U.S. patent application number 13/545908 was filed with the patent office on 2013-01-17 for multi-zone screened frac system.
This patent application is currently assigned to WEATHERFORD/LAMB, INC.. The applicant listed for this patent is Ronald van Petegem. Invention is credited to Ronald van Petegem.
Application Number | 20130014953 13/545908 |
Document ID | / |
Family ID | 47506462 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130014953 |
Kind Code |
A1 |
van Petegem; Ronald |
January 17, 2013 |
Multi-Zone Screened Frac System
Abstract
A multi-zone screened frac system combines screens with
integrated check valves, frac valves, and optional shunt tubes for
slurry dehydration. The system can also include fiber optic
technology. In particular, the system uses sliding sleeves and flow
devices for each section. The sliding sleeves open with dropped
balls or a service tool, and the flow devices have screens and act
as check valves. Dehydration tubes can also be used. The system
does not require a crossover tool, and in some implementations, the
system does not even require a complete service tool.
Inventors: |
van Petegem; Ronald;
(Montgomery, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
van Petegem; Ronald |
Montgomery |
TX |
US |
|
|
Assignee: |
WEATHERFORD/LAMB, INC.
Houston
TX
|
Family ID: |
47506462 |
Appl. No.: |
13/545908 |
Filed: |
July 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61506897 |
Jul 12, 2011 |
|
|
|
Current U.S.
Class: |
166/308.2 ;
166/177.5 |
Current CPC
Class: |
E21B 43/267 20130101;
E21B 43/08 20130101; E21B 43/14 20130101; E21B 43/26 20130101; E21B
34/14 20130101; E21B 2200/06 20200501 |
Class at
Publication: |
166/308.2 ;
166/177.5 |
International
Class: |
E21B 43/27 20060101
E21B043/27; E21B 43/08 20060101 E21B043/08 |
Claims
1. A multi-zone frac assembly for a borehole, comprising: a tubular
structure disposed in the borehole and defining a through-bore; and
a plurality of sections disposed on the tubular structure, each of
the sections comprising: an isolation element disposed on the
tubular structure and isolating a borehole annulus of the section
from the other sections, a flow valve disposed on the tubular
structure and selectively operable between opened and closed
conditions, the flow valve in the opened condition permitting fluid
communication between the through-bore and the borehole annulus,
the flow valve in the closed condition preventing fluid
communication between the through-bore and the borehole annulus, a
screen disposed on the tubular structure and communicating with the
borehole annulus, and a check valve disposed on the tubular
structure and in fluid communication between the screen and the
through-bore, the check valve permitting fluid communication from
the screen into the through-bore and preventing fluid communication
from the through-bore to the screen.
2. The assembly of claim 1, wherein the isolation element comprises
a swellable packer, a hydraulically-set packer, or a
mechanically-set packer.
3. The assembly of claim 1, wherein at least a portion of the
tubular structure for a given one of the sections comprises a
basepipe having the through-bore and defining at least one pipe
port communicating the through-bore outside the basepipe.
4. The assembly of claim 1, wherein the check valve is disposed on
the tubular structure adjacent at least one pipe port communicating
the through-bore outside the tubular structure, the check valve
permitting fluid communication from the screen to the at least one
pipe port and preventing fluid communication from the at least one
pipe port to the screen.
5. The assembly of claim 4, wherein the check valve comprises a
housing disposed on the tubular structure, the housing having at
least one internal flow passage and having at least one check ball,
the at least one internal flow passage communicating the screen
with the at least one pipe port, the at least one check ball
movable to one condition permitting fluid communication through the
at least one internal flow passage and movable to another condition
preventing fluid communication through the at least one internal
flow passage.
6. The assembly of claim 4, wherein the screen is disposed on the
tubular structure and has one end in fluid communication with the
check valve.
7. The system of claim 1, wherein the flow valve comprises: a
housing having a flow port communicating the through-bore outside
the housing; and an insert movable in the housing between the
closed condition preventing fluid communication through the flow
port and the opened condition permitting fluid communication
through the flow port.
8. The assembly of claim 7, wherein the insert comprises a seat
disposed therein, the seat seating a plug deployed in the tubular
structure thereon and moving the insert from the closed condition
to the opened condition in response to application of fluid
pressure against the seated plug.
9. The assembly of claim 1, further comprising a flow tube disposed
in the borehole annulus and communicating through the isolation
elements between one or more of the sections.
10. The assembly of claim 1, further comprising a workstring
disposing in the through-bore of the tubular structure, the
workstring operable to open and close the flow valve of each
section and operable to seal inside the assembly and place an
outlet port on the workstring in sealed communication with the
borehole annulus when the flow valve has the opened condition.
11. The assembly of claim 10, wherein the workstring comprises an
actuating tool operable to engage the flow valve in one direction
and actuate the flow valve open and operable to engage the flow
valve in another direction and actuate the flow valve closed.
12. The assembly of claim 10, wherein the assembly comprises seats
disposed in the through-bore on both uphole and downhole sides of a
flow port in the flow valve, and wherein the workstring comprises
seals disposed on both uphole and downhole sides of the outlet
port, the seals configured to seal against the seats disposed in
the through-bore.
13. The assembly of claim 10, further comprising a bypass tube for
at least one of the sections, the bypass tube communicating a first
portion of the through-bore on one side of a location of the
workstring sealed inside the assembly to another side of the
location.
14. A multi-zone frac assembly for a borehole, comprising: a
tubular structure disposed in the borehole and defining a
through-bore; and a plurality of sections disposed on the tubular
structure, each of the sections comprising: means for isolating a
borehole annulus of the section from the other sections, means for
selectively permitting and preventing fluid communication between
the through-bore and the borehole annulus through a first flow
path, means for exclusively screening fluid communication from the
borehole annulus to the through-bore through a second flow path,
and means for exclusively preventing fluid communication from the
through-bore to the borehole annulus through the second flow
path.
15. The assembly of claim 14, wherein the means for selectively
permitting and preventing fluid communication between the
through-bore and the borehole annulus through the first flow path
comprises means for selectively opening and closing ports in the
tubular structure.
16. The assembly of claim 14, wherein the means for exclusively
screening fluid communication from the borehole annulus to the
through-bore through the second flow path comprises means for
permitting fluid communication of the screened fluid into the
through-bore through the second flow path.
17. A multi-zone frac method for a borehole, the method comprising:
disposing the assembly in the borehole; isolating an annulus of the
borehole around the assembly into a plurality of isolated zones;
screening fluid communication from the annulus of the isolated
zones into a through-bore of the assembly with screens on the
assembly; preventing fluid communication from the through-bore to
the annulus of the isolated zones through the screens; and treating
each of the isolated zones with a treatment fluid by: selectively
opening a port in the assembly at the each isolated zone, and
flowing the treatment fluid down the through-bore to the each
isolated zone through the opened port.
18. The method of claim 17, wherein disposing the assembly in the
borehole comprises disposing the assembly in casing having
perforations, in an expanded liner having slots, or in an open
hole.
19. The method of claim 18, wherein isolating the annulus of the
borehole around the assembly into the isolated zones comprises
engaging packing elements on the assembly against a wall of the
casing, a wall of the expanded liner, or a wall of the open
hole.
20. The method of claim 17, wherein screening fluid from the
annulus of the isolated zones into the through-bore of the assembly
with screens on the assembly comprises allowing fluid communication
from the screens through perforations in the assembly communicating
with the through-bore.
21. The method of claim 20, wherein preventing fluid communication
from the through-bore to the annulus of the isolated zones through
the screens comprises disposing a check valve in fluid
communication between the screens and the perforations.
22. The method of claim 17, wherein selectively opening the port in
the assembly at the each isolated zone comprises opening the port
in the assembly by moving an insert in the assembly away from the
port.
23. The method of claim 22, further comprising selectively closing
the opened ports in the assembly at each of the isolated zones.
24. The method of claim 22, wherein moving the insert in the
assembly away from the port comprises: engaging a plug on the
insert; and moving the insert away from the port with application
of fluid pressure against the engaged plug.
25. The method of claim 24, wherein flowing the treatment fluid
down the through-bore to the each isolated zone through the opened
port comprises flowing the treatment fluid through the opened port
when the insert is moved away from the port.
26. The method of claim 24, wherein treating each of the isolated
zones with the treatment fluid comprises: successively treating the
isolated zones uphole on the assembly by successively engaging
plugs and moving inserts uphole on the assembly for successive ones
of the isolated zones.
27. The method of claim 24, further comprising: removing the
engaged plug; and selectively closing the insert over the opened
port in the assembly.
28. The method of claim 22, wherein moving the insert in the
assembly away from the port comprises: engaging the insert with a
workstring disposed in the through-bore of the assembly; and moving
the insert away from the port with movement of the engaged
workstring.
29. The method of claim 28, wherein flowing the treatment fluid
down the through-bore to the each isolated zone through the opened
port comprises flowing the treatment fluid through an outlet in the
workstring and through the opened port when the insert is moved
away from the port.
30. The method of claim 28, wherein treating each of the isolated
zones with the treatment fluid comprises: successively closing a
given one of the inserts with the workstring after treatment; and
successively opening another one of the inserts with the workstring
before treatment.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a non-provisional of U.S. Provisional Appl.
61/506,897, filed 12 Jul. 2011, which is incorporated herein by
reference and to which priority is claimed.
BACKGROUND
[0002] Many wells are fractured with a proppant (e.g., sand or the
like) to treat a formation and improve production. In many cases,
multiple fracs are performed in a single wellbore to treat various
zones of interest in the formation. Systems exist in the art that
allow operators to frac multiple zones in a single trip in the
wellbore. Some systems even use a wellscreen to prevent proppant
flowback during operations.
[0003] Unfortunately, current systems that include a wellscreen use
a service crossover tool for operation. The crossover tool crosses
over the fluid flow path from a workstring to the annulus outside
the wellscreen and vice versa. However, using the crossover tool
has a number of disadvantages.
[0004] The subject matter of the present disclosure is directed to
overcoming, or at least reducing the effects of, one or more of the
problems set forth above.
SUMMARY OF THE DISCLOSURE
[0005] A multi-zone frac assembly for a borehole has a tubular
structure disposed in the borehole and defining a through-bore. A
plurality of sections disposed on the tubular structure each has an
isolation element, a flow valve, a screen, and a check valve. The
isolation element, which can be a swellable packer, a
hydraulically-set packer, or a mechanically-set packer, isolates a
borehole annulus around the section from the other sections along
the borehole. If desired, a flow tube can be disposed in the
borehole annulus and can communicate through the isolation elements
between one or more of the sections.
[0006] The flow valve is selectively operable between opened and
closed conditions. Thus, the flow valve in the opened condition
permits fluid communication between the through-bore and the
borehole annulus, but the flow valve in the closed condition
prevents fluid communication between the through-bore and the
borehole annulus.
[0007] The screen disposed on the tubular structure communicates
with the borehole annulus, and the check valve is in fluid
communication between the screen and the through-bore. The check
valve permits fluid communication from the screen into the
through-bore, but prevents fluid communication from the
through-bore to the screen.
[0008] In one arrangement, at least a portion of the tubular
structure for a given one of the sections includes a basepipe
having the through-bore and defining at least one pipe port
communicating the through-bore outside the basepipe. Disposed on
the basepipe, the check valve permits fluid communication from the
screen to the at least one pipe port and prevents fluid
communication from the at least one pipe port to the screen.
[0009] In particular, the check valve can have a housing disposed
on the basepipe, and the screen can have one end in fluid
communication with the housing. The housing has at least one
internal flow passage and has at least one check ball. The at least
one internal flow passage communicates the screen with the at least
one pipe port. To control flow, the at least one check ball is
movable relative to the at least one internal flow passage. In one
condition, the at least one check ball permits fluid communication
through the at least one internal flow passage, while in another
condition, the at least one check ball prevents fluid communication
through the at least one internal flow passage.
[0010] In one arrangement, the flow valve is a sliding sleeve
having a housing and in insert movable therein. The housing has a
flow port communicating the through-bore outside the housing, and
the insert is movable in the housing between the closed condition
preventing fluid communication through the flow port and the opened
condition permitting fluid communication through the flow port.
[0011] To move the seat, the insert has a seat disposed therein
that seats a plug deployed in the tubular structure thereon and
moves the insert from the closed condition to the opened condition
in response to application of fluid pressure against the seated
plug.
[0012] In other arrangements, the insert can be moved by a shifting
tool. In particular, the assembly can have a workstring disposing
in the through-bore of the tubular structure. The workstring has an
actuating tool and defines a fluid passageway therethrough. An
outlet port communicates the fluid passageway outside the
workstring. In the assembly, the workstring is operable to open and
close the flow valve of each section with the actuating tool. The
workstring is operable to seal inside the assembly and place the
outlet port in sealed fluid communication with the borehole annulus
when the flow valve has the opened condition.
[0013] If desired, the assembly can have a bypass tube for at least
one of the sections. The bypass tube communicates a first portion
of the through-bore on one side of a location of the workstring
sealed inside the assembly to another side of the location.
[0014] In a multi-zone frac method for a borehole, an assembly
disposes in the borehole, and an annulus of the borehole around the
assembly is isolated into a plurality of isolated zones. To isolate
the annulus, for example, the method can involve engaging packing
elements on the assembly against the borehole.
[0015] Fluid communication from the annulus of the isolated zones
is screened into a through-bore of the assembly with screens on the
assembly, and fluid communication is prevented from the
through-bore to the annulus of the isolated zones through the
screens. For example, screening the fluid can involve allowing
fluid communication from the screens through perforations in the
assembly communicating with the through-bore, and prevent fluid
communication from the through-bore to the annulus can involve
disposing a check valve in fluid communication between the screens
and the perforations.
[0016] In the method, treating each of the isolated zones with a
treatment fluid is achieved by: selectively opening a port in the
assembly at the each isolated zone, and flowing the treatment fluid
down the through-bore to the each isolated zone through the opened
port. For example, selectively opening the port in the assembly at
the each isolated zone involves opening the port in the assembly by
moving an insert in the assembly away from the port. Further,
selectively closing the opened ports in the assembly can be
achieved at each of the isolated zones.
[0017] In moving the insert in the assembly away from the port, the
method in one arrangement involves engaging a plug on the insert;
and moving the insert away from the port with application of fluid
pressure against the engaged plug. Then, to flow the treatment
fluid down the through-bore to the each isolated zone through the
opened port, the treatment fluid can flow through the opened port
when the insert is moved away from the port. In this way, treating
each of the isolated zones with the treatment fluid involves
successively treating the isolated zones uphole on the assembly by
successively engaging plugs and moving inserts uphole on the
assembly for successive ones of the isolated zones. Once treatment
is completed, the engaged plug can be remove, and the insert can be
selectively closed over the opened port in the assembly.
[0018] In another arrangement to move the insert in the assembly
away from the port, the insert can be engaged with a workstring
disposed in the through-bore of the assembly, and the insert can be
moved away from the port with movement of the engaged workstring.
In this arrangement, flowing the treatment fluid down the
through-bore to the each isolated zone through the opened port
involves flowing the treatment fluid through an outlet in the
workstring and through the opened port when the insert is moved
away from the port. In this way, treating each of the isolated
zones with the treatment fluid involves successively closing a
given one of the insert with the workstring after treatment, and
successively opening another one of the inserts with the workstring
before treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 illustrates a multi-zone screened frac system
according to the present disclosure disposed in a cased borehole
and having sections with frac valves and flow devices, which
include wellscreens and check valve devices.
[0020] FIG. 2A illustrates the multi-zone screened frac system of
FIG. 1 having a dehydration tube.
[0021] FIG. 2B illustrates the multi-zone screened frac system of
FIG. 1 having an expandable liner.
[0022] FIG. 3 illustrates a multi-zone screened frac system
according to the present disclosure disposed in an open borehole
and having sections with frac valves and flow devices, which
include wellscreens and check valve devices.
[0023] FIG. 4 illustrates a multi-zone screened frac system
according to the present disclosure disposed in a cased borehole
and using a workstring in conjunction with frac valves and flow
devices, which include wellscreens and check valve devices.
[0024] FIG. 5 illustrates the multi-zone screened frac system of
FIG. 4 having flow tubes.
[0025] FIG. 6A illustrates a partial cross-section of a flow device
for the disclosed multi-zone screened frac system.
[0026] FIG. 6B illustrates a detailed view of an inflow control
device for the flow device of FIG. 6A.
[0027] FIG. 6C illustrates an isolated, partial cross-sectional
view of the inflow flow control device of FIG. 6A.
[0028] FIGS. 7A-7B illustrate partial cross-sections of a
multi-select sliding sleeve for the disclosed multi-zone screen
frac system in closed and opened states.
[0029] FIGS. 8A-8B illustrate shifting tools for use on a
workstring for the disclosed system of FIGS. 4-5.
DETAILED DESCRIPTION
[0030] Various embodiments of a multi-zone screened frac system are
disclosed. The system does not require a crossover tool as required
in the prior art. In some implementations, the system does not even
require a complete service tool. To perform a frac operation on
multiple zones in a cased or open borehole, the system combines:
(1) wellscreens with integrated check valves, (2) frac valves, and
(3) optional shunt tubes for slurry dehydration. The system can
also include fiber optic technology.
[0031] In a first embodiment according to the present disclosure,
FIG. 1 illustrates a multi-zone screened frac system 10 disposed in
a cased borehole and having sections with frac valves and flow
devices, which include wellscreens and check valve devices. The
system 10 includes an upper completion or workstring 14 disposed in
casing 12. This string 12 is engaged in an uphole end 24 of a
production string 22 of a frac assembly 20 and can engage the
casing 12 with an optional packer 16.
[0032] Internally, the production string 22 of the frac assembly 20
has a through-bore 25 communicating along the length of the string
22 and communicating with the completion string 14. Externally, the
frac assembly 20 has isolation devices 18, such as but not limited
to a hydraulic, a mechanical, or a swellable packer, to seal the
production string 22 in the casing 12. One of the isolation devices
18 is disposed at the string 22's uphole end 24, while other
isolation devices 18 are disposed along the length of the
production string 22. Separated by the isolation devices 18, the
frac assembly 20 has various sections 28 disposed at various
intervals or zones of interest in the surrounding formation. At its
downhole end 26, the frac assembly 20 has a bottom seat 50 for
engaging a setting ball 54 during frac operations.
[0033] Each section 28 has a selective frac valve 30 and a flow
device 40. Each of the selective frac valves 30 and flow devices 40
in a given section 28 is separated from other sections 28 by
isolation elements 18, which isolate the borehole annulus 15 for
the respective sections 28. As shown, the selective frac valves 30
are disposed uphole of the flow devices 40 in the various sections
28. As an alternative, the selective frac valves 30 can be disposed
downhole of the flow devices 40 in each section 28.
[0034] The selective frac valves 30 have one or more ports 32 that
can be selectively opened and closed during operation. In this
arrangement and as discussed in more detail below, for example,
each of the selective frac valves 30 can be opened to communicate
their ports 32 with the surrounding annulus 15 by using frac plugs
or balls 34 deployed downhole during frac operations. As treatment
is performed in the well, these dropped plugs or balls 34
selectively open the frac valves 30 and isolate lower sections 28
so the selective frac valves 30 can successively divert frac
treatment to adjacent zones of interest up the frac assembly
20.
[0035] The flow device 40 for each section 28 is disposed adjacent
or near perforations 13 in the casing 12. In this and other
assemblies disclosed herein, the flow devices 40 use wellscreens 42
with integrated check valves 44 to control the flow of fluid
through the devices 44. In particular, each flow device 40
exclusively screens fluid communication through a first flow path
(i.e., flow from the borehole annulus 15 to the through-bore 25 of
the assembly 20 through the flow device 40). At the same time, the
flow device 40 exclusively prevents fluid communication from the
through-bore 25 of the assembly 20 to the borehole annulus 15 along
this first flow path. Thus, the wellscreen 42 screens fluid flow
along the first flow path from the borehole annulus 15 to the
through-bore 25. However, the flow device 40 does not permit fluid
flow in the opposite direction along this same flow path, but in
the opposite direction from the through-bore 25 to the borehole
annulus 15.
[0036] In particular, the flow devices 40 can each include a
wellscreen 42 and an inflow control device 44, such as a FloReg.TM.
Deploy-Assist (DA) Device available from Weatherford International.
Preferably, the inflow control device 44 lacks nozzles and is used
in the system primarily as a check valve, but nozzles can be used
in other arrangements. Further details of a suitable flow device 40
having a wellscreen 42 and an inflow control device 44, such as the
FloReg.TM. Deploy-Assist (DA) Device, are provided below in FIGS.
6A-6C. Moreover, details of a suitable inflow control device 44
used with a wellscreen 42 are also disclosed in U.S. Pat. Nos.
6,371,210 and 7,828,067, which are incorporated herein by reference
in its entirety.
[0037] In this and other assemblies disclosed herein, each
selective frac valve 30 selectively permits and prevents fluid
communication through a second flow path (i.e., between the
through-bore 25 of the assembly 20 and the borehole annulus 15). In
particular, the selective frac valves 30 can be sliding sleeves,
such as a ZoneSelect.TM. MultiShift frac sliding sleeve available
from Weatherford International. The selective frac valve 30 is
designed to open when a ball 34 lands on a landing seat (not shown)
disposed in the selective frac valve 30 and tubing pressure is
applied to shear the selective frac valve 30 open to expose the
through-bore 25 to the surrounding annulus 15. The balls 34 are
dropped from the surface once the appropriate amount of proppant is
pumped into each zone 28. Further details of a suitable multi-shift
sliding sleeve, such as the ZoneSelect.TM. MultiShift frac sliding
sleeve, are provided below in FIGS. 7A-7B.
[0038] In this and other assemblies 10 disclosed herein, a fracing
operation uses the series of packers 18 and selective frac valves
30 to sequentially isolate the different zones or sections 28 of
the downhole formation. Initially, the assembly 20 having the
packers 18, selective frac valves 30, and flow devices 40 is run
downhole and set up using known techniques. Eventually, a bottom
plug or ball 54 is pumped downhole to close off the flow path
through the assembly's bottom end 50.
[0039] Next, operators set the packers 18 to create the multiple
isolated sections 28 down the borehole annulus 15. How the packers
18 are set depends on the type of packers 18 used. For example,
hydraulic pressure pumped down the assembly's through-bore 25 can
be used to set the packers 18. The closed bottom end 50, the closed
frac valves 30, and the integrated check valves 44 prevent fluid
pressure in the assembly 20 from escaping to the annulus 15 during
the setting procedures. Use of different types of packers 18 would
require other known procedures.
[0040] Once the packers 18 are set, operators apply a frac
treatment successively to each of the isolated sections 28 by
selectively opening the selective frac valves 30 and allowing the
treatment fluid to interact with the adjacent zones of the
formation through the opened ports 32. To open each frac valve 30,
for example, operators drop specifically sized plugs or balls 34
into the assembly 20 and land them on corresponding seats (not
shown) on the designated frac valves 30. Typically, the balls 34
increase in size up the borehole so that a smaller ball 34 can pass
through all of the seats (not shown) on the uphole frac valves 30
before engaging its designated seat further downhole. For example,
a range of plugs or balls 34 may allow fracturing up to 13, 19, and
21 sections in the borehole when 31/2 in., 41/2 in., and 51/2 in.
frac valves 30 are used, respectively. An additional section can be
added by using a toe sleeve (not shown).
[0041] Once a dropped ball 34 is seated, the ball 34 closes off the
lower section 28 just treated, and built up pressure on the seated
ball 34 forces the frac valve 30 open so frac fluid can interact
with the adjacent zone of the formation through the open flow ports
32. Operators repeat this process up the assembly 20 to treat all
of the sections 28 by successively dropping bigger balls 34 against
bigger seats (not shown) in the frac valves 30. Once the frac
treatment is complete, flow in the assembly 20 can float all the
balls 34 to the surface, or operators can mill out the balls 34 and
ball seats (not shown) from the frac valves 30. Finally, after
fracing, the system 10 may need a clean-out trip in which a fluid
wash is pumped down the assembly 10 to clear it of excess or
residual proppant and frac fluid.
[0042] The multi-zone frac system 10 of FIG. 1 can achieve higher
flow rates and can improve reservoir performance while only
requiring one trip upper and lower completions, using standard
packers, not requiring a crossover tool, and offering less risk.
The system 10 can also have any suitable length and spacing between
sections 28. A wet-connector is not required for using fiber
optics, and the system 10 allows for monitoring while fracing using
a fiber optic based sensor system.
[0043] In a second embodiment according to the present disclosure,
the multi-zone screened frac system 10 of FIG. 2A is similar to
that of FIG. 1 so that similar components are shown with the same
reference numerals. In contrast to the previous arrangement,
however, this system 10 has a dehydration tube (i.e., slurry or
flow tube) 60 disposed along the assembly 20 running from the
optional packer 16 at the uphole end 24 to the lower most packer 18
near the downhole end 26. Although the de-hydration tube 60 may be
a barrier issue, this can be mitigated by running a production
packer (not shown) uphole in the casing 12.
[0044] The dehydration tube 60 communicates with the borehole
annulus 15 of each of the sections 28 using flow ports (not shown)
or the like. Additionally, the tube 60 passes through the packers
18 isolating the sections 28. Use of the tube 60 is beneficial when
frac pack operations are performed, which involve fracing a zone of
interest and then gravel packing the borehole annulus 15 around the
wellscreen 42. In this way, use of the tube 60 in the system 10
allows dehydration of the annular gravel pack when performed.
[0045] After fracing operations, the system 10 in FIG. 2A may need
a clean-out trip and may require 3-4 MM in lower tertiary. The
multi-zone frac system 10 of FIG. 2A can provide higher rates and
improve reservoir performance while not requiring a crossover tool
and offering less risk. The system 10 can be any length and
spacing, may eliminate the need for a wet-connector for fiber
optic, and allows for monitoring while fracing.
[0046] As noted above in FIGS. 1 and 2A, the system 10 can be used
in cased borehole having casing 12 with perforations 13. Other
completion arrangements can be used. For example, instead of the
borehole having perforated casing 12, the borehole can have an
expandable pre-slotted or pre-perforated liner 17a as in FIG. 2B.
As is customary, such an expandable liner 17a can be suspended from
a liner hanger and packer assembly 17b disposed in casing 12. Below
the liner hanger and packer assembly 17b, the expandable liner 17a
extends into an open borehole section. The expandable liner 17a can
have slots or perforations (not shown) in those zones of the
formation to be produced. Although not shown, the expandable liner
17a can be constructed to suit the zones of the formation using
modular components, including expandable liner or sand screen
sections, blank pipe sections, and expandable zonal isolation
joints, such as are available in Weatherford's Expandable Reservoir
Completion systems.
[0047] How the liner hanger and packer assembly 17b and the
expandable liner 17a are installed in the borehole will be
appreciated by one skilled in the art with the benefit of the
present disclosure so that particular details are not provided
here. Briefly though, the liner hanger and packer assembly 17b and
expandable liner 17a are disposed downhole, and the hanger and
packer assembly 17b is set by dropping a ball and applying
pressure. Expansion of the liner 17a is then performed using liner
expansion tools. Once the liner is set, frac operations can be
performed by deploying the frac assembly 20 as described
previously.
[0048] Other than a cased or lined borehole as noted above, the
multi-zone screened frac system 10 can also be used for open hole
completions. In a third embodiment according to the present
disclosure, for example, the multi-zone screened frac system 10 of
FIG. 3 is used for an open hole completion and has many of the same
components as described previously so that like reference numeral
are used for similar components. In contrast to the cased or lined
hole arrangements of FIGS. 1 and 2A-2B, open hole packers 19 are
used for this system 10 in FIG. 3. These packers 19 can be
swellable and/or hydraulic set packers for open holes.
[0049] After fracing operations, the system 10 may need a clean-out
operation. As before, the frac valves 30 are disposed uphole of the
flow devices 40, but they could be disposed downhole of the flow
devices 40 in each section 28. As another alternative, slurry
de-hydration tubes (not shown) could also be used along the
assembly 10.
[0050] The multi-zone frac system 10 of FIG. 3 provides the highest
rates and improved reservoir performance. The system 10 can be of
any length and any spacing. The system 10 does not require
perforating to be performed and offers the option to step down one
casing size in its implementation, which can give significant
savings potential. Finally, the system 10 does not need
wet-connectors for using fiber optics, and the system 10 allows for
monitoring while fracing.
[0051] In a fourth embodiment according to the present disclosure,
the multi-zone screened frac system 10 in FIG. 4 is also used for
openhole completions as with the embodiment of FIG. 3. In contrast
to previous arrangements, this system 10 has a workstring 70 that
disposes in the frac assembly 20 to open the various frac valves 30
and treat portions of the formation. As shown, the workstring 70
has external seals 76 disposed near outlet ports 72 and a dropped
ball 74 can seat in an distal seat of the workstring 70 to divert
fluid flow down the workstring 70, out the outlet ports 72, and to
the open ports 32 in the frac valve 30 to treat the surrounding
formation.
[0052] The frac operation for the system 10 of FIG. 4 involves
running the assembly 20 downhole and setting the packers 19 to
create the multiple isolated sections 28 down the borehole annulus
15. Once the packers 19 are set, operators apply a frac treatment
successively to each of the isolated sections 28 by selectively
opening the selective frac valves 30 with a shifting tool 78 on the
workstring 70 since dropped balls are not used.
[0053] Details about opening the frac valves 30 are provided below
with reference to FIGS. 7A-7B and 8A-8B. In general, the shifting
tool 78 can be a "B" shifting tool for shifting an inner sleeve in
the frac valve 30 relative to the valve's ports 32. Thus, opening a
given frac valve 30 involves engaging the shifting tool 78 in an
appropriate profile of the valve's inner sleeve and moving the
inner sleeve with the workstring 70 to an opened condition so that
the assembly's through-bore 25 communicates with the borehole
annulus 15 via the now opened ports 32.
[0054] Once a given frac valve 30 is opened, the seals 76 on the
workstring 70 can engage and seal against inner seats 36, surfaces,
seals, or the like in the frac valve 30 or elsewhere in the
assembly 20 on both the uphole and downhole sides of the opened
ports 32. The seals 76 can use elastomeric or other types of seals
disposed on the inner workstring 70, and the seats 36 can be
polished seats or surfaces inside the frac valve 30 or other part
of the assembly 30 to engage the seals 76. Although shown with this
configuration, the reverse arrangement can be used with seals on
the inside of the frac valve 30 or assembly 20 and with seats on
the workstring 70.
[0055] Once the workstring 70 is seated, treatment fluid is flowed
down the through-bore 75 of the workstring 70 to the sealed and
opened ports 32 in the frac valve 30. The treatment fluid flows
through the outlet ports 72 in the workstring 70 and through the
opened ports 32 to the surrounding borehole annulus 15, which
allows the treatment fluid to interact with the adjacent zone of
the formation.
[0056] Once treatment is completed for the given zone, operators
manipulate the workstring 70 to engage the shifting tool 78 in the
frac valve 30 to close the ports 32. For example, the shifting tool
78 can engage another suitable profile on an inner sleeve of the
frac valve 30 to move the sleeve and close the ports 32. At this
point, the workstring 70 can be moved in the assembly 20 to open
another one of the frac valves 30 to perform treatment. Operators
repeat this process up the assembly 20 to treat all of the sections
28. Once the frac treatment is complete, the system 10 may not need
a clean-out trip.
[0057] The multi-zone frac system 10 of FIG. 4 can have higher
rates compared to a conventional single trip multi-zone system and
can improve reservoir performance. The system 10 can have any
suitable length and spacing, offers the option to step down one
casing size, does not require perforating, and does not require a
clean-out trip. Consideration should be given to potential sticking
the workstring 70 during operation and to annulus packing that can
occur for a particular implementation.
[0058] In a fifth embodiment of the multi-zone screened frac system
10 of FIG. 5 also has a workstring 70, as with the previous
embodiment of FIG. 4. In addition to all of the same components,
this system 10 has slurry dehydration tubes 80 disposed along the
various sections 28.
[0059] During a frac operation similar to that discussed above, the
tubes 80 help dehydrate slurry intended to gravel pack the borehole
annulus 15 of the sections 28 during a frac pack type of operation.
In addition, the tubes 80 can act as a bypass for fluid returns
during the operation. As treatment fluid flows from the workstring
70 seated in a frac valve 30, through the opened ports 32, and into
the borehole annulus 15, the wellscreen 42 screens fluid returns
from the annulus 15, and the fluid returns can flow into the
assembly 20 downhole of the engagement of the workstring 70 in the
assembly 20. The tubes 80 can, therefore, allow these fluid returns
to flow from the downhole section of the assembly 20 to the
micro-annulus between the workstring 70 and the inside of the
assembly 20 uphole of the sealed engagement of the workstring 70
with the ports 32. From this point, the fluid returns can then flow
to the surface.
[0060] The multi-zone frac system 10 of FIG. 5 can have higher
rates compared to a conventional single trip multi-zone system 10
and can improve reservoir performance. Furthermore, the system 10
can have any length and spacing, offers the option to step down one
casing size, does not require perforating, does not require a
clean-out trip, and can give good annulus packing. Consideration
should be given to potential sticking of the workstring 70 for a
particular implementation.
[0061] As noted above, the various embodiments of the multi-zone
frac system 10 in FIGS. 1-5 use flow devices 40 disposed on the
frac assembly 20, and the flow devices 40 includes wellscreens 42
and check valves 44. Turning now to FIGS. 6A-6B, a flow device 150
that can be used for the disclosed system 10 is shown in a partial
cross-sectional view and a detailed view, respectively. The flow
device 150 is a screen joint having a screen jacket 160 (i.e.,
wellscreen) and an inflow control device 170 (i.e., check valve)
disposed on a basepipe 152. (FIG. 6C shows the inflow control
device 170 in an isolated view without the basepipe and the screen
jacket.)
[0062] The flow device 150 is deployed on a completion string (22:
FIGS. 1-5) with the screen jacket 160 typically mounted upstream of
the inflow control device 170, although this may not be strictly
necessary. The basepipe 152 defines a through-bore 155 and has a
coupling crossover 156 at one end for connecting to another joint
or the like. The other 154 end can connect to a crossover (not
shown) of another joint on the completion string (22). Inside the
through-bore 155, the basepipe 152 defines pipe ports 158 where the
inflow control device 170 is disposed.
[0063] As noted above, the inflow control device 170 can be similar
to a FloReg deploy-assist (DA) device available from Weatherford
International. As best shown in FIG. 6B, the inflow control device
170 has an outer sleeve 172 disposed about the basepipe 152 at the
location of the pipe ports 158. A first end-ring 174 seals to the
basepipe 152 with a seal element 175, and a second end-ring 176
attaches to the end of the screen jacket 160. Overall, the sleeve
172 defines an annular space around the basepipe 152 communicating
the pipe ports 158 with the screen jacket 160. The second end-ring
176 has flow ports 180 that separate the sleeve's annular space
into a first inner space 186 communicating with the screen 160 and
second inner space 188 communicating with the pipe ports 158.
[0064] For its part, the screen jacket 160 is disposed around the
outside of the basepipe 152. As shown, the screen jacket 160 can be
a wire wrapped screen having rods or ribs 164 arranged
longitudinally along the base pipe 152 with windings of wire 162
wrapped thereabout to form various slots. Fluid can pass from the
surrounding borehole annulus to the annular gap between the screen
jacket 160 and the basepipe 152. Although shown as a wire-wrapped
screen, the screen jacket 160 can use any other form of screen
assembly, including metal mesh screens, pre-packed screens,
protective shell screens, expandable sand screens, or screens of
other construction.
[0065] Internally, the inflow control device 170 has a number
(e.g., ten) flow ports 180. Rather than providing a predetermined
pressure drop along the screen jacket 160 by using multiple open or
closed nozzles (not shown), the inflow control device 170 as shown
in FIGS. 6A-6C may lack the typically used restrictive nozzles and
closing pins for the internal flow ports 180. Instead, the flow
ports 180 may be relatively unrestricted flow passages and may lack
the typical nozzles, although a given implementation may use such
nozzles if a pressure drop is desired from screen jacket 160 to the
basepipe 152.
[0066] Internally, however, the inflow control device 170 does
include port isolation balls 182, which allow the device 170 to
operate as a check valve. Depending on the direction of flow or
pressure differential between the inner spaces 186 and 188, the
port isolation balls 182 can move to an open condition (to the
right in FIG. 6B) permitting fluid communication from the screen's
inner space 186 to the pipe's inner space 188 or to a closed
condition (to the left in FIG. 6B against a seat end 184 of the
flow port 180) preventing fluid communication from the pipe's inner
space 188 to the screen's inner space 186.
[0067] In general, the inflow control device 170 can facilitate
fluid circulation during deployment and well cleanup and can be
used in interventionless deployment and setting of openhole
packers. In deployment, for example, the isolation balls 182
maximize fluid circulation through the completion shoe (50: FIGS.
1-5) of the frac assembly (20) to aid efficient deployment of the
completion string (22) and assembly (20). When the housing
components (172, 174, 175, & 176) are disposed on the basepipe
150, the isolation balls 182 are retained in-place. During initial
installation and production, the isolation balls 182 can prevent
formation surging, thereby reducing damage to the formation. In
some arrangements, the isolation balls 182 within the device 170
can be configured to erode over a period of time, allowing access
to the interval for workover activity such as stimulation.
[0068] Should a pressure drop be desired from the screen jacket 160
to the basepipe 152, the flow ports 180 can include nozzles (not
shown) that restrict flow of screened fluid (i.e., inflow) from the
screen jacket 160 to the pipe's inner space 188. For example, the
inflow control device 170 can have ten nozzles, although they all
may not be open. Operators can set a number of these nozzles open
at the surface to configure the device 170 for use downhole in a
given implementation. Depending on the number of open nozzles, the
device 170 can thereby produce a configurable pressure drop along
the screen jacket 160.
[0069] As noted above, the various embodiments of the multi-zone
frac system 10 in FIGS. 1-5 use frac valves 30 disposed on the frac
assembly 20 that can be opened and closed to communicate ports 32
with the borehole annulus 15. Turning now to FIGS. 7A-7B, a frac
valve 210 for the disclosed multi-zone screen frac system 10 is
shown in partial cross-section in a closed state (FIG. 7A) and an
opened state (FIG. 7B). As noted above, the frac valve 210 can be a
sliding sleeve similar to Weatherford's ZoneSelect MultiShift frac
sliding sleeve and can be placed between isolation packers in the
multi-zone completion. The sliding sleeve 210 includes a housing
220 with upper and lower subs 222 and 224. An inner sleeve or
insert 230 movable within the housing 220 opens or closes fluid
flow through the housing's flow ports 226 based on the inner sleeve
230's position.
[0070] When initially run downhole, the inner sleeve 230 positions
in the housing 220 in a closed state (FIG. 7A). In this state, a
holder 234 holds the inner sleeve 230 toward the upper sub 222, and
locking dogs 238 fit into an annular slot within the housing 220.
Outer seals 236 on the inner sleeve 230 engage the housing 220's
inner wall both above and below the flow ports 226 to seal them
off. In addition, the flow ports 226 may be covered by a protective
sheath 227 to prevent debris from entering into the sliding sleeve
apparatus 210. Such a sheath 227 can be composed of a destructible
material, such as a composite.
[0071] As noted previously with respect to FIGS. 1-3, the sliding
sleeve 210 is designed to open when a ball 34 lands on the landing
seat 232 and tubing pressure is applied to move the inner sleeve
230 open. To open the sliding sleeve 210 in a frac operation, for
example, operators drop an appropriately sized ball 34 downhole and
pump the ball 34 until it reaches the landing seat 232 disposed in
the inner sleeve 230 as shown in FIG. 7B. The designated ball 34
for the landing seat 232 of this particular sleeve 210 is dropped
from the surface once the appropriate amount of proppant has been
pumped into the lower formation's zone.
[0072] Once the ball 34 is seated, built up pressure forces against
the inner sleeve 230 in the housing 220, thereby shearing any shear
pins and freeing the dogs 238 from the housing's annular slot to
the inner sleeve 230 can slide downward. As it slides, the inner
sleeve 230 uncovers the flow ports 226. Preferably, as the inner
sleeve 230 shifts past the flow ports 226, fracturing does not
occur through the inner sleeve 230, which protects it from
erosion.
[0073] To mitigate potential damage to the sleeve 210 as the inner
sleeve 230 moves downward, a shock absorber 240 can be connected to
the inner sleeve 230's lower end. As shown in FIG. 7A, this shock
absorber 240 is initially connected in an extended position by
shear pins 242 within the inner sleeve 230. As the inner sleeve 230
moves downward during opening, the absorber's distal lip 245
engages a shoulder 225 on the housing's lower sub 224, thereby
breaking the downward energy of the moving inner sleeve 230.
[0074] After the fracturing job, the well is typically flowed clean
and the ball seat 232 and remaining ball 34 is milled out. The ball
seat 232 can be constructed from cast iron to facilitate milling,
and the balls can be composed of aluminum or non-metallic material.
Once milling is complete, the inner sleeve 230 can be closed or
opened with a standard "B" shifting tool on the tool profiles 234
and 236 in the inner sleeve 230 so the sliding sleeve 210 can then
function like any conventional sliding sleeve shifting with a "B"
tool. The ability to selectively open and close the sliding sleeve
210 with a "B" shifting tool after milling enables operators to
isolate the particular section (28: FIGS. 1-5) of the assembly
(20).
[0075] For those embodiments of the disclosed multi-zone screen
frac system 10 that do not use a ball and seat arrangement, such as
in FIGS. 4-5, the sliding sleeve 210 may lack a seat 232
altogether. Instead as noted above, the workstring (70: FIGS. 4-5)
has a shifting tool (78), such as a standard "B" shifting tool,
that can engage on the tool profiles 234 and 236 in the inner
sleeve 230 so workstring 70 can selectively move the inner sleeve
230 and open and close the ports 226.
[0076] Turning now to FIGS. 8A-8B, details of shifting tools 78 for
the workstring 70 of FIGS. 4-5 are discussed. As shown in FIG. 8A,
one shifting tool 78 includes upper and lower shifting tools 310
and 320 disposed on the workstring 70 with a mandrel 302 disposed
between upper and lower sections of the workstring 70. Because the
mandrel 302 is part of the workstring 70, it has a bore (not shown)
therethrough for flow of fluid.
[0077] In the present example, the upper tool 310 is designed to be
an closing tool for closing a sliding sleeves (e.g., 210: FIGS.
7A-7B) by engaging the upper profile (234), jarring up of the
workstring 70, and shifting the inner sleeve (230) upward in the
sliding sleeve (210). Likewise in this example, the lower tool 320
is designed to be an opening tool for opening the sliding sleeves
(210) by engaging the lower profile (236), jarring down with the
workstring 70, and shifting the inner sleeve (230) downward in the
sliding sleeve (210). A reverse arrangement could also be used.
[0078] As detail of the closing shifting tool 310 shows a biased
collet 312 that fits around the mandrel 302 and that connects at
both ends to stops 314 and 316 on the mandrel 302. The collet 312
has B-profiles 318 that include an upward facing shoulder, an upper
(shortened) cam, and a lower (extended) cam. As discussed above,
the B-profiles 318 enable the collet 312 to engage the recessed
profile (234) in the sliding sleeve (210) in the up direction and
bypass the recessed profiles (234 and 236) in the sliding sleeve
(210) in the down direction. This type of shifting tool is
typically referred to as a B shifting tool with a B-profile.
[0079] Another arrangement of the shifting tool 78 uses a two-way
shifting tool 330 as shown in FIG. 8B. Here, the two-way shifting
tool 330 a biased collet 332 that fits around the mandrel 302 and
that connects at both ends to stops 334 and 336 on the mandrel 302.
The collet 332 has dual B-profiles 328 having a downward-facing
shoulder 340, an upper cam 342, an upward-facing shoulder 345, and
a lower cam 347. Depending on the configuration of the sliding
sleeve (210) and its profiles (234 and 236) and the direction the
workstring 70 is being moved, the shifting tool 330 can open/close
the sliding sleeve (210) by jarring down/up.
[0080] The foregoing description of preferred and other embodiments
is not intended to limit or restrict the scope or applicability of
the inventive concepts conceived of by the Applicants. It will be
appreciated with the benefit of the present disclosure that
features described above in accordance with any embodiment or
aspect of the disclosed subject matter can be utilized, either
alone or in combination, with any other described feature, in any
other embodiment or aspect of the disclosed subject matter.
[0081] In exchange for disclosing the inventive concepts contained
herein, the Applicants desire all patent rights afforded by the
appended claims. Therefore, it is intended that the appended claims
include all modifications and alterations to the full extent that
they come within the scope of the following claims or the
equivalents thereof.
* * * * *