat bottom center portion
82
. Radially outwardly extending from flat bottom center portion
82
are angular bottom portions
92
and
94
. Angular bottom portion
92
extends radially outwardly toward sidewall
96
of recess
54
while angular bottom portion
94
extends radially outwardly toward sidewall
98
of recess
54
. As such, the depth of recess
54
at the center is greater than the depth of recess
54
near the longitudinal perimeters of recess
54
, i.e., near sidewalls
96
and
98
. In the illustrated embodiment, the angle of angular bottom portions
92
and
94
relative to flat bottom center portion
82
is angle θ, which is the same angle of angular bottom portions
84
and
86
relative to flat bottom center portion
82
in
FIG. 3
as recess
54
is symmetric about its central axis.
Utilizing a charge carrier having recesses, such as recess
54
with contoured bottom surface
80
, not only enhances the performance of shaped charges for which recess
54
is the first target, but also, reduces the likelihood that debris will be left in the well following perforation as such a charge carrier will contain the fragments created when the shaped charges are detonated. Specifically, a smaller opening is made when a jet passes through recess
54
with contoured bottom surface
80
than when a jet passes through conventional recesses. With recess
54
, not only does the jet pass through a thinner metal section, contoured bottom surface
80
is not susceptibly to the longitudinal pealing effect as the thickness of the metal behind recess
54
becomes progressive thicker in angular bottom portions
92
and
94
.
Unlike the present invention, with conventional flat bottom recesses, as seen in
FIG. 6
, the thickness of the metal in the longitudinal direction behind the recess is constant. As such, a jet penetrating a conventional flat bottom recess tends to create a large opening as the metal behind the recess peals back toward the sidewalls of the recess. In some cases, this longitudinal pealing effect results in an opening that is substantially as wide as the diameter of the conventional flat bottom recess in the longitudinal direction. As such, the fragments created when the shaped charges are detonated tend to fall or be blasted out of these large openings to become debris in the well. In addition, the pealed section of metal from behind the conventional flat bottom recess sometimes protrudes outwardly beyond the exterior of a charge carrier having conventional flat bottom recesses and scores the casing as such a charge carrier is retrieved uphole.
Referring now to
FIG. 7
, therein is depicted a longitudinal cross sectional view of a recess
100
of a carrier
102
. Recess
100
has a contoured bottom surface
104
. In the illustrated embodiment, recess
100
has a flat bottom center portion
106
. Radially outwardly extending from flat bottom center portion
106
are angular bottom portions
108
and
110
. Angular bottom portions
108
and
110
extend radially outwardly to the exterior surface of carrier
102
. As such, the depth of recess
100
at the center is greater than depth of recess
100
near the longitudinal perimeters of recess
100
, i.e., at the intersection with the exterior surface of carrier
102
.
Referring next to
FIG. 8
, therein is depicted a longitudinal cross sectional view of a recess
120
of a carrier
122
. Recess
120
has a contoured bottom surface
124
. In the illustrated embodiment, recess
120
has an apex
126
. Radially outwardly extending from apex
126
are angular bottom portions
128
and
130
. Angular bottom portion
128
extends radially outwardly toward sidewall
132
of recess
120
while angular bottom portion
130
extends radially outwardly toward sidewall
134
of recess
120
. As such, the depth of recess
120
at the center is greater than the depth of recess
120
near the longitudinal perimeters of recess
120
, i.e., near sidewalls
132
and
134
.
Referring to
FIG. 9
, therein is depicted a longitudinal cross sectional view of a recess
140
of a carrier
142
. Recess
140
has a contoured bottom surface
144
. In the illustrated embodiment, recess
140
has an arcuate contour that extends from a maximum at location
146
to minimums at sidewalls
148
and
150
. As such, the depth of recess
140
at the center is greater than the depth of recess
140
near the longitudinal perimeters of recess
140
.
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
Claims
- 1. A shaped charge perforating apparatus comprising:a support member having a plurality of shaped charge mounting locations; a plurality of shaped charges positioned in the mounting locations of the support member, each of the shaped charges having an initiation end and a discharge end; a detonator cord operably coupled to the initiation end of each shaped charge; and a carrier having a plurality of recesses spaced on an exterior surface thereof, each of the recesses being longitudinally and radially aligned with the discharge end of one of the shaped charges, the recesses having a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion toward the perimeter of the recesses thereby forming a contoured bottom surface of the recesses.
- 2. The shaped charge perforating apparatus as recited in claim 1 wherein the recesses have a center depth that is greater than a perimeter depth thereby forming the contoured bottom surface of the recesses.
- 3. The shaped charge perforating apparatus as recited in claim 1 wherein the recesses have a center depth that is greater than a perimeter depth in a longitudinal direction from the center thereby forming the contoured bottom surface of the recesses.
- 4. The shaped charge perforating apparatus as recited in claim 1 wherein the recesses have a center depth that is greater than a perimeter depth in a circumferential direction from the center thereby forming the contoured bottom surface of the recesses.
- 5. The shaped charge perforating apparatus as recited in claim 1 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 10 and 40 degrees.
- 6. The shaped charge perforating apparatus as recited in claim 1 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 15 and 25 degrees.
- 7. The shaped charge perforating apparatus as recited in claim 1 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to a sidewall portion of the recesses.
- 8. The shaped charge perforating apparatus as recited in claim 1 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to the exterior surface of the carrier.
- 9. The shaped charge perforating apparatus as recited in claim 1 wherein the recesses have an angular bottom portion that extends from the perimeter of the recesses to the center of the recesses thereby forming the contoured bottom surface of the recesses.
- 10. The shaped charge perforating apparatus as recited in claim 1 wherein the contoured bottom surface of the recesses further comprises an arcuate contour.
- 11. A shaped charge perforating apparatus adapted for use in a borehole, comprising:a plurality of shaped charges each having an initiation end and a discharge end; a detonator cord operably coupled to the initiation end of each shaped charge; and a carrier enclosing the shaped charges, the carrier including a plurality of recesses corresponding, respectively, to the discharge ends of the plurality of shaped charges, the plurality of recesses having a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion toward the perimeter of the recesses thereby forming a contoured bottom surface of the recesses.
- 12. The shaped charge perforating apparatus as recited in claim 11 wherein the recesses have a center depth that is greater than a perimeter depth thereby forming the contoured bottom surface of the recesses.
- 13. The shaped charge perforating apparatus as recited in claim 11 wherein the recesses have a center depth that is greater than a perimeter depth in a longitudinal direction from the center thereby forming the contoured bottom surface of the recesses.
- 14. The shaped charge perforating apparatus as recited in claim 11 wherein the recesses have a center depth that is greater than a perimeter depth in a circumferential direction from the center thereby forming the contoured bottom surface of the recesses.
- 15. The shaped charge perforating apparatus as recited in claim 11 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 10 and 40 degrees.
- 16. The shaped charge perforating apparatus as recited in claim 11 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 15 and 25 degrees.
- 17. The shaped charge perforating apparatus as recited in claim 11 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to a sidewall portion of the recesses.
- 18. The shaped charge perforating apparatus as recited in claim 11 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to the exterior surface of the carrier.
- 19. The shaped charge perforating apparatus as recited in claim 11 wherein the recesses have an angular bottom portion that extends from the perimeter of the recesses to the center of the recesses thereby forming the contoured bottom surface of the recesses.
- 20. The shaped charge perforating apparatus as recited in claim 11 wherein the contoured bottom surface of the recesses further comprises an arcuate contour.
- 21. A carrier for a shaped charge perforating apparatus having a plurality of shaped charges, each of the shaped charges having an initiation end and a discharge end and a detonator cord coupled to the initiation end of each shaped charge, the carrier comprising:an elongated tubular member having a plurality of recesses spaced on an exterior surface thereof, each of the recesses being longitudinally and radially aligned with the discharge end of one of the shaped charges, the recesses having a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion toward the perimeter of the recesses thereby forming a contoured bottom surface of the recesses.
- 22. The shaped charge perforating apparatus as recited in claim 21 wherein the recesses have a center depth that is greater than a perimeter depth thereby forming the contoured bottom surface of the recesses.
- 23. The shaped charge perforating apparatus as recited in claim 21 wherein the recesses have a center depth that is greater than a perimeter depth in a longitudinal direction from the center thereby forming the contoured bottom surface of the recesses.
- 24. The shaped charge perforating apparatus as recited in claim 21 wherein the recesses have a center depth that is greater than a perimeter depth in a circumferential direction from the center thereby forming the contoured bottom surface of the recesses.
- 25. The shaped charge perforating apparatus as recited in claim 21 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 10 and 40 degrees.
- 26. The shaped charge perforating apparatus as recited in claim 21 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 15 and 25 degrees.
- 27. The shaped charge perforating apparatus as recited in claim 21 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to a sidewall portion of the recesses.
- 28. The shaped charge perforating apparatus as recited in claim 21 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to the exterior surface of the carrier.
- 29. The shaped charge perforating apparatus as recited in claim 21 wherein the recesses have an angular bottom portion that extends from the perimeter of the recesses to the center of the recesses thereby forming the contoured bottom surface of the recesses.
- 30. The shaped charge perforating apparatus as recited in claim 21 wherein the contoured bottom surface of the recesses further comprises an arcuate contour.
- 31. A method for perforating a subterranean well comprising the steps of:running downhole a shaped charge perforating apparatus having a plurality of shaped charges that are enclosed in a carrier having a plurality of recesses corresponding, respectively, to the plurality of shaped charges, the recesses having contoured bottom surfaces with a flat bottom portion proximate the center of the recesses and an angular bottom portion extending from the flat bottom portion toward the perimeter of the recesses; detonating the shaped charges; and discharging jets formed from the shaped charges through the respective contoured bottom surfaces of the recesses in the carrier.
- 32. The method as recited in claim 31 wherein the step of discharging jets further comprises discharging jets formed from the shaped charges through the respective recesses in the carrier wherein the recesses have a center depth that is greater than a perimeter depth.
- 33. The method as recited in claim 31 wherein the step of discharging jets further comprises discharging jets formed from the shaped charges through the respective recesses in the carrier wherein the recesses have a center depth that is greater than a perimeter depth in a longitudinal direction from the center.
- 34. The method as recited in claim 31 wherein the step of discharging jets further comprises discharging jets formed from the shaped charges through the respective recesses in the carrier wherein the recesses have a center depth that is greater than a perimeter depth in a circumferential direction from the center.
- 35. The method as recited in claim 31 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 10 and 40 degrees.
- 36. The method as recited in claim 31 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses has an angle of between about 15 and 25 degrees.
- 37. The method as recited in claim 31 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to a sidewall portion of the recesses.
- 38. The method as recited in claim 31 wherein the angular bottom portion extending from the flat bottom portion to the perimeter of the recesses extends to an exterior surface of the carrier.
- 39. The method as recited in claim 31 wherein the recesses have an angular bottom portion that extends from the perimeter of the recesses to the center of the recesses.
- 40. The method as recited in claim 31 wherein the contoured bottom surface of the recesses further comprises an arcuate contour.
- 41. The method as recited in claim 31 wherein the step of discharging jets formed from the shaped charges through the respective contoured bottom surfaces of the recesses further comprises minimizing the size of openings created by the discharge of the jets.
- 42. The method as recited in claim 31 wherein the step of discharging jets formed from the shaped charges through the respective contoured bottom surfaces of the recesses further comprises preventing peeling of the recesses in the longitudinal direction.
US Referenced Citations (15)