U.S. patent application number 13/180029 was filed with the patent office on 2012-01-12 for method and apparatus for a well employing the use of an activation ball.
Invention is credited to Piro Shkurti, Tracy Speer, John Chrysostom Wolf.
Application Number | 20120006562 13/180029 |
Document ID | / |
Family ID | 45437762 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120006562 |
Kind Code |
A1 |
Speer; Tracy ; et
al. |
January 12, 2012 |
METHOD AND APPARATUS FOR A WELL EMPLOYING THE USE OF AN ACTIVATION
BALL
Abstract
A system includes a tubular string and a hollow ball. The
tubular string is adapted to be deployed downhole in a well and
includes a seat. An activation ball adapted to be deployed in the
well to lodge in the seat. The ball includes an outer shell that
forms a spherical surface. The outer shell forms an enclosed volume
therein, and the outer shell is formed from a metallic
material.
Inventors: |
Speer; Tracy; (Houston,
TX) ; Shkurti; Piro; (The Woodlands, TX) ;
Wolf; John Chrysostom; (Houston, TX) |
Family ID: |
45437762 |
Appl. No.: |
13/180029 |
Filed: |
July 11, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61364267 |
Jul 14, 2010 |
|
|
|
61363547 |
Jul 12, 2010 |
|
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|
Current U.S.
Class: |
166/373 ;
166/318 |
Current CPC
Class: |
E21B 23/04 20130101 |
Class at
Publication: |
166/373 ;
166/318 |
International
Class: |
E21B 34/06 20060101
E21B034/06; E21B 34/00 20060101 E21B034/00 |
Claims
1. A system comprising: a tubular string adapted to be deployed
downhole in a well, the string comprising a seat; and an activation
ball adapted to be deployed in the tubular string to lodge in the
seat, the ball comprising an outer shell forming a spherical
surface, wherein the outer shell forms an enclosed volume therein
and the outer shell is formed from a metallic material.
2. The system of claim 1, further comprising a tool comprising the
seat, wherein the ball is adapted to lodge in the seat to create an
obstruction such that fluid pressure created due to the obstruction
activates the tool.
3. The system of claim 1, wherein the seat comprises one of a
plurality of seats of the string.
4. The system of claim 3, wherein the seats have form a set of
graduated openings to allow each of the seats to be selectively
targeted by an activation ball having a size associated with the
seat.
5. The system of claim 1, wherein the outer shell comprises a first
portion joined to a second portion.
6. The system of claim 5, wherein the first portion and the second
portions are joined using at least one selected from a group
consisting of welding, friction stir welding, threading, and
pressure fitting.
7. The system of claim 1, wherein the metallic material comprises
at least one selected from a group consisting of aluminum alloy,
magnesium alloy, nickel-cobalt base alloy, and steel.
8. The system of claim 1, wherein the aluminum alloy is one
selected from a group consisting of 6000 series aluminum alloys and
7000 series aluminum alloys.
9. The system of claim 1, further comprising a coating disposed on
the spherical surface of the outer shell.
10. The system of claim 1, wherein the enclosed volume is
hollow.
11. The system of claim 1, wherein the enclosed volume comprises a
filling, wherein the filling comprises at least one selected from a
group consisting of plastic, foam, fiber reinforced phenolic,
polyether ether ketone, thermoplastic, and pressurized gas.
12. The system of claim 1, further comprising a support structure
disposed on an inner surface of the outer shell.
13. The system of claim 12, wherein the support structure comprises
at least one selected from a group consisting of ribs, spindles,
and reinforcing rings.
14. The system of claim 12, wherein the support structure is formed
integral with the outer shell.
15. The system of claim 12, wherein the support structure is
connected to the inner surface of the outer shell using at least
one selected from a group consisting of welding, brazing, adhering,
mechanical fastening, and interference fitting.
16. The system of claim 1, wherein the specific gravity of the
activation ball is between about 1.00 and about 1.85.
17. The system of claim 1, wherein a pressure inside the enclosed
volume is greater than atmospheric pressure.
18. The system of claim 1, further comprising equipment disposed
within the enclosed volume, wherein the equipment comprises at
least one selected from a group consisting of sensors, receivers,
transceivers, transmitters, transponders, radio frequency
identification tags, and magnets.
19. A method comprising: deploying an activation ball in a downhole
tubular string in a well, the activation ball comprising an outer
shell having an enclosed volume therein, wherein the outer shell
comprises a metallic material; communicating the ball through a
passageway of the string until the ball lodges in a seat of the
tubular string to form an obstruction; and using the obstruction to
pressurize at region of the string.
20. The method of claim 19, further comprising using the
pressurization to activate a downhole tool.
21. The method of claim 19, wherein the communicating comprises
flowing the ball through at least one other seat associated with a
ball size larger than a size of the ball.
22. The method of claim 19, further comprising: flowing the ball
out of the seat and to the surface of the well.
23. The method of claim 19, wherein the outer shell comprises at
least one selected from a group consisting of aluminum alloy,
magnesium alloy, nickel-cobalt base alloy, and steel.
24. The method of claim 19, wherein the outer shell comprises at
least two portions.
25. The method of claim 19, wherein the ball further comprises a
fill material within the enclosed volume, the fill material being
different from the shell.
26. The method of claim 19, wherein the ball further comprises a
support structure in the enclosed volume of the outer shell.
27. The method of claim 26, wherein the support structure comprises
at least one selected from a group consisting of ribs, spindles,
and reinforcing rings.
28. The method of claim 19, wherein a pressure within the enclosed
volume of the outer shell is greater than atmospheric pressure.
Description
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application Ser. No.
61/364,267 entitled, "HOLLOW METALLIC ACTIVATION BALL," which was
filed on Jul. 14, 2010, and which is hereby incorporated by
reference in its entirety. This application also claims the benefit
under 35 U.S.C. .sctn.119(e) to U.S. Provisional Patent Application
Ser. No. 61/363,547 entitled, "ALLOY METALLIC ACTIVATION BALL,"
which was filed on Jul. 12, 2010, and which is hereby incorporated
by reference in its entirety.
TECHNICAL FIELD
[0002] The invention generally relates to a method and apparatus
for a well employing the use of an activation ball.
BACKGROUND
[0003] For purposes of preparing a well for the production of oil
and gas, at least one perforating gun may be deployed into the well
via a deployment mechanism, such as a wireline or a coiled tubing
string. Shaped charges of the perforating gun(s) may then be fired
when the gun(s) are appropriately positioned to form perforating
tunnels into the surrounding formation and possibly perforate a
casing of the well, if the well is cased. Additional operations may
be performed in the well to increase the well's permeability, such
as well stimulation operations and operations that involve
hydraulic fracturing, acidizing, etc. During these operations,
various downhole tools may be used, which require activation and/or
deactivation. As non-limiting examples, these tools may include
fracturing valves, expandable underreamers and liner hangers.
SUMMARY
[0004] In an embodiment, a system includes a tubular string and an
activation ball. The tubular string is adapted to be deployed in
the well, and the activation ball is adapted to be deployed in the
tubular string to lodge in the seat. The activation ball includes
an outer shell that forms a spherical surface. The outer shell
forms an enclosed volume therein, and the outer shell is formed
from a metallic material.
[0005] In another embodiment, a technique includes deploying an
activation ball in a downhole tubular string in a well. The
activation ball includes an outer shell that has an enclosed volume
therein. The outer shell includes a metallic material. The
technique includes communicating the ball through a passageway of
the tubular string until the ball lodges in a seat of the string to
form an obstruction (or fluid tight barrier), and the method
includes using the obstruction to pressurize a region of the
string.
[0006] Other features and advantages will become apparent from the
following description and the appended claims.
BRIEF DESCRIPTION OF DRAWING
[0007] FIG. 1 is a schematic diagram of a well according to an
embodiment of the invention.
[0008] FIG. 2 is a flow diagram depicting a technique using an
activation ball in a well according to an embodiment of the
invention.
[0009] FIGS. 3A, 3B and 3C are cross-sectional views of an
exemplary ball-activated tool of FIG. 1 according to an embodiment
of the invention.
[0010] FIG. 4 is a cross-sectional view of an activation ball in
accordance with embodiments disclosed herein.
[0011] FIG. 5 is a cross-sectional view of an activation ball in
accordance with embodiments disclosed herein.
[0012] FIG. 6 is a cross-sectional view of an activation ball in
accordance with embodiments disclosed herein.
[0013] FIG. 7A is a perspective view of an activation ball in
accordance with embodiments disclosed herein.
[0014] FIGS. 7B-7D are cross-sectional views of a portion of an
activation ball in accordance with embodiments disclosed
herein.
[0015] FIG. 7E is a perspective view of a portion of an activation
ball in accordance with embodiments disclosed herein.
DETAILED DESCRIPTION
[0016] Systems and techniques are disclosed herein for purposes of
using a light weight activation ball to activate a downhole tool.
Such an activation ball may be used in a well 10 that is depicted
in FIG. 1. For this example, the well 10 includes a wellbore 12
that extends through one or more reservoir formations. Although
depicted in FIG. 1 as being a main vertical wellbore, the wellbore
12 may be a deviated or horizontal wellbore, in accordance with
other embodiments of the invention.
[0017] As depicted in FIG. 1, a tubular string 20 (a casing string,
as a non-limiting example) extends into the wellbore 12 and
includes packers 22, which are radially expanded, or "set," for
purposes of forming corresponding annular seal(s) between the outer
surface of the tubular string 20 and the wellbore wall. The packers
22, when set form corresponding isolated zones 30 (zones 30a, 30b
and 30c being depicted in FIG. 1, as non-limiting examples), in
which may be performed various completion operations. In this
manner, after the tubular string 20 is run into the wellbore 12 and
the packers 22 are set, completion operations may be performed in
one zone 30 at a time for purposes of performing such completion
operations as fracturing, stimulation, acidizing, etc., depending
on the particular implementation.
[0018] For purposes of selecting a given zone 30 for a completion
operation, the tubular string 20 includes tools that are
selectively operated using light weight activation balls 36. As
described herein, each activation ball 36 is constructed from an
outer metallic shell and may be hollow, in accordance with some
implementations.
[0019] For the particular non-limiting example that is depicted in
FIG. 1, the downhole tools are sleeve valves 33. In general, for
this example, each sleeve valve 33 is associated with a given zone
30 and includes a sleeve 34 that is operated via a deployed
activation ball 36 to selectively open the sleeve 34. In this
regard, in accordance with some embodiments of the invention, the
sleeve valves 33 are all initially configured to be closed when
installed in the well as part of the string 20. Referring to FIG.
3A in conjunction with FIG. 1, when closed (as depicted in zones
30b and 30c), the sleeve 34 covers radial ports 32 (formed in a
housing 35 of the sleeve valve 33, which is concentric with the
tubular string 30) to block fluid communication between a central
passageway 21 of the tubular string 20 and the annulus of the
associated zone 30. Although not shown in these figures, the sleeve
valve 33 has associated seals (o-rings, for example) for purposes
of sealing off fluid communication through the radial ports 32.
[0020] The sleeve valve 33 may be opened by deployment of a given
activation ball 36, as depicted in zone 30a of FIG. 1. Referring to
FIG. 3B in conjunction with FIG. 1, in this regard, the activation
ball 36 is deployed from the surface of the well and travels
downhole (in the direction of arrow "A") through the central
passageway 21 to eventually lodge in a seat 38 of the sleeve 34.
Referring to FIG. 3C in conjunction with FIG. 1, when lodged in the
seat 38, an obstruction (or fluid tight barrier) is created, which
allows fluid pressure to be increased (by operating fluid pumps at
the surface of the well, for example) to exert a downward force on
the sleeve 34 due to the pressure differential (i.e., a high
pressure "P.sub.high" above the ball 36 and a low pressure
"P.sub.low" below the ball 36) to cause the sleeve valve 33 to open
and thereby allow fluid communication through the associated radial
ports 32.
[0021] Referring to FIG. 1, in accordance with an exemplary,
non-limiting embodiment, the seats 38 of the sleeve valves 33 are
graduated such that the inner diameters of the seats 38 become
progressively smaller from the surface of the well toward the end,
or toe, of the wellbore 12. Due to the graduated openings, a series
of varying diameter hollow activation balls 36 may be used to
select and activate a given sleeve valve. In this manner, for the
exemplary arrangement described herein, the smallest outer diameter
activation ball 36 is first deployed into the central passageway 21
of the tubular string 20 for purposes of activating the lowest
sleeve valve. For the example depicted in FIG. 1, the activation
ball 36 that is used to activate the sleeve valve 33 for the zone
30a is thereby smaller than the corresponding hollow activation
ball 36 (not shown) that is used to activate the sleeve valve 33
for the zone 30b. In a corresponding manner, an activation ball 36
(not shown) that is of a yet larger outer diameter may be used
activate the sleeve valve 33 for the zone 30c, and so forth.
[0022] Although FIG. 1 depicts a system of varying, fixed diameter
seats 38, other systems may be used in accordance with other
embodiments of the invention. For example, in accordance with other
embodiments of the invention, a tubular string may contain valve
seats that are selectively placed in "object catching states" by
hydraulic control lines, for example. Regardless of the particular
system used, a tubular string includes at least one downhole tool
that is activated by an activation ball, which is deployed through
a passageway of the string. Thus, other variations are contemplated
and are within the scope of the appended claims.
[0023] Removing a given activation ball 36 from its seat 38 may be
used to relieve the pressure differential resulting from the
obstruction of the passageway 37 (see FIG. 3C) through the sleeve
valve 33. A seated actuation ball 36 may be removed from the seat
38 in a number of different ways. As non-limiting examples, the
activation ball 36 may be made of a drillable material so that
activation ball 36 may be milled to allow fluid flow through the
central passageway 21. Alternatively, the valve seat 38, the sleeve
34 or the activation ball 36 may be constructed from a deformable
material, such that the activation ball 36 may be extruded through
the seat 38 at a higher pressure, thereby opening the central
passageway 21. As yet another example, the flow of fluid through
the central passageway 21 may be reversed so that the activation
ball 36 may be pushed upwardly through the central passageway 21
toward the surface of the well. In this manner, a reverse
circulation flow may be established between the central passageway
21 and the annulus to retrieve the ball 36 to the surface of the
well. By reversing fluid flow to dislodge the activation ball 36,
the activation ball 36 is non-destructably removed from the well so
that both the activation ball 36 and the corresponding sleeve valve
may be reused.
[0024] When the activation ball 36 is retrieved by flowing fluid
upwardly through the central passageway 21, the activation ball 36
may have a particular specific gravity so that upwardly flowing
fluid can remove the activation ball 36 from the seat 38. While the
specific gravity of the activation ball 36 may be a relatively
important constraint, the activation ball 36 should be able to
withstand the impact of seating in the seat 38, the building of a
pressure differential across the ball 36 and the higher
temperatures present in the downhole environment. The failure of
the activation ball 36 to maintain its shape and structure during
use may lead to failure of the downhole tool, such as the sleeve
valve. For example, deformation of the activation ball 36 under
impact loads, high pressure for high temperatures may conceivably
prevent the activation ball 36 from properly sealing against the
seat 38, thereby preventing the effective buildup of a pressure
differential. In other scenarios, the deformation of the activation
ball 36 may cause the activation ball 36 to slide through the seat
38 and to become lodged in the sleeve 34, such that it may be
relatively challenging to remove the activation ball 36.
[0025] In embodiments where activation ball 36 is designed to be
retrieved by flowing fluid upwardly through the central passageway
21, the activation ball 36 may have the following specific physical
properties. Specifically, the activation ball 36 may have a
particular specific gravity so that the upward flowing fluid can
remove the activation ball 36 from the seat 38 and carry it upward
through central passageway 21. While the specific gravity of the
activation ball 36 may be a relatively important constraint, the
activation ball 36 may also be able to withstand the impact of
seating in the downhole tool, the building of a pressure
differential across the activation ball 36, and the high
temperatures of a downhole environment. Failure of the activation
ball 36 to maintain its shape and structure during use may lead to
failure of the downhole tool. For example, deformation of the
activation ball 36 under impact loads, high pressures, or high
temperatures may prevent activation ball 36 from properly sealing
against seat 38, thereby preventing the effective build up of a
pressure differential. In other scenarios, deformation of the
activation ball 36 may cause the activation ball 36 to slide
through the seat 38 and to become lodged in the sleeve 34, such
that conventional means of removing activation ball 112 may be
ineffective.
[0026] As disclosed herein, traditional activation balls may be
solid spheres, which are constructed from plastics, such as for
example, polyetheretherketone, or fiber-reinforced plastics, such
as, for example, fiber-reinforced phenolic. While a traditional
activation ball may meet specific gravity requirements,
inconsistency in material properties between batches may present
challenges such that the activation balls may be overdesigned so
that their strength ratings, pressure ratings and temperature
ratings are conservative. In accordance with embodiments of the
disclosed herein, the activation ball 36 is constructed out of a
metallic shell and as such, may be a hollow ball or sphere, which
permits the activation ball 36 to have desired strength properties
while being light enough to allow removal of the ball 36 from the
well.
[0027] Referring to FIG. 2, thus, in accordance with some
embodiments of the invention, a technique 50 includes deploying
(block 52) a shell-based activation ball, such as a hollow
activation ball, into a tubular string in a well and allowing
(block 54) the ball to lodge in a seat of the string. The technique
50 includes using (block 56) an obstruction created by the
activation ball lodging in the seat to increase fluid pressure in
the tubular string and using (block 58) the increased fluid
pressure to activate a downhole tool.
[0028] Referring to FIG. 4, a cross-sectional view of a hollow
activation ball 200 in accordance with embodiments disclosed herein
is shown. Hollow activation ball 200 includes an outer shell 202
having an enclosed hollow volume 204. Outer shell 202 may be formed
from a first portion 206 and a second portion 208 which may be
joined together using joining methods such as, for example,
welding, friction stir welding, threading, adhering, pressure
fitting, and/or mechanical fastening. As shown in FIG. 4, first and
second portions 206, 208 of outer shell 202 are joined using a weld
210; however, those of ordinary skill in the art will appreciate
that any known method of joining two parts may be used.
[0029] In certain embodiments, outer shell 202 may be formed from a
metallic material. The metallic material may include a metallic
alloy such as, for example, aluminum alloy and/or magnesium alloy.
Aluminum alloys from the 6000 series and 7000 series may be used
such as, for example, 6061 aluminum alloy or 7075 aluminum alloy.
Although the specific gravity of most metallic materials is greater
than 2.0, a hollow activation ball 200 in accordance with the
present disclosure may have a specific gravity less than 2.0.
Preferably, the specific gravity of hollow activation ball 200 in
accordance with embodiments disclosed herein is between about 1.00
and about 1.85.
[0030] Referring to FIG. 5, a cross-section view of an activation
ball 300 in accordance with embodiments disclosed herein is shown.
Similar to hollow activation ball 200 (FIG. 4), hollow activation
ball 300 includes an outer shell 302 having an enclosed volume 304.
Outer shell 302 may be formed from a first portion 306 and a second
portion 308, joined together using threads 320. One of ordinary
skill in the art will appreciate that other joining or coupling
methods may be used such as, for example, welding. Hollow
activation ball 300 may further include a coating 322 disposed over
an outer surface of outer shell 302. Coating 322 may be a corrosion
resistant material such as, for example, polytetrafluoroethylene,
perfluoroalkoxy copolymer resin, fluorinated ethylene propylene
resin, ethylene tetrafluoroethylene, polyvinylidene fluoride,
ceramic material, and/or an epoxy-based coating material. In
certain embodiments, coating 322 may include Fluorolon.RTM. 610-E,
available from Southwest Impreglon of Houston, Tex.
[0031] Coating 322 may be between 0.001 and 0.005 inches thick, and
may be applied by dipping outer shell 302 in the coating material,
by spraying the coating material onto outer shell 302, by rolling
outer shell 302 through the coating material, or by any other known
coating application method. In certain embodiments, coating 322 may
include a plating, an anodized layer, and/or a laser cladding. The
coating material and the thickness of coating 322 may be selected
such that activation ball 300 has an overall specific gravity
between about 1.00 and about 1.85. Additionally, the coating
material may be chosen to provide activation ball 300 with improved
properties such as, for example, improved corrosion resistance
and/or improved abrasion resistance. Specifically, the coating
material may be selected to prevent a reaction between the metallic
material of outer shell 302 and downhole fluids such as drilling
mud or produced fluid.
[0032] Referring to FIG. 6, a cross-section view of an activation
ball in accordance with embodiments disclosed herein is shown.
Hollow activation ball 400 includes an outer shell 402 having an
enclosed volume 404. Outer shell 402 may include a first portion
406 and a second portion 408 joined using an interference fit 424;
however, other joining methods such as welding, adhering, and
threading may be used. Enclosed volume 404 may include a fill
material 426 to provide additional support to shell 402 under high
impact loads, pressures, and temperatures. In certain embodiments,
fill material 426 may include at least one of a plastic, a
thermoplastic, a foam, and a fiber reinforced phenolic. Fill
material 426 may be selected such that the overall specific gravity
of activation ball 400 is between about 1.00 and about 1.85.
Although activation ball 400 is not shown including a coating, a
coating may be added similar to coating 322 shown on activation
ball 300 (FIG. 5).
[0033] In other embodiments, hollow volume 404 may be filled with a
gas such as, for example, nitrogen. The gas may be pressurized to
provide support within outer shell 402 which may allow activation
ball 400 to maintain its spherical shape under high impact loads,
pressures, and temperatures. Hollow volume 404 may be filled with
gas using an opening or port (not shown) disposed in outer shell
402. After a desired amount of gas is pumped into hollow volume 404
and a desired internal pressure is reached, the port (not shown)
may be sealed or capped to prevent gas from leaking out of
activation ball 400.
[0034] Referring to FIG. 7A, a perspective view of a joined outer
shell 502 including a first portion 506 and a second portion 508 in
accordance with embodiments disclosed herein is shown. Referring
now to FIG. 7B, a side cross-sectional view of second portion 508
of outer shell 502 is shown. Only second portion 508 of outer shell
502 is shown for simplicity, and those of ordinary skill in the art
will appreciate that the corresponding first portion 506 may be
substantially the same as second portion 508.
[0035] Outer shell 502 includes a hollow volume 504, an inner
surface 528, and a support structure 530 disposed on the inner
surface 528. Support structure 530 may include a reinforcing ring
532 as shown which may be coupled to inner surface 528 of second
portion 508 of outer shell 502. Although only one reinforcing ring
532 is shown, those of ordinary skill in the art will appreciate
that multiple reinforcing rings may be used having any desired
thickness, t, and any desired maximum width, w. Additionally,
although an inner face 534 of reinforcing ring 532 is shown
parallel to a central axis 536 of second portion 508, inner face
534 may alternatively be angled relative to central axis 536, or
may be arced to correspond with the curve of inner surface 528.
[0036] Referring to FIG. 7C, a side cross-sectional view of second
portion 508 of outer shell 502 is shown having a second type of
support structure 530 disposed therein. Ribs 538 are shown disposed
on inner surface 528 of second portion 508. Ribs 538 may take any
shape or size, and may extend along inner surface 528 in any
desired direction. As shown, ribs 538a, 538b, and 538c intersect
each other at junction 540; however, a plurality of ribs 538 may be
positioned within second portion 508 such that no contact between
ribs 538 occurs.
[0037] Referring to FIG. 7D, a side cross-sectional view of second
portion 508 of outer shell 502 is shown having a third type of
support structure 530 disposed therein. Specifically, spindles 542
may be used to help support outer shell 502, thereby maintaining
the shape of outer shell 502 under high pressures, impact loads,
and temperatures. In certain embodiments, a plurality of spindles
542 may extend radially outwardly from a center point 446 of an
assembled activation ball 500, and may contact inner surface 528 of
second portion 508 at an intersection 544. While specific examples
of support structure configurations have been described, one of
ordinary skill in the art will appreciate that other support
structure configurations may be used without departing from the
scope of embodiments disclosed herein.
[0038] Support structures 530 such as, for example, reinforcing
rings 532, ribs 538, and spindles 542, shown in FIGS. 7B-7D, may be
formed from a plastic, metal, ceramic, and/or composite material.
Specifically, metal support structures may be formed from cast iron
or low grade steel. In certain embodiments, support structures 530
may be formed integrally with first or second portions 506, 508 of
outer shell 502. Alternatively, support structures 530 may be
formed separately and may be assembled within outer shell 502 using
welding, brazing, adhering, mechanical fastening, and/or
interference fitting. Those of ordinary skill in the art will
appreciate that materials, designs, and dimensions of support
structures 530 may be selected to provide increased strength to
outer shell 502 while maintaining an overall specific gravity of
activation ball 500 between about 1.00 and about 1.85.
[0039] Referring to FIG. 7E, a perspective view of a first portion
506 of outer shell 502 of activation ball 500 is shown. Support
structure 530 is shown disposed in hollow volume 504 of first
portion 506. The support structure 530 is an assembly of
reinforcing rings 532, ribs 538, and a spindle 542. Those of
ordinary skill in the art will appreciate that various
configurations of reinforcing rings 532, ribs 538, and spindles 542
may be used to create a support structure 530. Additionally,
although not specifically shown, a support structure 530 as
discussed above may be used in combination with a fill material
injected into enclosed volume 504.
[0040] In certain embodiments, enclosed volume 504 may also be used
to house equipment such as, for example, sensors. Sensors
configured to measure pressure, temperature, and/or depth may be
disposed within enclosed volume 504. Data collected by the sensors
may be stored in a storage device enclosed within volume 504, or
the data may be relayed to the surface of the wellbore.
[0041] Additionally, equipment such as, for example, receivers,
transmitters, transceivers, and transponders, may be disposed
within enclosed volume 504 and may send and/or receive signals to
interact with downhole tools. For example, radio frequency
identification (RFID) tags may be used as activation devices for
triggering an electrical device in another downhole tool. For
example, as the activation ball housing RFID tags passes through
the wellbore, the RFID tags may activate a timer linked to the
electrical device, which may lead to the performance of a desired
task. In certain embodiments, a frac valve may be opened by
initiating a corresponding timer using RFID tags and/or magnets
housed within an activation ball. A magnet disposed within enclosed
volume 504 may also be used to trigger and/or actuate downhole
tools.
[0042] An activation ball in accordance with some embodiments may
be manufactured by forming an outer shell out of a metallic
material, wherein the outer shell includes an enclosed volume
therein. In certain embodiments, the outer shell may be formed from
a magnesium alloy, an aluminum alloy, a steel alloy, or
nickel-cobalt base alloy. Specifically, an aluminum alloy may be
selected from 6000 series aluminum alloys or 7000 series aluminum
alloys, and a steel alloy may be selected from 4000 series steel
alloys. In particular 4140 steel may be used. A nickel-cobalt base
alloy such as, for example MP35N.RTM. may also be used. For ease of
manufacturing, the outer shell may be made up of multiple portions
joined together using, for example, welding, friction stir welding,
brazing, adhering, threading, mechanical fastening, and/or pressure
fitting. A wall thickness, tw, may vary depending on the material
selected for outer shell 502, so that an overall specific gravity
of activation ball 500 between about 1.00 and about 1.85 may be
achieved. An activation ball formed from high strength materials
such as MP35N.RTM. or 4140 steel may have an overall specific
gravity of about 1.2. The low specific gravity of an activation
ball formed from MP35N or 4140 steel may greatly increase the
likelihood of recovering the activation ball using reversed fluid
flow through the center bore in which the activation ball is
seated.
[0043] In some embodiments, manufacturing the activation ball may
further include filling the enclosed volume within the outer shell
with a fill material such as, for example, plastic, thermoplastic,
polyether ether ketone, fiber reinforced phenolic, foam, liquid, or
gas. The outer shell enclosed volume may be filled such that a
pressure inside of the outer shell is greater than atmospheric
pressure, thereby providing the activation ball with increased
strength against impact loads and high pressures.
[0044] Alternatively, a rigid support structure may be provided
within the enclosed volume of the outer shell. As discussed above,
reinforcing rings, ribs, and spindles may be used separately or in
combination to form the support structure. The support structure
may be formed integrally with the outer shell by machining,
casting, or sintering the outer shell. In another embodiment, the
support structure may be formed as a separate component and may be
later installed within the outer shell. In embodiments having a
support structure fabricated separately from the outer shell, the
support structure may be installed using welding, brazing,
adhering, mechanical fastening, and/or pressure fitting. The
support structure may be designed such that, when assembled within
the activation ball, pressure applied by the support structure to
the inner surface of the outer shell is greater than atmospheric
pressure.
[0045] Advantageously, embodiments disclosed herein provide for an
activation ball having increased strength under impact loads, high
pressures, and high temperatures, while having an overall specific
gravity between about 1.00 and about 1.85. Activation balls in
accordance with the present disclosure may also have greater
durability than activation balls formed from composite materials
which degrade over time. Further, activation balls having a metal
shell as disclosed herein may be more reliable due to the
consistency of mechanical properties between different batches of
metallic materials. Because of the consistency of mechanical
properties of metallic materials, and because of their high
strength, activation balls in accordance with the present invention
can be designed to have less contact area between the activation
ball and a corresponding bearing area. As such, activation balls
disclosed herein may allow for an increased number of ball
activated downhole tools to be used on a single drill string. As a
non-limiting example, by using an activation ball described in the
embodiments above, approximately twelve fracturing valves (such as
the sleeve valves 33) may be used during a multi-stage fracturing
process, whereas approximately eight fracturing valves may be used
with traditional activation balls.
[0046] While the present invention has been described with respect
to a limited number of embodiments, those skilled in the art,
having the benefit of this disclosure, will appreciate numerous
modifications and variations therefrom. It is intended that the
appended claims cover all such modifications and variations as fall
within the true spirit and scope of this present invention
* * * * *