Note: Descriptions are shown in the official language in which they were submitted.
CA 02674223 2009-07-31
RELIABLE SLEEVE ACTIVATION FOR MULTI-ZONE FRAC OPERATIONS
USING CONTINUOUS ROD AND SHIFTING TOOLS
FIELD OF THE INVENTION
The present invention relates to multiple zone fracturing operations.
More specifically, the present invention relates to fracturing multiple zones
of
interest by using continuous rod and shifting tools to actuate a sliding
sleeve
adjacent a zone of interest.
BACKGROUND OF THE INVENTION
Selectively fracing multiple zones of a formation improves the
production capabilities of a well. The equipment string for such a frac
operation
uses a series of packers to sequentially isolate different zones of a downhole
formation. Sliding sleeves on the tubing string position between each of the
packers and provide exit ports for frac fluid to interact with the adjacent
zones of the
formation. Performing successive frac treatments on the isolated zones
requires
the sliding sleeves to be opened and closed in a desired sequence so that
zones of
interest can be fraced independently of the other zones. To do this, the frac
operation uses several steps. First, one sliding sleeve is opened, while the
others
remain closed. Frac fluid is pumped downhole and through the open sleeve to
interact with the adjacent zone of the formation. When facing is done for this
zone,
the sliding sleeve is then closed, and another sliding sleeve is opened so the
next
zone can be treated.
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Sliding sleeves can be activated using many types of devices,
including balls, darts, and pulling tools. Currently, operators experience
problems
when performing frac operations. For example, the number of zones that can be
treated may be limited by the method used to actuate the sleeves. Also,
operators
can have difficulties ensuring that the proper sleeve is open for the frac
treatment
and then that the proper sleeve is closed and sealed after that treatment.
This
difficulty can be even more problematic when fracing a horizontal well.
When balls are used to actuate the sliding sleeves, for example, the
frac treatment is applied successively to each isolated zones by selectively
opening
the sliding sleeves and allowing the treatment fluid to interact with the
adjacent
zones of the formation. To open each sliding sleeve, operators drop a
specifically
sized ball into the tubing string and land the ball on a corresponding ball
seat on a
designated sliding sleeve. Once seated, the ball closes off the lower zone
just
treated, and built up pressure on the seated ball forces the sliding sleeve
open so
frac fluid can interact with the adjacent zone of the formation. Operators
repeat this
process up the tubing string by successively dropping larger balls against
larger ball
seats in the sliding sleeves.
The required diameters of the ball seats and the required increments
between ball sizes limits how many zones can be treated using balls to open
the
sliding sleeves. For example, the lowermost ball seat must be the smallest,
and
each shallower seat must be sized slightly larger. In general, the balls can
range in
size from 1-in. to 3 3/.-in. Therefore, only a finite number of frac zones can
be
successfully used when opening the sleeves with balls due to the needed
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increments between ball sizes to differentiate them from one another.
Therefore,
actuating sliding sleeves with balls is not practical for frac operations
involving
several (e.g., more than about eleven) frac zones. In addition to the limit on
the
number of frac zones that can be handled, using balls and darts to open
sliding
sleeves only allows for one shot operations. In other words, the balls and
darts are
only capable of opening the sleeves, which cannot be closed unless another
device
is used. Finally, any balls and darts used to operate sleeves must be removed
either by floating or milling them, which involves time and expense to
perform.
Other than balls and darts, a pulling tool connected to wireline can be
used to actuate sliding sleeves during a frac operation. However, actuating
sliding
sleeves using wireline can be limited in horizontal sections downhole. In many
cases, wireline has no real pushing capabilities, which limits its use in
operating
sliding sleeves or other flow control systems within a welibore.
Using coiled tubing can overcome the limitations of wireline.
Unfortunately, a pulling tool on coiled tubing can still have limited access
in
extended horizontal wellbores, making it difficult for the pulling tool to
reach sliding
sleeves in horizontal sections. This difficulty is due at least in part to the
fact that
coiled tubing has some memory inherent in its material. Therefore, the coiled
tubing
as it is run downhole with the pulling tool is more likely to produce friction
within the
tubing string in which it is run, making moving the coiled tubing and the
pulling tool
more difficult. When used under these circumstances, the coiled tubing
requires
operators to spend an excessive amount of time to locate and subsequently open
or
close a sliding sleeve-sometime without success altogether. Furthermore, coil
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tubing is expensive and is preferably removed from the tubing string with each
frac
treatment to avoid damage to the coil tubing. Finally, the physical nature of
coiled
tubing inherently limits the coil tubing's ability to operate sliding sleeves
by pushing.
All of these issues greatly increase the time and cost of performing a frac
operation
with coiled tubing and make coiled tubing less desirable for operating sliding
sleeves.
What is needed is a solution for cycling sliding sleeves open and
closed in extended horizontal applications that can be better manipulated from
the
surface and that is more reliable in opening and closing the sleeves downhole.
SUMMARY OF THE INVENTION
An apparatus for opening and closing downhole tools, such as sliding
sleeves is disclosed. The apparatus has a first shifting tool connected to a
continuous rod, an intermediate rod connected to the first shifting rod and a
second
shifting tool connected to the intermediate rod.
In a broad aspect of the invention, a downhole tool actuating system
has a surface rig operable to deploy and move a continuous rod, having a
distal end,
in a first and second direction downhole. A tool actuating device is coupled
to the
distal end of the continuous rod, the tool actuating device having a first
profile
adapted to selectively actuate a downhole tool in the first direction to a
first
operative condition, and having a second profile adapted to selectively
actuate the
downhole tool in the second direction to a second operative condition.
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In another broad aspect of the invention, a downhole tool actuating
method comprises the steps of installing a first shifting tool to an end of a
continuous rod, installing an intermediate rod below the first shifting tool;
installing a
second shifting tool to the end of the intermediate rod, deploying the
continuous rod,
and the first and second shifting tools, and actuating the downhole tool.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic view of a system using continuous rod and a
tool actuating device;
Figure 2A shows a cross-section of a sliding sleeve in a closed
condition;
Figure 2B shows a cross-section of the sliding sleeve in an opened
condition;
Figure 3 shows a tool actuating device on an end of a continuous rod;
Figure 4A shows an isolated cross-section of an upper (opening)
shifting tool for the tool actuating device;
Figure 4B shows a cross-section of the upper (opening) shifting tool
having the continuous rod and an intermediate sucker rod coupled at its ends;
Figure 5 shows a cross-section of a lower (closing) shifting tool for the
tool actuating device;
Figure 6A shows the upper (opening) shifting tool opening a sliding
sleeve initially in the closed (up) condition;
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Figure 6B shows the lower (closing) shifting tool closing a sliding
sleeve initially in the opened (down) condition;
Figures 7A-7E shows stages of actuating sliding sleeves with the tool
actuating device;
Figure 8A shows another tool actuating device; and
Figure 8B shows a cross-section of the tool actuating device of FIG.
8A.
DETAILED DESCRIPTION OF THE INVENTION
A system 10 schematically shown in FIG. 1 uses a continuous rod 40
and a tool actuating device 60 to actuate downhole tools during well
operations. In
the current example, the system 10 is used in conjunction with frac
operations, and
the continuous rod 40 and tool actuating device 60 allow operators to
selectively
open and close sliding sleeves 50 downhole. In the typical implementation as
shown, a cased borehole 12 passes through a formation, and a tool string 14
installed in the borehole 12 has several sliding sleeves 50 positioned
adjacent
perforations 13 at various intervals in the cased borehole 12. Packers 20
isolate
portions of the annulus 15 of the borehole 12 and string 14 between each
section of
perorated borehole 12. In this way, frac fluid pumped down the tool string 14
can
be diverted by an open sliding sleeve 50 through the isolated perforations 13
to
treat the isolated zone of the formation.
As shown, the cased borehole 12 can have an extended horizontal
section that makes actuating the sliding sleeves 50 difficult with
conventional coiled
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tubing or wireline techniques. To overcome these difficulties, the tool
actuating
device 60 is disposed on the distal end of the continuous rod 40, and the rod
40 and
device 60 are used together to effectively and reliably open and close the
sliding
sleeves 50 in such an extended horizontal section. (The system 10 can be used
equally as well in vertical applications). In general, the tool actuating
device 60 can
be moved up or down in the string 14 to selectively actuate a given sleeve 50
between opened and closed conditions by engaging specific profiles on the
device
60 with profiles in the sleeve 50. The rigid continuous rod 40 stiffly conveys
the
desired movement of the device 60 relative to the sleeves 50, making the
opening
and closing of the sleeves 50 more predictable and ensuring that more complete
travel of the sleeves 50 is achieved.
As noted previously, coiled tubing has some memory inherent in its
material and produces undesirable friction when conveyed in a horizontal
borehole.
As a result, operators must spend an unwarranted amount of time attempting to
locate and actuate the sliding sleeves downhole-sometimes with no success.
However, the continuous rod 40 attempts to straighten out in the tubing string
14
and produces a lower friction component. The reduced friction allows operators
to
move the tool actuating device 60 as needed with better control from the
surface. In
this way, the rod 40 and device 60 facilitate frac operations in the
horizontal length
of the borehole.
As shown, the continuous rod 40 deploys in the tool string 14 to
convey the device 60 downhole to the sliding sleeves 50. At the surface, a rig
30
for extended continuous rod is used to manipulate (raise and lower) the
continuous
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rod 40 in the string 14 and thereby move the actuating device 60 relative to
the
sliding sleeves 50. This rig 30 can be similar to that used with extended
continuous
rod. For example, the rig 30 can include a reel for the continuous rod 40 and
a
variable-speed, hydraulically driven gripper mechanism (not shown), and the
rig 30
can be adapted to operate like a heavy duty slickline unit at the surface to
deploy
the continuous rod 40 and device 60 downhole. In addition to the rig 30, other
components (not shown), such as wellhead, lubricator, etc., are also used at
the
surface.
The sliding sleeves 50 can be selectively opened and closed to divert
frac fluid in the tubing string 14 to the isolated zone of the annulus 15
between
packers 20. An example sliding sleeve 50 shown in FIG. 2A has a housing 52
with
an insert 54 movably disposed therein. When closed as shown in FIG. 2A, the
insert 54 is positioned toward the lower end of the housing 52. In this
position, slots
55 in the insert 54 do not align with ports 53 in the side of the housing 52
so that
fluid passing in the sleeve 50 is not diverted outside the sleeve 50 and the
tubing to
which it is coupled at both ends. When opened as shown in FIG. 2B, the insert
54
is positioned toward the upper end of the housing 52. In this position, the
slots 55 in
the insert 54 align with the ports 53 in the side of the housing 52 so that
fluid
passing in the sleeve 50 can be diverted outside the sleeve 50.
To move the insert 54 between the opened and closed conditions, the
insert 54 has a lower profile 56 and an upper profile 58 that allow the insert
54 to be
engaged and moved within the housing 52. For the present sleeve 50, the lower
profile 56 is used to move the insert 54 downward in the housing 52, thereby
closing
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the sleeve 50. By contrast, the upper profile 58 is used to move the insert 54
upward in the housing 52, thereby opening the sleeve 50. A reverse arrangement
is
also possible in which upward movement of the insert 54 by the upper profile
58 can
close the sleeve 50 and downward movement by the lower profile 56 can open the
sleeve 50.
With an understanding of the system 10, continuous rod 40, sliding
sleeves 50, and tool actuating device 60 provided above, discussion now turns
to a
more detailed description of the tool actuating device 60. As shown in FIG. 3,
the
tool actuating device 60 couples to a threaded pin 42 on the continuous rod
40. At
top, the device 60 has an upper (opening) shifting tool 100 that couples to
the rod's
threaded pin 42 using a rod coupling 70. At bottom, the device 60 has a lower
(closing) shifting tool 200 that couples below the upper tool 100 using rod
couplings
70 and an intermediate length of sucker rod 80. When the continuous rod 40 is
moved upper or down in a tubing string, the upper and lower tools 100/200 move
together.
In the present example, the upper tool 100 is designed to be the
opening tool for opening the sliding sleeves 50 by engaging the upper profile
(58)
and shifting the insert (54) upward in the housing (50). (see FIGS. 2A-2B).
Likewise
in this example, the lower tool 200 is designed to be the closing tool for
closing the
sliding sleeves 50 by engaging the lower profile (56) and shifting the insert
(54)
downward in the housing (50). (see FIGS. 2A-2B). Thus, the upper shifting tool
100
opens the sleeve 50 by jarring up, and the lower shifting tool 200 closes the
sleeve
50 by jarring down. However, a reverse arrangement could also be used. For
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example, the arrangement of tools 100 and 200 on the device 60 could be
switched
so that the (closing) shifting tool 200 can be the upper tool and the
(opening)
shifting tool 100 can be the lower tool. Congruent with this, the sliding
sleeves 50
could also be open and closed by respectively shifting down and up-opposite to
that shown in FIGS. 2A-2B.
The upper (opening) shifting tool 100 shown in FIG. 4A has a core
mandrel 110 with fishneck couplings 102 and 104 threaded at both ends. A
biased
collet 120 fits around the mandrel's recessed intermediate portion 116 and
connects
at both ends to stops 112 and 114 fixed to the core mandrel 110. The collet
120
has B-profiles 122 that include an upward facing shoulder 124, an upper
(shortened) cam 126, and a lower (extended) cam 128. As discussed in more
detail
later, the B-profiles 122 enable the collet 120 to engage recessed profiles in
the
sliding sleeve in one direction and bypass the recessed profiles in the
sliding sleeve
in the opposite direction. This type of shifting tool is typically referred to
as a B
shifting tool with a B-profile.
As shown in FIG. 4B, the upper (opening) shifting tool 100 couples to
the distal end 42 of the continuous rod 40 using a sucker rod coupling 70. As
shown, this coupling 70 has a cylindrical body 72 with internal thread 74 that
connects to the rod's threaded pin 42 and to the pin 103 on the tool's upper
fishneck
coupling 102. The sucker rod coupling 70 can use thread 74 that is preferably
cold
form-rolled as opposed to cut and can use the PRO/KC design available from
Weatherford/Lamb, Inc. As shown, the coupling 70 can also use a center torque
button 76 positioned between the threaded pins 42/103 of the rod 40 and
fishneck
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102 for equal contact pressure of both pin noses. In a similar fashion,
another
sucker rod coupling 70 couples the tool's lower fishneck 104 to the upper pin
on the
device's intermediate sucker rod 80.
As with upper tool 100, the lower (closing) shifting tool 200 shown in
FIG. 5 includes similar components, including a core mandrel 210 with a
fishneck
coupling 202 threaded at its top and including a collet 220 fitting around the
mandrel's recessed intermediate portion 216 and connected at both ends to
stops
212 and 214 fixed to the core mandrel 110. The tool 200 has a nose 204 at its
distal end. The collet 220 has B-profiles 222 that include a shoulder 224, an
upper
cam 226, and a lower cam 228. For this closing tool 200, however, the B-
profile
222 is reversed so that the shoulder 224 is downward facing and the upper cam
228
is extended.
Operation of the upper tool's B-profile 122 in opening a sliding sleeve
50 is shown in FIG. 6A. Operators manipulate the upper tool 100 upward in the
sleeve's housing 52 using the continuous rod 40 and rig equipment at the
surface.
The B-profile's (upward-facing) shoulder 124 engages a downward-facing
shoulder
in the insert's upper recess profile 58. When engaged, further upward movement
of the tool 100 moves the insert 54 upward within housing 52 toward an opened
condition in which the insert's slots align with the housing's ports so fluid
can be
diverted. Eventually, full upward movement on the tool 100 causes the upper
cam
(126) to engage an upper release 59 defined in the housing 52, biasing the
collet
120 inward and releasing the shoulder 124 from the insert's profile 58. At
this point,
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the tool 100 can move out of the housing 52 while the insert 54 remains in the
opened (upward) condition.
Operation of the lower tool's B-profile 222 in closing the sliding sleeve
50 is shown in FIG. 6B and follows a reversed configuration. Here, the B-
profile's
(downward-facing) shoulder 224 engages an upward-facing shoulder in the
insert's
lower recess profile 56. When engaged, further downward movement of the tool
200 moves the insert 54 downward within housing 52 toward a closed condition.
Eventually, the lower cam (228) engages a lower release 57 so the shoulder 224
is
released and the tool 200 can move out of the housing 52 while the insert
remains
in the closed (downward) condition.
As discussed above, the continuous rod 40 and tool actuating device
60 can be deployed by a surface rig 30 to open and close sliding sleeves
during a
frac operation. In stages of a frac operation shown in FIGS. 7A-7E, the tool
actuating device 60 selectively actuates the various sliding sleeves 50
downhole by
successively opening and closing the sleeves 50 to treat isolated zones. Using
the
continuous rod 40 to manipulate the device 60 is more reliable than using
coiled
tubing, which would tend to produce more friction and would require more time
to
actuate the sleeves 50.
As initially shown in FIG. 7A, the sliding sleeves 50 are deployed on
the string 14 downhole before the frac operation. Operators couple the upper
shifting tool 100 to the distal end of the continuous rod 40, couple the
intermediate
rod 80 to the bottom of the upper tool 100, and coupled the lower shifting
tool 200 to
the free end of the intermediate rod 80. Operators then install the device 60
in a
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lubricator fitted atop the wellhead at the surface and deploy the continuous
rod 40
and selective shifting tools 100/200 downhole using the drive and other
components
of the rig (30; see FIG. 1).
When lowered, the tools 100/200 are passed through each of the
sliding sleeves 50A-C, which are initially installed closed on the string 14.
The
sleeves 50A-C may be deployed with grease or other material packed inside to
maintain the sliding inserts (54) in the closed condition in the sleeves 50A-C
during
deployment. As the tools 100/200 are deployed downhole, they cam past each of
the sleeves' inserts (54) without engaging the profiles (56, 58). Eventually,
the
upper (opening) tool 100 passes into the lowermost sliding sleeve 50A. Using a
upward jarring movement, the upper (opening) tool 100 opens the lowermost
sliding
sleeve 50A by engaging the collet's B-profiles (122) into the insert's upper
recess
(58) (see FIG. 6A). A jar (not shown) installed on the continuous rod 40 or
the rig
(30) at the surface can impart this jarring movement. Once the sleeve 50A
opens
and the B-profiles (122) cams free, the continuous rod 40 and tools 100/200
are
moved below the open lowermost sleeve 50A, as shown in FIG. 7B.
As then shown in FIG. 7B, operators perform a frac treatment by
pumping frac fluid down the tool string 14 while the continuous rod 40 remains
in
the tubing sting 14. Leaving the continuous rod 40 and shifting tools 100/200
in the
string 14 during the frac treatment below the open sleeve 50A eliminates the
rig
time that would be required to trip the tools 100/200 and rod 40 out of the
sting 14
between frac treatments, as would conventionally be done to protect coiled
tubing if
used to actuate the sleeves.
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During treatment, the frac fluid diverts through the open sleeve 50A
and treats the adjacent isolated zone though the perforations 13. Once this
zone
has been treated, operators use the rig to lift the continuous rod 40 in the
string 14.
As shown in FIG. 7C, the upper tool 100 freely passes through the lowermost
sliding sleeve 50A that remains open. With further lifting, the lower
(closing) tool
200 is positioned to engage this open sliding sleeve 50A. Using a downward
jarring
movement, the lower tool 200 closes this lowermost sleeve 50A.
As shown in FIG. 7D, the device 60 and rod 40 are then lifted in the
tubing string 14, and the upper (opening) tool 100 engages the next uppermost
sliding sleeve 50B (which is closed). Using an upward jarring movement, the
tool
100 is used to open this sleeve 50B. As shown in FIG. 7E, once the upper tool
100
cams free, operators position the two tools 100/200 in between the sliding
sleeves
50A-50B, pump frac fluid in the string 14, and treat the next isolated zone
adjacent
the open sleeve 50B. Once fracing is complete for this zone, operators lift
the tools
100/200 and again close the open sliding sleeve 50B, open the next upper most
sliding sleeve 50C, and frac the next zone. Operations then continue in this
same
manner up the string 14 as each successively higher isolated zone is treated.
Although the frac operation discussed above involved opening the
sleeves 50 in the uphole direction and closing them in the downhole direction,
the
reverse arrangement could be used. Likewise, treatment of successive zones
could
proceed successively from the uppermost zone to the lowermost zone or could be
performed selectively at any of the various zones. In addition, although the
device
60 and continuous rod 40 are initially deployed from the surface downhole to
the
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lowermost sleeve 50A in the above discussion, it is also possible to deploy
the
device 60 independently in a bottomhole assembly (not shown) coupled in a
conventional manner to the tubing string 14 below the lower most sliding
sleeve 50A.
In this case, the continuous rod 40 can then be deployed downhole with a
suitable
coupling known in the art to connect to the device 60 and retrieve if from the
bottomhole assembly to conduct the successive frac operations up the wellbore.
The tool actuating device 60 of FIG. 3 uses upper and lower shifting
tools 100 and 200 separated by an intermediate sucker rod 80. Another
arrangement of the device 60 can uses a two-way shifting tool 300 as shown in
FIGS. 8A-8B. Here, the two-way shifting tool 300 couples to the threaded pin
42 of
the continuous rod 40 using a sucker rod coupling 70. The two-way tool 300
includes many of the same components as the upper and lower tools discussed
previously so that the tool 300 includes a core mandrel 310, a fishneck
coupling 302,
stops 312/314, a biased collet 320, and a nose 304. On this tool 300, the
collet 320
has dual B-profiles 322 having a downward-facing shoulder 324, an upper cam
326,
an upward-facing shoulder 325, and a lower cam 328. Depending on the sleeve's
configuration, the shifting tool 300 can open/close the sleeve by jarring down
and
can close/open the sleeve by jarring up. This tool 300 can be used for
selective frac
treatments of isolated zones in a similar fashion to that discussed above with
reference to FIGS. 7A-7E.
In general, the continuous rod 40 used with the system 10 can be
COROD and can have similar properties and characteristics. (COROD is a
registered trademark of Weatherford/Lamb, Inc.). For example, the continuous
rod
CA 02674223 2009-07-31
40 can be composed of carbon steel, chromium-molybdenum alloy steel (e.g.,
AISI
4142), or other suitable material and can have round or semi-elliptical cross-
section
with a diameter ranging from 12/16-inch to 18/16-inch, for example.
As shown in FIGS. 2A-2B and 6A-6B, the system 10 when used for
frac operations can be used with a mono-bore type of sliding sleeve, but other
types
of sliding sleeves could also be used. Examples of suitable sliding sleeves,
also
available from Weatherford/Lamb, Inc., include the OtimaxTM Sliding Sleeve,
the
OptislimTM Sliding Sleeve, and WXO and WXA Standard Sliding Sleeves. (the
OptimaxTM Sliding Sleeve, and OptislimTM Sliding Sleeve are trademarks of
Weatherford/Lamb, Inc.).
Although the system 10 has been described for opening and closing
sliding sleeves on a frac string, the system of continuous rod 40 and tool
actuating
device 60 can also be used to actuate other downhole tools that can be
actuated to
a first operative condition in a first direction and to a second operative
condition in a
second direction. Some other suitable downhole tools include, for example, a
gravel pack closing sleeve, a completion isolation valve, or other downhole
tool
having shiftable operation. With any of these downhole tools, the ability to
actuate
the tool with the continuous rod 40 and actuating device 60 can be enhanced by
the
reliable and efficient operation that the rod 40 and device 60 offer in either
vertical
or horizontal wells.
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