U.S. patent application number 09/982727 was filed with the patent office on 2002-02-28 for early formation evaluation tool.
This patent application is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Skinner, Neal G..
Application Number | 20020023780 09/982727 |
Document ID | / |
Family ID | 23947601 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020023780 |
Kind Code |
A1 |
Skinner, Neal G. |
February 28, 2002 |
Early formation evaluation tool
Abstract
An early formation evaluation tool is provided which includes
formation fluid sampling capabilities. In one disclosed embodiment,
fluid pressure in a drill string in which the tool is
interconnected is utilized to operate packers of the tool and to
operate fluid samplers of the tool. To successively control
actuation of the samplers, a ratchet mechanism responsive to
altering fluid pressures in the drill string aligns a piercing
member with a series of frangible pressure barriers associated with
the samplers.
Inventors: |
Skinner, Neal G.;
(Lewisville, TX) |
Correspondence
Address: |
KONNEKER SMITH
660 NORTH CENTRAL EXPRESSWAY
SUITE 230
PLANO
TX
75074
|
Assignee: |
Halliburton Energy Services,
Inc.
|
Family ID: |
23947601 |
Appl. No.: |
09/982727 |
Filed: |
October 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09982727 |
Oct 18, 2001 |
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09490334 |
Jan 24, 2000 |
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Current U.S.
Class: |
175/59 ;
166/264 |
Current CPC
Class: |
E21B 23/006 20130101;
E21B 49/081 20130101 |
Class at
Publication: |
175/59 ;
166/264 |
International
Class: |
E21B 049/08 |
Claims
What is claimed is:
1. A method of sampling fluid from at least one formation
intersected by a wellbore, the method comprising the steps of:
interconnecting a tool in a tubular string; positioning the tool in
the wellbore; altering fluid pressure in the tubular string; and
receiving successive formation fluid samples in respective
successive fluid samplers of the tool in response to the fluid
pressure altering step.
2. The method according to claim 1, wherein the receiving step is
performed without repositioning the tool in the wellbore.
3. The method according to claim 1, wherein the receiving step
further comprises repositioning the tool between reception of
successive ones of the formation fluid samples.
4. The method according to claim 1, wherein the fluid pressure
altering step further comprises alternately increasing and
decreasing fluid pressure in the tubular string.
5. The method according to claim 1, further comprising the step of
retaining fluid pressure in an inflatable packer of the tool in
response to the altering step.
6. The method according to claim 1, wherein the receiving step
further comprises successively operating actuators of the samplers
in response to the fluid pressure altering step.
7. The method according to claim 6, wherein the operating step is
performed by breaking a frangible barrier associated with each of
the samplers.
8. The method according to claim 6, wherein the operating step
further comprises orienting a ratchet mechanism relative to
pressure barriers associated with the samplers, each of the
pressure barriers being associated with one of the samplers.
9. The method according to claim 8, wherein the orienting step
further comprises aligning a piercing member of the ratchet
mechanism with successive ones of the pressure barriers.
10. A method of operating a packer in a wellbore, the method
comprising the steps of: interconnecting a tool in a tubular
string, the tool including at least one inflatable packer;
positioning the tool in the wellbore; altering fluid pressure in
the tubular string, thereby inflating the inflatable packer; and
isolating fluid pressure in the inflatable packer from fluid
pressure in the tubular string in response to the fluid pressure
altering step.
11. The method according to claim 10, wherein the fluid pressure
altering step further comprises increasing fluid pressure in the
tubular string, and wherein the isolating step is performed in
response to increasing fluid pressure in the tubular string to a
predetermined level.
12. The method according to claim 10, wherein the tool further
includes an inflation fluid passage in fluid communication with the
inflatable packer, and wherein the fluid pressure altering step
further comprises placing the inflation fluid passage in fluid
communication with the interior of the tubular string.
13. The method according to claim 12, wherein the isolating step
further comprises isolating the inflation fluid passage from fluid
communication with the interior of the tubular string.
14. A formation fluid sampling system, comprising: a tubular string
positioned in a wellbore, the tubular string including a fluid
sampling apparatus, and the apparatus including at least one fluid
sampler having an actuator, the actuator being operative to admit
fluid into the sampler in response to fluid pressure applied to the
tubular string.
15. The sampling system according to claim 14, wherein the
apparatus further includes a plurality of the fluid samplers, the
actuators of the samplers being successively operated in response
to respective successive fluid pressures applied to the tubular
string.
16. The sampling system according to claim 15, wherein the
apparatus further includes a ratchet mechanism, the ratchet
mechanism displacing incrementally in response to the respective
successive fluid pressures applied to the tubular string.
17. The sampling system according to claim 16, wherein the ratchet
mechanism includes a J-slot member, the J-slot member displacing
relative to the sampler actuators in response to the respective
successive fluid pressures applied to the tubular string.
18. The sampling system according to claim 17, wherein the ratchet
mechanism further includes a piercing member, the piercing member
being displaced by the J-slot member in response to the respective
successive fluid pressures applied to the tubular string.
19. The sampling system according to claim 14, wherein the
apparatus further includes at least one inflatable packer, the
inflatable packer being inflatable in response to fluid pressure
applied to the tubular string.
20. The sampling system according to claim 19, wherein the tubular
string further includes a valve, the valve selectively permitting
and preventing fluid flow through the tubular string in response to
fluid pressure applied to the tubular string.
21. A fluid sampling apparatus, comprising: a first internal fluid
passage; a packer in communication with the first fluid passage
when fluid pressure in the first fluid passage is below a
predetermined level, and the packer being isolated from fluid
communication with the first fluid passage when fluid pressure in
the first fluid passage is above a predetermined level; and a fluid
sampler including an actuator, the actuator being placed in fluid
communication with the first fluid passage, thereby admitting fluid
into the sampler, when fluid pressure in the first fluid passage is
above the predetermined level.
22. The apparatus according to claim 21, wherein the actuator
admits fluid from a second internal fluid passage of the apparatus
into the sampler when fluid pressure in the first fluid passage is
above the predetermined level.
23. The apparatus according to claim 21, further comprising a
pressure barrier isolating the actuator from fluid communication
with the first fluid passage.
24. The apparatus according to claim 23, wherein the pressure
barrier is opened to thereby permit fluid communication between the
actuator and the first fluid passage when fluid pressure in the
first fluid passage is above the predetermined level.
25. Apparatus operatively positionable in a subterranean well, the
apparatus comprising: a ratchet mechanism; a member displaceable by
the ratchet mechanism; and a series of frangible pressure barriers,
the member being successively alignable with each of the pressure
barriers to open the pressure barriers to pressure transmission
therethrough in response to fluid pressure applied to the
apparatus.
26. The apparatus according to claim 25, wherein the ratchet
mechanism includes a J-slot.
27. The apparatus according to claim 25, wherein each of the
pressure barriers is penetrable by the member in response to fluid
pressure applied to the apparatus.
28. The apparatus according to claim 25, wherein the ratchet
mechanism aligns the member with successive ones of the pressure
barriers in response to alternating increases and decreases in
fluid pressure applied to the apparatus.
29. A method of sampling fluid from at least one formation
intersected by a wellbore, the method comprising the steps of:
interconnecting a tool in a tubular string; positioning the tubular
string in the wellbore opposite the formation; increasing fluid
pressure in the tubular string to a first predetermined level to
thereby set at least one inflatable packer of the tool in the
wellbore; and further increasing fluid pressure in the tubular
string to a second predetermined level greater than the first
predetermined level to thereby admit fluid from the formation into
a first fluid sampler of the tool.
30. The method according to claim 29, further comprising the steps
of decreasing fluid pressure in the tubular string after admitting
fluid from the formation into the first fluid sampler, and then
increasing fluid pressure in the tubular string to the second
predetermined level to thereby admit fluid into a second fluid
sampler of the tool.
31. The method according to claim 29, further comprising the step
of altering a differential pressure between the interior and
exterior of the tubular string to thereby permit fluid
communication between the interior of the tubular string and an
internal fluid passage of the tool fluid communicable with the
packer and the first sampler, the altering step being performed
prior to the step of increasing fluid pressure in the tubular
string to the first predetermined level.
32. The method according to claim 29, further comprising the step
of manipulating the tubular string to thereby pump fluid from the
formation into the tool prior to the step of increasing fluid
pressure in the tubular string to the second predetermined level.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to tools utilized in
conjunction with subterranean wells and, in an embodiment described
herein, more particularly provides an early formation evaluation
tool having formation fluid sampling capability.
[0002] It is well known that it is desirable to have the capability
of evaluating characteristics of formations intersected by a
wellbore before drilling operations are completed. This type of
formation evaluation is known as "early" formation evaluation by
those skilled in the art. For this purpose, tools have been
developed Which are interconnected in drill strings, and which are
capable of performing tests on formations, such as pressure
drawdown and buildup tests. These tests may be performed
periodically during drilling operations.
[0003] However, it would also be advantageous to be able to collect
samples of fluid from formations intersected by a wellbore during a
drilling operation. Furthermore, it would be desirable to be able
to collect such samples in conjunction with tests performed on
formations, since this would be more economical and convenient than
performing the formation tests and sample collections at different
times, with separate tools, or on separate trips into the wellbore.
Performing a formation test and a sample collection without moving
the drill string between these operations would also aid in
correlating the results of these operations to a particular
location in the formation.
[0004] From the foregoing, it can be seen that it would be quite
desirable to provide an early formation evaluation tool with the
capability of collecting formation fluid samples.
SUMMARY OF THE INVENTION
[0005] In carrying out the principles of the present invention, in
accordance with an embodiment thereof, an early formation
evaluation tool is provided in which fluid samples may be
conveniently collected therein.
[0006] In one aspect of the present invention, successive fluid
samples are received in respective successive fluid samplers of a
tool by alternately increasing and decreasing fluid pressure in a
tubular string in which the tool is interconnected. The fluid
samples may be received in the samplers either without
repositioning the tool in the wellbore, or with the tool being
repositioned in the wellbore between sample collections.
[0007] In another aspect of the present invention, fluid pressure
in the tubular string may also be utilized to sealingly engage one
or more packers of the tool with a wellbore. The fluid pressure
used to operate the packers may be maintained in the tool while the
fluid pressure in the tubular string is altered to operate the
samplers.
[0008] In yet another aspect of the present invention, the tubular
string to which fluid pressure is applied to collect fluid samples
in the tool may also be manipulated to pump fluid from a formation
into the tool. Thus, various operations of the tool may be
conveniently and separately accomplished as desired by merely
manipulating or applying fluid pressure to the tubular string.
[0009] In still another aspect of the present invention, the tool
may include a ratchet mechanism responsive to fluid pressure
applied to the tubular string. In one embodiment described herein,
a J-slot is used to incrementally displace a piercing member
relative to a series of pressure barriers. Fluid pressure applied
to the tubular string may also be utilized to cause the member to
pierce one of the barriers with which the member is aligned.
[0010] In a further aspect of the present invention, the tool
includes at least one fluid sampler including an actuator. The
actuator is placed in fluid communication with one fluid passage of
the tool to thereby cause the sampler to receive a fluid sample
therein from another fluid passage of the tool. In one embodiment
described herein, the one fluid passage used to operate the
actuator is placed in fluid communication with the interior of the
tubular string in which the tool is interconnected.
[0011] 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
[0012] FIG. 1 is a schematic partially cross-sectional view of a
method embodying principles of the present invention;
[0013] FIGS. 2A-V are quarter-sectional views of successive axial
sections of an early formation evaluation tool which may be
utilized in the method of FIG. 1; and
[0014] FIG. 3 is an elevational developed view of a J-slot member
of the tool of FIGS. 2A-V.
DETAILED DESCRIPTION
[0015] 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 and methods
described herein, directional terms, such as "above", "below",
"upper", "lower", etc., are used 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., without departing from the
principles of the present invention.
[0016] In the method 10, a formation testing system 12 is
interconnected in a tubular string 14, such as a drill string, and
is positioned in a wellbore 16. As depicted in FIG. 1, the
formation testing system 12 is utilized as a part of the drill
string 14 during drilling operations. Preferably, after a formation
18 of interest has been intersected by the wellbore 16, drilling is
momentarily halted while the formation testing system 12 is used to
evaluate characteristics of the formation. However, it is to be
clearly understood that principles of the present invention may be
utilized in other methods, for example, after drilling operations
have been completed, or wherein the formation testing system 12 is
conveyed into the wellbore 16 as a part of another type of tubular
string, etc.
[0017] The formation testing system 12 is similar in many respects
to the formation testing system described in U.S. Pat. No.
5,791,414, the disclosure of which is incorporated herein by this
reference. However, the present applicant has devised unique
manners of adding fluid sampling capability to the formation
testing system described in that patent, so that formation fluid
samples may be collected in the system. Of course, principles of
the present invention may be incorporated into other types of
downhole systems, and it is not necessary for the present invention
to be used in conjunction with the formation testing system of U.S.
Pat. No. 5,791,414.
[0018] The formation testing system 12 used in the method 10 as
depicted in FIG. 1 includes a valve actuating section, apparatus or
tool 20 and a fluid sampling section, apparatus or tool 22.
Preferably, the valve actuating section 20 is similar to, or the
same as, the valve actuating section described in the incorporated
patent. The valve actuating section 20 includes a valve portion
operative to selectively permit and prevent flow through a main
axial flow passage of the drill string 14 in response to altering a
fluid pressure differential between the interior and exterior of
the drill string. Such fluid pressure differential changes are
preferably caused by changing a rate of circulation of fluid
through the drill string 14. When the valve portion closes, the
interior of the drill string 14 above the valve portion is placed
in fluid communication with an internal inflation fluid passage of
the fluid sampling section 22, so that fluid pressure in the drill
string above the valve portion may be used to inflate inflatable
packers 24 of the fluid sampling section. The packers 24 sealingly
engage the wellbore 16, thereby isolating a portion of the
formation 18 between the packers from the remainder of the
wellbore. Fluid from the formation 18 may then be drawn into the
fluid sampling section 22 by manipulating the drill string 14, as
described in further detail in the incorporated patent.
[0019] Referring additionally now to FIGS. 2A-V, a fluid sampling
apparatus 30 embodying principles of the present invention is
representatively illustrated. The apparatus 30 may be used for the
fluid sampling section 22 of the fluid sampling system 12 in the
method 10, or the apparatus may be used in other systems or
methods.
[0020] The apparatus 30 is similar in many respects to the fluid
sampling section described in the incorporated patent. For example,
fluid pressure applied to an internal fluid passage 32 of the
apparatus 30 may be used to inflate axially spaced apart packers 34
carried on the apparatus. After the packers 34 have been sealingly
engaged with a wellbore, such as the wellbore 16 in the method 10,
a pump assembly 36, including a piston 38 and check valves 40, may
be operated by stroking the piston axially, such as by raising and
lowering the drill string 14, which is interconnected to the piston
via an upper connector 42. Such operation of the pump assembly 36
may be used to pump fluid from a formation into a crossover 44
positioned between the packers 34, and thence into another internal
fluid passage 46. One or more instruments 48 in communication with
the passage 46 may then be used to measure/record pressure drawdown
and buildup, temperature, resistivity, etc., or other parameters
useful in characterizing the formation and/or the fluid contained
in the formation, etc.
[0021] However, in one unique aspect of the present invention,
fluid pressure in the passage 32 may also be used in operating one
or more actuators 50 of corresponding respective one or more fluid
samplers 52. The apparatus 30 representatively includes six
circumferentially distributed and equally spaced apart samplers 52.
Only two of the samplers 52, including one of the corresponding
actuators 50, are visible in FIG. 2J, but there may be any number
of the samplers.
[0022] The samplers 52 are preferably, although not necessarily, of
the type described in U.S. application Ser. No. 08/935,867, filed
Sep. 23, 1997, the disclosure of which is incorporated herein by
this reference. In the sampler described in that application, an
actuator of the sampler includes a rupture disc which is broken to
actuate the sampler to receive a fluid sample therein. The samplers
52 of the apparatus 30 depicted in FIG. 2J are somewhat modified
from the sampler described in the incorporated application,
however, in that their actuators 50 do not include the rupture
disc. Instead, each actuator 50 is connected via an adapter 54 and
conduit 56 to an internal fluid passage 58 of the apparatus 30. For
example, if there are six of the samplers 52 in the apparatus 30,
then there are correspondingly six of the adapters 54, six of the
conduits 56 and six of the passages 58. Thus, when fluid pressure
is applied to one of the passages 58, the pressure is transmitted
to the corresponding actuator 50, which is thereby operated to
cause the corresponding sampler 52 to receive a fluid sample
therein.
[0023] As used herein, the term "sampler" is used to indicate a
container in which a fluid sample may be retained, isolated from
contamination, for retrieval and subsequent analysis. As used
herein, the term "actuator", when used in conjunction with a
sampler, is used to indicate a mechanism or device of the sampler
which is operated to cause the sampler to receive a fluid sample
therein. It is to be clearly understood that principles of the
present invention may be incorporated into apparatus which utilize
samplers and actuators other than those described herein.
[0024] Fluid pressure is applied successively to the passages 58 by
successively breaking corresponding respective frangible pressure
barriers 60. Only one of the pressure barriers 60 is shown in FIG.
2H, but it is to be understood that a pressure barrier is
preferably associated with each of the passages 58 to initially
isolate each of the passages from the passage 32. Note that the
passages 58 and pressure barriers 60 are circumferentially
distributed and equally spaced apart in the apparatus 30.
[0025] As used herein, the term "pressure barrier" is used to
indicate any means of selectively permitting and preventing fluid
pressure communication therethrough. For example, the pressure
barrier 60 may be a pierceable disc or rupture disc as depicted in
FIG. 2H, or the pressure barrier may be a valve, etc.
[0026] The pressure barriers 60 are opened to fluid pressure
communication therethrough by successively piercing them with a
penetrator or piercing member 62 attached to a ring 64. The ring 64
is rotatably attached to a piston assembly 66. A circular clip 70
axially retains the ring 64 relative to the piston assembly 66
while permitting rotation of the ring relative to the piston
assembly.
[0027] Note that the passage 32 extends at least partially through
the piston assembly 66 and acts on an upwardly facing differential
area of the piston assembly. Fluid pressure in the passage 32
biases the piston assembly 66 axially downward against an upwardly
biasing force exerted by a compression spring 68. Thus, when a
downwardly directed force on the piston assembly 66 (due to fluid
pressure in the passage 32) exceeds the upwardly biasing force
exerted on the piston assembly by the spring 68, the piston
assembly displaces downward, thereby displacing the penetrator 62
toward one of the barriers 60 with which the penetrator is axially
and circumferentially aligned.
[0028] A pin 72 is attached to the ring 64 and extends inwardly
therefrom. The pin 72 is received in a J-slot profile 74 formed
externally on a generally annular-shaped internal portion 76 of an
intermediate housing member 78 of an overall outer housing assembly
80. The J-slot profile 74 extends circumferentially about the
annular portion 76 and is continuous.
[0029] Referring additionally now to FIG. 3, a developed view of
the J-slot profile 74 on the portion 76 is representatively
illustrated with various positions of the pin 72 therein being
shown in dashed lines. J-slot profiles such as the profile 74 are
well known to those skilled in the art and, therefore, the manner
in which the profile is used to incrementally rotate the ring 64
and thereby align the penetrator 62 with successive ones of the
barriers 60 will be only briefly described herein. Those skilled in
the art refer to such mechanisms as "ratchet" mechanisms, in which
one member is displaced incrementally relative to another member of
the mechanism. However, it is to be clearly understood that other
types of ratchet mechanisms, and other displacement devices and
mechanisms, may be utilized in the apparatus 30, without departing
from the principles of the present invention.
[0030] The J-slot profile 74 is depicted in FIG. 3 as if it were
"unrolled", that is, from a two-dimensional perspective, wherein
the direction to the right in FIG. 3 is the downward direction as
viewed in FIG. 2H. Thus, when the pin 72 displaces downward due to
the piston assembly 66 displacing downward in response to fluid
pressure in the passage 32, the pin correspondingly displaces to
the right as viewed in FIG. 3. For convenience, axially downwardly
elongated portions 74a of the profile 74 have been numbered (1, 2,
3, 4, 5 and 6) adjacent the right-hand side of FIG. 3 to indicate
the corresponding one of the pressure barriers 60 aligned with each
of the portions 74a. The number 4 is repeated at the top and bottom
of the figure, since the corresponding portion 74a is continuous
between the top and bottom of the figure.
[0031] When the piston assembly 66 is in the position shown in
FIGS. 2A-V, the pin 72 is upwardly disposed in the profile 74 in
axially upwardly elongated portions 74b of the profile. When the
piston assembly 66 is downwardly displaced (due to increased fluid
pressure in the passage 32 overcoming the upwardly biasing force of
the spring 68), the pin 72 displaces downwardly in the profile 74
(to the right in FIG. 3) and eventually enters one of the portions
74a. Of course, due to compression of the spring 68, fluid pressure
in the passage 32 sufficient to initiate downward displacement of
the pin 72 in the profile 74 is thereafter increased further to
displace the pin into one of the portions 74a. For example,
approximately 800 psi in the passage 32 may be sufficient to
initiate downward displacement of the pin 72 when it is at a
position 72b as indicated in FIG. 3, and approximately 1,500 psi
may be required to fully downwardly displace the pin to a position
72a as indicated in FIG. 3.
[0032] Note that the pin 72 rotates when traversing from position
72b to position 72a. This is seen as an upward displacement of the
pin 72 in FIG. 3. Of course, by decreasing the pressure in the
passage 32, the pin 72 may be upwardly displaced in the profile 74
from a position 72a to a next adjacent position 72b, due to the
spring 68 upwardly biasing the piston assembly 66. Thus, it will be
readily appreciated by one skilled in the art that the pin 72 may
be sequentially and incrementally rotated with respect to the
profile 74 by alternately increasing and decreasing the pressure in
the passage 32. In one embodiment of the apparatus 30, fluid
pressure in the passage 32 may be alternated between 1,000 and
1,500 psi to thereby incrementally rotate the pin 72 about the
profile 74. Other pressures may be utilized without departing from
the principles of the present invention. A position 72c of the pin
72 is used when the apparatus 30 is initially assembled.
[0033] Referring again to FIG. 2H, the penetrator 62 is
circumferentially offset relative to one of the barriers 60 when
the piston assembly 66 is in its illustrated upwardly disposed
position. When sufficient fluid pressure is applied to the passage
32 to downwardly displace the pin 72 into one of the portions 74a,
the penetrator 62 will then be circumferentially and axially
aligned with one of the barriers 60, due to the fact that the
profile 74 rotates the ring 64 as described above and each of the
profile portions 74a is circumferentially aligned with one of the
barriers. Downward displacement of the pin 72 to one of the
positions 72a results in the penetrator 62 piercing one of the
barriers 60 and thereby permitting fluid communication between the
passage 32 and a corresponding one of the passages 58.
[0034] Therefore, by alternately increasing and decreasing fluid
pressure in the passage 32, the penetrator 62 may be sequentially
and incrementally aligned with successive ones of the barriers 60,
and each of the barriers may be opened by applying sufficient fluid
pressure to the passage 32 when the penetrator is aligned with that
barrier. Furthermore, since each barrier 60 is associated with a
corresponding one of the passages 58 as described above, such
altering of the fluid pressure in the passage 32 results in
successive operation of the actuators 50 of the samplers 52,
thereby causing the samplers to successively receive fluid samples
therein.
[0035] Referring specifically now to FIGS. 2I & J, it may be
seen that each sampler 52 has a conduit 82 providing fluid
communication with the passage 46. As described above, the passage
46 is the passage into which fluid is drawn from the formation when
the pump assembly 36 is operated. Thus, when one of the samplers 52
is actuated, it receives fluid therein from the passage 46, which
passage preferably contains fluid pumped from a portion of a
formation isolated between the packers 34 as described above.
[0036] Note that the passage 32 is also utilized for inflating the
packers 34 as described above. In order to stabilize fluid pressure
within the packers 34 after they have been inflated, the apparatus
30 includes a unique feature which isolates an internal fluid
passage 84 leading to the packers from the passage 32 while fluid
pressure in the passage 32 is alternately increased and decreased
to actuate the samplers 52.
[0037] Recall that the piston assembly 66 in one embodiment of the
apparatus 30 begins to displace downwardly when fluid pressure in
the passage 32 reaches approximately 800 psi. Referring
specifically now to FIG. 2H, it may be seen that the passage 32 is
initially in fluid communication with the passage 84, that is, when
the piston assembly 66 is in its upwardly disposed position.
However, when fluid pressure in the passage 32 has been increased
to approximately 1,000 psi, a seal 86 carried on the piston
assembly 66 traverses an opening 88 formerly providing fluid
communication between the passages 32, 84. Thus, at approximately
1,000 psi (which pressure, in one embodiment of the apparatus 30,
is sufficient to inflate the packers 34 into sealing engagement
with a wellbore), the passages 32, 84 are isolated from each other
and that fluid pressure is "trapped" in the passage 84, thereby
maintaining inflation of the packers at a stable pressure.
[0038] When fluid pressure in the passage 32 is again decreased
below approximately 1,000 psi, the seal 86 again traverses the
opening 88 (albeit in an opposite direction) and thereby permits
fluid communication between the passages 32, 84. Thus, the packers
34 may be conveniently deflated when desired by merely decreasing
fluid pressure in the passage 32.
[0039] In order to fully appreciate the many benefits of the
present invention, an exemplary operation of the apparatus 30 is
described below. Operation of the apparatus 30 is described as if
the apparatus were utilized for the fluid sampling section 22 in
the method 10 depicted in FIG. 1. However, it is to be clearly
understood that the apparatus 30 may be otherwise utilized and
operated, and that other apparatus may be constructed and other
methods may be performed, without departing from the principles of
the present invention.
[0040] The apparatus 30 is interconnected in the drill string 14 as
the fluid sampling section 22 of the formation testing system 12.
The drill string 14 is conveyed into the wellbore 16 and drilling
is commenced, for example, by rotating the drill string and
circulating drilling mud therethrough.
[0041] When a formation of interest has been intersected, such as
the formation 18, drilling is ceased. The drill string 14 is raised
or otherwise displaced to position the apparatus 30 opposite the
formation 18, so that inflation of the packers 34 will isolate a
desired portion of the formation for analysis.
[0042] Fluid is circulated through the drill string 14 as described
in the incorporated U.S. Pat. No. 5,791,414 to thereby close the
valve portion of the valve actuating section 20 and provide fluid
communication between the passage 32 of the apparatus 30 and the
interior of the drill string above the valve portion. Fluid
pressure applied to the drill string 14 at the surface may then be
conveniently used to operate the apparatus 30 as described
above.
[0043] Fluid pressure in the drill string 14 above the valve
portion is increased to approximately 1,000 psi. This fluid
pressure is transmitted to the passage 32 and results in inflation
of the packers 34, thereby sealingly engaging the packers with the
wellbore 16 and isolating the desired portion of the formation 18
from the remainder of the wellbore. The 1,000 psi fluid pressure in
the passage 32 also results in downward displacement of the piston
assembly 66 and isolation of the passage 84 from the passage 32.
This traps the 1,000 psi in the packers 34, maintains their
inflation at a stable pressure and secures the apparatus 30 and
drill string 14 therebelow relative to the wellbore 16.
[0044] The drill string 14 above the apparatus 30 is manipulated by
alternately raising and lowering it, thereby operating the pump
assembly 36 of the apparatus. Fluid is pumped into the apparatus
30, initially from the annular area radially between the apparatus
and the wellbore and axially between the packers 34, but eventually
from the portion of the formation 18 isolated between the packers.
In this manner, fluid is pumped from the formation 18, through the
crossover 44 of the apparatus 30 and into the passage 46. The
instruments 48 may be utilized to measure/record parameters such as
fluid pressure, resistivity. etc. of the fluid in the passage 46,
internal and/or external to the apparatus 30, etc. as described
above and in the incorporated patent.
[0045] Fluid pressure in the passage 32 is then further increased
to approximately 1,500 psi. This increase in fluid pressure further
downwardly displaces the piston assembly 66, thereby rotating the
ring 64 and causing the penetrator 62 to become circumferentially
and axially aligned with one of the barriers 60. Such further
downward displacement of the piston assembly 66 also causes the
penetrator 62 to pierce the barrier with which it is aligned.
[0046] When the barrier 60 is pierced, fluid communication is
permitted between the passage 32 and a corresponding one of the
passages 58. Fluid pressure in the passage 32 is thus communicated
via the passage 58 to a corresponding one of the conduits 56 and to
a corresponding one of the actuators 50. Fluid pressure
communicated to the actuator 50 causes a corresponding one of the
samplers 52 to receive a fluid sample therein from the passage 46
via a corresponding one of the conduits 82.
[0047] If it is desired to collect additional fluid samples from
the same portion of the formation 18, fluid pressure in the passage
32 may be decreased to approximately 1,000 psi and then increased
again to approximately 1,500 psi. This causes the piston assembly
66 to displace upwardly and then downwardly, thereby rotating the
ring 64, aligning the penetrator 62 with the next successive
barrier 60 and downwardly displacing the penetrator to pierce the
barrier. Upon piercing of the barrier 60, another fluid sample is
collected in another corresponding one of the samplers 52 from the
passage 46. Between successive fluid sample collections, the drill
string 14 above the apparatus 30 may be raised and lowered as
desired to pump further fluid from the formation 18 into the
passage 46.
[0048] If it is desired to collect additional fluid samples from
another portion of the formation 18, or from another formation
intersected by the wellbore 16, the packers 34 may be deflated by
decreasing fluid pressure in the passage 32 and the apparatus 30
may be repositioned in the wellbore. When fluid pressure in the
passage 32 has been decreased below approximately 1,000 psi, fluid
communication is again permitted between the passages 32, 84. Fluid
pressure in the packers 34 may then be bled off through the passage
32 to the drill string 14 above the valve portion of the valve
actuating section 20. The apparatus 30 is repositioned as desired
and fluid pressure in the passage 32 is again increased to
approximately 1,000 psi to inflate the packers 34. The pump
assembly 36 is operated to pump fluid from the formation into the
passage 46 and fluid pressure in the passage 32 is again increased
to approximately 1,500 psi to cause another of the samplers 52 to
receive a fluid sample therein from the passage 46.
[0049] Once the desired fluid samples are collected, fluid pressure
in the passage 32 is relieved, thereby deflating the packers 34 as
described above. The valve portion of the valve actuating section
20 is then opened as described in the incorporated patent and
drilling may commence, or the apparatus 30 may be retrieved from
the well for analysis of the fluid sample(s) contained therein. If,
instead of retrieving the apparatus 30 from the well, further
drilling is performed and another formation of interest or portion
thereof is intersected by the wellbore 16, the apparatus may again
be operated to collect further fluid samples as described
above.
[0050] 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.
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.
* * * * *