Note: Descriptions are shown in the official language in which they were submitted.
CA 02776598 2012-05-08
WELLBORE TOOLS AND METHODS
FIELD
The invention relates to wellbore tools and methods for wellbore completions
and, in
particular, for fluid control and injections.
BACKGROUND
Wellbore completion operations require tools for fluid control and injections.
For
example, packers are employed to control fluid flows and to isolate and direct
fluid
pressures. In addition or alternately, fluid delivery ports may be employed to
direct
injected fluid from delivery strings into particular areas of the formation.
SUMMARY
In accordance with a broad aspect of the present invention, there is provided
a straddle
packer tool comprising: a drag assembly including a tubular body defining an
inner bore
extending along the length of the tubular body and an outer facing surface
carrying a
locking mechanism for locking a position of the drag assembly relative to the
constraining wall; a mandrel including a first end formed for connection to a
tubular
string and an opposite end, the tubular mandrel installed in and axially
moveable
through the inner bore of the drag assembly; and a packing element housing
including a
first annular packing element and a second annular packing element spaced from
the
first annular packing element, the packing element housing encircling and
axially
moveable along the mandrel and positioned between a stop shoulder on the
mandrel
and the drag assembly, the packing element being settable to expand the first
annular
packing element and the second annular packing element by compression between
the
drag assembly and the stop shoulder.
Also provided is a method for pressure isolating an area along a wellbore wall
in a
wellbore, the method comprising: running into a wellbore with a straddle
packer tool
connected to a tubing string, the straddle packer tool including a drag
assembly
including a tubular body defining an inner bore extending along the length of
the tubular
WSLegal\ 067641\00005 \ 77368 I 9v2
CA 02776598 2012-05-08
2
body and an outer facing surface carrying a locking mechanism for locking a
position of
the drag assembly relative to the wellbore wall; a mandrel including a first
end formed
for connection to a tubular string and an opposite end, the tubular mandrel
installed in
and axially moveable through the inner bore of the drag assembly; and a
packing
element housing including a first annular packing element and a second annular
packing element spaced from the first annular packing element, the packing
element
housing encircling and axially moveable along the mandrel and positioned
between a
stop shoulder on the mandrel and the drag assembly; positioning the straddle
packer
tool with the first annular packing element and the second annular packing
element
straddling the area of the wellbore; and pulling the tubing string into
tension to expand
the first annular packing element and the second annular packing element by
compression between the drag assembly and the stop shoulder to seal against
the
wellbore wall and pressure isolate the area between the first annular packing
element
and the second annular packing element.
There is further provided a wellbore treatment assembly comprising: a tubular
string
manipulatable from surface; a swivel connected to the tubular string, the
swivel having a
first end and a second end and configured to permit rotation between its ends;
a
straddle packer tool for setting against a constraining wall of the wellbore
including: a
drag assembly including a tubular body defining an inner bore extending along
the
length of the tubular body and an outer facing surface carrying a locking
mechanism for
locking a position of the drag assembly relative to the constraining wall; a
mandrel
including a first end connected for movement by the tubular string through the
swivel
and an opposite end, the tubular mandrel installed in and axially moveable
through the
inner bore of the drag assembly; and a packing element housing including a
first
annular packing element and a second annular packing element spaced from the
first
annular packing element, the packing element housing encircling and axially
moveable
along the mandrel and positioned between a stop shoulder on the mandrel and
the drag
assembly, the packing element being settable to expand the first annular
packing
element and the second annular packing element by compression between the drag
assembly and the stop shoulder.
WSLega1\067641 \00005\7736819v2
CA 02776598 2012-05-08
3
According to another aspect of the invention, there is provided a wellbore
valve sub
comprising: a tubular wall including an upper end, a lower end, an inner bore
extending
between the upper end and the lower end and a outer surface; a port extending
through
the tubular wall providing fluid access between the inner bore and the outer
surface; a
valve piston installed in the tubular wall and moveable between a closed port
position,
wherein the closes the port and an open port position, wherein valve piston is
retracted
from the port; a first pressure communication path through the tubular wall to
a first end
of the valve piston, the first pressure communication path positioned between
the port
and the lower end; and a second pressure communication path to a second end of
the
valve piston, the second pressure communication path being positioned between
the
port and the upper end, the valve piston being moveable from the closed port
position to
the open port position by increasing the pressure in the first pressure
communication
path relative to the second pressure communication path to establish a
pressure
differential between the first end and the second end to move the valve piston
upwardly
toward the upper end.
It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein
various embodiments of the invention are shown and described by way of
illustration.
As will be realized, the invention is capable for other and different
embodiments and its
several details are capable of modification in various other respects, all
without
departing from the spirit and scope of the present invention. Accordingly the
drawings
and detailed description are to be regarded as illustrative in nature and not
as
restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
A further, detailed, description of the invention, briefly described above,
will follow by
reference to the following drawings of specific embodiments of the invention.
These
drawings depict only typical embodiments of the invention and are therefore
not to be
considered limiting of its scope. In the drawings:
Figure 1 is an enlarged sectional view of a straddle packer tool;
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
4
Figures 2A to 21, sometimes referred to herein generally as Figures 2, are
sectional
views of a straddle packer tool in operation in a well;
Figure 3 is an enlarged plan layout of a J-slot geometry useful in the
straddle packer of
Figures 2;
Figure 4 is a sectional view along a long axis of a wellbore sliding sleeve
valve; and
Figures 5A and 5B are sectional views along a long axis of a wellbore assembly
including a straddle packer tool operating in a wellbore sliding sleeve valve.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
The description that follows and the embodiments described therein are
provided by
way of illustration of an example, or examples, of particular embodiments of
the
principles of various aspects of the present invention. These examples are
provided for
the purposes of explanation, and not of limitation, of those principles and of
the
invention in its various aspects. The drawings are not necessarily to scale
and in some
instances proportions may have been exaggerated in order more clearly to
depict
certain features. Throughout the drawings, from time to time, the same number
is used
to reference similar, but not necessarily identical, parts.
A straddle packer tool, a sliding sleeve valve and assemblies and methods for
wellbore
operations have been invented.
With reference to Figures 1 and 2, one embodiment of a straddle packer tool 18
is
shown. The straddle packer tool includes a tubular mandrel 20 including an
upper end
20a, a lower end 20b and an outer surface 20c extending therebetween.
The straddle packer tool can be incorporated in a string by connection of
string 10
directly, or via string components 14a, at end 20a. Possibly a lower portion
of the string
and/or further components 14b may be connected at end 20b. The ends may
therefore
be formed for connection into a string in various ways. For example, they can
be
threaded, as shown. Alternately, the ends may have other forms or structures
to permit
alternate forms of string connection.
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
The straddle packer tool further includes a drag assembly 22 and a packer
element
housing 24. Each of drag assembly 22 and packer element housing 24 have a
tubular
form and have an inner facing surface 22a, 24a defining an inner bore
therethrough.
Each of drag assembly 22 and packer element housing 24 are mounted over
tubular
mandrel 20 with the mandrel passing through their inner bores. Each of drag
assembly
22 and packer element housing 24 are axially moveable along at least a portion
of the
length of the tubular mandrel and are configurable between a packing element
unset
position (Figure 2A) and a packing element set position (Figures 1 and 2D).
Packer element housing 24 includes an upper packing element 26 and a lower
packing
element 28, spaced from the upper packing element. Each of the packing
elements are
annularly formed and encircle mandrel 20. Packer element housing 24 further
includes
element compression collars 30a, 30b, these collars also being annularly
formed to
encircle mandrel 20. In this packer, packing elements 26, 28 become set to
create a
seal in the wellbore by compression. For example, in the packing element unset
position (Figure 2A) packer element housing 24 is in a neutral, uncompressed
position
with packing elements 26, 28 retracted, for example, to an outer diameter less
than the
inner diameter ID of any bore, shown here as constraining wall 12, in which
packer tool
18 is positioned. However, when in the packing element set position (Figure 1
and 2D),
packer element housing 24 is in a compressed condition with the packing
elements
extruded radially outwardly. For example, when in use and in a set position,
elements
26, 28 have an outer diameter pressed against the constraining wall and
therefore equal
to the inner diameter of any bore in which the packer tool is positioned.
Packer tool 18
may be returned to the packing element unset position (Figure 2G to 21) by
releasing
the compressive force on the packing element housing 24, after which the
packing
elements will return to a retracted position.
Packing elements 26, 28 are formed of deformable, elastomeric materials such
as
rubber or other polymers and upon application of compressive forces against
the sides
thereof, they can be squeezed radially out. In use, when the packing elements
are
squeezed out, Figure 20, their outer facing surfaces 26a, 28a are driven into
contact
with a constraining wall 12 of the bore in which the straddle packer tool is
positioned. At
WSLegal \ 067641 \00005 \7736819v2
CA 02776598 2012-05-08
6
the same time, the backsides 26b, 28b of the packing elements become pressed
against the mandrel. As such, elements form a pair of spaced apart seals in
the annular
area between the mandrel and a constraining wall such that fluids are
prevented from
passing through the annular area therepast. Compression collars 30a, 30b or
other
walls, such as shoulder 20d of mandrel, are formed of rigid materials such as
steel and
transfer compressive forces to the packing elements. Compression collars 30a,
30b
and mandrel at shoulder 20d also may have a radial thickness selected to
resist
problematic lateral extrusion of the packing elements, instead directing
elements 26, 28
radially outwardly as they are compressed. In this illustrated embodiment,
compression
collar 30a is positioned at an end of the packing element housing adjacent
upper
packing element 26 and compression collar 30b is positioned between elements
26, 28.
While a compression collar could be positioned at the end of the packing
element
housing on the opposite side of element 28 from collar 30b, in this
embodiment, lower
packing element 28 is instead directly adjacent shoulder 20d on mandrel and
that
shoulder works with collars 30a, 30b to effect compression and setting of
packing
elements 26, 28.
The force to achieve compression of elements 26, 28 may be as a result of
pushing one
of the parts, shoulder 20d or 30a, toward the other of the parts, while the
other part is
held stationary. Of course, the other part may also have a pushing force
applied
thereto, but as the straddle packer tool is intended for downhole use,
routinely force is
applied from surface by manipulation of the tubing string into which the
straddle packer
tool is connected, while a part of the tool is held steady. For example, if
straddle packer
tool 18 is installed with end 20a connected to a tubing string 10, directly or
through
components 14, with the string extending uphole toward surface, force can be
applied
by lowering or pulling on the string. In this embodiment, as shown, the
packing
elements of the straddle packer tool can be compressed by pulling on the
tubing string
attached at end 20a, while collar 30a is held stationary. This straddle packer
tool, then
may be tension set and can be deployed using string 10 such as of coiled
tubing or
jointed tubing. The packer may be set and released using tubing reciprocation:
pull the
string in tension to set the packer and put weight into the string to release
the packer.
WSLega11067641100005 \7736819v2
CA 02776598 2012-05-08
7
Drag assembly 22 acts as an anchor for permitting compression of housing 24.
Drag
assembly 22 is employed to create a fixed stop against which the packing
element
housing can be compressed. Drag assembly 22 works with mandrel 20 to effect
compression.
As noted above, drag assembly 22 has a tubular form and is sleeved over and
axially
moveable along mandrel 20. Drag assembly 22 includes a locking mechanism for
locking its position relative to a constraining wall 12 in which packer tool
18 is employed.
For example, drag assembly 22 may include an annular body 32 and a drag
mechanism
carried by the annular body, which is formed to engage constraining wall 12.
Drag
mechanism may include for example, blocks 34 that are biased radially
outwardly from
annular body 32, for example as by springs 36. Blocks 34 each include an outer
engaging face 34a formed to frictionally engage, and provide resistance to
movement of
its block along, wall 12 surface. While drag blocks 34 can be forced to move
across the
wall surface, the blocks frictionally engage against wall 12 such that a
resistance force
is generated by movement of blocks across the surface. This resistance is
transferred
to body 32 such that the movement of drag assembly 22 relative to the
constraining wall
12 is also resisted such that if packer tool 18 is moved through a bore
defined by wall
12, the drag assembly can only be moved along by applying a force to it, for
example by
pushing or pulling the mandrel against the drag assembly. When in a bore, for
example, where drag blocks engage against a constraining wall of the bore, the
mandrel
can be moved through drag assembly 22, while the drag assembly remains
stationary,
until the mandrel butts against the drag assembly. Thereafter, the drag
assembly can
be moved along with the mandrel. If the mandrel is stopped and moved in an
opposite
direction, mandrel 20 moves through drag assembly 22, with the drag assembly
remaining stationary, until the mandrel applies a force against the drag
assembly to
move it in that opposite direction. Mandrel 20 therefore may include a
shoulder or other
engagement mechanism to apply force to the drag assembly, for example shoulder
20d
of mandrel can apply a force through housing 24 to effect movement of drag
assembly
22.
wsLegal\ 067641 \00005 \7736819v2
CA 02776598 2012-05-08
8
As noted above, drag assembly 22 can be locked into a position relative to
packing
element housing 24 while mandrel 20 is pulled up through these members until
housing
24 and, in particular, elements 26, 28 are compressed between the drag
assembly and
shoulder 20d. While the drag blocks 34 may be selected to lock drag assembly
22 in a
position for this purpose, a stronger locking mechanism may be required to
lock the
position of drag assembly. Thus, in this embodiment, drag assembly 22 further
includes
slips 38 carried on body 32. Slips 38 are normally retracted but can be driven
radially
out into engagement with constraining wall 12 to lock drag assembly 22 in a
selected
position, when it is appropriate to do so. Slips 38 include a keeper 39 that
hold them on
body 32. Slips 38 also include on their outer facing sides teeth 38a, such as
whickers,
selected to bite into the material of the constraining wall and may be
selected with
consideration as to the hardness and material of the constraining wall, be it
a steel
surface such as of casing or liner or an open hole surface such as an exposed
wellbore
wall. Drag assembly 22 further includes a mechanism for driving the slips to
expand
radially out. The slips may be driven by employing various mechanisms. In this
embodiment, the driving mechanism operates in response to compressive force
applied
to the drag assembly. For example, in the illustrated embodiment, expansion
force is
driven by frustoconical guide surfaces 38b formed on the backsides of the
slips that
function in cooperation with a compressive force applied along long axis x of
the
packing tool. In this embodiment, the compressive force is applied from
mandrel 20,
through housing 24 to the slips, while drag assembly 22 is maintained in a
position fixed
against axial movement. Since drag assembly 22 cannot move, any compressive
force
applied acts to move slips 38 out due to the form of surfaces 38b.
In this embodiment, it is compression collar 30a that bears against the slips.
Slips 38
are in a position to be lifted by collar 30a, when the end of the collar is
urged beneath
the slips. For example, when a compressive force is exerted by mandrel 20
against
housing 24, collar 30a passes beneath the slips 38 and acts to move the slips
radially
outwardly into contact with constraining wall 12. As will be appreciated, the
outer
diameter of the collar 30a and the thickness of slips 36 where they overlap
must be
selected with consideration as to the distance between tool 18 and
constraining surface
12 when in use.
WSLegal\ 067641 \ 00005 \ 7736819v2
CA 02776598 2012-05-08
9
To more efficiently and stably translate compressive axial motion into
radially directed
force to drive the slips radially outwardly, end 30a' of the collar may also
be shaped
frustoconically, as shown, to have an angled face substantially similar to
that of
frustoconical guide surface 38b of the slips.
In this embodiment, drag blocks 34 provide resistance to permit slips 38 to
become
engaged, while slips 38 provide the locking effect necessary for setting the
packing
elements. In particular, drag blocks 34 through engagement with constraining
wall,
provide an initial locking effect to hold the drag assembly stationary such
that
compressive force can be applied to urge slips 38 outwardly and, thereafter,
once slips
38 are firmly engaged to hold the drag assembly more firmly in a locked
position, further
compressive force can be applied to compress and extrude packing elements 26,
28
into a set position.
While the straddle packer tool 18 can be employed for creating a seal in a
well, in this
embodiment, straddle packer tool 18 can further be employed to provide fluid
communication therethrough to a port 40 between elements 26, 28. Thus, while
mandrel 20 may have a solid form, in this embodiment mandrel includes an inner
bore
25 therethrough defined by an inner facing surface 20e of the mandrel. The
inner bore
extends from upper end 20a toward the lower end to port 40. Port 40 opens to
outer
surface 20c of the mandrel and an opening 30b' in collar 30b permits fluid
flow (arrows
Fl) from the inner bore to an annular area between elements 26, 28. In this
embodiment, an end wall 42 stops inner bore 25 at a position just below port
40. It is
noted that end wall 42 in this embodiment is formed as a diverter, with an
angled
surface leading to port 40, to direct fluid laterally from the inner bore out
through port 40.
In some embodiments, the inner bore defined by inner facing surface 20e may
extend
from end 20a to end 20b of the mandrel to provide a flow path fully
therethrough.
When the illustrated straddle packer tool 18 is connected into a string, bore
25 of the
straddle packer tool is placed in communication with a bore 10a of the string
such that
fluids passing through the string and string components 14 can enter the bore
and can
WSLegal\ 067641 \ 00005 \7736819v2
CA 02776598 2012-05-08
pass therethrough to and through port 40. The straddle packer tool allows the
passage
of fluid therethrough to a position in the string between packing elements 26,
28.
While flow is shown outwardly through port 40 it is to be understood that flow
can be
reversed to also flow in through port 40 from outer surface 20c to bore 25, as
desired.
There is no one-way flow restrictor in the passage and, therefore, fluid can
flow in either
direction depending on fluid pressure differentials.
Drag assembly 22 and packing element housing 24 are sleeved over and axially
movable along tubular mandrel 20 and the parts are intended to remain as such
during
operation such that they cannot fully separate from the mandrel. However, as
noted,
the drag assembly and the packing element housing are axially moveable
relative to the
mandrel between the packing element unset position, wherein the parts are
neutral and
uncompressed and the packing element set position, wherein the parts are
compressed
causing the slips and the packing elements to be driven outwardly into contact
with the
constraining wall.
While housing 24 could be fully moveable along mandrel, a shoulder 20f may be
provided to limit the movement of housing 24 toward end 20a. This shoulder may
prevent the housing from accidentally migrating up to set under slips, for
example
during run in. Also, since the wedging effect of collar 30a under slips 38 may
be
significant in a set packer, collar 30a may not be easily moved from under the
slips and
shoulder 20f may be useful to impact against housing 24 when the packer is
unset to
urge the collar out from under the slips.
The straddle packer tool may be reciprocated between the unset and the set
positions
by movement of the mandrel relative to the drag assembly. For example,
movement of
the mandrel to push shoulder 20d away from drag assembly 22 causes the packing
elements and the slips to become unset, while movement of the mandrel to move
shoulder 20d toward drag assembly 22 causes the mandrel to be pulled up
through
drag assembly 22, movement of the drag assembly is resisted by action of drag
blocks
34 and eventually housing 24 becomes sandwiched between shoulder 20d and drag
assembly 22 and a compressive force is applied to the packing elements and 38
slips,
WSLega1\067641 \00005 \7736819v2
CA 02776598 2012-05-08
11
causing them to set. However, it may occur that the drag assembly which
normally has
movement resisted by action of drag blocks may accidentally cause the packer
to set.
For example, whenever the packer is moved up through a wellbore toward
surface, the
packer could set. Thus, in one embodiment straddle packer tool 18 includes a
position
indexing mechanism employed to direct the movement of the drag assembly
relative to
the tubular mandrel, between a position where it will operate to drive the
packing
elements to set and positions in which drag assembly 22 is inactive and
inoperative to
drive the packing elements to set. The position indexing mechanism may, for
example,
include J-slot indexing mechanism including a slot 52 and a key 54. The slot
and the
key may be positioned between the drag assembly and the mandrel, for example
in the
gap between outer facing surface 20c and inner facing surface 22a. In this
embodiment,
slot 52 is formed on the inner facing surface of the drag assembly body and
key 54 is
installed on the mandrel, but this orientation can be reversed if desired. The
key is
sometimes termed a guide pin or J-pin since it rides along within the J-slot.
The position indexing mechanism guides the axial movement between the drag
assembly and the mandrel. For example, the axial length of slot 52 between its
ends
and the relative position of the key may be selected to allow sufficient axial
movement
of the sleeve and the mandrel to allow the packer to be set and unset and slot
can
further be laid out to permit axial movement of the sleeve and the tubular
member to be
positively stopped in an intermediate inactive, unsettable position, wherein
setting of the
packer is prevented in spite of movement of the mandrel which would otherwise
cause
the packer to set. This can be achieved, for example, by forming the slot as a
J-type
slot.
In one embodiment a continuous J-type slot may be provided about the
circumference
of tool 18 so that the mandrel can be continuously cycled between active
positions and
inactive positions relative to the drag assembly. One possible layout for a J-
type slot 52
is shown in Figure 3.
The key reacts with the side and end walls of J-slot 52 to provide a guiding
function to
move mandrel 20 axially and rotationally relative to drag assembly 22 and
permits the
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
12
drag assembly and the mandrel to be indexed into the unset, uncompressed and
the
set, compressed positions and also positively into at least one intermediate
unset
position. While the slot geometry can vary, in this illustrated embodiment,
the J-slot
includes four stop areas and adjoining angled slot sections therebetween. The
four stop
areas include: end wall 60, end area 62, end wall 64 and end wall 66, which is
herein
illustrated as separated into two parts, since this J-slot is continuous and
therefore
extends about the circumference of the tool. Each stop area has an angled slot
section
extending away toward the next stop area: angled slot section 61 leads from
end wall
60 to stop area 62; angled slot section 63 leads from stop area 62 to end wall
64;
angled slot section 65 leads from end wall 64 to end wall 66; and, since the J-
slot is
continuous, angled slot section 67 leads from end wall 66 back to end wall 60.
The slot
geometry allows the mandrel to be moved axially within the drag assembly
according to
the linear spacing between the various end walls. Bearing in mind that the
drag
assembly is selected to resist movement during use, the angled slot sections
cause
axial movement of the mandrel within the drag assembly to be converted into
rotational
movement to move the mandrel from stop area to stop area along the slot, as
the tool is
reciprocated. In particular, any pushing or pulling movement of the straddle
packer tool
acting axially through end 20a will cause key 54 to ride through the slot and
eventually
land against an end wall in a stop area. Thereafter, any pushing or pulling
movement in
an opposite direction causes key to move axially away from the previous end
wall and
engage an axially aligned angled slot section. As the angled slot section is
contacted
by key 54, an indexing rotation will be applied to the tubular mandrel and the
key will
move until stopped against the next end wall in the slot. The key can only
advance to
the next position, if the pushing or pulling movement is again reversed. The
angled
sections are formed such that the key is always forced to move in a predefined
path,
and reverse movement cannot be readily achieved. In the illustrated
embodiment, the
end walls are separated by 90 and so the parts move about 360 when passing
from a
starting end wall position, through all the other positions and back to that
position.
The slot geometry is shown in Figure 3 and the movement of key 54 through slot
52 can
be further understood by reference to Figures 2, which show the packer in use
in a
wellbore. Figure 2A shows the packer in a run in condition being moved through
the
WSLega1\067641\00005\7716819v2
CA 02776598 2012-05-08
13
bore within constraining walls 12. In this condition, string 10 is applying a
push force,
arrow P, from above and mandrel 20 is pushed through the drag assembly, which
is
resisting movement by normal engagement of blocks 34 against wall 12. This
movement sets key 54 against end wall 60. Drag assembly 22 is moved along with
the
mandrel but rides along close to end 20a, in a position established by J-slot,
possibly
with the additional support of stop walls acting between the mandrel and the
assembly.
There is no compressive force on housing 24 and, therefore, elements 26, 28
remain
retracted. Elements 26, 28 may be selected to have an outer diameter in the
relaxed
state that is less than the inner diameter ID of wall 12 such that they do not
contact the
wall as the packer is moved along. This mitigates stuck conditions and avoids
problematic packer wear.
Port 40 is open and, therefore, fluid can be circulated
through bore 25 and port 40 and out into the annulus, if desired.
When the packer is positioned in a selected area of the well, the packer can
be prepped
for setting. String 10 is pulled into tension, also called "picked up", which
draws
mandrel 20 toward surface. As shown in Figure 2B, when mandrel 20 is pulled
toward
surface, drag assembly 22 remains in place due to the engagement of blocks 34
with
wall 12. This movement therefore draws mandrel 20 through the drag assembly
and
key 54 rides along slot 52 toward stop area 62, as directed by angled slot
section 61.
Mandrel 20 thus moves into a position with housing 24, and in particular
collar 30a,
close to drag assembly 22 and as drag assembly 22 is held by drag blocks 34,
continued movement of mandrel 20 drives collar 30a under slips 38 so that they
move
outwardly into engagement with wall 12. This further ensures that drag
assembly
cannot move relative to the constraining wall.
When it is desirable to set the packer, mandrel 20 may be further pulled
uphole, as
shown in Figure 20, and this movement draws shoulder 20d against housing 24,
while
the housing is held at its opposite end by collar 30a wedged under drag
assembly 22.
Thus, this compresses housing 24 and causes both elements 26, 28 to extrude
outwardly against wall 12 (Figure 2D). During this movement of mandrel 20
through the
drag assembly, key 54 continues along slot 52 until it reaches a position in
stop area 62.
Stop area 62 may, in fact, be formed with sufficient space such that key 54
never stops
WSLegal \ 067641 \ 00005 \7736819v2
CA 02776598 2012-05-08
14
against a wall during normal use such that the compressive load applied into
elements
26, 28 is not limited by any interaction of key and slot.
In this position, the space between elements 26, 28 is isolated from the
annulus
adjacent ends 20a, 20b. Port 40 is open and fluid can be injected, arrows Fl,
through
bore 25 and port 40 out into the annulus, if desired. Because of the seals
provided by
elements 26, 28 considerable pressures can be achieved in the space and such
fluid
can be directed out to effect the walls or to treat the formation accessed
behind the
walls.
When it is desired to unset the packer, the weight on string 10 can be
increased (also
called "setting down") such that mandrel 20 is pushed through the drag
assembly.
Initially, the mandrel's movement will remove shoulder 20d from its
compressing
position against element 28, which allows that packing element to relax and
retract out
of a sealing position (Figure 2E). Thereafter, as the mandrel is further set
down, the
remaining components of housing 24, including element 26, will become
uncompressed
and relax (Figure 2F). Eventually, mandrel 20 is moved sufficiently to remove
collar 30a
from under slips 38 such that they can be retracted from engagement with wall
12
(Figure 2H). Since the wedging effect of collar 30a under slips 38 may be
significant,
collar 30a may not be easily moved from under the slips and shoulder 20f may
be useful
to impact against housing 24 as the packer is being unset (Figure 2G). During
this
movement, key 54 rides along the slot, as directed by angled slot section 63,
until it is
set against end wall 64 (Figure 2H).
At this point, work at this area is done and the packer can be moved up or
down through
the wellbore. If it is desired to move further down the wellbore, the packer
can remain in
the position shown in Figure 2H and the string and mandrel 20 can be pushed
down,
with drag assembly 20 dragged along with the mandrel.
If, however, packer 18 is to be pulled up through the wellbore, the string
will then be
picked up drawing mandrel 20 back up through drag assembly 22 (as the
assembly's
movement is resisted by blocks 34). Without any movement guide, it would be
appreciated that this movement would likely create an effect as shown in
Figures 2B to
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
2D wherein the packer would become compressed and set. However, J-slot 52
allows
the packer to be pulled uphole without setting by providing an intermediate
position in
slot 52: at end wall 66. Thus, as the mandrel is pulled up through drag
assembly 22,
key 54 rides along the slot and, as directed by angled slot section 65, until
it is set
against end wall 66 (Figure 21). The orientation of slot 52 and key 54
provides that
when the key is at end wall 66, collar 30a remains spaced from slips 38 such
that the
packer cannot set. The packer can then be moved uphole, towards surface (arrow
S),
with the string pulling the mandrel uphole and with drag assembly 20 dragged
along
with the mandrel by engagement of key 54 against wall 66.
After positioning the packer in a configuration as shown in Figure 21 with the
housing
maintained away from slips 38, it may be desired to reset the packer. To do
this, the
process of Figures 2A to 2D is repeated. For example, the mandrel is pushed
down
through drag assembly 22 and key 54 rides along the slot, as directed by
angled slot
section 67, from end wall 66 back until it is set against end wall 60.
Thereafter, the
mandrel can be pulled back up toward end wall 62 after which the packer can be
set.
If debris accumulates above the packer, it may be circulated off.
It will be appreciated from the foregoing description, that reciprocation of
the string is
necessary to shift the packer between the set and the unset positions. The
movement
of mandrel 20 within housing should be easy and the operations of the
presently
illustrated packer rely on the full rotation of the mandrel in the drag
assembly.
Excessive friction between the packer mandrel and the drag assembly and/or the
string
may cause the drag assembly to rotate with the mandrel, preventing the packer
from
setting or releasing. Thus, swivels may be provided between string 10 and
mandrel 20.
A swivel may be provided in string components 14a at upper end 20a of the
mandrel
where it connects to string. If the string extends from both ends of the
mandrel or string
components 14b may create resistance to the free rotation of mandrel, a swivel
may
also be incorporated in string components 14b at end 20b of the mandrel.
Swivels
reduce the force required to rotate the mandrel during string reciprocation.
WSLegal\ 067641 \00005\7736819v2
CA 02776598 2012-05-08
16
In addition or alternately, the space in which J-slot 52 operates may be
protected from
infiltration of debris. For example, J-slot 52 may be in a protected chamber
70. The
chamber may be pressure balanced with the area around the tool, but may
include a
screen 72 that permits pressure communication between the chamber and the
exterior
of the tool to avoid a pressure lock, but excludes debris from infiltration
into the
chamber. Seals 74 such as wiper seals may be provided, if desired, to further
protect
against infiltration of debris.
The packer has features that reduce the chances of getting stuck in the well,
such as
the relaxed condition of elements 26, 28 out of contact with the wellbore wall
while
running through the well and the ability to circulate through bore 25 and port
40.
However, components 14 may include a tension or hydraulic release to permit
detachment of the straddle packer tool from string 10, if necessary.
Components 14a
may further include a normally closed, bypass circulation valve above tool 18
to permit
fluid communication from string 10 and fluid circulation to remove of debris
from above
the tool when necessary. The bypass valve may be closed when in tension and
when
in compression but opened in neutral (i.e. at a position between tension and
compression), so the open/closed condition of the valve can be readily known
and
controlled and the valve is not open when the straddle packer is set, since in
the set
condition, fluids are often required to be injected between the set packing
elements.
To facilitate positioning and setting of the packer, one or more landing
locator profiles
76 may be provided in the wellbore wall 12 into which blocks may land
when/where it is
desired to set a packer. The locator profiles may be cylindrical areas of
larger diameter
relative to the normal diameter ID of the wellbore wall. Locator profiles 76
may have an
axial length at least as long as the axial length of blocks 34 such that the
blocks can
expand into the locator profiles, when they are aligned with them. The locator
profiles
may be a depth such that extra force is required for a block to ride out of a
locator
profile than what is required to move the block along the wellbore wall. They
can ride
out of the locator profiles but extra force is required to do so. This
provides that (i) drag
assembly 22 may be more firmly held in position when blocks are located in
locator
profiles 76, (ii) the depth of the packer in the wellbore may be determined by
monitoring
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
17
string weight and noting the number of locator profiles through which the
packer has
passed, and (iii) locator profiles 76 may used to ensure proper positioning of
the packer
in the well by positioning a profile adjacent a position in the well in which
it is desired to
set the packer. For example, the packer may be intended to straddle a selected
area in
the wellbore and locator profile 76 may be axially spaced from the port with
considerations as to the compressed distance between the lower element 28 and
drag
blocks 34 such that when the drag blocks are located in the associated locator
profile
and the packing elements, including lower element 28, straddle the port. if
using locator
profiles, they may be selected to have an axial length greater than normal
tubing
discontinuities, such as casing connections, J-spaces, etc., in the wellbore,
such that it
is possible to identify the effect of the profiles 76 over passing
into/through other
discontinuities.
The packer may be used to isolate a portion of the well and with the injection
port 40,
may be used to both isolate and pressure effect an area along the wellbore.
For
example, packer may be employed to straddle perforations, burst disks or
shiftable
sleeves on a liner such as casing in a cemented or an open hole application.
The
packer may be employed to pressure effect the straddled component (i.e. burst
the disk,
hydraulically open the sleeve, etc.) and/or to pressure effect the formation
accessed at
that area of the wellbore (i.e. to pump fluid through port 40 into the
formation).
For example, the packer can be employed wherein constraining wall 12 is a
liner with
perforations formed therethrough. The packer can be positioned with elements
26, 28
straddling the perforations in the wellbore liner and stimulation fluid can be
pumped
down the string, through bore 25 and diverted out through port 40 into the
annular area
between the packer and the liner. Elements 26, 28, being set above and below
the
perforations, seal the packer against the liner such that stimulation fluid is
forced out
through the perforations into the formation.
As another example, straddle packer 18 may be set across a burst disk in a
liner.
Pressure applied through the packer can be used to rupture the burst disk and
open
WSLegal\067641\00005\7736819v2
CA 02776598 2012-05-08
18
communication with the formation. Stimulation fluid can then be pumped through
the
port opened by bursting the disk and into the formation.
Packer 18 can also be employed to open a hydraulically shifted wellbore valve,
such as
one having a piston such as a sleeve or poppet and possibly thereafter to
inject fluid
into the formation accessed behind the wellbore valve. While many such
wellbore
valves may be employed, one particularly useful valve sub 80 is shown in
Figure 4.
The valve sub 80 includes a hydraulically driven piston member, which herein
is a
sleeve 82 but may take other forms such as non-cylindrical sleeves, poppets,
pocket
pistons, etc, installed in a tubular wall 84. The sleeve may be installed such
that a
pressure differential can be established across the sleeve, between its ends
82a, 82b,
and it can be moved as a piston. The sleeve, for example, may be installed in
the wall
with a pressure communication path accessing one end 82a of the sleeve and
another,
separate pressure communication path accessing the other end 82b of the
sleeve.
Sleeve 82 can be positioned in wall 84 to be shifted up towards an upper end
84a of the
sub to open, rather than down. Stated another way, valve sub 80 also may be
constructed such that the pressure differential across the sleeve may be
established
with the high pressure source to be communicated below the sleeve and with a
space
above the sleeve into which it can move. This upward movement is useful as the
liner
may sometimes be fully closed below the sleeve, for example, the valve may be
incorporated in a string with upper end 84a connected to an upper end portion
and its
lower end connected to a lower distal tubing string portion ending in a toe
and the entire
lower distal string portion from the valve to the toe may be closed and
pressure tight.
To shift a sleeve down, fluid must be displaced and a fully closed string may
not be able
to accommodate such displacement unless a conductivity path is opened from the
string
below (i.e. by cutting or otherwise opening a port through the string wall).
Thus, by
providing a shift-up to open valve, the valve can be employed and opened even
when
the string is fully closed below and close to the bottom of the string, as
fluid
displacement necessary to open the sleeve can be accommodated above the
sleeve,
for example if necessary, at surface.
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
19
In one embodiment, for example, tubular wall 84 can include an upper end 84a
and a
lower end 84b. The tubular wall may be formed for connection into a string,
such as by
forming ends 84a, 84b as threaded pins or boxes. The tubular wall has an outer
surface 84c and an inner facing surface 84d which defines therewithin a bore
112.
Wall 84 includes chamber 86 formed therein between outer surface 84c and inner
facing surface 84d and sleeve 82 is positioned in the chamber. Chamber 86 is
formed
such that sleeve can slide axially in chamber, except as limited by releasable
locking
structures if any. Since in this embodiment, the sleeve has cylindrical
structure,
chamber 86 herein has an annular form following the circumference of the
tubular wall.
A formation communication port 88 extends through wall 84 passing through
annular
chamber 86 and port 88 provides fluid communication between bore 112 and outer
surface 84c, which is placeable in communication with a formation when the sub
is
installed in a string and the string is installed in a wellbore. Formation
communication
port 88 is actually two openings, one through the wall thickness between inner
facing
surface 84d and chamber 86 and the other through the wall thickness between
chamber
86 and the outer surface, but these two openings can be collectively
considered as the
port through which fluids may be communicated between inner bore 112 and outer
surface 84c.
Sleeve 82 is positioned to open and close port 88. For example, sleeve 82 can
be
placed in a position in annular chamber 86 to close port 88, wherein it spans
across the
port, and sleeve 82 can be placed in a position in the annular chamber wherein
it is
retracted from across the port, wherein port 88 is open to fluid flow
therethrough.
Sleeve 82 is moveable within chamber 86 between a closed port position and an
opened port position. As noted above, sleeve 82 may be moved from the closed
port
position to the opened port position by generating a pressure differential
between ends
82a and 82b of the sleeve. Chamber 86 is sized to accommodate this movement
having an enlarged space on at least one side of the sleeve into which sleeve
82 can
move.
WSLega1\067641\00005\7736819v2
CA 02776598 2012-05-08
An opening 90 is provided from bore 112 to chamber 86 where it is open to end
82a of
the sleeve and another opening 92, that is separate and spaced from opening
90, is
provided from bore 112 to chamber 86 where it is open to end 82b of the
sleeve. Thus,
pressure can be communicated from bore 112 to the ends of the sleeve through
ports
90, 92 to create a pressure differential thereacross. In the illustrated sub,
sleeve 82 is
configured to open by moving up toward end 84a. Chamber 86 has an enlarged
space
86a between port 88 and end 84a that is sized to accommodate sleeve 82 when it
is
moved from across port 88. Chamber 86 may further have an end wall 86b
positioned
between port 88 and end 84a. Opening 90, which communicates the opening
pressure
to chamber 86 is positioned between port 88 and end 84b. Opening 92, which
acts as a
vent from chamber 86 to prevent a pressure lock as the sleeve moves is
positioned
between port 88 and end 84a. As will be appreciated, if chamber 86 is closed
except
for opening 92, a pressure lock would occur if sleeve 82 was sought to be
moved
beyond opening 92. Thus, opening 92 is spaced sufficiently from port 88, for
example a
length corresponding to the length of the sleeve, to permit the sleeve to move
through
chamber 86 to open the port. In one embodiment, opening 92 is positioned well
on the
opposite side of space 86a from port 88, close to end wall 86b. When a
pressure
differential is established between opening 90 and opening 92, these pressures
are
communicated to ends 82a, 82b of the sleeve, respectively, and the sleeve will
move to
the lower pressure side.
Opening 90 and port 88 are spaced from opening 92 with a length L of inner
facing wall
84d between them. The sleeve is positioned behind that length of the inner
facing wall
and access to the sleeve is prevented by wall 84d except through openings 90,
92 and
port 88.
Seals 94 are provided between the walls defining chamber 86 and sleeve 82 to
resist
leakage between bore 112 and outer surface 84c past the sleeve when its closed
and to
resist fluid leakage between end 82a and end 82b to ensure that a pressure
differential
can be established therebetween. Since some fluid may be communicated to the
sleeve through port 88 as well, as to port 90. Seals 94 may be positioned to
also
ensure that a pressure differential can be established between port 88 and end
82b.
WSLegah 067641 \00005 \7736819v2
CA 02776598 2012-05-08
21
Releasable locking devices may be employed to releasably hold the sleeve in a
closed
position and/or an open position. For example, shear pins, snap rings,
collets, etc. may
be employed between the sleeve and the wall. In the illustrated embodiment,
shear
pins 96a are installed between the sleeve and wall 84 to hold the sleeve in
the closed
position. The shear pins may be selected such that the sleeve only moves after
a
sufficient pressure differential is achieved across the sleeve. A collet/gland
96b/c is
employed to hold the sleeve in the open position.
In use, as shown in Figures 5a and 5b, valve sub 80 may be connected into a
liner
string 105, such as of casing, liner, etc., and installed in a borehole B to
provide access
via ports 88 from its inner bore 112 to the formation through which the
borehole is
drilled. Valve sub 80 can accommodate and be operated by a straddle packer.
Figures
5, for example, show a straddle packer 118 similar to that disclosed
hereinbefore in an
operative position in sub 80. The packer includes a mandrel 120 with an inner
bore 125
and a fluid port 140, a drag assembly 122 with drag blocks 134 and slips 138
and a
packing element housing 124 with an upper packing element 126 and a lower
packing
element (cannot be seen in this view) positioned between the drag housing and
a
shoulder (not shown but similar to shoulder 20d of Figure 1) on the mandrel.
The
packer can be set to expand element 126 and the lower element across the sub's
inner
diameter ID out into sealing engagement with inner facing wall 84d. To operate
the
sleeve of the sub to be hydraulically opened, packer 118 can be positioned
with element
126 and the lower packing element straddling the pressure communication path
to one
end 82a of the sleeve while the pressure communication path to opposite end
82b is
outside of the area between elements. Using a straddle packer, therefore, a
pressure
differential can be readily established across the sleeve from end 82a to end
82b
thereof and the sleeve can be moved as a piston.
As noted above, length L of inner facing surface 84d spans between port 88 and
opening 92. This length is sufficient to accept sealing engagement of element
126
thereagainst, between openings 90 and 92 while the lower packing element is
set on
the opposite side of port 90, opposite the location of port 90. Port 90, being
straddled
by the packing elements, is in communication with bore 125 and port 140 and,
thus,
WSLega1\ 06764 I \ 00005 \7736819v2
CA 02776598 2012-05-08
22
pressures can be communicated thereto and to end 82a (arrows P1). A pressure
differential may be established across sleeve 82 by increasing the pressure P1
between
the packing elements, which is communicated to end 82a, while the area about
the
packer and therefore the pressure at end 82b, remains at ambient P2. When a
sufficient pressure differential is reached P1 > P2 to shear pins 96a, the
sleeve moves
up toward end 84a from a closed position (Figure 5A) to an open position
(Figure 5B).
When the dogs of collet 96b reach gland 96c, the dogs will lock into the gland
to hold
the sleeve up in an opened position.
When sleeve 82 is opened, fluids (arrows F) can continue to be pumped through
bore
125 and ports 140 and 88 to treat the formation accessed by borehole B.
Sub 80 may include a locator profile 176 in its inner facing surface 84d to
facilitate
location of the packer relative to port 88 and openings 90, 92. Locator
profile 176 has
an inner diameter greater than the normal ID of sub may be axially spaced from
port 88
with considerations as to the compressed distance between upper packing
element
126, the lower element and drag blocks 134 such that when the drag blocks are
located
in the associated locator profile and the packing elements are properly
positioned in the
sub. For example, element 126 is positioned to be set in length L between port
88 and
opening 92 such that it properly isolates communication to end 82a from end
82b.
After the sleeve is opened and the formation is fluid treated, for example by
fracing,
various operations can be carried out. For example, while the packer elements
remain
set against inner facing surface 84d, the sleeve can be closed by pressuring
up the
annulus about the packer to generate a pressure at end 82b greater than at end
82a.
Alternately, if it is desired to allow the formation to backflow right away,
with the sleeve
open, the packer can be unset and moved through the string. String 105 may
include
one or more further valve subs like sub 80 or other structures such as burst
plugs, ports
etc. that the packer can act upon as it moves up or down through the string.
While the valve sub selected to open with the sleeve moving up toward surface
offers
some benefits, it is to be understood that the valve sub could be installed
upside down
so that port 92 is closer to bottom hole.
In such an orientation, however, the string
WSLegal\ 067641 \ 00005 \7736819v2
CA 02776598 2012-05-08
23
below the valve must provide for or be opened to provide for displacement of
the vented
fluid from port 92 into the string below.
The processes can be conducted in horizontal or vertical wellbore
orientations, in lined
or open wells, etc.
The previous description of the disclosed embodiments is provided to enable
any
person skilled in the art to make or use the present invention. Various
modifications to
those embodiments will be readily apparent to those skilled in the art, and
the generic
principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
consistent
with the claims, wherein reference to an element in the singular, such as by
use of the
article "a" or "an" is not intended to mean "one and only one" unless
specifically so
stated, but rather "one or more". All structural and functional equivalents to
the
elements of the various embodiments described throughout the disclosure that
are
know or later come to be known to those of ordinary skill in the art are
intended to be
encompassed by the elements of the claims. Moreover, nothing disclosed herein
is
intended to be dedicated to the public regardless of whether such disclosure
is explicitly
recited in the claims. No claim element is to be construed under the
provisions of 35
USC 112, sixth paragraph, unless the element is expressly recited using the
phrase
"means for" or "step for".
WSLegal\ 067641 \ 00005 \7736819v2
