U.S. patent application number 17/424668 was filed with the patent office on 2022-03-17 for asymmetric shaped charges and method for making asymmetric perforations.
The applicant listed for this patent is GEODYNAMICS, INC.. Invention is credited to Nathan CLARK, John HARDESTY, Phil SNIDER, David WESSON, Wenbo YANG.
Application Number | 20220081999 17/424668 |
Document ID | / |
Family ID | 1000006026464 |
Filed Date | 2022-03-17 |
United States Patent
Application |
20220081999 |
Kind Code |
A1 |
WESSON; David ; et
al. |
March 17, 2022 |
ASYMMETRIC SHAPED CHARGES AND METHOD FOR MAKING ASYMMETRIC
PERFORATIONS
Abstract
There is a shaped charge for making an asymmetrical perforation
into a casing. The shaped charge includes a case extending along a
symmetry axis X and having a back wall and an open end; an
explosive material located within the case; a liner located within
the case, over the explosive material; a booster material; and an
asymmetrical feature. The asymmetrical feature is selected to
generate an asymmetrical perforation into the casing.
Inventors: |
WESSON; David; (Ft. Worth,
TX) ; SNIDER; Phil; (Houston, TX) ; CLARK;
Nathan; (Mansfield, TX) ; YANG; Wenbo;
(Kennedale, TX) ; HARDESTY; John; (Fort Worth,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GEODYNAMICS, INC. |
Millsap |
TX |
US |
|
|
Family ID: |
1000006026464 |
Appl. No.: |
17/424668 |
Filed: |
December 20, 2019 |
PCT Filed: |
December 20, 2019 |
PCT NO: |
PCT/US19/67937 |
371 Date: |
July 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62795685 |
Jan 23, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F42B 1/028 20130101;
E21B 43/117 20130101; F42B 1/032 20130101; F42B 1/024 20130101 |
International
Class: |
E21B 43/117 20060101
E21B043/117; F42B 1/024 20060101 F42B001/024; F42B 1/028 20060101
F42B001/028; F42B 1/032 20060101 F42B001/032 |
Claims
1. A liner for covering an explosive material in a case of a shaped
charge, the liner comprising: a metallic powdered material; a
binder that holds together the metallic powdered material; and an
insert located partially within the metallic powdered material,
wherein the liner has a concave shape.
2. The liner of claim 1, wherein the insert is fully immersed
within the liner.
3. (canceled)
4. The liner of claim 1, wherein the insert is asymmetric relative
to a symmetry axis of the liner.
5-7. (canceled)
8. The liner of claim 1, wherein one face of the insert is flush
with a surface of the liner and the remaining of the insert is
fully embedded into the liner.
9. (canceled)
10. A shaped charge for making an asymmetric perforation in a
casing of a well, the shaped charge comprising: a case extending
along a symmetry axis X and having a back wall and an open end; an
explosive material located at the back wall of the case; a liner
located within the case, over the explosive material; and a booster
material located in a channel formed in the back wall of the case,
wherein the liner includes: a metallic powdered material; a binder
that holds together the metallic powdered material; and an insert
located partially within the metallic powdered material, wherein
the liner has a concave shape.
11-27. (canceled)
28. A shaped charge for making an asymmetrical perforation into a
casing, the shaped charge comprising: a case extending along a
symmetry axis X and having a back wall and an open end; an
explosive material located within the case; a liner located within
the case, over the explosive material; a booster material; and an
asymmetrical feature, wherein the asymmetrical feature is selected
to generate an asymmetrical perforation into the casing.
29. The shaped charge of claim 28, wherein the asymmetrical feature
is the liner being tilted relative the symmetry axis X so that one
side of the liner touches the case at a first height and the other
side of the liner touches the case at a second height, different
from the first height.
30. The shaped charge of claim 29, wherein the channel and the
booster material are symmetrically distributed relative to the
symmetry axis X.
31. The shaped charge of claim 28, wherein the asymmetrical feature
is that the symmetry axis X and an axis of symmetry X' of the liner
make a non-zero angle.
32. The shaped charge of claim 28, wherein the asymmetrical feature
is that the channel has a longitudinal axis X'', which makes a
non-zero angle with the symmetry axis X.
33. The shaped charge of claim 32, wherein the case, the explosive
material and the liner are symmetrical relative to the symmetry
axis.
34. The shaped charge of claim 32, wherein the channel is offset
relative to the symmetry axis.
35. The shaped charge of claim 28, further comprising: another
channel formed in the back wall of the case.
36. The shaped charge of claim 35, wherein the another channel and
the channel are asymmetrically located relative to the symmetry
axis X.
37. The shaped charge of claim 28, wherein the asymmetrical feature
is that the booster material fires along an axis that is not the
symmetry axis X.
38. The shaped charge of claim 28, wherein the asymmetrical feature
is that the booster material fires toward a side wall of the
case.
39. The shaped charge of claim 28, wherein the asymmetrical feature
is that a first volume of the explosive material has a
characteristic that is different from a second volume of the
explosive material.
40. The shaped charge of claim 39, wherein the characteristic is a
density.
41. The shaped charge of claim 39, wherein the characteristic is a
chemical composition.
42. The shaped charge of claim 28, wherein the asymmetrical feature
is an insert placed inside the case.
43. The shaped charge of claim 42, wherein the insert is fully
embedded into the explosive material.
44-68. (canceled)
Description
BACKGROUND
Technical Field
[0001] Embodiments of the subject matter disclosed herein generally
relate to shaped charges and associated perforations made in the
casing of a well, and more specifically, to methods and systems for
generating an asymmetric jet of material for perforating the casing
to obtain a desired perforation profile.
Discussion of the Background
[0002] In the oil and gas field, once a well 100 is drilled to a
desired depth H relative to the surface 110, as illustrated in FIG.
1, and the casing 102 protecting the wellbore 104 has been
installed and cemented in place, it is time to connect the wellbore
104 to the subterranean formation 106 to extract the oil and/or
gas. This process of connecting the wellbore to the subterranean
formation may include a step of plugging a previously fractured
stage of the well with a plug 112, a step of perforating a portion
of the casing 102, corresponding to a new stage, with a perforating
gun string 114 such that various channels 116 are formed to connect
the subterranean formation 106 to the inside of the casing 102, a
step of removing the perforating gun assembly, and a step of
fracturing the various channels 116 of the new stage. These steps
are repeated until all the stages are fractured.
[0003] During the perforating step for a given stage, perforating
guns 115i of the perforating gun string 114 are used to create
perforation clusters in the horizontal multistage hydraulically
fractured unconventional well 100. Clusters are typically spaced
along the length of a stage 140 (a portion of the casing that is
separated with plugs from the other portions of the casing), and
each cluster comprises multiple perforations (or holes) 130. Each
cluster is intended to function as a point of contact between the
wellbore 104 and the formation 106. After each stage 140 is
perforated, a slurry of proppant (sand) and liquid (water) is
pumped into the stage at high rates and then, through the
perforation holes 130, into the formation 106, with the intent of
hydraulically fracturing the formation to increase the contact area
between that stage and the formation. A typical design goal is for
each of the clusters to take a proportional share of the slurry
volume, and to generate effective fractures, or contact points,
with the formation, so that the well produces a consistent amount
of oil cluster to cluster and stage to stage.
[0004] In typical wells, the distribution of the slurry and
proppant between the various clusters is not uniform. There can be
more slurry deposited near the toe end 140A of the stage 140,
resulting in a toe biased stage, or more deposited near the heel
end 140B of the stage 140, resulting in a heel biased stage.
Sometimes, the clusters may not take appreciable amounts of slurry
at all. Size, shape, distribution, and uniformity of perforation
holes may contribute to this treatment nonuniformity.
[0005] The perforation geometry is typically a round hole 130, as
shown in FIG. 2, punched at a 90 degree angle to the well axis X.
During the fracturing treatment, holes that are taking fluid and
sand may erode to new shapes 132, as the sand wears against the
perforation hole while turning from moving down the well and into
the perforation hole. This process is exaggerated if only a few of
the holes in the stage are taking the slurry, and the eroded holes
continually take more fluid, thus propagating the effect even
further as the eroding hole 132 becomes much larger than all of the
other holes 130 in the stage.
[0006] Constant Entry Hole or Equal Entry Hole (CEH or EEH) charges
have proven to be very beneficial in this application. Baseline
conventional shaped charges 150 (FIG. 3 shows two shaped charges of
the gun 115i, one 150 oriented downward and one 152 upward) tend to
create a much larger hole 151 in the short water gap G1 when the
gun 115i rests on the low-side 102A of the casing 102 and a much
smaller hole 153 in the high-side 102B of the casing 102 through
the longer water gap G2. This means that the water gap negatively
affects the size of the holes made in the casing by the shaped
charges. The larger holes 151 take more fluid than the smaller
holes 153, and they erode over time, resulting in the large holes
taking eventually all of the fluid. CEH charges promote more
uniform distribution of fluid, and allow the overall reduction of
the nominal hole size, which further enables high-density
perforation techniques.
[0007] One mechanism to promote a more equal distribution of the
slurry into the hole is the SANDIQ system, belonging to the
assignee of this application, in which the perforation charges with
CEH or Constant Entry Hole design are angled toward the toe so as
to create a perforation which might more readily accept fluid and
sand with less erosion, and with a lower pressure drop. Field
results have been promising, with lower pressure drops observed
during treatment, and hinting that the discharge coefficient might
be higher than with systems having shaped charges with no
angle.
[0008] Shaped charges which create slots have also been used to
create noncircular perforation tunnels. These charges have been
used in arrangements where the slot was perpendicular to the well
axis (as shown in FIG. 2 for slot 132) for the purpose of plug and
abandonment (channel finding), and at an angle to the axis for
fracturing in vertical wells (Saber jet technology). The slots have
been generated through nonuniformity in the casing, or as a modular
linear charge that has been shortened for use in perforating guns.
Slot based charges have the disadvantage that the resultant jet is
spread over a broad area, resulting in extreme sensitivity to the
water gap in the pressurized well. Slot creating perforators
therefore would create a large variation in the hole size in the
horizontal wells, which would be disadvantageous for this
application. Further, slot perforators have not been developed in
systems where the slots are oriented in line with the well axis so
as to provide beneficial proppant and fluid transport from the well
to the formation during hydraulic fracturing operations.
[0009] Thus, there is a need to form slots into the casing, to
control an orientation of the slots along the casing, and to design
shaped charges that would achieve these results on a consistent
basis.
SUMMARY
[0010] According to an embodiment, there is a shaped charge for
making an asymmetrical perforation into a casing. The shaped charge
includes a case extending along a symmetry axis X and having a back
wall and an open end; an explosive material located within the
case; a liner located within the case, over the explosive material;
a booster material; and an asymmetrical feature. The asymmetrical
feature is selected to generate an asymmetrical perforation into
the casing.
[0011] According to another embodiment, there is a liner for
covering an explosive material in a case of a shaped charge. The
liner includes a metallic powdered material, a binder that holds
together the metallic powdered material, and an insert located
partially within the metallic powdered material. The liner has a
concave shape.
[0012] According to still another embodiment, there is a shaped
charge for making an asymmetric perforation in a casing of a well.
The shaped charge includes a case extending along a symmetry axis X
and having a back wall and an open end, an explosive material
located at the back wall of the case, a liner located within the
case, over the explosive material, and a booster material located
in a channel formed in the back wall of the case. The liner
includes a metallic powdered material; a binder that holds together
the metallic powdered material; and an insert located partially
within the metallic powdered material. The liner has a concave
shape.
[0013] According to yet another embodiment, there is a gun for
perforating asymmetrically a casing of a well. The gun includes a
gun carrier; and a shaped charge located inside the gun carrier and
having a liner placed over an explosive material, where the liner
includes a metallic powdered material; a binder that holds together
the metallic powdered material; and an insert located partially
within the metallic powdered material. The liner has a concave
shape.
[0014] According to another embodiment, there is a method for
making a shaped charge that is capable of making an asymmetric
perforation into a casing. The method includes providing a case
that extends along a symmetry axis X and has a back wall and an
open end; making a channel through the back wall; installing a
booster material into the channel; adding an explosive material to
the back wall of the case; forming a liner; and placing the liner
within the case, over the explosive material. The shaped charge has
an asymmetrical feature selected to make the asymmetric perforation
into the casing.
[0015] According to another embodiment, there is a gun for
perforating a casing in a well. The gun includes a gun carrier and
an asymmetric shaped charge located inside the gun carrier. The
shaped charge has an asymmetrical feature selected to make an
asymmetric perforation into the casing.
[0016] According to another embodiment, there is a casing that was
perforated with an asymmetrical shaped charge. The casing includes
a round wall; and an elongated perforation formed in the round wall
with the shaped charge. A longitudinal axis x2 of the elongated
perforation extends along a desired direction as a result of using
the asymmetrical shaped charge.
[0017] According to another embodiment, there is a method for
making an asymmetrical perforation in a casing. The method includes
lowering a gun into the casing of a well; firing an asymmetric
shaped charge located inside a gun carrier of the gun; and forming
the asymmetrical perforation in the casing due to the asymmetric
shaped charge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate one or more
embodiments and, together with the description, explain these
embodiments. In the drawings:
[0019] FIG. 1 illustrates a well and associated equipment for well
completion operations;
[0020] FIG. 2 illustrates various holes formed in a casing due to
shaped charges;
[0021] FIG. 3 illustrates how the size of the holes made in the
casing is influenced by the water gap between the casing and the
gun;
[0022] FIG. 4 illustrates an asymmetrical shaped charge having a
tilted liner;
[0023] FIG. 5 illustrates an asymmetrical shaped charge having an
asymmetrical channel and booster material;
[0024] FIG. 6 illustrates an asymmetrical shaped charge having two
asymmetrical channels;
[0025] FIG. 7 illustrates an asymmetrical shaped charge having an
explosive material with a varying characteristic;
[0026] FIG. 8 illustrates an asymmetrical shaped charge having an
insert;
[0027] FIG. 9 illustrates an asymmetrical shaped charge having an
insert with a window;
[0028] FIG. 10 illustrates an asymmetrical shaped charge having an
insert attached to a liner;
[0029] FIG. 11 is a top view of the asymmetrical shaped charge
having the insert attached to the liner;
[0030] FIG. 12 illustrates the distribution of the initiation
points;
[0031] FIG. 13 illustrates an asymmetrical shaped charge having an
asymmetrical case;
[0032] FIG. 14 is a flowchart of a method for making an
asymmetrical shaped charge;
[0033] FIG. 15 illustrates a liner having an insert completely
embedded into the liner;
[0034] FIG. 16 illustrates a liner having an insert asymmetrically
embedded into the liner;
[0035] FIG. 17 illustrates a liner having an insert flush with a
surface of the liner;
[0036] FIG. 18 illustrates a liner having an insert and a certain
profile;
[0037] FIGS. 19A to 19D illustrate various perforations that may be
made in a casing with one or more of the shaped charges discussed
herein;
[0038] FIG. 20 is a flowchart of a method for making a liner as
illustrated in one of the FIGS. 15-18; and
[0039] FIG. 21 illustrates a gun that has one or more of the shaped
charges discussed herein.
DETAILED DESCRIPTION
[0040] The following description of the embodiments refers to the
accompanying drawings. The same reference numbers in different
drawings identify the same or similar elements. The following
detailed description does not limit the invention. Instead, the
scope of the invention is defined by the appended claims. The
following embodiments are discussed, for simplicity, with regard to
a perforating gun used for perforating a casing in a well. However,
the embodiments discussed herein may be used for guns in another
context.
[0041] Reference throughout the specification to "one embodiment"
or "an embodiment" means that a particular feature, structure or
characteristic described in connection with an embodiment is
included in at least one embodiment of the subject matter
disclosed. Thus, the appearance of the phrases "in one embodiment"
or "in an embodiment" in various places throughout the
specification is not necessarily referring to the same embodiment.
Further, the particular features, structures or characteristics may
be combined in any suitable manner in one or more embodiments.
[0042] According to an embodiment, a shaped charge includes a case,
an explosive material, a liner, and a booster material. The
explosive material is sandwiched between the case and the liner and
the booster material is in contact with the explosive material, at
one edge of the explosive material. At least one of these elements
of the shape charge is made to be asymmetrical regarding a
longitudinal axis (symmetry axis) of the shaped charge. In one
variation, although all the above elements of the shaped charge are
symmetrical relative to the symmetry axis, one or more inserts are
added to one or more of these elements and the insert is made
asymmetrical. For example, the insert may be asymmetrical in shape
relative to the longitudinal axis. However, in one application, the
insert may have a symmetrical shape, but asymmetrical properties,
i.e., different physical properties as, for example, a melting
point, impedance, etc. In one application, the insert is made of an
inert material, i.e., a material that does not explode, ignite, or
burns under natural conditions. These possible implementations of
an asymmetrical shaped charge are now discussed.
[0043] A shaped charge 400 is illustrated in FIG. 4 as having a
case 402. Case 402 may be made of any material that is strong
enough to resist when the explosive material explodes. For example,
the case may be made of steel or a metal. The case may take any
shape, for example, conical, cylindrical, spherical, hemispherical,
bell-shaped, parabolic or hyperboloid. FIG. 4 shows the case 402
having a cup shape, with a solid back wall 404 having a channel 406
in which the booster material 430 is located. The back wall 404 is
also called herein a closed end. A pedestal 405, which is attached
to the back wall 404 (made either integrally or separately of the
pedestal) is used to attach the shaped charge to a carrier (not
shown) in the gun and affix the detonation cord. The channel 406
may extend through the pedestal 405, along the symmetry axis X. The
back wall 404 continues with a side wall 408 that is shaped as a
cup. A top 409 of the case 402 is open. For this reason, this part
of the case is called an open end.
[0044] An explosive material 410 is placed inside the cup shaped
case 402. The explosive material 410 is typically packed inside the
case 402 by micro-forging or other methods. The explosive material
may be a high explosive material, like NONA, ONT, RDX, HMX, HNS,
BRX, PETN, CL-20, HNIW, PYX, TATB, TNAZ, HNIW, or other known
explosive. The liner 420 covers the explosive material 410 and
keeps it inside the case 402. The liner 420 may be made of a
reactive or an inert material, e.g., metal particles mixed with a
light glue, so that the liner appears like a metallic sheet.
[0045] The booster material 430 is placed at the bottom of the case
402, in the channel 406. The booster material 430 is connected to a
detonation cord 440, which initiates the detonation of the booster
material 430. The booster material includes a detonation material,
which may be the same as the explosive material 410 or different.
When the gun is fired, the gun detonator is first detonated, which
initiates the detonation cord 440. The detonation cord 440
initiates the booster material 430. The detonation of the booster
material 430 starts the explosion of the explosive material 410.
Thus, in the embodiment of FIG. 4, there is a single initiation
point, at the interface between the booster material 430 and the
explosive material 410. The explosive material 410 is then
initiated, which generates a detonation wave. The detonation wave
collapses the liner 420 and melts it at the same time, resulting in
a jet of material, which is expelled from the case 402 through the
open end 409 with a high energy. If the arrangement of the elements
shown in FIG. 4 is symmetrical relative to the longitudinal axis X
(the terms "longitudinal axis X" and "symmetry axis X" are used
herein interchangeably), then the jet has substantially a circular
cross-section and would generate substantially a circular hole in
the casing of the well.
[0046] However, in the embodiment of FIG. 4, the liner 420 is not
made to be symmetrical to the longitudinal axis X. As shown in the
figure, the case 402 extends along the longitudinal axis X up to a
height having the coordinate x1. One side 420A of the liner 420
extends to a height having the coordinate x2 (which may be the same
or smaller than x1) and the opposite side 420B of the liner 420
extends to a height having the coordinate x3, which is different
from coordinate x2. This means that the liner 420 is tilted
relative to the case 402 and the symmetry axis. If the symmetrical
reference position 422 of the traditional liner relative to the
symmetry axis X is considered to correspond to a zero angle, the
tilted novel liner 420 can make any non-zero angle .theta. with the
reference position. In one application, it is possible that the
liner has its own symmetry axis X' and the entire liner is tilted
so that the symmetry axis X' makes the non-zero angle .theta. with
the symmetry axis X. However, in another embodiment, only a portion
of the liner is tilted while the remaining part of the liner is not
tilted, so that the liner itself has no symmetry axis. Irrespective
of how the non-symmetrical liner is implemented, the non-symmetry
of the liner would also make the explosive material 410 to be not
symmetric relative to the longitudinal axis X.
[0047] In another embodiment illustrated in FIG. 5, the explosive
material 410, the liner 420, and the case 402 are all symmetrical
relative to the longitudinal axis X. However, the booster material
430 is not symmetrical. FIG. 5 shows that the channel 506 is formed
to extend along a longitudinal axis X'', which makes a non-zero
angle .alpha. with the symmetry axis X. Note that in the embodiment
of FIG. 4, the longitudinal axis X and the axis X'' would have been
coincident if axis X'' would have been shown there. In other words,
the channel in FIG. 5 has a longitudinal axis X'', which makes a
non-zero angle with the symmetry axis X. This means that the
booster material fires along an axis that is not the symmetry axis
X. In one application, the booster material fires toward a side
wall 408 of the case 402.
[0048] As previously discussed, the booster material 430
constitutes the initiation point for the explosive material. Due to
the asymmetry of the booster material, the propagation of the
detonation front becomes also asymmetrical inside the explosive
material 410 while inside the case 402, which results in the
expelled jet being non-symmetrical. As will be discussed later, by
controlling the asymmetry of the shaped charge, the expelled jet is
expected to form a key hole shape in the casing or a slot with a
desired orientation relative to a longitudinal axis of the casing
of the well.
[0049] In one embodiment, it is possible to combine the asymmetric
features shown in FIGS. 4 and 5, i.e., to have a shaped charge with
a tilted liner and the booster material oriented away from the
symmetry axis X of the case.
[0050] According to another embodiment, as illustrated in FIG. 6,
the channel 606 is physically offset from the symmetry axis X, with
a given distance d. In this way, the channel 606 is asymmetrically
positioned relative to the symmetry axis X and/or the case 402, so
that the generated jet is expected to form a key hole or slot shape
into the casing of the well. In still another embodiment, the
channel 606 axis X'' may make a non-zero angle with the symmetry
axis X, similar to the embodiment shown in FIG. 5, except that the
channel 606 is also offset from the symmetry axis X. In yet another
embodiment, one or more additional channels 606' may be formed in
the base wall 404, also offset from the symmetry axis X. The
additional channel 606' extends along its own longitudinal axis
X''', which may be parallel to axis X'' of channel 606, or they may
make a non-zero angle. In one application, the two channels 606 and
606' are located asymmetrically relative to the symmetry axis X, as
shown in FIG. 6. In still another application, one of the channels
606 and 606' is oriented to have the longitudinal axis parallel to
the symmetry axis X while the other channel makes a non-zero angle
with the symmetry axis X. Any other variation of these arrangements
that achieves a non-symmetrical jet may be used, for example,
combining one or both of the embodiments illustrated in FIGS. 4 and
5 with this embodiment.
[0051] According to another embodiment, which is illustrated in
FIG. 7, the explosive material 410 is made to have at least two
different volumes 712 and 714 that differ from each other in one
characteristic. The volumes may have any shape, may be the same or
different, as long as an asymmetry in the generated jet is
achieved. The characteristic may be the chemical composition,
density, electrical impedance, strength, thermodynamic stability,
etc. This embodiment may be combined with one or more of the
previously discussed embodiments to further control the asymmetry
of the generated jet.
[0052] In another embodiment, as illustrated in FIG. 8, an insert
800 is added to the shaped charge to achieve the desired asymmetry.
The insert 800 may have any shape, may be made of ferrous, inert or
composite materials, may have any thickness and may be positioned
anywhere inside the explosive material 410 as long as it generates
an asymmetry in the detonation wave, to obtain a controlled
asymmetrical jet. Although the insert 800 is shown in FIG. 8 as
being placed in one half of the case 402, it is possible to place
the insert to extend in both halves of the case. Also, the
thickness of the insert does not have to be constant as illustrated
in the figure. The insert 800 is not placed to separate the
explosive material 410 from the booster material 430.
[0053] In one variation of the embodiment of FIG. 8, the insert is
attached to the case 402, either as insert 810 to the wall 408, or
as insert 820 to the back wall 404. In still another application,
an insert 830 may be placed inside the channel 406. In one
embodiment, one or more of the inserts 800, 810, 820, and 830 may
be located inside the case 402. One or more of the inserts 800,
810, 820, and 830 may have a window 802 cut into it, as illustrated
in FIG. 9, which shows a top view of the shaped charge 400. Th
inserts discussed herein may be combined in any way.
[0054] In another variation of the embodiment of FIG. 8, the insert
may be attached to the liner 420 as illustrated in FIG. 10 (see
element 1000). The insert 1000 may be made of metal, ceramic,
polymer or other materials. Similar to the embodiments of FIGS. 8
and 9, the insert 1000 may have any shape, thickness or may have a
window. The insert 1000 may directly deposited on the liner with a
3D printer. In one application, the insert 1000 is achieved by
painting the back of the liner 420 with a thick bead substance, for
example, glyptol, glue, epoxy, or other polymers. In still another
application, the insert 1000 may be a pocket of air or air trapped
within a printed or foamed material. The insert 1000, similar to
the insert 800, may be attached to only a sector of the liner 420,
or all around the liner as illustrated in FIG. 11, which shows a
top view of the liner. While FIGS. 10 and 11 shows the formation of
the insert 1000 on the back of the liner, i.e., between the liner
and the explosive material 410, it is also possible to form the
insert on top of the liner, on the opposite side of the explosive
material. Note that the various asymmetric features discussed in
the previous embodiments may be combined in any way.
[0055] For any of the above discussed embodiments, if two inserts
1200 and 1210 are used, they may be distributed inside the case 402
so that an angle .beta. between the two inserts is in the range of
165 to 195.degree., as illustrated in FIG. 12. In this way, a
variable initiation profile in the initiation section (i.e.,
booster material) of the shaped charge is obtained, which is
responsible for the generation of an asymmetric detonation wave
front, which ultimately results in the asymmetric jet. This
asymmetric jet then creates the key hole and/or slots in the casing
of the well. The inserts discussed above can be made, not only of
metallic, polymer or plastic materials, but also from ceramic,
e.g., silica sand.
[0056] In still another embodiment, as illustrated in FIG. 13, it
is possible to make the case 402 to be asymmetrical. The wall 408
is made to have a part 408A having a first shape and another part
408B having a different shape. The shape is directly associated
with the volume of explosive material 410 held by the respective
part. For example, FIG. 13 shows the part 408A of the wall being
shaped to hold less explosive material 410 than the wall part 408B.
The same is true for the parts 404A and 404B of the back wall. Note
that channel 406 still extends along the former symmetry axis X,
which is not a symmetry axis for this embodiment.
[0057] The liner 420 has a smaller part 422 that corresponds to the
smaller volume of explosive material hold by the part 408A of the
lateral wall 408 and a larger part 424 corresponding to the part
408B. Thus, for the embodiment shown in FIG. 13, each of the case
402, the liner 420, and the explosive material 410 are asymmetrical
relative to the symmetry axis X. In one modification of this
embodiment, it is possible to make the liner 420 and the explosive
material 410 symmetrical relative to an axis X' parallel to
symmetry axis X. Further, in another modification, it is also
possible to tilt the liner, or to implement any of the asymmetries
discussed above with regard to FIGS. 4-12.
[0058] A method for manufacturing an asymmetrical shaped charge 400
(as shown in any of the FIGS. 4-13) is now discussed with regard to
FIG. 14. In step 1400, a case 402 is provided. The case 402 may
have a symmetry axis X, which is also a longitudinal axis. However,
the case may also be asymmetric. In step 1402, the channel 406 is
made into the back wall 404 of the case 402. The channel 406 may be
made along the symmetry axis X, inclined relative to this axis, or
offset from the symmetry axis. If the channel 406 is made offset
from the symmetry axis X, it may also be made to extend along an
axis X'' that is parallel to the symmetry axis X, or axis X'' makes
a non-zero angle with the symmetry axis X. In one embodiment, more
than one channel 406 is formed into the back wall 404 of the case
402, so that all these channels are asymmetrically distributed
relative to the symmetry axis X.
[0059] In step 1404, the booster material 430 is placed into the
channel 406 by any known method. If more than one channel 406 is
formed, the channels may be distributed as illustrated in FIG. 12,
to achieve a desired angle between the initiation points. In step
1406, the explosive material 410 is added to the interior of the
case 402. The explosive material can be added by any known means.
The explosive material 410 may be made to be uniform or not. If the
explosive material is not uniform, at least one characteristic of
the explosive material may vary inside the case, as discussed above
with reference to FIG. 7. In one application, another material may
be inserted at specific locations inside the case to vary the
characteristic (e.g., density, explosive strength, flammability) of
the explosive material. The another material may be the insert 800
or 1000 discussed above, or even air or another inert material. The
explosive material 410 may be made to be symmetrical or not
relative to the symmetry axis X. The symmetry refers to the
volumetric distribution of the explosive material, or to at least
another characteristic (as discussed above) of the explosive
material.
[0060] In step 1408 the liner 420 is formed. The liner may be
formed by injection mold, 3D print, machined, cast, extrusion,
stamping, mold, microforge, etc. The liner 420 may be made to be
symmetric relative to the symmetry axis X or not. In one
embodiment, one side of the liner is made larger than the other
side of the liner, as illustrated in FIG. 13. In one application,
the liner is shaped as a trumpet for directing the explosive energy
to a desired location. In optional step 1410, an insert 1000 may be
attached to the liner as illustrated in FIG. 10. Alternatively, an
insert 800 may be added to the explosive material 410 or the case
402 as illustrated in FIG. 8. In still another application, the
insert may be added to the channel 406, to make the entire shaped
charge asymmetrical, as shown in FIG. 8. Step 1410 may be performed
at any time during the method, depending where the insert is
placed. Finally, in step 1412 the liner is attached to the case so
that the shaped charge is ready to be used.
[0061] In the above discussed embodiments, the asymmetry of the
shaped charge has been added to one of the elements of the shaped
charge. However, it is possible to introduce an asymmetry into the
structure of the liner itself. Thus, the next embodiments discuss
these possibilities. FIG. 15 shows a liner 420 disposed
symmetrically around the symmetry axis X. However, different from
the previous embodiments, an insert 1500 is located completely
within the liner 420, i.e., no face or edge of the insert 1500 is
facing the explosive material 410 or the ambient above the shaped
charge 400. The insert 1500 may be made of the same materials as
the inserts 800 and 1000, and it may be manufactured by forging,
molding, or printing. The insert 1500 may be symmetric relative to
the symmetry axis X, extends along the liner 420, but not over the
entire liner so that a central portion 426 of the liner 420 has the
insert and a peripheral portion 428 of the liner is free of the
insert. Thus, in this embodiment, both the liner 420 and the insert
1500 are symmetrical relative to the symmetry axis X, but the
asymmetry of the shaped charge is achieved because the insert does
not extend over the entire liner.
[0062] The liner 1500 (and other liners illustrated in other
figures) may have a generally concave shape. The concave shape may
be symmetrical or not relative to the symmetry axis X. The concave
shape may be implemented in many ways, for example, as a trumpet,
cone, bell, hemispherical, etc. The liner 420 includes at least one
type of powdered metal 1502. The metal may be copper, tin, nickel,
tungsten, lead, molybdenum or a combination of these materials. The
metallic powder is held together with a binder 1504. The binder can
be a glue, polymer or other material. In one application, the liner
is machined from a solid piece of material. In another application,
the liner is printed, forged, or molded.
[0063] In another embodiment illustrated in FIG. 16, an insert 1600
is located only in one portion of the liner and not in an opposite
portion. Thus, the asymmetry of the shaped charge is achieved in
this embodiment because of the location of the insert within the
liner. The asymmetry shown in either FIG. 15 or FIG. 16 may be
combined with any of the previously discussed asymmetries of the
shaped charge.
[0064] The embodiment of FIG. 17 is similar to that of FIG. 16,
except that a face 1700A of the insert 1700 is fully exposed either
to the ambient or to the explosive material 410, i.e., a face of
the insert is flush with a front or back face of the liner 420.
[0065] The embodiment illustrated in FIG. 18 shows the liner 420
having the insert 1800 distributed according to any of the
embodiments of FIGS. 15-17, but an angle .gamma. between the
symmetry axis X and an arm of the liner is between 20 and
40.degree., or between 100 and 120.degree..
[0066] Any of the configurations discussed above achieves a jet of
material that is not symmetrical. Based on experiments performed by
the inventors, one or more of these asymmetrical configurations may
generate the following holes in a casing. FIG. 19A shows a part of
a casing 1902 that extends along a longitudinal axis X2, which
coincides with the longitudinal axis X1 of the well. A slot 1910 is
formed in the casing with one of the above shaped charge
configurations. The slot 1910 extends along the longitudinal axis
X1 due to the orientation of the asymmetry of the shaped charge.
The slot 1910 is defined as having a middle portion 1912 that has
the largest size along an axis Y1 perpendicular to the longitudinal
axis X1, and two end portions 1914 and 1916 that narrow when moving
away from the middle portion 1912.
[0067] FIG. 19B shows a key hole perforation 1920 formed in the
casing 1902. The key hole perforation 1920 is defined as having a
head portion 1922 that is substantially circular, and a tail
portion 1924, that has a decreasing size. The key hole perforation
1920 was made so that it extends along the X2 axis, with its head
portion closer to a heel of the casing (when the casing is used in
a horizontal well) so that the pumping of the slurry does not
erodes substantially this portion. In this embodiment, the shaped
charge is selected to have the longitudinal axis X2 of the key hole
aligned with the longitudinal axis X1 of the casing.
[0068] By changing the orientation and/or location of the asymmetry
in the shaped charge, it is possible to control the position of the
longitudinal axis X2 of the slot 1910 or key hole 1920. For
example, as shown in FIG. 19C, four key holes 1930-1 to 1930-4 are
formed so that their head portions are substantially superimposed
and their tails are distributed as the spokes of a wheel. For
obtaining such a configuration, four different shaped charges are
used. After the first key hole 1930-1 is made with a first shaped
charge, the gun is moved so that a second shaped charge is aligned
with the head portion of the first key hole. As the second shaped
charge is rotated relative to the first shaped charge, i.e., the
initiation point(s) of the first shaped charge are angularly offset
from the initiation point(s) of the second shaped charge, the
second shaped charge forms the second key hole 1930-2. The process
continues until all four shaped charges are fired and the
configuration shown in FIG. 19C is obtained. More or less than four
shaped charges may be fired at the same location of the casing for
obtaining a star configuration or a triangle configuration, or
other configurations.
[0069] FIG. 19D shows a configuration in which a slot 1940 and two
key holes 1950-1 and 1950-2 are formed to have a common area 1942.
Similar to the embodiment of FIG. 19C, more or less shaped charges
may be used to obtain different perforation configurations.
[0070] For all the embodiments discussed herein, while the
asymmetric shaped charges may be attached to the gun carrier to be
perpendicular to the longitudinal axis of the casing, it is also
possible to have the shaped charges installed with a non-zero angle
relative to the axial direction of the casing. In one embodiment,
it is possible that some asymmetrical shaped charges are
perpendicular to the longitudinal direction of the casing while the
other asymmetrical shaped charges are tilted to the axial
direction. Further, in one application it is possible to combine
traditional, symmetrical, shaped charges with one or more of the
novel asymmetrical shaped charges discussed above.
[0071] One advantage of making key hole perforations is that it can
be made in a consistent manner. Traditional slot charges are very
sensitive to the water gap and pressure, and will produce
suboptimal results in downhole conditions. The key hole perforation
produced with the asymmetrical shaped charge discussed above has a
consistent hole size, with the key hole extending the opportunity
for sand placement.
[0072] Another possible advantage is that the traditionally eroded
holes tend to be shaped like a key hole, so that by directly
producing a key hole perforation, it is likely to be less eroded by
the sand placement.
[0073] In one embodiment, the perforations will be a tapered slot,
generated by a slot producing charge being held at an angle within
the gun body (generally tilted toe-ward, but could be either way)
so that the travel distances for the various parts of the jet are
not symmetric, which will result in a narrowing slot.
[0074] A method for making the liner shown in FIGS. 15-18 is now
discussed with regard to the flowchart illustrated in FIG. 20. In
step 2000, the material for an insert 1500, 1600, 1700 or 1800 is
selected. In step 2002, the insert is made into the desired shape.
Any known method that is used for making the liner may be used to
form the insert. Then, in step 2004, the insert is positioned at
one of the positions shown in FIGS. 15-18, inside the material of
the liner, and in step 2006 the material of the liner is pressed
(other methods may be used) to create the liner. Note that at least
a first face of the insert is fully embedded within the liner as
illustrated in any of the embodiments of FIGS. 15-18. In one
embodiment, at least a second face of the insert is partially, if
not totally embedded within the liner. In some embodiments, more
than two faces (even all the faces) of the insert are fully
embedded into the liner. In still another embodiment, only one face
is not fully embedded into the liner.
[0075] A gun having one or more of the shaped charged discussed
with regard to FIGS. 4-20 is illustrated in FIG. 21. Gun 2100
includes a gun carrier 2110 that houses one or more shaped charges
400. The gun carrier may be shaped as a cylinder and may be sealed
from the casing of the well. A first shaped charge 400 has its
symmetry axis X making a non-zero angle with a radial axis Y, which
is perpendicular on the longitudinal axis L of the gun carrier.
However, a second shaped charge 400 is shown having its symmetry
axis X making a zero angle with the radial axis Y. Any number of
shaped charges 400 may be positioned within the gun carrier. In one
embodiment, traditional shaped charges 150 (discussed with regard
to FIG. 3) are mixed up with the asymmetrical shaped charges
400.
[0076] The disclosed embodiments provide methods and systems for
generating a slot or key hole perforation into a casing of a well,
by using at least a shaped charge that has an asymmetrical feature.
It should be understood that this description is not intended to
limit the invention. On the contrary, the exemplary embodiments are
intended to cover alternatives, modifications and equivalents,
which are included in the spirit and scope of the invention as
defined by the appended claims. Further, in the detailed
description of the exemplary embodiments, numerous specific details
are set forth in order to provide a comprehensive understanding of
the claimed invention. However, one skilled in the art would
understand that various embodiments may be practiced without such
specific details.
[0077] Although the features and elements of the present exemplary
embodiments are described in the embodiments in particular
combinations, each feature or element can be used alone without the
other features and elements of the embodiments or in various
combinations with or without other features and elements disclosed
herein.
[0078] This written description uses examples of the subject matter
disclosed to enable any person skilled in the art to practice the
same, including making and using any devices or systems and
performing any incorporated methods. The patentable scope of the
subject matter is defined by the claims, and may include other
examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims.
* * * * *