U.S. patent application number 12/103486 was filed with the patent office on 2009-10-15 for apparatus and method for obtaining formation samples.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to Michael H. Shammai, Angus J. Simpson.
Application Number | 20090255672 12/103486 |
Document ID | / |
Family ID | 41163030 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090255672 |
Kind Code |
A1 |
Simpson; Angus J. ; et
al. |
October 15, 2009 |
APPARATUS AND METHOD FOR OBTAINING FORMATION SAMPLES
Abstract
An apparatus and method for collecting a fluid from a
subterranean formation are disclosed. A fluid sample container has
an elongated body. The elongated body includes an internal cavity,
a first end having a first opening for receiving the downhole fluid
into the internal cavity, a second end axially displaced from the
first end, the second end having a second opening for expelling at
least a portion of the downhole fluid from the internal cavity.
Fluid collecting includes establishing fluid communication with a
formation of interest and the fluid sample container receiving the
downhole fluid into the internal cavity through the first opening
and expelling at least a portion of the downhole fluid from the
internal cavity through the second opening.
Inventors: |
Simpson; Angus J.; (Cypress,
TX) ; Shammai; Michael H.; (Houston, TX) |
Correspondence
Address: |
CANTOR COLBURN LLP- BAKER ATLAS
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
Baker Hughes Incorporated
|
Family ID: |
41163030 |
Appl. No.: |
12/103486 |
Filed: |
April 15, 2008 |
Current U.S.
Class: |
166/264 ;
166/69 |
Current CPC
Class: |
E21B 49/081
20130101 |
Class at
Publication: |
166/264 ;
166/69 |
International
Class: |
E21B 49/08 20060101
E21B049/08 |
Claims
1. An apparatus for collecting a downhole fluid, the apparatus
comprising: a fluid sample container having an elongated body, the
elongated body including an internal cavity, a first end having a
first opening for receiving the downhole fluid into the internal
cavity, a second end axially displaced from the first end, the
second end having a second opening for expelling at least a portion
of the downhole fluid from the internal cavity.
2. An apparatus according to claim 1, wherein the internal cavity
is defined in part by a wall having a curvilinear cross section
profile for fluid sticking, fluid resistance or a combination
thereof within the internal cavity.
3. An apparatus according to claim 2, wherein the wall curvilinear
cross section profile approximates at least a portion of one or
more of a circle and an oval.
4. An apparatus according to claim 1, wherein the internal cavity
is defined in part by a wall having a surface treatment that
reduces fluid sticking, fluid resistance or a combination
thereof.
5. An apparatus according to claim 4, wherein the surface treatment
is selected from one or more of a coating, a polished surface and
an insert.
6. An apparatus according to claim 1 further comprising a flow
control device that is controllable to cease downhole fluid
expulsion from the second opening when a predetermined parameter is
met for the downhole fluid.
7. An apparatus according to claim 1, further comprising a pressure
control device for controlling fluid pressure within the internal
cavity.
8. An apparatus according to claim 7, wherein the pressure control
device includes a pump for controlling pressure in the internal
cavity.
9. An apparatus according to claim 7, wherein the pressure control
device includes a member disposed within the internal cavity for
controlling pressure in the internal cavity.
10. An apparatus according to claim 9, wherein the member includes
a piston that moves in the internal cavity to control pressure in
the internal cavity.
11. An apparatus according to claim 9 further comprising a check
valve coupled to the pressure control device to allow fluid flow
through a central opening of the pressure control device.
12. An apparatus according to claim 1 further comprising a fluid
monitoring device for estimating a property of the downhole
fluid.
13. An apparatus according to claim 12, wherein the property of the
downhole fluid includes a level of contamination.
14. A method for collecting a downhole fluid, the method
comprising: establishing fluid communication with a formation of
interest and a fluid sample container having an elongated body, the
elongated body including an internal cavity, a first end having a
first opening, a second end axially displaced from the first end,
the second end having a second opening; receiving the downhole
fluid into the internal cavity through the first opening; and
expelling at least a portion of the downhole fluid from the
internal cavity through the second opening.
15. A method according to claim 14 further comprising reducing
fluid perturbations within the internal cavity using a wall having
a curvilinear cross section profile defining at least in part the
internal cavity.
16. A method according to claim 15, wherein the wall curvilinear
cross section profile approximates at least a portion of one or
more of a circle and an oval.
17. A method according to claim 14, wherein reducing fluid
perturbations includes using a wall having a surface treatment that
reduces fluid sticking, fluid resistance or a combination
thereof.
18. A method according to claim 17, wherein the surface treatment
is selected from one or more of a coating, a polished surface and
an insert.
19. A method according to claim 14 further comprising ceasing the
downhole fluid expulsion when a predetermined parameter is met for
the downhole fluid using a flow control device that is controllable
to cease downhole fluid expulsion from the second opening.
20. A method according to claim 14 further comprising controlling
fluid pressure within the internal cavity using a pressure control
device.
21. A method according to claim 20, wherein controlling fluid
pressure within the internal cavity includes using a pump as part
of the pressure control device.
22. A method according to claim 20, wherein controlling fluid
pressure within the internal cavity includes controllably changing
a volume within the internal cavity using a member disposed within
the internal cavity.
23. A method according to claim 22, wherein the member includes a
piston and controllably changing a volume within the internal
cavity includes moving the piston to control pressure within the
internal cavity.
24. A method according to claim 22 further comprising, flowing the
downhole fluid through a check valve in the member.
25. A method according to claim 14 further comprising estimating a
property of the downhole fluid using a monitoring device.
26. A method according to claim 25, wherein the property of the
downhole fluid includes a level of contamination.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure generally relates to apparatuses and
methods for evaluating formations traversed by a well borehole and
in particular to formation sampling and testing.
[0003] 2. Background Information
[0004] Formation sampling and testing tools have been used in the
oil and gas industry for collecting formation samples, for
monitoring formation parameters such as pressure along a well
borehole, and for predicting performance of reservoirs around the
borehole. Such formation sampling and testing tools typically
include an elastomer packer or pad that is pressed against a
borehole wall portion to form an isolated zone from which formation
samples are collected. Information that helps in determining the
viability of the formation for producing hydrocarbons and in
determining drilling operation parameters may then be acquired by
evaluating the formation samples.
[0005] Information about the subterranean formations traversed by
the borehole may be obtained by any number of techniques.
Techniques used to obtain formation information include obtaining
one or more downhole fluid samples produced from the subterranean
formations. Downhole fluids, as used herein include any one or any
combination of drilling fluids, return fluids, connate formation
fluids, and formation fluids that may be contaminated by materials
and fluids such as mud filtrates, drilling fluids and return
fluids. Downhole fluid samples are often retrieved from the
borehole and tested in a rig-site or remote laboratory to determine
properties of the fluid samples, which properties are used to
estimate formation properties. Modern fluid sampling also includes
various downhole tests to estimate fluid properties while the fluid
sample is downhole.
[0006] Some formations produce hazardous fluids, and local
governmental regulations may greatly control and restrict the
amount of formation fluids that are introduced into the well
borehole to reduce the risk of exposing the surface environment and
personnel to these hazardous fluids. This is the case even when it
is necessary to retrieve connate formation samples from formations
that produce hazardous downhole fluids. It is difficult to retrieve
connate formation samples from these hazardous fluid producing
formations, because borehole fluids and filtrates often contaminate
the formation samples. One obstacle is that cleanup processes used
to remove borehole contaminants from a fluid sample to obtain a
connate fluid sample substantially free of borehole contaminants
usually results in ejecting large amounts of formation fluid into
the borehole. Thus, the hazardous formation fluids are produced
into the return fluid posing environmental threats and hazards to
personnel at the surface.
SUMMARY
[0007] The following presents a general summary of several aspects
of the disclosure in order to provide a basic understanding of at
least some aspects of the disclosure. This summary is not an
extensive overview of the disclosure. It is not intended to
identify key or critical elements of the disclosure or to delineate
the scope of the claims. The following summary merely presents some
concepts of the disclosure in a general form as a prelude to the
more detailed description that follows.
[0008] An apparatus for collecting a fluid from a subterranean
formation is disclosed that includes a fluid sample container that
has an elongated body. The elongated body includes an internal
cavity, a first end having a first opening for receiving the
downhole fluid into the internal cavity, a second end axially
displaced from the first end, the second end having a second
opening for expelling at least a portion of the downhole fluid from
the internal cavity.
[0009] A method for collecting a downhole fluid includes
establishing fluid communication with a formation of interest and a
fluid sample container having an elongated body, the elongated body
including an internal cavity, a first end having a first opening, a
second end axially displaced from the first end, the second end
having a second opening. The method further includes receiving the
downhole fluid into the internal cavity through the first opening
and expelling at least a portion of the downhole fluid from the
internal cavity through the second opening.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For detailed understanding of the present disclosure,
references should be made to the following detailed description of
the several embodiments, taken in conjunction with the accompanying
drawings, in which like elements have been given like numerals and
wherein:
[0011] FIG. 1 schematically illustrates a non-limiting example of a
well logging system in a wireline arrangement according to several
non-limiting embodiments of the disclosure;
[0012] FIG. 2 illustrates a non-limiting example of extendable
probes useful in several embodiments of the disclosure;
[0013] FIG. 3 illustrates a non-limiting example of a straddle
packer arrangement useful in several embodiments of the
disclosure;
[0014] FIG. 4 illustrates a non-limiting example of a fluid sample
container suitable for operation as a flush-through sample
container; and
[0015] FIG. 5 illustrates an exemplary fluid sample container
including one or more devices for controlling pressure within the
container during transport.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] FIG. 1 schematically illustrates a non-limiting example of a
well logging system 100 in a wireline arrangement according to
several non-limiting embodiments of the disclosure. The exemplary
logging system 100 includes a downhole sub 102 shown disposed in a
borehole 104 and supported by a wireline cable 106. The exemplary
downhole sub 102 may include one or more centralizers 108, 110 for
centralizing the downhole sub 102 in the borehole 104. The cable
106 may be supported by a sheave wheel 112 disposed in a drilling
rig 114. The cable 106 may be wound on a drum 116, shown here
mounted on a truck 118, for lowering or raising the downhole sub
102 in the borehole. The cable 106 may comprise a multi-strand
cable having electrical conductors for carrying electrical signals
and power from the surface to the downhole sub 102 and for
transmitting information to and from the downhole sub 102. The
downhole sub 102 may send information to and receive information
from the surface for processing and/or for executing commands. A
surface transceiver 120 and a controller 122 may be located on the
truck 118 or at any suitable surface location. The exemplary
downhole sub 102 communicates with the surface controller 122 via
the surface transceiver 120 and a downhole transceiver 124.
[0017] The exemplary wireline FIG. 1 operates as a carrier, but any
carrier is considered within the scope of the disclosure. The term
"carrier" as used herein means any device, device component,
combination of devices, media and/or member that may be used to
convey, house, support or otherwise facilitate the use of another
device, device component, combination of devices, media and/or
member. Exemplary non-limiting carriers include drill strings of
the coiled tube type, of the jointed pipe type and any combination
or portion thereof. Other carrier examples include casing pipes,
wirelines, wireline sondes, slickline sondes, downhole subs, BHA's,
drill string inserts, modules, internal housings and substrate
portions thereof.
[0018] In the non-limiting embodiment of FIG. 1, the downhole sub
102 includes a downhole evaluation tool 126, and the downhole
evaluation tool 126 may include an assembly of several tool
segments that are joined end-to-end by threaded sleeves or mutual
compression unions 128. An assembly of tool segments suitable for
the present disclosure may include an arrangement as shown in FIG.
1. The exemplary arrangement includes the transceiver 124 discussed
above, and a downhole controller 130 is shown below the transceiver
124. The downhole controller 130 may further include a processor
and memory for processing information and for executing commands
used for controlling aspects of the downhole sub 102. A power unit
132 may be coupled below the controller 130. The power unit 132 may
include one or more of a hydraulic power unit, an electrical power
unit and an electromechanical power unit. A formation sampling tool
134 is shown coupled to the downhole evaluation tool 126 below the
power unit 132.
[0019] The exemplary formation sampling tool 134 shown in FIG. 1
includes a formation sampling member 136 and a sample expulsion
member 138. The formation sampling member 136 may be extendable as
shown in this example or the formation sampling member 136 may be a
tool portion having a port for receiving a formation sample.
Likewise, the sample expulsion member 138 may be extendable as
shown in this example or the sample expulsion member 138 may be a
tool portion having a port for expelling a formation sample from
the tool. The exemplary formation sampling tool 134 may be
configured for acquiring and/or extracting a formation core sample,
a formation fluid sample, formation images, nuclear information,
electromagnetic information, and/or other downhole samples.
[0020] Referring to FIGS. 1, 2 and 3, several non-limiting
embodiments may be configured with the formation sampling tool 134
operable as a fluid sampling tool. In these embodiments, the
formation sampling member may include an extendable probe having a
sealing pad 200 for isolating a portion of the well borehole. The
fluid expulsion member 138 may also include an extendable probe
having a sealing pad 200 as depicted in FIG. 2. Other exemplary
arrangements may use straddle packers 300 as depicted in FIG. 3 for
isolating borehole portions for the respective formation sampling
member 136 and fluid expulsion member 138. Combinations of
extendable pad seals and straddle packers are also within the scope
of the disclosure. A fluid pump 140 may be placed in fluid
communication with the formation sampling member 136 included with
the formation sampling tool 134 for collecting fluid samples. The
fluid pump 140 may be a single pump or may include one pump for
line purging and a smaller displacement pump for collecting samples
and for quantitatively monitoring fluid received by the downhole
evaluation tool via the formation sampling tool 134. The fluid pump
140 may be a variable rate pump or a constant rate pump.
[0021] One or more flush-through fluid sample containers 142 may be
included below the fluid pump 140 and above the sample expulsion
member 138. In several examples, the fluid sample containers 142
are individually or collectively detachable from the downhole
evaluation tool formation sampling tool 134. Further details of
several exemplary flush-through fluid sample containers will be
provided below with reference to FIGS. 4-5.
[0022] FIG. 4 illustrates a non-limiting example of a fluid sample
container 400 suitable for operation as a flush-through sample
container according to one or more embodiments described above and
shown in FIG. 1 at reference numeral 142. The exemplary fluid
sample container 400 may be used in a wireline arrangement, in a
while-drilling drilling arrangement, a slickline arrangement or by
using any suitable carrier for conveying the fluid sample container
400 in a well borehole. The exemplary embodiment of FIG. 4 is shown
detachably mounted in a downhole sub 102.
[0023] The exemplary fluid sample container 400 shown in FIG. 4
includes an elongated body 402 having an internal cavity 404 for
receiving fluid samples 406. The elongated body 402 portion of the
exemplary fluid sample container 400 includes a first end 408 and a
second end 410 axially displaced from the first end. The elongated
body 402 has a first opening 412 in the first end for receiving the
fluid 406 into the internal cavity 404, and a second opening 414 in
the second end 410 for expelling at least a portion of the fluid
406 from the internal cavity 404. The fluid sample container 400 of
this non-limiting embodiment includes a fluid flow control device
416 proximate the second end 410 of the body 402 and coupled to the
downhole sub for controlling fluid expulsion from the internal
cavity 404. The fluid flow control device 416 shown may be a
controlled valve or any suitable fluid flow control device that is
controllable to control fluid expulsion from the second opening 414
during fluid sampling and may be operable to cease fluid expulsion
when a predetermined parameter is met for the downhole fluid
expelled from the fluid container 400.
[0024] Additional fluid control devices 416 are shown in the
exemplary embodiment of FIG. 4 coupled to the downhole sub input
flow line 420 and within the container 400 proximate the body first
end 408 to control fluid flow to and within the first end. The
first end fluid control devices may be substantially similar to the
fluid control devices 416 proximate the second end 410, but the
fluid control devices 416 may be of different types without
departing from the scope of the disclosure.
[0025] The exemplary embodiment shown in FIG. 4 includes a flow
line connector 418 connected to an input flow line 420 at the body
first end 408 for allowing fluid flow into the internal cavity 404.
A similar flow line connector 418 and flow control device 416 are
shown coupled to an output flow line 422 at the body second end 410
for allowing fluid expulsion from the internal cavity 404. The
input flow line 420 and the output flow line 422 in the example
shown here are flow line portions of the downhole sub 102 that are
in fluid communication with the internal cavity 404 of the
formation sample container 400.
[0026] The fluid sample container 400 may be detachable from the
downhole sub 102 using detachable flow line connectors 418 and one
or more detachable mounting members 424 that couple the fluid
sample container body 402 to the downhole sub 102. The downhole sub
102 may include a pump 140 for conveying fluid through a fluid flow
control device 416, which may be a valve controllable downhole
using command signals. The fluid flow control device 416 is in
communication with the internal cavity 404.
[0027] The exemplary fluid sample container 400 may further include
a check valve 426 as shown coupled to the input flow line connector
418 and a similar check valve 426 coupled to the output flow line
connector 418 to help ensure fluid flows through the fluid sample
container 400 in one direction during a downhole sample cleanup
process.
[0028] The non-limiting embodiment of FIG. 4 may further include a
fluid evaluation module 428. In one or more embodiments, the fluid
evaluation module 428 may be in fluid communication with the output
flow line 422 for estimating fluid content of fluid expelled from
the internal cavity 404. In one or more embodiments, the fluid
evaluation module 428 may be in fluid communication with the input
flow line 420 for estimating fluid content of fluid entering the
internal cavity 404. In one or more embodiments, a fluid evaluation
module 428 may be in fluid communication with both the input flow
line 420 and the output flow line 422 for estimating fluid content
of fluid entering and exiting the internal cavity 404. The fluid
evaluation module may be a single module as shown or may be
implemented using two or more modules.
[0029] The fluid evaluation module 428 may include any number of
fluid measurement devices for estimating fluid characteristics of
the fluid 406 entering or leaving the internal cavity 404. The
fluid evaluation module 428 may be arranged to estimate optical
characteristics, electrical characteristics, physical
characteristics and any combination of characteristics of the fluid
406. For example, some test devices may be in fluid contact with
fluid flowing in the fluid evaluation module, some devices may be
in optical communication, some devices may be in acoustic
communication, some devices may be in physical contact with the
fluid, and still others may be in pressure and/or thermal
communication with the fluid.
[0030] Optical characteristics may be estimated using a downhole
fluorescence test device, a reflectometer, a spectrometer, or any
combination thereof. Physical characteristics of the fluid may be
estimated using a viscometer, a pressure sensor, a temperature
sensor, fluid density transducer, or any combination thereof.
Electrical characteristics of the fluid 406 may be estimated using
resistivity measurement devices, capacitance and dielectric
constant measurement devices, or combinations thereof. Other
devices may be included with the fluid evaluation module 428 for
estimating fluid chemical properties and compositional properties.
Exemplary devices include, but are not limited to, a gas
chromatograph, a pH test device, a salinity test device, a CO2 test
device, an H2S test device, a device for determining wax and
asphaltene components, a device for determining metal content,
(mercury or other metal), a device for determining acidity of the
fluid, or any combination thereof.
[0031] In one or more embodiments, the internal cavity 404 is
defined by a smooth curvilinear surface 430 within the body 402.
The surface 430 may be selected based on the desired cavity volume,
overall size of the body and on fluid flow characteristics. In the
exemplary embodiment of FIG. 4, the internal cavity 404 has a
substantially oval cross section along a longitudinal axis. In one
or more embodiments, the internal cavity 404 may be spherical with
a substantially circular cross section. In one or more embodiments,
the internal cavity 404 may have a cylindrical center portion with
flat end portions, hemispherical end portions, conical end
portions, or any other end portion shape that provides relatively
free fluid flow within the internal cavity 404. A surface treatment
that reduces fluid adhesion may be used to further reduce sticking
and resistance in the fluid flow within the internal cavity 404.
Exemplary surface treatments include, but are not limited to,
polishing, coatings, laminates, inserts and combinations
thereof.
[0032] Turning now to FIG. 5, an exemplary fluid sample container
500 may further include one or more devices for controlling
pressure within the container 500 during transport. The
non-limiting embodiment shown in FIG. 5 is coupled to a downhole
sub 102 and includes a substantially cylindrical internal cavity
504. Many of the items in FIG. 5 may be substantially similar to
the like-numbered items describe above and shown in FIG. 4. For
brevity, the following description will focus more on the
additional features shown in FIG. 5.
[0033] The exemplary fluid sample container 500 includes an
elongated body 502 having an internal cavity 504 for receiving
fluid samples 506. The elongated body 502 portion of the exemplary
fluid sample container 500 includes a first end 508 and a second
end 510 axially displaced from the first end. The elongated body
502 has a first opening 512 in the first end 508 for receiving the
fluid into the internal cavity 504 from the formation sampling
member 136. A second opening 514 in the second end 510 may be used
for expelling at least a portion of the fluid 506 from the internal
cavity 504 through the fluid expulsion member 138. The fluid sample
container 500 of this non-limiting embodiment includes a pressure
control device 516 for controlling pressure of the fluid sample
506. The pressure control device 516 provides a flow path via a
check valve 522 for fluid 506 flowing through the internal cavity
504 and allows for substantially unrestricted flow during the
cleanup process and expulsion of fluid from the internal cavity 504
via the expulsion member 138. The pressure control device 516 in
one or more non-limiting embodiments includes a piston 526 that is
movably disposed within the cavity 504. One or more O-rings 518
provide a fluid and pressure seal between the piston 526 and cavity
wall 530. The check valve 522 is positioned within the piston 526
to provide a flow path through the piston 526 to the opening 514 in
the second end 510.
[0034] The piston 526 is shown positioned toward the second end 510
with the sample 506 shown with an arrow to indicate the direction
of flow through the container 500. The check valve 522 prevents
flow in the opposite direction. In this manner, the fluid flow
through the internal cavity is substantially free flowing during
sample cleanup.
[0035] The pressure control device 516 may be actuated using a
device controller 520. In one or more embodiments, the device
controller 520 may be a pump substantially similar to the pump 140
described above and shown in FIG. 1. In one or more embodiments,
the pump 140 may be used as the controller for the pressure control
device 516. A gas supply 524 is shown in communication with one end
of the piston 526 and with the device controller 520. In one or
more embodiments, the gas supply may include a pressurized inert
gas such as nitrogen. When actuated, the device controller may be
used to add pressure to the gas supply and/or to urge gas toward
the piston 526. When pressurized, the piston tends to move toward
the first end 508, thereby decreasing the volume in the cavity 504
and/or increasing the pressure within the cavity 504 when one or
more of the inflow and outflow fluid control devices 416 are
actuated to cease fluid flow. In this manner, the fluid 506 may be
maintained at a predetermined pressure once a fluid sample is
collected in the internal cavity 504. For example, the fluid 506
may be maintained above its bubble point pressure for transport to
the surface.
[0036] Several non-limiting operational embodiments for formation
sampling will now be described with reference to FIGS. 1 through 5.
In one or more embodiments a downhole sub 102 may be conveyed in a
well borehole to a formation of interest. A portion of the borehole
is isolated using straddle packers, a pad seal disposed on the end
of an extendable probe or by using a combination of packers and
extendable probe to create an isolated zone. Fluid communication is
established between the formation of interest and the downhole sub
by exposing a tool port to the isolated zone. In some embodiments,
formation pressure may be sufficient to flow fluid from the
formation into the tool. In one or more embodiments, a pump 140 or
other flow controller may be used to urge fluid into the downhole
sub.
[0037] Fluid flow into the downhole sub may be maintained in a
substantially continuous manner to perform a cleanup process for
removing borehole contaminants from the downhole fluid entering the
downhole sub. The sample cleanup process may include initially
expelling fluid from the downhole sub while the pump or formation
pressure urges fluid through the downhole sub. In one or more
embodiments, the fluid is monitored for content properties during
the cleanup process to estimate a cleanliness level of the fluid
flowing within the tool. In one or more embodiments, fluid
expulsion is accomplished by reinjecting the expelled fluid into
the formation proximate the downhole sub to limit or prevent the
fluid from entering the borehole annulus. In one or more
embodiments, the fluid is injected into the formation using an
extendable expulsion member that is extended to establish fluid
communication with the formation. The fluid expulsion may be halted
when the fluid within the tool is estimated to be substantially
free of contaminants.
[0038] In one or more embodiments, fluid samples may be contained
within the tool using an internal fluid sample container 400, 500.
In one or more embodiments, the fluid cleanup process may include
urging the fluid received in the tool through a first end of the
fluid sample container and expelling the fluid from a second end of
the fluid sample container. Once the estimations show that the
fluid within the fluid sample container are substantially free of
contaminants, the second container end flow path may be closed
using a sub-carried valve 416 that is in fluid communication with
the output flow line 422.
[0039] The pump 140 may be used to increase the pressure in the
container internal cavity 404, 504 to a desired pressure. Once the
pressure within the internal cavity reaches the desired pressure,
then the pump may be halted and a second sub-carried valve 416 that
is in fluid communication with the input flow line 420 may be
actuated to close the flow path into the internal cavity 404, 504.
In this manner, the fluid sample 406, 506 is sealed within a volume
defined between the two sub-carried valves 416.
[0040] Pressure within the internal cavity may be controlled after
sample collection and during transport using a pressure control
device. Fluid may flow through the pressure control device during
the cleanup process and a check valve may be used to allow fluid
flow in only one direction through the pressure control device. An
inert gas may be used to move a piston within the internal cavity
to control pressure.
[0041] In one or more embodiments, the fluid sample container 400,
500 may be transported to a surface location and removed from the
downhole sub without losing fluid containment within the internal
cavity 404, 504. Surface operations may include actuating the first
end and second end fluid control devices 416 within the container
body 402, 502 to seal the respective first end and second end
portions of the internal cavity 404, 504. The fluid sample
container 400, 500 may then be disconnected from the downhole sub
102 by disconnecting the detachable couplings 424 and the flow line
connectors 418.
[0042] The sample container internal cavity 404, 504 may be flushed
of contaminants and/or connate fluids without leaving substantial
residue within the internal cavity. The pump 140 may generate a
fluid flow through the cavity. In some embodiments, the cavity 404,
504 includes a curvilinear wall 430, 530 that reduces fluid
sticking within the cavity. The wall 430, 530 may further include a
surface treatment that further reduces fluid resistance and may be
used to reduce sample sticking along the wall 430, 530.
[0043] Fluid initially urged into the downhole sub 102 may include
one or more contaminants such as borehole fluid and filtrates.
Undesirable fluid sample components such as the above-noted
contaminants may be cleaned from the fluid entering the downhole
evaluation tool 126 by pumping the fluid into the tool and then
expelling the fluid through the sample expulsion member 138 until
the fluid entering the tool is substantially free of the
undesirable contaminants.
[0044] In one or more embodiments, pumping and expulsion is
performed for a period of time without separate content monitoring
with the period of time selected to establish substantially
contaminant-free connate fluid flow in the tool. The fluid sample
expulsion may be halted on or after completion of the time-based
pumping. In one or more embodiments, fluid flowing in the tool is
monitored using a downhole tester to estimate fluid content in
substantially real-time. The fluid sample expulsion may be halted
on or after the content estimate establishes that the fluid flowing
in the tool is substantially contaminant-free connate fluid.
[0045] One or more operational embodiments address fluid expulsion
where environmental regulations, safety concerns or other factors
make it desirable to reduce or avoid introducing produced formation
fluid to the well borehole. Fluid communication may be established
between the sample expulsion member 138 and the formation proximate
the sample expulsion member. In this manner, fluid expelled from
the tool may be directly injected into the formation with leakage
into the well borehole being reduced to levels in compliance with
the applicable regulations or to levels that mitigate the safety
hazards or that otherwise meet the selected leakage standards set
for the particular sampling operation. Formation fluid samples that
are substantially free of contaminants may be brought to the
surface for testing on-site or in a laboratory environment using
the flush through sample container 142.
[0046] The present disclosure is to be taken as illustrative rather
than as limiting the scope or nature of the claims below. Numerous
modifications and variations will become apparent to those skilled
in the art after studying the disclosure, including use of
equivalent functional and/or structural substitutes for elements
described herein, use of equivalent functional couplings for
couplings described herein, and/or use of equivalent functional
actions for actions described herein. Such insubstantial variations
are to be considered within the scope of the claims below.
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