U.S. patent application number 13/423158 was filed with the patent office on 2013-03-21 for multistage production system incorporating valve assembly with collapsible or expandable c-ring.
The applicant listed for this patent is Raymond Hofman, William Sloane Muscroft. Invention is credited to Raymond Hofman, William Sloane Muscroft.
Application Number | 20130068475 13/423158 |
Document ID | / |
Family ID | 47879541 |
Filed Date | 2013-03-21 |
United States Patent
Application |
20130068475 |
Kind Code |
A1 |
Hofman; Raymond ; et
al. |
March 21, 2013 |
Multistage Production System Incorporating Valve Assembly With
Collapsible or Expandable C-Ring
Abstract
A valve assembly, and related system and method, with an annular
sleeve having an inner surface with a diameter, a first cylindrical
outer surface, and a plurality of openings extending between the
inner surface and the first cylindrical outer surface. The annular
sleeve includes a second cylindrical outer surface having a
different diameter than the first cylindrical outer surface. A
first C-ring having a body with a seating surface, opposing
terminal ends, and an outer diameter extending from the body is at
least partially within the inner surface of the sleeve. A coil
spring is positioned around a portion of the sleeve and in an
annular space at least partially defined by an annular body and the
second cylindrical outer surface.
Inventors: |
Hofman; Raymond; (Midland,
TX) ; Muscroft; William Sloane; (Midland,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hofman; Raymond
Muscroft; William Sloane |
Midland
Midland |
TX
TX |
US
US |
|
|
Family ID: |
47879541 |
Appl. No.: |
13/423158 |
Filed: |
March 16, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61453288 |
Mar 16, 2011 |
|
|
|
61475333 |
Apr 14, 2011 |
|
|
|
61453281 |
Mar 16, 2011 |
|
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Current U.S.
Class: |
166/373 ;
166/316 |
Current CPC
Class: |
E21B 34/06 20130101;
E21B 43/26 20130101; E21B 34/14 20130101; E21B 2200/06
20200501 |
Class at
Publication: |
166/373 ;
166/316 |
International
Class: |
E21B 34/06 20060101
E21B034/06 |
Claims
1. A valve assembly for use in a subterranean well for oil, gas, or
other hydrocarbons, said valve assembly comprising: an annular
sleeve having an inner surface with a diameter, a first cylindrical
outer surface, and a plurality of openings extending between said
inner surface and said first cylindrical outer surface, wherein
said annular sleeve further comprises a second cylindrical outer
surface having a different diameter than the first cylindrical
outer surface. a first C-ring having a body with a seating surface,
opposing terminal ends, and an outer diameter extending from the
body, wherein the first C-ring is at least partially within the
inner surface of the sleeve; and a coil spring positioned around a
portion of the sleeve and in an annular space at least partially
defined by an annular body and the second cylindrical outer
surface.
2. The valve assembly of claim 1 wherein said first C-ring is
aligned with a circumferential groove formed in the inner surface
of the sleeve.
3. The valve assembly of claim 1 further comprising a plurality of
dogs positioned between radially outward of the outer diameter.
4. The valve assembly of claim 1 further comprising a second
seating surface having a second seating diameter.
5. The valve assembly of claim 4 wherein the second seating surface
is formed in a ball seat.
6. The valve assembly of claim 4 wherein the second seating surface
is formed in a second C-ring having a body, opposing terminal ends,
and an outer diameter extending from the body, wherein the second
C-ring is at least partially within the inner surface of the
sleeve.
7. The valve assembly of claim 6 wherein when one of said first
C-ring and said second C-ring is compressed, the other of said
first C-ring and said second is uncompressed.
8. The valve assembly of claim 6 wherein the diameter of the
seating surface of the first C-ring in a compressed state is
smaller than the diameter of the seating surface of the second
seating surface; and wherein the diameter of the seating surface of
the first C-ring in an uncompressed state is larger than the
diameter of the seating surface of the second seating surface.
9. The valve assembly of claim 6 wherein one of the first C-ring
and the second C-ring is compressed and the other of the first
C-ring and the second C-rings is uncompressed.
10. The valve assembly of claim 1 further comprising at least one
first mounting element having a first diameter and at least one
mounting element having a second diameter, wherein the sleeve is
movable between a first position wherein the openings are aligned
with the at least one first mounting element to the first C-ring
and a second position wherein the openings are aligned with the at
least one second mounting element.
11. A system of valve assemblies for use in a subterranean well for
oil, gas, or other hydrocarbons, said valve assembly comprising: a
first set of at least two tools, wherein each tool of the first set
of tools comprises a C-ring sized to be actuated by a first
resistor element having a first size and movable within the tool
interior between a first position in which the C-ring is compressed
and a second position in which the C-ring is uncompressed; a second
set of at least two tools, wherein each tool of the second set of
tools comprises a C-ring sized to be actuated by a second resistor
element having a second size that is smaller than the first size,
and is further movable within the tool interior between a first
position in which the C-ring is compressed and a second position in
which the C-ring is uncompressed; a first static seat tool
positioned between the first set of tools and the second set of
tools, said first static seat having seating surface sized to
engage with the first resistor element and not engage with the
second resistor element; and wherein each tool of said first set of
tools and said second set of tools comprises an annular sleeve at
least partially encircling the corresponding C-ring and a spring
positioned in an annular space partially defined by the
corresponding sleeve and operative to exert an expansive force
against the sleeve to resist a force applied to the seat by an
resistor element of corresponding ball size.
12. A method for treating a well for oil, gas or other
hydrocarbons, the method comprising: causing a first resistor
element to pass through a first set of tools and a first static
seat to at least one compressed C-ring of a second set of tools;
seating the first resistor element to against the seating surface
of the at least one compressed C-ring, wherein the at least one
compressed C-ring is associated with at least one sleeve in a first
position; causing a pressure differential of a first pressure value
across the first resistor element, said pressure value greater than
an opposing expansive force of at least one spring associated with
the at least one compressed C-ring to move the at least one sleeve
to a second position wherein the at least one C-ring becomes
uncompressed; causing the first resistor element to flow through
the at least one C-ring; and returning the at least one sleeve to
the first position using an expansive force of the at least one
spring.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This original nonprovisional application claims the benefit
of U.S. Provisional Application Ser. No. 61/453,288, filed Mar. 16,
2011 entitled "Multistage Production System Incorporating Valve
assembly With Collapsible or Expandable Split Ring," and U.S.
Provisional Application 61/475,333 filed Apr. 14, 2011 entitled
"Valve Assembly and System for Producing Hydrocarbons", each of
which is incorporated by reference herein.
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The described embodiments and claimed invention relate to a
tool for sequentially engaging and releasing a restrictor element
onto and from its corresponding valve seat, as well as systems and
methods incorporating such a tool for producing hydrocarbons from
multiple stages in a hydrocarbon production well.
[0005] 2. Background of the Art
[0006] In hydrocarbon wells, tools incorporating valve assemblies
having a restrictor element such as a ball or dart and a seat
element such as a ball seat or dart seat have been used for a
number of different operations. Such valve assemblies prevent the
flow of fluid past the assembly and, with the application of a
desired pressure, can actuate one or more tools associated with the
assembly.
[0007] One use for such remotely operated valve assemblies is in
fracturing (or "fracing"), a technique used by well operators to
create and/or extend one or more cracks, called "fractures" from
the wellbore deeper into the surrounding formation in order to
improve the flow of formation fluids into the wellbore. Fracing is
typically accomplished by injecting fluids from the surface,
through the wellbore, and into the formation at high pressure to
create the fractures and to force them to both open wider and to
extend further. In many case, the injected fluids contain a
granular material, such as sand, which functions to hold the
fracture open after the fluid pressure is reduced.
[0008] Fracing multiple-stage production wells requires selective
actuation of valve assemblies, such as fracing sleeves, to control
fluid flow from the tubing string to the formation. For example,
U.S. Published Application No. 2008/0302538, entitled Cemented Open
Hole Selective Fracing System and which is incorporated by
reference herein, describes one system for selectively actuating a
fracing sleeve that incorporates a shifting tool. The tool is run
into the tubing string and engages with a profile within the
interior of the valve. An inner sleeve may then be moved to an open
position to allow fracing or to a closed position to prevent fluid
flow to or from the formation.
[0009] That same application describes a system using multiple
valve assemblies which incorporate ball-and-seat seals, each having
a differently-sized ball seat and corresponding ball. Frac valves
connected to ball and seat seals do not require the running of a
shifting tool thousands of feet into the tubing string and are
simpler to actuate than frac valves requiring such shifting tools.
Such ball and seat seals are operated by placing an appropriately
sized ball into the well bore and bringing the ball into contact
with a corresponding ball seat. The ball engages on a sealing
section of the ball seat to block the flow of fluids past the valve
assembly. Application of pressure to the valve assembly causes the
valve assembly to "shift", opening the frac sleeve.
[0010] Some valve assemblies are selected for tool actuation by the
size of ball or other restrictor element introduced into the well.
If the well or tubing string contains multiple ball seats, the ball
must be small enough that it will not seal against any of the ball
seats it encounters prior to reaching the desired ball seat. For
this reason, the smallest ball to be used for the planned operation
is the first ball placed into the well or tubing and the smallest
ball seat is positioned in the well or tubing the furthest from the
wellhead. Thus, these traditional valve assemblies limit the number
of valves that can be used in a given tubing string because each
ball size is only able to actuate a single valve. Further, systems
using these valve assemblies require each ball to be at least 0.125
inches larger than the immediately preceding ball. Therefore, the
size of the liner restricts the number of valve assemblies with
differently-sized ball seats. In other words, because a ball must
be larger than its corresponding ball seat and smaller than the
ball seats of all upwell valves, each ball can only seal against a
single ball seat and, if desired, actuate one tool.
[0011] The valve assembly provides a method for sequentially
sealing multiple valve seats with a single restrictor element and,
where desired, actuating tools associated with the valve assembly.
One embodiment allows multiple balls of the same size to actuate
tools in sequential stages.
BRIEF DESCRIPTION
[0012] The valve assembly described herein comprises a C-ring (also
called a split ring) having a body with a seating surface, opposing
terminal ends, and an external diameter extending radially from the
body. The C-ring may be compressed such that terminal ends of the
C-ring are in contact. In addition, the C-ring may be in an
uncompressed state wherein the terminal ends are not in contact.
The valve assembly further comprises one or more mounting elements
to engage the outer diameter of the split ring. Engagement of
mounting elements with the outer diameter causes the split ring to
expand or contract.
[0013] Valve assemblies as described herein may further comprise a
sleeve contained within a tubular housing, the sleeve having an
inner surface, an outer surface, and a plurality of openings
extending between said inner and outer surfaces. The openings are
aligned to engage with the external diameter of the split ring. The
tubular housing may have one or more mounting elements aligned
within the openings in the sleeve, such that the mounting elements
may engage the external diameter of the split ring when the sleeve
is located at a desired position in the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side partial sectional view of a preferred
embodiment valve assembly with an inner sleeve in an upwell first
position.
[0015] FIG. 2 is a front elevation of the C-ring of the preferred
embodiment shown in FIG. 1.
[0016] FIG. 3 is a sectional view through line 3-3 in FIG. 1.
[0017] FIG. 4 is a side partial sectional view of a preferred
embodiment valve assembly shown in FIG. 1 with the inner sleeve in
a downwell second position.
[0018] FIG. 5 is a sectional view through line 5-5 of FIG. 4.
[0019] FIG. 6 is a side partial sectional view of the preferred
embodiment with the inner sleeve in an intermediate position
between the first and second positions described with reference to
FIG. 1 and FIG. 4, respectively.
[0020] FIG. 7 is a side sectional elevation of a system
incorporating multiple tools having the features of the preferred
embodiment.
[0021] FIGS. 8A & 8B illustrate an alternative embodiment
showing a valve assembly with two seating elements
DETAILED DESCRIPTION
[0022] When used with reference to the figures, unless otherwise
specified, the terms "upwell," "above," "top," "upper," "downwell,"
"below," "bottom," "lower," and like terms are used relative to the
direction of normal production and/or flow of fluids and or gas
through the tool and wellbore. Thus, normal production results in
migration through the wellbore and production string from the
downwell to upwell direction without regard to whether the tubing
string is disposed in a vertical wellbore, a horizontal wellbore,
or some combination of both. Similarly, during treatment of a well,
which may include a fracturing, or "fracing," process, fluids move
from the surface in the downwell direction to the portion of the
tubing string within the formation to be treated.
[0023] FIG. 1 shows a preferred embodiment tool 20, which comprises
a housing 22 connected to a bottom connection 24 at a threaded
section 26. The housing 22 has a plurality of radially-oriented,
circumferentially-aligned ports 28 providing communication paths to
and from the exterior of the tool.
[0024] The housing 22 has a first cylindrical inner surface 30
having a first inner diameter, a second cylindrical inner surface
32 located downwell of the first inner surface 30 and having a
second inner diameter that is greater than the first inner
diameter, and a third cylindrical inner surface 34 having a third
inner diameter that is greater than the second cylindrical inner
surface 32. The first inner surface 30 is longitudinally adjacent
to the second inner surface 32, forming a downwell-facing shoulder
having an annular shoulder surface 38. The second and third inner
surfaces 32, 34 are separated by a partially-conical surface
40.
[0025] The bottom connection 24 includes a first cylindrical inner
surface 42 having a first inner diameter and a second cylindrical
inner surface 44 having a second inner diameter. The first and
second inner cylindrical surfaces 42, 44 are separated by an inner
partially-conical inner surface 46. An annular upper end surface 47
is adjacent to the first inner surface 42.
[0026] The tool 20 comprises an annular sleeve 48 nested radially
within the housing 22 and positioned downwell of the shoulder 38.
The sleeve 48 has an upper outer surface 50 with a first outer
diameter and a second outer surface 52 with a second outer diameter
less than the first inner diameter. The first outer surface 50 and
second outer surface 52 are separated by an annular shoulder
surface 54. The sleeve 48 further comprises a cylindrical inner
surface 56 that extends between annular upper and lower end
surfaces 58, 60 of the sleeve 48.
[0027] In FIG. 1, the sleeve 48 is in a first position radially
between the plurality of housing ports 28 and the center of the
flowpath. In this position, the annular sleeve 48 inhibits fluid
flow between the flowpath and the exterior of the tool. The sleeve
48 extends between the shoulder 38 of the housing and the first
inner surface 42 of the bottom connection 24.
[0028] The valve assembly may further comprise a guide element to
position the split ring in the desired location. The guide element
in the embodiment of FIG. 1 is a spring 64 residing in an annular
spring return space 62. The annular spring return space 62 is
partially defined by the second outer surface 52 of the sleeve 48
and the third inner surface 34 of the housing 22. The spring return
space is further defined by the upper end surface 47 of the bottom
connection 24, the partially-conical surface 40 of the housing 22,
and the shoulder surface 54 and first outer surface 50 of the
sleeve 48.
[0029] In the embodiment illustrated by the figures, the C-ring 70
is positioned within the annular sleeve 48 between the upper end
surface 58 and the shoulder surface 54. The C-ring 70 fits into a
groove formed in the inner surface 56 of the shifting sleeve 48.
The groove is sufficiently deep to allow the C-ring seating surface
to expand to the desired maximum diameter. In some embodiments, the
desired maximum diameter may be as large as or larger than the
inner diameter of the shifting sleeve. Those of skill in the art
will appreciate that, in embodiments in which the C-ring activates
a sleeve or other valve assembly, the C-ring 70 may be positioned
at any point along the sleeve or tool, or above or below the
sleeve, provided that the C-ring and the sleeve or other tool are
connected such that sufficient pressure applied to the C-ring will
slide the sleeve in relation to the inner housing or otherwise
activate the tool.
[0030] The C-ring 70 has an inner surface 74 an outer surface 76
defining the outer perimeter of the C-ring, and a seating surface
72 engagable with a restrictor element having a corresponding size.
In the illustrated embodiment, the C-ring 70 is held in a radially
compressed state by the first inner surface 50 of the housing
22.
[0031] FIG. 2 shows a front elevation of one embodiment of the
C-ring 70 in a normal uncompressed state. In this embodiment, the
outer surface 76 of the C-ring 70 is castellated with a plurality
of radial protrusions 78, said radial protrusions defining the
outer diameter of the C-ring. The circumference of the outer
surface of the C-ring 70 may be larger than the circumference of
inner surface 56 of the sleeve 48. The C-ring 70 has a machined
slot 80 forming terminal ends 82. The slot 80 shown in the
illustrative figures is within a protrusion 78, but the slot 80 may
be formed at any point along the C-ring and does not have to be
formed in a protrusion 78.
[0032] Referring to the embodiment in FIG. 3, each of the radial
protrusions 78 of the illustrated C-ring 70 is aligned with and
extends through an opening 84 in the sleeve 48 between the first
outer surface 50 and the inner surface 56. When the C-ring 70 is
upwell of the partially-conical shoulder 40 of the housing 22, the
C-ring 70 has the operating diameter shown in FIG. 3 and terminal
ends 82 of C-ring 70 are in contact to form the seat defined by the
seating surface 72. An associated ball may thereafter seat against
the seating surface 72 and a pressure differential created across
the ball to move the sleeve 48 in the downwell direction.
[0033] FIGS. 4-5 show the tool 20 with the sleeve 48 in a second
position, which is downwell of the first position in one preferred
embodiment. The upper end surface 58 of the sleeve 48 has moved
past the ports 28, allowing fluid flow therethrough between the
flowpath and the exterior of the tool 20. The coil spring 64 is
under compression between the sleeve 48 and the bottom connection
24, with the upper end coil 66 of the spring 64 in contact with the
sleeve shoulder 54 and the spring lower end 68 is in contact with
the upper end surface 47 of the bottom connection 24. In this
position, the spring 64 exerts an expansive force to urge the
sleeve 48 in the upwell direction relative to the bottom connection
24.
[0034] Referring to FIG. 5, the C-ring 70 is positioned adjacent to
the third inner surface 34. Because the third inner surface 34 has
a larger diameter than the second inner surface 32, the C-ring 70
radially expands towards its uncompressed shape shown in FIG. 2.
The protrusions 78 extend past the outer surface 50 of the sleeve
48, opening the seating surface 72 and allowing the associated
restrictor element to pass through the C-ring 70, after which the
spring 64 pushes against the sleeve shoulder 54 to move the sleeve
48 upwell toward the first position shown in FIG. 1. Movement of
the sleeve 48 past the position shown in FIG. 1 is limited by
contact of the upper end surface 58 with the housing shoulder
38.
[0035] FIG. 6 shows the sleeve 48 in an intermediate third position
between the first position shown in FIG. 1 and the second position
shown in FIG. 4. A restrictor element 100 is seated against the
seating surface 72 and obstructs fluid flow from through the C-ring
70 to create a differential pressure to move the sleeve 48 against
the expansive force of the spring 64. The upper end surface 58 of
the sleeve 48 is positioned such that the flow ports 28 are in
fluid communication with the interior of the tool 20, allowing
fluid communication between the interior of the tool 20 with the
exterior of the tool 20. The C-ring 70 is held in a closed state by
the second inner surface 32 of the housing 22. In some embodiments,
a retaining element, not shown, may be placed in the sleeve to
define this intermediate position, such retaining element being set
such that it stops movement of the C-ring and sleeve up to a first
pressure, but allows movement of the c-ring at a second pressure.
Those of skill in the art will appreciate that many retaining
elements such as a shear ring, shear pins, or other device may be
used in conjunction with the valve assemblies described herein.
Further, mechanisms, assemblies, methods or devices other than a
retaining element may be used for defining the intermediate third
position in a valve assembly and any such method or element is
within the scope of the valve assemblies contemplated herein.
[0036] When the sleeve 48 is in the second position shown in FIG.
6, the well operator may thereafter cause the flow of fluids,
including acid, fracing fluids, or other fluid desired by the
operator, through the housing ports and into the formation adjacent
to the tool. In the illustrated embodiment, flow of such materials
will be blocked from downwell flow by the ball 100 positioned
against the seating surface 72, causing flow to be directed to the
surrounding formation through the housing ports 28. After fracing,
the differential pressure across the ball 100 may be increased to
cause the ball 100 to move the sleeve 48 further downwell to the
position shown in FIG. 3, where upon the ball will be released by
the expanding C-ring.
[0037] FIG. 7 shows a hydrocarbon producing formation 200 and a
system comprising an upper set of tools 202 positioned in an upper
stage 204 of the formation 200, an intermediate set of tools 206
positioned in an intermediate stage 208, and a lower set of tools
210 positioned within a lower stage 212. An upper static-seat tool
214 is positioned between the upper set of tools 202 and the
intermediate set of tools 206 and has an internal ball seat
corresponding to an upper-stage ball. An intermediate static-seat
tool 216 is positioned between the intermediate set of tools 206
and the lower set of tools 210 and has an internal ball seat
corresponding to an intermediate-stage ball. A lower static-seat
tool 218 is positioned downwell of the lower set of tools and has
an internal ball seat corresponding to a lower-stage ball. The
static-seat tools 214, 216, 218 have ball seats designed to allow
fluid flow therethough in either the upwell direction or the
downwell direction, but the ball seats are not connected to sleeves
or other movable components.
[0038] Each tool of the sets of the tools 202, 206, 210 has the
features described with reference to FIGS. 1-6. Each tool within
the upper set of tools 202 has a C-ring and associated sleeve sized
to be actuated by the associated upper-stage ball. Each tool within
the intermediate set of tools 206 has a C-ring and associated
sleeve sized to be actuated by an associated intermediate ball
smaller than the upper-stage ball. Each tool within the lower set
of tools 210 has a C-ring and associated sleeve sized to be
actuated by an associated lower-stage ball, which is smaller than
the upper ball, and the intermediate-stage ball.
[0039] To actuate the lower set of tools 210, the lower-stage ball
is caused to move through the tubing string and upper and
intermediate sets of tools 202, 206. The lower-stage ball is sized
to pass through the upper and intermediate sets of tools 202, 206
without being inhibited from further downwell flow by the
corresponding ball seat inserts.
[0040] Upon reaching the upwell tool 210a of the lower set of tools
210, the lower-stage ball seats against the closed C-ring of the
tool. The well operator can then increase the pressure within the
tubing string to overcome the expansive force of the associated
coil spring and shift the sleeve to the intermediate third position
described with reference to FIG. 6. When desired, the pressure
within the flowpath may be increased further to move the sleeve to
the second position described with reference to FIG. 4. After
moving the lower-stage ball through the C-ring, the pressure may be
decreased to cause the lower-stage ball to seat against the closed
C-ring of the lower tool 210b of the lower set of tools 210. While
the lower set of tools 210 only shows two tools 210a, 210b, any
number of similar tools may compose this stage. After moving
through all of such tools, the lower-stage ball seals against the
lower static-seat ball 218, which is sized to prevent passage
therethrough up to a pressure which damages the structure of the
ball This process may then be repeated, first with the intermediate
stage 208 using the intermediate-stage ball with the intermediate
sets of tools 206 and the intermediate static-seat tool 216, and
second with the upper stage 204 using the upper-stage ball with the
upper sets of tools 202 and upper static seat tool 214.
[0041] While the lower set of tools is shown comprising only three
stages of tools, the process could be repeated for any number of
tools within this stage. In addition, the same process described
above with respect to the lower set of tools is repeatable in
similar fashion for the intermediate and upper sets of tools 202,
206.
[0042] In an additional embodiment, the inwardly directed force
exerted on the outer surface of the C-ring is caused by a plurality
of dogs. In a preferred embodiment, the dogs are positioned in the
openings 84 of the sleeve, and each dog has a surface corresponding
to the curvature of the second inner surface 50 of the housing 22.
The surface profile of the dogs may have other shapes provided the
dogs can engage the protrusions 78 defining the outer surface of
the C-ring 70 as desired. The dogs are aligned with and adapted to
contact and exert a radially inward force on the protrusions 78 of
the C-ring 70 to force the C-ring 70 into the compressed state. In
this embodiment, the openings 84 have a length along the
longitudinal axis of the sleeve to allow the C-ring and sleeve to
move in relation to the dogs.
[0043] The dogs extend past first outer surface 50 of the sleeve
48, effectively reducing the diameter available to the protrusions.
When the C-ring 70 is positioned such that that protrusions 78
engage the dogs, the terminal ends 82 are in contact and the
diameter of the seating surface 72 and inner surface 74 of the
C-ring 70 are such that a properly-sized ball flowing through the
shifting sleeve will engage with the seat of the C-ring 70 as
described with reference to FIGS. 1-7. In one embodiment, the
C-ring and sleeve are engaged near the bottom of each of the
openings 84 such that movement of the C-ring in the downwell
direction moves the sleeve in the same direction and movement of
the sleeve in the upwell direction, typically by the force of a
spring or other guide device, will move the C-ring in the upwell
direction.
[0044] FIGS. 8A-8B show yet another embodiment in which a C-ring 70
starts in an uncompressed state and a sleeve 48 is oriented such
that the protrusions 78 comprising the outer surface of the C-ring
are in a larger-diameter section 300 of the housing 22 (shown in
FIG. 8A) The sleeve 48 is then shifted to the position shown in
FIG. 8B so that the protrusions 78 or forced from the
larger-diameter section 300 to a smaller-diameter section 302 of
the housing 22, which forces the C-ring 70 to a compressed state.
Thereafter, a properly-sized ball flowing 308 through the sleeve
would seat against compressed C-ring 70.
[0045] Still referring to FIG. 8A-8B, a system incorporating the
above-described embodiments may comprise multiple ball seats,
including multiple C-rings initially in either compressed and
uncompressed states. One such system would have an upper C-ring 70
fixed to the sleeve 48 and a lower seat 304 spaced sufficiently
apart to allow a first ball 306 of a particular size to seat on the
lower seat 304 without engaging or interfering with the upper seat
72. Systems in which the first ball engages the upper seat 72
without interfering with the lower seat 304 are also possible. A
first ball 306 engages the lower seat 304 and, using fluid
pressure, shifts the sleeve 48 to allow compression of the upper
seat 72 by positioning the upper seat 72 such that the outer
surface 76 of the C-ring 70 engages a smaller diameter surface 302
or appropriately positioned dogs. The C-ring 70 of the upper seat
72 becomes compressed and can thereafter engage a second ball 308
of a diameter selected for use with the upper seat 72. Those of
skill in the art will appreciate that, in the uncompressed state,
the upper C-ring 70 is configured such that balls large enough to
engage the lower seat 300 will pass without engaging the upper
C-ring 70. Further, the upper C-ring 70, when compressed, will
engage balls with a diameter that is too small to engage and hold
pressure on the lower seat 304.
[0046] One advantage to the system illustrated in FIGS. 8A-8B is
that restrictor elements which would activate the sleeve if the
C-ring were compressed can pass through the valve assembly of this
embodiment to activate tools further downwell. In other words, this
embodiment will allow the placement of valve seats configured to
utilize smaller restrictor elements upwell of valve seats
configured to use larger restrictor elements. This will increase
the flexibility of systems incorporating such valve assemblies and
can increase the number of valves that can be operating in a single
well.
[0047] This arrangement can be continued with any number of valve
assemblies in series per stage, with no limit on the number of
sleeves. Moreover, this system allows for an increase in the number
of stages. For example, a trio of tools using single valve seats
configured for a 2.0 inch, 1.875 inch, and 1.75 inch ball
respectively, can be placed in a well. A second trio of tools using
double valve seats with upper valves configured for use with 2.0
inch, 1.875 inches, and 1.75 inches are then placed upwell of the
first trio. The upper valve seats of this second trio of stages are
C-rings in the uncompressed state (as described with referenced
with respect to FIG. 8A) such that a 2.0 inch ball can pass through
each upper seat without engaging the seat sufficiently to move the
valve assembly in a downwell direction. The lower valve seats of
the second trio comprise C-ring valve seats configured to engage a
2.0 inch ball and to shift the assembly in response thereto.
[0048] In operation, a first 1.75 inch ball is placed in the well
and allowed to engage and activate the 1.75 inch stage of the first
trio of stages. A first 1.875 ball is placed in the well and
allowed to engage and activate the 1.875 inch stage of the first
trio of stages. Following the 1.875 inch ball, a first 2.0 inch
ball is placed in the well. This ball first engages the lower seat
of the 2.0 inch stage of the second trio of stages causing the seat
to shift and moving the upper ring from an uncompressed state to a
compressed state. The first 2.0 ball then engages the lower seat of
the 1.875 inch stage of the second trio of stages, causing the seat
to shift and moving the upper ring from an uncompressed to a
compressed state. The first 2.0 inch ball then engages the lower
seat of the 1.75 inch stage of second trio of stages, causing the
seat to shift and moving the upper ring from an uncompressed state
to a compressed state. Finally, the first 2.0 inch ball engages the
2.0 inch stage of the first trio of stages and activates the tools
associated with the valve assemblies of this stage.
[0049] At this point, three stages, associated with a 1.75 inch, a
1.875 inch, and a 2.0 inch valve assembly have been activated.
Further, the well now contains three additional stages that can be
activated by sequentially placing a 1.75 inch ball, a 1.875 inch
ball, and 2.0 inch ball into the well and allowing the balls to
engage their respective seats. This means that 6 stages, each stage
having the potential for multiple sleeves, can be activated through
use of 3 ball sizes. Further, the embodiments are not limited to
the nesting of three sizes. Further nesting is possible with the
valve assemblies and method of use contemplated herein, such
nesting limited only by the ability of the uncompressed ring to
allow larger sized balls to pass without shifting the seat.
[0050] It is possible that the lower seat is not a C-ring but
rather a solid seat for the ball or other restrictor means. Such a
solid seat can be paired with the applicants' resilient deformable
ball, described in applicant's U.S. patent application Ser. No.
13/423,154, entitled "Downhole System and Apparatus Incorporating
Valve Assembly With Resilient Deformable Engaging Element," filed
Mar. 16, 2012 and incorporated by reference herein, to allow for
engagement and subsequent release of the lower seat. In fact, any
method or device for engaging the lower seat to initially shift the
sleeve is permissible provided that it does not prevent the
treatment of any previously untreated stage.
[0051] The ball or other restrictor devices of the present valve
assemblies can either seat on the C-ring itself or the inside
diameter of the sleeve above the C-ring, where the sleeve is sized
sufficiently small such that the ball creates an interference seal
between the ball and sleeve, in which case the C-ring provides only
the mechanical restriction required to impart a load on the sleeve
for shifting.
[0052] This specification contains description of preferred
embodiments in which a specific system and apparatus are described.
Those skilled in the art will recognize that alternative
embodiments of such system and apparatus can be used. Other aspects
and advantages of the embodiments the invention as claimed may be
obtained from a study of this disclosure and the drawings, along
with the appended claims. Moreover, the recited order of the steps
of any method described herein is not meant to limit the order in
which those steps may be performed.
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