U.S. patent application number 10/602109 was filed with the patent office on 2004-01-08 for open hole formation testing.
This patent application is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Bianco, Samuel, MacPhail, Charles M., Maldonado, Ricardo, Manke, Kevin R., Nivens, Harold Wayne.
Application Number | 20040003657 10/602109 |
Document ID | / |
Family ID | 25362383 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040003657 |
Kind Code |
A1 |
Manke, Kevin R. ; et
al. |
January 8, 2004 |
Open hole formation testing
Abstract
Systems and methods particularly suitable for open hole
formation testing are provided. In a described embodiment, a method
of performing a test on a formation intersected by a wellbore
includes the steps of flowing fluid into an apparatus from the
formation, displacing a fluid barrier of the apparatus in one
direction, flowing the formation fluid out of the apparatus and
back into the formation by applying pressure to the apparatus, and
displacing the fluid barrier in an opposite direction.
Inventors: |
Manke, Kevin R.; (Marlow,
OK) ; Nivens, Harold Wayne; (Runaway Bay, TX)
; Bianco, Samuel; (Stavanger, NO) ; MacPhail,
Charles M.; (Gladewater, TX) ; Maldonado,
Ricardo; (Carrollton, TX) |
Correspondence
Address: |
KONNEKER SMITH
660 NORTH CENTRAL EXPRESSWAY
SUITE 230
PLANO
TX
75074
|
Assignee: |
Halliburton Energy Services,
Inc.
|
Family ID: |
25362383 |
Appl. No.: |
10/602109 |
Filed: |
June 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10602109 |
Jun 23, 2003 |
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09873814 |
Jun 4, 2001 |
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6622554 |
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Current U.S.
Class: |
73/152.39 |
Current CPC
Class: |
E21B 33/124 20130101;
E21B 49/088 20130101; E21B 49/081 20130101 |
Class at
Publication: |
73/152.39 |
International
Class: |
E21B 049/00 |
Claims
What is claimed is:
1. A method of performing a test on a formation intersected by a
wellbore, the method comprising the steps of: installing a test
apparatus in the wellbore, the test apparatus including a fluid
barrier reciprocably displaceable within the apparatus, the barrier
having first and second opposite sides; flowing fluid from the
formation into the apparatus on the first side of the barrier, the
barrier displacing in a first direction in the apparatus as the
formation fluid flows into the apparatus; and applying pressure to
the apparatus on the second side of the barrier, thereby displacing
the barrier in a second direction opposite to the first direction
in the apparatus and forcing the formation fluid to flow back into
the formation from which the fluid originated.
2. The method according to claim 1, wherein in the installing step,
the apparatus includes a tubular string extending to a remote
location, and wherein the barrier is axially reciprocably received
in the string.
3. The method according to claim 2, wherein in the applying step,
pressure is applied to the string at the earth's surface to
displace the barrier downwardly.
4. The method according to claim 1, wherein in the installing step,
the barrier is a plug sealingly received in a bore of the
apparatus.
5. The method according to claim 1, further comprising the step of
closing a valve of the apparatus in response to the barrier
displacing in the first direction in the flowing step.
6. The method according to claim 5, further comprising the step of
opening the valve in response to the pressure applying step.
7. The method according to claim 5, wherein in the closing step,
the valve prevents flow through a flow passage in which the barrier
is reciprocably received.
8. The method according to claim 7, wherein in the installing step,
the apparatus includes a tubular string extending to a remote
location, and the flow passage is in fluid communication with an
interior of the tubular string.
9. The method according to claim 8, wherein in the applying step,
pressure is applied to the interior of the tubular string, the
valve opens in response to the pressure, and the pressure is
communicated through the open valve from the tubular string
interior to the barrier second side.
10. The method according to claim 1, further comprising the step of
setting at least one packer of the apparatus in response to
displacement of the barrier in the second direction prior to the
flowing step.
11. The method according to claim 10, wherein the setting step is
performed further in response to applying pressure to the apparatus
on the second side of the barrier, which pressure applying step
causes the barrier to displace in the second direction.
12. The method according to claim 11, wherein in the installing
step, the apparatus includes a tubular string extending to a remote
location, and wherein in the setting step, pressure is applied to
the tubular string at the remote location to displace the barrier
in the second direction.
13. The method according to claim 1, further comprising the step of
opening a waste chamber of the apparatus prior to flowing the
formation fluid into the apparatus, opening of the waste chamber
permitting wellbore fluid to flow into the waste chamber.
14. The method according to claim 13, wherein the waste chamber
opening step is performed in response to pressure applied to an
annulus formed between the apparatus and the wellbore.
15. The method according to claim 13, further comprising the step
of setting at least one packer of the apparatus in the wellbore
prior to the flowing step, and wherein the waste chamber opening
step is performed after the setting step.
16. The method according to claim 13, wherein there are multiple
waste chambers, and wherein the waste chamber opening step further
comprises sequentially and selectively opening each of the waste
chambers.
17. The method according to claim 16, wherein there are multiple
formations intersected by the wellbore, wherein the flowing and
applying steps are performed for each of multiple selected ones of
the formations, and wherein the waste chamber opening step is
performed for each of the selected formations, each of the waste
chambers being opened for a corresponding one of the selected
formations prior to the respective flowing step.
18. The method according to claim 1, wherein there are multiple
formations intersected by the wellbore, wherein the flowing and
applying steps are performed for each of multiple selected ones of
the formations.
19. A system for performing a test on a formation intersected by a
wellbore, the system comprising: a fluid barrier reciprocably
displaceable within an apparatus into which fluid from the
formation is flowed, the barrier displacing when the formation
fluid is flowed between the apparatus and the formation; and a
valve in the apparatus, the valve being operated in response to
displacement of the barrier.
20. The system according to claim 19, wherein the valve operates in
response to displacement of the barrier in a first direction, and
wherein the barrier displaces in the first direction when formation
fluid is flowed into the apparatus.
21. The system according to claim 20, wherein the valve closes in
response to displacement of the barrier in the first direction.
22. The system according to claim 20, wherein the valve operates
when the barrier displaces in a second direction opposite to the
first direction, and wherein the barrier displaces in the second
direction when formation fluid is flowed out of the apparatus.
23. The system according to claim 19, wherein the apparatus
includes a tubular string positioned in the wellbore, the tubular
string having an interior in fluid communication with a flow
passage extending through the valve.
24. The system according to claim 23, wherein the barrier displaces
in the first direction, thereby closing the valve and preventing
flow through the flow passage, when pressure in the tubular string
interior is less than pressure in the formation, and the barrier
displaces in the second direction and the valve opens, thereby
permitting flow through the flow passage, when pressure in the
tubular string interior is greater than pressure in the
formation.
25. A system for performing a test on a formation intersected by a
wellbore, the system comprising: at least one packer interconnected
as part of an apparatus positioned in the wellbore; a fluid barrier
reciprocably displaceable within the apparatus when fluid is flowed
between the apparatus and the formation; and a module
interconnected to the packer, the module alternately permitting and
preventing setting and unsetting of the packer in response to
reciprocal displacements of the barrier.
26. The system according to claim 25, wherein the module responds
to reciprocal displacements of the barrier in the following
sequence: displacement of the barrier in a first direction causes
the module to permit setting of the packer; displacement of the
barrier in a second direction opposite to the first direction
causes the module to prevent unsetting of the packer; displacement
of the barrier in the first direction causes the module to permit
unsetting of the packer when the barrier next displaces in the
second direction; and displacement of the barrier in the second
direction causes the module to permit unsetting of the packer.
27. The system according to claim 26, wherein the module is
configured to permit repetition of the sequence.
28. A system for performing a test on a formation intersected by a
wellbore, the system comprising: a formation testing apparatus
including at least one waste chamber, and at least one packer
configured for isolating the formation when set in the wellbore,
the waste chamber being opened in response to pressure in an
annulus formed between the apparatus and the wellbore after the
packer is set.
29. The system according to claim 28, wherein the waste chamber
receives therein wellbore fluid from the annulus when the waste
chamber is opened.
30. The system according to claim 28, wherein there are multiple
waste chambers, and wherein there are multiple formations
intersected by the wellbore, and further comprising a module of the
apparatus which opens each of the waste chambers in sequence prior
to a corresponding one of the formations being tested.
Description
BACKGROUND
[0001] The present invention relates generally to formation testing
in subterranean wells and, in an embodiment described herein, more
particularly provides a method and system for open hole formation
testing.
[0002] Open hole formation testing is well known in the art.
Typically, compression-set or inflatable packers are used to
straddle a formation intersected by an uncased wellbore, and
formation fluid is drawn from the formation into a test string
extending to the earth's surface. Generally, the formation fluid is
flowed to the surface, where it may be sampled, tested, etc.
[0003] Because of safety and environmental concerns with flowing
the formation fluid to the surface, it would be advantageous to be
able to perform formation testing without flowing the formation
fluid to the surface. The formation fluid should be flowed only
into the test string, and then flowed back (i.e., re-injected) into
the formation from which it originated, or into another disposal
formation.
[0004] Unfortunately, satisfactory methods and systems for
accomplishing such a formation test in an open hole environment
have not yet been developed. Therefore, it would be highly
advantageous to provide systems and methods whereby a formation
test may be performed in an uncased wellbore, and without flowing
formation fluid to the surface.
SUMMARY
[0005] In carrying out the principles of the present invention, in
accordance with an embodiment thereof, systems and methods for open
hole testing are provided. The systems and methods utilize a fluid
barrier reciprocably received within an apparatus and displaceable
when fluid is flowed between the apparatus and a formation. Other
systems and methods are provided, as well.
[0006] In one aspect of the invention, a method of performing a
test on a formation intersected by a wellbore is provided. The
method includes the steps of installing a test apparatus in the
wellbore, flowing fluid from the formation into the apparatus and
applying pressure to the apparatus, thereby forcing the formation
fluid to flow back into the formation from which it originated.
[0007] The test apparatus includes a fluid barrier reciprocably
displaceable within the apparatus. The barrier has first and second
opposite sides. The barrier displaces in a first direction in the
apparatus as the formation fluid flows into the apparatus.
[0008] When pressure is applied to the apparatus on the second side
of the barrier, the barrier displaces in a second direction
opposite to the first direction. The formation fluid is forced by
the applied pressure to flow back into the formation from which it
originated.
[0009] In another aspect of the invention, a system for performing
a test on a formation intersected by a wellbore is provided. The
system includes at least one packer interconnected as part of an
apparatus positioned in the wellbore, a fluid barrier reciprocably
displaceable within the apparatus when fluid is flowed between the
apparatus and the formation, and a module interconnected to the
packer, the module alternately permitting and preventing setting
and unsetting of the packer in response to reciprocal displacements
of the barrier.
[0010] In yet another aspect of the invention, a system for
performing a test on a formation intersected by a wellbore is
provided. The system includes a fluid barrier reciprocably
displaceable within an apparatus into which fluid from the
formation is flowed, the barrier displacing when the formation
fluid is flowed between the apparatus and the formation, and a
valve in the apparatus, the valve being operated in response to
displacement of the barrier.
[0011] In still another aspect of the invention a system for
performing a test on a formation intersected by a wellbore is
provided. The system includes a formation testing apparatus
including at least one waste chamber and at least two packers
configured for straddling the formation when set in the wellbore,
the waste chamber being opened after the packers are set in
response to pressure in an annulus formed between the apparatus and
the wellbore.
[0012] Where there are multiple formations intersected by the
wellbore to be tested, there may be a corresponding number of waste
chambers. A module of the apparatus opens one of the waste chambers
in sequence prior to each of the formations being tested.
[0013] These and other features, advantages, benefits and objects
of the present invention will become apparent to one of ordinary
skill in the art upon careful consideration of the detailed
description of a representative embodiment of the invention
hereinbelow and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic partially cross-sectional view of a
method and system for open hole formation testing which embody
principles of the present invention, wherein a test string is being
run into a wellbore;
[0015] FIG. 2 is a schematic partially cross-sectional view of the
system and method, wherein packers of the test string have been set
in the wellbore;
[0016] FIG. 3 is a schematic partially cross-sectional view of the
system and method, wherein formation fluid has been drawn into the
test string;
[0017] FIG. 4 is a schematic partially cross-sectional view of the
system and method, wherein the formation fluid is being injected
back into the formation from which it originated; and
[0018] FIG. 5 is a schematic partially cross-sectional view of the
system and method, wherein the formation fluid has been re-injected
and the packers have been unset from the wellbore.
DETAILED DESCRIPTION
[0019] Representatively illustrated in FIG. 1 is a method 10 which
embodies principles of the present invention. In the following
description of the method 10 and other apparatus, systems and
methods described herein, directional terms, such as "above",
"below", "upper", "lower", etc., are used only for convenience in
referring to the accompanying drawings. Additionally, it is to be
understood that the various embodiments of the present invention
described herein may be utilized in various orientations, such as
inclined, inverted, horizontal, vertical, etc., and in various
configurations, without departing from the principles of the
present invention.
[0020] As depicted in FIG. 1, the method 10 utilizes a tubular test
string 12 positioned in a wellbore 14 for performing a test on a
formation intersected by the wellbore. The test string 12 includes
multiple waste chambers 16, a waste chamber control module 18, an
accumulator 20, a lower equalization sub 22, a lower packer 24, a
ported sub 26, an upper packer 28, a packer inflation sub 30, an
upper equalization sub 32, a sensor 34 and a sampler 36 mounted to
a carrier 38, a combined no-go and packer inflation actuator 40, a
fluid chamber 42, a combined no-go and valve 44, a communication
module 46, a circulating valve 48, a fill valve 50, and tubing or
pipe 52.
[0021] The waste chambers 16 are used to remove wellbore fluid from
an annulus 54 between the string 12 and the wellbore 14 in the area
between the packers 24, 28 in the beginning stages of a test, as
will be described in more detail below. Multiple waste chambers 16
are shown in FIG. 1, since multiple formation tests may be
performed on respective multiple formations using the string 12 on
a single trip into the wellbore 14. One of the waste chambers 16 is
opened for each of the formations tested, that is, each of the
waste chambers is opened when a corresponding one of the formations
is tested.
[0022] Of course, a single formation may be tested multiple times,
in which case one or more waste chambers 16 may be opened for that
formation's tests. In addition, it is to be clearly understood that
use of the waste chambers 16 is optional, or only a single waste
chamber may be used, in keeping with the principles of the present
invention.
[0023] Opening of the waste chambers 16 is controlled by the
control module 18.
[0024] The control module 18 is actuated by pressure applied to the
annulus 54. Thus, when it is desired to open one of the waste
chambers 16, pressure, or a coded sequence of pressures, is applied
to the annulus 54 above the upper packer 28. This annulus pressure
causes the control module 18 to open the next waste chamber 16 in
sequence.
[0025] For example, the control module 18 may include a ratchet
mechanism, such as a J-slot mechanism, to select which waste
chamber 16 is to be opened in response to the annulus pressure. Of
course, if the waste chambers 16 are not used, the control module
18 would also not be used. Note that, instead of opening the waste
chambers 16 sequentially, the control module 18 could alternatively
open a single waste chamber repeatedly, that is, the waste chamber
could be opened each time a formation is tested.
[0026] The accumulator 20 is used to store inflation pressure used
to inflate the packers 24, 28. For example, the accumulator 20 may
be of the type known to those skilled in the art as a nitrogen dome
charge. The accumulator 20 is in fluid communication with the
inflation fluid passages (not shown) for the packers 24, 28 so
that, when pressure is applied to the passages to inflate the
packers, the accumulator acts as a "cushion" to prevent
overpressurization of the packer elements.
[0027] The upper and lower equalization subs 22, 32 are used to
equalize pressure across the packers 24, 28. An internal
equalization line 56 extends between the equalization subs 22, 32.
Basically, the equalization subs 22, 32 prevent a pressure
differential from occurring in the annulus 54 across the packers
24, 28 when they are set in the wellbore 14. Use of such
equalization subs 22, 32 is well known to those skilled in the
art.
[0028] The packers 24, 28 are preferably conventional inflatable
packers of the type well known in the art. For example, they may be
Hydroflate.TM. packers available from Halliburton Energy Services.
Of course, other types of packers may be used, in keeping with the
principles of the present invention.
[0029] The ported sub 26 extends between the packers 24, 28 and
provides a means for receiving fluid into the string 12. After the
packers 24, 28 are set, one of the waste chambers 16 is opened and
wellbore fluid in the annulus 54 between the packers enters the
ported sub 26 and flows into the waste chamber. During a formation
test, fluid from a formation isolated between the packers 24, 28 is
drawn into the ported sub 26 and flows into the string 12 as
described more fully below.
[0030] The packer inflation sub 30 receives pressurized inflation
fluid from the no-go/actuator 40 via a line 58. The inflation sub
30 directs the inflation fluid to the packers 24, 28. The use of
the inflation sub 30 is conventional and well known in the art.
[0031] The carrier 38 with the sensor 34 and sampler 36 is used to
detect certain fluid properties and take one or more samples of
fluid received in the string 12. Although only one sensor 34 and
one sampler 36 are depicted, any number of sensors and samplers may
be used. For example, pressure, temperature, flow, density, pH, or
any other type of sensor may be used, and a separate sampler may be
used for each formation tested. Such sensors and samplers are
conventional and well known in the art.
[0032] The illustrated sensor 34 and sampler 36 are in
communication with the communication module 46 via lines 60. In
this manner, the communication module 46 is able to receive data
from the sensor 34 and sampler 36. For example, pressure and
temperature indications may be communicated from the sensor 34, and
confirmation of receipt of a fluid sample may be communicated from
the sampler 36, via the lines 60. In addition, the sampler 36 may
be actuated in response to a signal received at the communication
module 46.
[0033] The communication module 46 provides a means of retrieving
the data communicated from the sensor 34 and sampler 36.
Preferably, the communication module 46 provides a means of
retrieving the data in real time. For example, the communication
module 46 may be a telemetry device which communicates directly or
indirectly with a remote location, such as the earth's surface. For
instance, the communication module 46 could be an acoustic
telemetry device which communicates with the earth's surface using
pressure pulses transmitted via fluid in the wellbore 14 or
transmitted via the tubing string 52, such as the ATS.TM. system
available from Halliburton Energy Services.
[0034] As another example, the communication module 46 could be a
wet connect device which permits a wireline-conveyed tool to
retrieve the data from the module, either in real time or as stored
data. As yet another example, the data could be communicated via
one or more lines installed in the well with the string 12, such as
lines embedded in a sidewall of the string or extending through an
interior passage of the string.
[0035] If the string 12 is wireline-conveyed, instead of
tubing-conveyed, into the well, then communication of the data may
be via the wireline. Thus, any means of communicating the data may
be utilized, without departing from the principles of the present
invention.
[0036] A plug, pig, wiper or other type of fluid barrier 62 is
reciprocally and sealingly received within a flow passage 64 formed
within the string 12. The no-go/actuator 40 defines a lower limit
of the plug's travel, and the no-go/valve 44 defines an upper limit
of the plug's travel. As depicted in FIG. 1, the plug 62 is at the
lower limit of its travel and is received within the no-go/actuator
40.
[0037] The no-go/actuator 40 is additionally used to provide
inflation fluid pressure for inflating the packers 24, 28. When the
plug 62 is received in the no-go/actuator 40 and pressure is
applied to the string 12 above the plug, the plug is biased
downwardly. This downwardly biasing force is used to discharge
inflation fluid from the actuator portion of the no-go/actuator 40
via the line 58.
[0038] For example, the plug 62 may engage a piston of the
no-go/actuator 40 when it is received therein. Pressure applied to
the string 12 above the plug 62 would then displace the piston
downward, forcing inflation fluid to flow from the no-go/actuator
40 to the packer inflation sub 30 via the line 58.
[0039] Note that, although the no-go/actuator 40 is depicted in
FIG. 1 and described herein as a single tool in the string 12, the
no-go portion could be separate from the actuator portion. In
addition, other or alternate means of supplying inflation fluid
pressure to the packers 24, 28 could be provided, without departing
from the principles of the present invention.
[0040] The chamber 42 provides a substantial volume in which to
receive fluid from a formation being tested. For example, the
chamber 42 may have a capacity of approximately 20 barrels. Of
course, other volumes may be used in keeping with the principles of
the present invention.
[0041] Preferably, the chamber 42 is made up of multiple sections
of flush joint tubing having a relatively smooth bore in which the
plug 62 may be sealingly and reciprocally received. This provides a
relatively inexpensive means of making up a substantial volume,
while enabling the plug 62 to sealingly travel between the
no-go/valve 44 and the no-go/actuator 40. Other types of chambers
may be used, without departing from the principles of the present
invention.
[0042] The no-go/valve 44 is used to define an upper limit to the
travel of the plug 62 as described above, and to operate a valve
portion thereof to selectively permit and prevent flow through the
passage 64 above the plug. The valve portion of the no-go/valve 44
provides an additional form of isolation between the formation
during a test and the tubing 52 extending to the earth's surface.
That is, both the plug 62 and the valve portion of the no-go/valve
44 are barriers to fluid flow between the formation being tested
and the earth's surface when the tubing string 52 extends to the
earth's surface.
[0043] Some regulatory agencies require multiple forms of isolation
during formation tests where the test string extends to the earth's
surface. However, it is to be understood that the valve portion of
the no-go/valve is not strictly necessary to the performance of a
formation test using the string 12, and its use may not be required
by regulatory agencies when, for example, other forms of isolation
are used, the string is conveyed on wireline instead of on the
tubing 52, etc.
[0044] Note that, although the no-go/valve 44 is depicted in FIG. 1
and described herein as a single tool in the string 12, the no-go
portion could be separate from the valve portion. In addition,
other or alternate means of isolation could be provided, without
departing from the principles of the present invention.
[0045] When the plug 62 is received in the no-go/valve 44 and
pressure above the plug is less than pressure in the passage 64
below the plug, the plug is biased upwardly. This upward biasing
force on the plug 62 is used to close the valve. For example, if
the valve is a ball valve, the biasing force may be used to rotate
the ball of the valve in a manner well known to those skilled in
the art. Of course, other types of valves may be used in keeping
with the principles of the present invention.
[0046] When it is desired to open the valve of the no-go/valve 44,
pressure is increased above the valve. A differential pressure
across the valve, for example, across a ball of the valve,
generates a downwardly biasing force. The valve opens in response
to the downwardly biasing force, for example, by rotating a ball of
the valve.
[0047] The circulating valve 48 is used to circulate fluid between
the interior of the tubing string 52 and the annulus 54. For
example, the circulating valve 48 may be opened after the formation
testing operations are completed to allow fluid to drain out of the
tubing string 52 as it is retrieved from the well, or the
circulating valve may be opened to circulate fluids for purposes of
well control, etc. The circulating valve 48 is conventional and its
use is well known in the art.
[0048] The fill valve 50 is used to permit the tubing string 52 to
fill with fluid as it is run into the well. The fill valve 50 may
close automatically when a certain hydrostatic pressure is
achieved, or the fill valve may be closed by application of
pressure thereto after a desired depth has been reached. Various
types of commercially available valves may be used for the fill
valve 50, such as the AutoFill.TM. valve available from Halliburton
Energy Services.
[0049] The tubing string 52 is used to convey the test string 12
into the well. The tubing string 52 could be made up of multiple
lengths of tubing, or it could be coiled tubing. As discussed above
other types of conveyance may be used in place of the tubing string
52. For example, a wireline could be used. In that case, the fill
valve 50 and circulating valve 48 would not be used, since there
would be no need for these tools. Thus, any form of conveyance may
be used, without departing from the principles of the present
invention.
[0050] In FIG. 1, the string 12 is depicted as it is being run into
the wellbore 14. The packers 24, 28 are unset. The plug 62 is
received in the no-go/actuator 40, but inflation pressure is not
yet being supplied to the packer inflation sub 30. The plug 62
could actually be positioned anywhere between the no-go/actuator 40
and the no-go/valve 44 while the string 12 is run into the
well.
[0051] The fill valve 50 is open, permitting the tubing 52 to fill
with fluid. The circulating valve 48 is closed.
[0052] Referring additionally now to FIG. 2, the test string 12 is
positioned opposite a formation 66 to be tested. As used herein,
the term "formation" is used to indicate a subterranean formation
or portion of a formation, such as a zone.
[0053] The packers 24, 28 have been set in the wellbore 14 as
described above. That is, with the plug 62 received in the no-go
actuator 40 as depicted in FIG. 1, pressure is applied to the
passage 64 above the plug to thereby cause inflation fluid to flow
from the actuator portion of the no-go/actuator to the packer
inflation sub 30. Once the packers 24, 28 have been set, the
actuator is operated to close off flow of inflation fluid between
the actuator and the packer inflation sub 30, for example, by
closing a valve controlling flow through the line 58. This valve
may be operated, for example, by a ratchet mechanism, such as a
J-slot mechanism, in the actuator.
[0054] Note that the fill valve 50 should be closed prior to
setting the packers 24, 28, to permit pressure to be applied to the
tubing string 52. As described above, the fill valve 50 may be
closed in any of a variety of ways. For example, the fill valve 50
may be configured to close when a certain hydrostatic pressure is
reached, pressure may be applied to the wellbore 14, etc. In FIG.
2, the fill valve 50 is shown as being closed.
[0055] After the packers 24, 28 are set, the waste chamber control
module 18 is operated to open one of the waste chambers 16. When
opened, the waste chamber 16 draws fluid into the chamber from the
annulus 54 between the packers 24, 28 through the ported sub 26. Of
course, fluid from the interior of the string 12 below the plug 62
is also drawn into the open waste chamber 16.
[0056] The fluid drawn into the waste chamber 16 will principally
be wellbore fluid, although some fluid from the formation 66 may
also be drawn into the waste chamber at this time. The main
objective of using the waste chamber 16 is to remove a substantial
portion of the wellbore fluid prior to initiating the formation
test, so that measurements and samples taken by the sensor 34 and
sampler 36 are representative of the formation fluid rather than
the wellbore fluid.
[0057] After use of the waste chamber 16, pressure above the plug
62 is decreased relative to pressure in the formation 66, so that
the plug is displaced upwardly and fluid from the formation is
drawn into the string 12 via the ported sub 26. This pressure
differential across the plug 62 may be accomplished in any of a
variety of manners. For example, a lighter density fluid may be
circulated into the tubing string 52 using the circulating valve
48, gas, such as nitrogen, may be used to displace fluid from the
tubing string 52, etc.
[0058] Note that, since flow of inflation fluid between the
no-go/actuator 40 and the packer inflation sub 30 has been
prevented at this point, the packers 24, 28 do not deflate when the
plug 62 displaces upwardly in the passage 64. Instead, the packers
24, 28 remain inflated.
[0059] As the volume of formation fluid in the string 12 increases,
the plug 62 displaces upwardly. Eventually, the plug 62 is received
in the no-go/valve 44.
[0060] This drawing of fluid from the formation 66 into the string
12 is known as the drawdown phase of the formation test. The sensor
34 measures parameters, such as pressure and temperature, during
this phase in order to facilitate determination of various
characteristics of the formation 66. The communication module 46
preferably makes this sensor data available for analysis at a
remote location while the test is being performed.
[0061] Referring additionally now to FIG. 3, the method 1o is
representatively illustrated wherein the plug 62 has been received
in the no-go/valve 44. The pressure differential across the plug 62
applies a biasing force to the no-go/valve 44, thereby closing the
valve 68 thereof. As described above, the valve 68 provides
additional isolation from the formation 66 in the tubing string
52.
[0062] Pressure in the flow passage 64 will continue to build until
it substantially equals the pressure in the formation 66. This is
known as the buildup portion of the formation test. Again, the
sensor 34 detects various parameters used to characterize the
formation and the properties of the fluid therein.
[0063] Once the buildup portion of the formation test is completed,
the sampler 36 is actuated to obtain a sample of the formation
fluid received into the string 12. One or more samples may be taken
for each formation test. As described above, the sampler 36 may be
actuated to obtain a sample in response to a signal received by the
communication module 46.
[0064] Referring additionally now to FIG. 4, the method 10 is
representatively illustrated wherein the formation fluid received
into the string 12 is being re-injected back into the formation 66
from which it originated. Pressure above the valve 68 of the
no-go/valve 44 has been increased to apply a downwardly biasing
force to the valve and cause it to open as described above. The
increased pressure may now be applied through the open valve 68 to
the plug 62.
[0065] A pressure differential from above to below the plug 62
causes the plug to displace downwardly in the passage 64. The plug
62 thus forces the formation fluid received in the string 12
downward and out of the ported sub 26. The formation fluid flows
back into the formation 66 due to the pressure differential. Note
that the pressure above the plug 62 and transmitted via the plug to
the formation fluid in the string 12 must be greater than pressure
in the formation 66 for the formation fluid to flow back into the
formation.
[0066] Referring additionally now to FIG. 5, the method 10 is
representatively illustrated wherein the plug 62 has been displaced
downwardly so that it is now received in the no-go/actuator 40. A
pressure differential from above to below the plug 62 after it is
received in the no-go/actuator 40 causes the actuator to permit
flow of inflation fluid from the packer inflation sub 30 back into
the actuator when pressure above the plug is decreased, thereby
permitting the packers 24, 28 to deflate.
[0067] Thus, after the formation fluid has been re-injected into
the formation 66, the plug 62 has engaged the no-go/actuator 40 and
the actuator has been operated to permit flow of inflation fluid
from the packer inflation sub 30 back into the actuator, pressure
above the plug is decreased to deflate the packers 24, 28 by
flowing inflation fluid from the packer inflation sub to the
actuator.
[0068] The packers 24, 28 are now unset, and the string 12 is ready
to be repositioned in the well to perform another formation test,
or is ready to be retrieved from the well. Note that the formation
test described above did not result in any formation fluid being
flowed to the earth's surface. In addition, the formation test was
performed very simply and conveniently by alternately increasing
and decreasing pressure above the plug 62, for example, by applying
and releasing pressure on the tubing string 52.
[0069] Of course, a person skilled in the art would, upon a careful
consideration of the above description of representative
embodiments of the invention, readily appreciate that many
modifications, additions, substitutions, deletions, and other
changes may be made to these specific embodiments, and such changes
are contemplated by the principles of the present invention. For
example, although the method 10 has been described above as being
performed using straddle packers 24, 28, a formation may be
isolated for testing using only a single packer. As another
example, although the method 10 has been described above as being
performed in an open hole or uncased wellbore 14, the principles of
the present invention are applicable in cased wellbores.
Accordingly, the foregoing detailed description is to be clearly
understood as being given by way of illustration and example only,
the spirit and scope of the present invention being limited solely
by the appended claims and their equivalents.
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