Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Formation Sampler with Cleaning Capability
Background of the Disclosure
[0001] Sampling tools are used to extract samples of underground reservoir
fluids. The
extracted samples can either be analyzed down-hole or stored in a container
for subsequent
laboratory analyses. In either case, the fluid sample must be representative
of both the chemical
composition and physical properties of the formation fluid about the volume of
sampling
acquisition. Often, one sampling tool is used to acquire fluids from several
locations within a
reservoir. It is highly likely that fluid sampled at a first location in the
reservoir may have
adhered to the inner walls of the flow line or other hydraulic components of
the sampling tool.
Consequently, fluid extracted from a second location within the same reservoir
may be
contaminated by that remaining from the first acquisition. As a consequence,
the chemical
composition and physical properties determined by analyses of the second fluid
may not actually
be of the formation fluid but of a mixture of the first and second fluid and
thus be
unrepresentative of the formation fluid at that second location. Such mixing
of fluids from two
zones of the same reservoir may plausibly lead to wrong decisions regarding
the fluid type
within the reservoir. One such example regards the distinction of a fluid as a
volatile oil when it
is actually a gas condensate, a decision that would have catastrophic
consequences on the
designed and commissioned surface separator systems.
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Summary of the Disclosure
[0002] Some embodiments of the present disclosure may address the above-
described problem
of cross contamination between two sampling locations with an apparatus
described herein that
may be used to advantage, but not exclusively, for sampling a reservoir fluid
having very vicious
hydrocarbons such as heavy oils.
[0003] For
example, the present disclosure introduces a method of cleaning a portion of
the
internal tubulars that form the passage through which hydrocarbon fluid flows
within a down-
hole tool conveyed by any method available to the industry including cables
and drill pipe. In
the remainder of this application, we may refer to this as a flow line, a
hydraulic circuit, and/or a
portion of a hydraulic circuit, in a downhole tool. In at least one
embodiment, the method
comprises lowering a tool in a borehole, the tool having a flow line and/or
other portion of a
hydraulic circuit for facilitating formation fluid flow; cleaning at least a
portion of the hydraulic
circuit portion, wherein cleaning the hydraulic circuit portion comprises at
least one of purging
and flushing the hydraulic circuit portion with a cleaning fluid to remove
contaminant from the
hydraulic circuit portion; and flowing fluid from the formation through the
cleaned portion of the
hydraulic circuit portion. The method may further comprise heating the
hydraulic circuit portion
to reduce adhesion of the contaminant to a wall of the hydraulic circuit
portion. The method
may further comprise altering the temperature of the hydraulic circuit portion
to reduce adhesion
of the contaminant to the hydraulic circuit portion. The cleaning fluid may
comprise at least one
of a solvent, a bead loaded fluid, fluid with an additive for modifying
interfacial tension, and an
immiscible fluid having a viscosity that acts as a displacement fluid. The
method may further
comprise scraping a wall of the hydraulic circuit portion with a moveable
device. The method
may further comprise exposing at least one of a wall of the hydraulic circuit
portion and fluid in
the hydraulic circuit portion to a vibration source. The method may further
comprise at least one
of stretching and shortening a dimension of the hydraulic circuit portion. The
hydraulic circuit
portion may comprise a memory shape alloy.
[0004] The
present disclosure also introduces an apparatus for cleaning a flow line
and/or
other portion of a hydraulic circuit in a downhole tool. In at least one
embodiment, the apparatus
comprises an inlet selectively coupled fluidly to a formation; a flow line
and/or other portion of a
hydraulic circuit fluidly coupled to the inlet; means for facilitating
formation fluid flow from the
inlet; means for introducing cleaning fluid into the hydraulic circuit
portion; and means for
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cleaning at least a portion of the hydraulic circuit portion with the cleaning
fluid. The means
for facilitating formation fluid flow may include a pump and at least one flow
line fluidly
coupled between the inlet and the pump.
[0005] The present disclosure also introduces a method for cleaning a
sensing face of
a sensor of a hydraulic circuit in a downhole tool. In at least one
embodiment, the method
comprises lowering a tool in a borehole, the tool having a flow line and/or
other portion of a
hydraulic circuit for facilitating formation fluid flow; sensing a parameter
of at least one of a
formation fluid and a wellbore fluid with a sensor; cleaning a sensing face of
the sensor
disposed in the hydraulic circuit portion; and flowing fluid from the
formation towards the
sensor, wherein cleaning the sensing face involves purging or flushing at
least a portion of the
hydraulic circuit portion with a cleaning fluid.
[0005a] The present disclosure also introduces a method of cleaning a
portion of
a hydraulic circuit in a downhole tool, comprising: lowering a tool in a
borehole, the
tool having a hydraulic circuit for facilitating formation fluid flow;
subsequent to
flowing viscous formation fluid through at least a portion of the hydraulic
circuit,
cleaning said at least a portion of the hydraulic circuit with a cleaning
fluid, wherein
the cleaning occurs while the tool is in the borehole, wherein the cleaning
fluid
comprises at least one of an additive configured to modify interfacial tension
and an
immiscible fluid having a viscosity that acts as a displacement fluid; and
flowing fluid
from the formation through the cleaned portion of the hydraulic circuit.
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Brief Description of the Drawings
[0006] The present disclosure is best understood from the following
detailed description
when read with the accompanying figures. It is emphasized that, in accordance
with the standard
practice in the industry, various features are not drawn to scale. In fact,
the dimensions of the
various features may be arbitrarily increased or reduced for clarity of
discussion.
[0007] Fig. 1 is a schematic view of apparatus according to one or more
aspects of the
present disclosure.
[0008] Fig. 2 is a flow-chart diagram of at least a portion of a method
according to one or
more aspects of the present disclosure.
[0009] Fig. 3 is a schematic view of apparatus according to one or more
aspects of the
present disclosure.
[0010] Fig. 4 is a schematic view of apparatus according to one or more
aspects of the
present disclosure.
[0011] Fig. 5 is a schematic view of apparatus according to one or more
aspects of the
present disclosure.
[0012] Fig. 6 is a schematic view of apparatus according to one or more
aspects of the
present disclosure.
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Detailed Description
[0013] It is to be understood that the following disclosure provides many
different
embodiments, or examples, for implementing different features of various
embodiments.
Specific examples of components and arrangements are described below to
simplify the present
disclosure. These are, of course, merely examples and are not intended to be
limiting. In
addition, the present disclosure may repeat reference numerals and/or letters
in the various
examples. This repetition is for the purpose of simplicity and clarity and
does not in itself dictate
a relationship between the various embodiments and/or configurations
discussed. Moreover, the
formation of a first feature over or on a second feature in the description
that follows may
include embodiments in which the first and second features are formed in
direct contact, and
may also include embodiments in which additional features may be formed
interposing the first
and second features, such that the first and second features may not be in
direct contact.
[0014] Fig. 1 is a schematic view of an embodiment of a wireline tool
string 100 according
to one or more aspects of the present disclosure. The tool string 100 has a
power and telemetry
cartridge 105 configured for communicating power and data between the tool
string 100 and the
surface via a cable 107. The tool string 100 comprises a heating module 110
configured for
increasing the temperature of the formation F and reducing the viscosity of
the formation fluid.
The tool string 100 also comprises a nuclear magnetic resonance (NMR) tool 115
configured to
monitor formation fluid properties related to the formation fluid viscosity.
The tool string 100
also comprises a sampling tool 120 comprising a probe module having an
extendable probe 122
configured to establish a fluid communication between flow lines in the tool
and the borehole
wall 102. Such flow lines may include a clean-up flow line 125 and a sample
flow line 127. The
sampling tool 120 also comprises or is coupled to one or more pump modules
130a/130b
configured to draw fluid from the formation F into the flow lines. The
sampling tool 120 further
comprises or is coupled to a DFA module 135 configured to monitor the
properties of the fluid in
the flow lines of the sampling tool 120. The sampling tool 120 also comprises
or is coupled to a
sample chamber carrier 140 having one or more containers 142 configured to
capture and convey
fluid samples.
[0015] During formation fluid sampling, the tool string 100 is located at a
point of interest in
the formation F. The heating tool 110 may be operated to increase the
temperature of a portion
of the formation F. By subsequently moving the tool string 100 upwards to
place the NMR pad
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117 of the NMR module 115 in front of the now heated portion of the formation
F, the formation
heating process can be monitored using the NMR module 115. However, NMR
sensors 118 of
the NMR module 115 may be located in close proximity to the heat source 112 of
the heating
tool 110, in which case moving the tool string 100 may not be needed.
[0016] Once sufficient heating has been achieved, the probe 122 is disposed
close to the
heated portion of the formation F and extended toward the borehole wall 102.
Fluid is drawn
into the sample flow line 127 and the clean-up flow line 125 using pumps
132a/b of the pump
modules 130a/b. The pressure and temperature in the flow lines may be measured
with pressure
(and temperature) sensors 133a/b. Fluid viscosity, density, NMR spectrum,
optical spectrum,
etc. may also be monitored by sensors 137a/b/c in the DFA module 135. The DFA
module 135
may also be provided with sensors configured to detect particular chemical
species (e.g., H2S).
[0017] The measured fluid properties may then be displayed at the surface.
They may be
used for controlling the sampling job (sampling flow rate) and also for
obtaining information
about the formation fluid. If desired, a sample may be stored in one or more
of the sample
chambers 142 and brought up at the surface for further analysis. Once the
sampling job is
finished, setting pistons 123 of the sampling module 120 are retracted and the
downhole tool 100
may be moved to another location of the reservoir.
[0018] It will be appreciated that, while moving the downhole tool 100 to
another location of
the reservoir, the formation fluid that still exists in the flow lines,
connectors, valves, pumps,
sensors, and another components of the tool 100 will begin to cool down. If
the formation fluid
is or contains heavy oil, the formation fluid viscosity will also increase as
the temperature
decreases, making the captured formation fluid less susceptible to removal by
pumping other
fluid that might, for example, occur when pumping to clean the sample by
removing filtrate or
drilling mud. The more viscous oil that remains in the tubular may also adhere
to the walls of
the hydraulic components. In the extreme case, the flowlines, sensors, and/or
any other
hydraulic components may even become blocked by the retained formation fluid.
[0019] Additionally, when another part of the formation is tested, a fluid
having different
properties will enter the downhole tool 100. If the new fluid is heated, its
viscosity will be lower
than the cooled fluid that is still coating the hydraulic components.
Therefore, the new fluid will
not efficiently displace the old fluid that coats the walls of the hydraulic
circuit. In some cases,
the new fluid will very slowly mix with the old fluid and contaminate it.
There is also the
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potential for the old cooled fluid to coat the sensors. The measurements
performed by such
sensors will then be biased. For example, if the measurement is dependent on
the fluid within a
skin depth of the sensor, if as most are, the result will reflect the old or
new fluids or a mixture of
both unless subsequent fluid flown in the flow-lines displaces the old fluid.
Thus, drawing fluid
from the bore-hole or formation for the purpose of cleaning the flow-line will
be in addition to
the volume required to extract the invased bore-hole fluids in the formation
so that the fluid
obtained is in terms of the chemical composition and physical properties
representative of the
formation fluid. To draw a large amount of fluid from a heavy oil formation
requires energy be
used to mobilize the hydrocarbon by increasing the formation temperature and
owing to either
the temperature control of either a resistive heater or electromagnetic source
of energy. The
former requires time for propagation of a thermal wave by thermal diffusivity
while the latter
also requires time to select the appropriate frequency for the given
electrical conductivity of the
formation and avoiding excessive temperature increments for particular parts
of the formation.
Excessive temperature increments may give rise to changes in the chemical
composition by
cracking and polar molecules can absorb disproportionate amounts of
electromagnetic energy
and result in local heating through motion that can also result in changes in
the chemical
composition. These processes are costly. Indeed, variations in chemical
composition may result
in the deposition of solids.
[0020] In order to reduce the effect of chemical composition changes, and
to expedite the
cleaning of a flow line and/or other portion of the hydraulic circuit of the
sampling tool 120 and
related components of the downhole tool 100, the method 200 depicted in Fig. 2
may be used.
The method 200 allows for in-situ cleaning of at least a portion of the
sampling tool 120 and
other components of the downhole tool 100. After the downhole tool 100 is
lowered downhole
(205) and fluid is drawn from a first location in the reservoir (210), the
sampling job proceeds to
one or more other locations along the borehole (215). The new location is
presumably but not
necessarily in the same reservoir.
[0021] Testing is then performed to determine if clean-up of a flow line
and/or other portion
of the hydraulic circuit of the tool is desired (220). This may be achieved by
a surface operator,
in view of the sampling data obtained at the first location. For example, if
the fluid viscosity of
the fluid obtained at the first location is high at downhole conditions, a
clean-up may be desired.
Alternatively, mud or another known fluid (conveyed down-hole in a container)
may be flowed
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in the sampling tool and the response of the sensor in the DFA module may be
monitored; the
properties of the fluid are known and so is the response of the sensor. If the
properties measured
by the sensors match the properties expected for the fluid flown in the tool
(e.g., the mud
properties), this may indicate that the sensing face of the sensor in the DFA
module is clean.
This may further indicate that the other hydraulic components of the sampling
tool are clean, and
that sufficient time has been employed in cleaning.
[0022] In the case a clean-up of the tool is desired, the clean-up may be
initiated (225). The
clean-up comprises flowing a flushing fluid through at least a portion of the
downhole tool
hydraulics. However, flushing may not suffice to eliminate a film of very
viscous oil that may
have formed on the walls of the flow lines for examples. Indeed, if the
flushing fluid is less
viscous than the contaminating oil, a significant volume of oil may be
bypassed by the flushing
fluid and may remain in the sampling tool. This contaminating oil may
gradually mix with the
sampled oil, modifying its chemical properties. Thus, flushing may be assisted
by a viscosity
reduction of the contaminating oil (with heat and/or a solvent), a mechanical
action on the oil
(scraping, abrasion, vibration), and/or a change of the shape of the
components of the hydraulic
circuit.
[0023] The method 200 may also comprise an optional step of monitoring the
cleaning
process (230). For example, sensors (e.g., thermocouples) may be used for
measuring and
controlling the temperature of the components of the tool hydraulics. The
temperature may be
controlled to achieve a desired limit, at which the tool components survive
and at which oil
remaining in the tool is expected to have a significantly reduced viscosity.
Other sensors (e.g.,
position sensors, acoustic impedance sensors) may be used to monitor a
quantity related to the
efficiency of the cleaning process. Alternatively, or additionally, sensors in
the DFA module
may be used for monitoring a fluid property as the flushing fluid circulates
in the downhole tool.
When the sensor of the DFA module indicates a stable reading of a fluid
property, and if this
property value is close (that might be within the anticipated uncertainty of
the combined
measurements within an acceptable certainty or confidence interval or a
predetermined value
found suitable by prior practice) to the expected value for the flushing
fluid, this may indicate
that the clean-up can be terminated. Whether monitored or not, the clean-up is
terminated in step
235, perhaps after the expiration of a predetermined time limit, for example.
The sampling
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operation may continue by drawing fluid from a second location in the
reservoir (240) and
returning to step 220 for the next iteration of at least a portion of the
method 200.
[0024] Returning to Fig. 1, the downhole tool 100 may comprise a heating
element, such as a
heating wire 145. The heating wire 145 is thermally coupled to the fluid drawn
into the
sampling tool 120. For example, the tool hydraulics are preferably made of
material that conduct
heat and that have a low heat capacity. The heating wire 145 may be wrapped
around or
partially embedded into the material from which the hydraulic lines are made.
[0025] The heating wire 145 may span from the sampling tool inlet (e.g.,
probe 122) to the
last hydraulic component for which sample purity matters (in the illustrated
example, all the way
to the sample storage and possibly also transportation chambers 142). In the
shown example,
only the sample line 127 is shown equipped with the heating wire 145, but both
additional flow
lines (including clean-up flow line 125) may also be equipped with the heating
wire 145 and/or
other viscosity reducing device. The heating wire can be a wire of known and
suitable
resistance.
[0026] The heating wire 145 may be energized by an electrical current at a
voltage (or
voltage at a current) power source (not shown) and thus be configured to
selectively deliver
energy to the fluid in the hydraulic circuit for lowering its viscosity. One
or more thermocouples
may be used for monitoring the temperature of the hydraulic components and for
controlling the
heating process.
[0027] Once the tool hydraulics are hot, mud from the wellbore may be
pumped and used for
flushing the remaining oil that coats the tool hydraulics (the probe 122 is
not extended). A
property measured by one of the sensors may be monitored for confirming that
the sampling tool
120 is clean (e.g., drilling mud properties are measured). Once the sampling
tool 120 is clean, a
new sampling operation may begin by extending the probe 122 against the
formation.
[0028] Thus, by delivering heat to the oil that adheres to the hydraulic
components of the
tool 100, the viscosity of the oil coating the hydraulic components may be
reduced. As the
viscosity of the fluid is lowered, the cleaning of the hydraulic circuit by
circulating a fluid (e.g.
mud) is enhanced. Thereby, cross-contamination of fluid between two sampling
stations may be
reduced or eliminated. This, in turn, may lead to more efficient sampling
operations with more
accurate in-situ fluid property data, better quality samples, reduced sampling
volume to achieve
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a clean sample, reduced energy needed to get a sample, and/or reduced time
needed to get a
representative sample, among other possible advantages.
[0029] In an alternative example, heat is not generated by the heating wire
145 as shown in
Fig. 1, but by another tool component. The additional tool component may also
be employed in
conjunction with the heating wire 145. The additional tool component could be
power
electronics (electronics that transform the electrical power obtained from the
wireline cable into
power that is usable by, e.g., the pump motors in the tool string). The
additional tool component
could alternatively be a heat pump disposed in one of the tool modules, the
heat pump having a
cold end thermally coupled to a source (e.g., wellbore fluid, power
electronics component) and a
hot end thermally coupled to a heat transport device. For both of these cases,
the heat is
conveyed from the additional tool component to the hydraulic components in the
tool string with
a heat transport device. The heat transport device may be a heat pipe and/or a
hydraulic circuit
circulating a fluid having an appropriate thermal capacity and can circulate
in the temperature
range required of the system (that might be an energy transfer medium of water
or butane etc.).
The heat transport device may thus thermally couple the additional tool
component (heat source)
to the oil stuck in the tool hydraulics.
[0030] Viscosity-reducing heat may also or alternatively be provided to a
flushing fluid
contained in a sample bottle. One such embodiment in shown in Fig. 3. The
fluid is heated and
then circulated in the hydraulic circuit of the tool 300. The hot fluid
transfers part of the heat to
the oil that coats the wall of the hydraulic circuit. The heated oil is
removed by circulating or by
pulsing clean fluid in the hydraulic circuit.
[0031] The tool 300 includes a heating module 310 that includes a flushing
fluid container
312 and a heater 314. A valve 301 controls fluid flow from the container 312.
Fluid flowing
from the valve 301 is either directed out of the tool 300 via a valve 302 or
to an inter-module
connector 316.
[0032] The tool 300 also includes a sampling module 320, similar to the
sampling module
120 shown in Fig. 1, and including a probe 322. Fluid flowing from the inter-
module connector
316 is either directed into the probe 322 and/or to another inter-module
connector 324 via valves
303 and 304.
[0033] The tool 300 also includes one or more pump modules 330, similar to
the pump
module 130a or 130b shown in Fig. 1, and including at least one bidirectional
pump 332
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configured to draw fluid from the formation F into sample flow line 334 and/or
clean-up flow
line 336.
[0034] The tool 300 also includes a sample chamber carrier 340 comprising
at least one
sample chamber 342. For example, one of the sample chambers 342 shown in Fig.
3 receives
fluid from the sample flow line 334 via valve 305. The carrier 340 may also
comprise valve 306
for directing fluid flow from sample flow line 334 to out of the tool 300,
and/or valve 307 for
directing fluid flow from clean-up flow line 336 to out of the tool 300. The
carrier 340 may also
include a heater 344 proximate one or more of the sample chambers 342, and/or
a heater 346
proximate one or more of the flow lines.
[0035] Note that in the tool of 300 Fig. 3, the probe 322 has an outer seal
326 and an inner
seal 328. The inner seal 328 can be selectively moved in the direction
indicated by the arrow
and can be either in contact with the borehole wall 350 or recessed with
respect to the formation
wall 350 (further details of this configuration, if needed, are shown in U.S.
Pat, No. 6,964,301).
The outer seal 326 is applied against the formation
and the inner seal 328 may be recessed during the clean up.
[0036] In one example, valves 302, 303, and 305 are closed, and valves 301,
304, and 306
are open. By pumping down with the pump on the sample flow line 334, hot
flushing fluid
contained in the upper bottle 312 is routed through open valve 301 into the
sealed interval by the
probe 322, then into the sample flow line 334, down to the exit port
associated with the valve
306. In this configuration, the sample flow line 334 is efficiently cleaned
front the 322 probe to
a flow line associated with the exit port.
[0037] In another example, valves 301, 303, and 306 are closed, and valves
302, 304, and
305 are opened. By pumping up with the pump 332 on the sample flow line 334,
hot flushing
fluid contained in a lower bottle 342 is routed through the sample flow line
334 through open
valve 305, into the sealed interval by the probe 322, then into the clean up
flow line 336, up to
the exit port associated with the valve 302.
[0038] In another example, only a lower sample bottle 342 is provided. The
probe 322 is
retracted and does not seal with the wellbore wall 350 during the cleaning
operation. Fluid (e.g.,
mud or cleaning fluid disposed in a sample bottle), is heated and circulated
up towards the probe
322, where it is dumped into the wellbore.
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[0039] The flushing fluid in any embodiment within the scope of the present
disclosure may
be water or any immiscible fluid of greater or lesser viscosity, or may be a
liquid that is miscible
with formation fluid, such as a solvent. In some cases, a polar solvent may be
preferred;
however, non-polar solvent may also be used. The solvent may be heated as
described herein,
but it is also possible to use a solvent that has not been heated.
[0040] The flushing fluid may be a liquid having an additive for
facilitating the removal of
the oil coating on the hydraulic circuit. For example, the fluid may comprise
beads or abrasive
particles. The flushing fluid may contain an additive for modifying
interfacial tension. The
cleaning fluid may comprises at least one of a solvent, a bead loaded fluid,
fluid with an additive
for modifying interfacial tension, and an immiscible fluid having a viscosity
that acts as a
displacement fluid. However, other cleaning fluids are also within the scope
of the present
disclosure.
[0041] Although heating has been discussed in detail, more generally, the
temperature of
formation fluid in the flow line may be altered. Thus, the flushing or purging
of the flow line
may be assisted by chilling the flow line. To that respect, a heat pump may be
used.
[0042] Fig. 4 depicts another way for assisting the cleaning of a flow
line. In the illustrated
embodiment, a movable device is used for scraping the walls of the flow line.
For example, a
brush or a scraping plug 410 is swept along a portion of a flow line 420 of a
sampling tool. The
brush or scraping plug 410 may be affixed to one extremity of a flexible shaft
430. The flexible
shaft 430 may extend through a seal 425, and may be wound around a drum 440
that is
operatively coupled to a motor 450. As shown, the brush 410 may be disposed in
a rat hole 460
while the tool is in sampling mode. However, other equivalent devices (e.g.,
analogous to a PIG
used in natural gas transmission lines) may alternatively be used.
[0043] Fig. 5 shows yet another way for cleaning of a flow line. In the
illustrated example,
an auger or Archimedes screw 510 is snuggly fitted into a portion of a flow
line 520 of the
sampling tool. The auger 510 is coupled to a motor 550, and may extend through
a seal 525.
The motor 550 may be activated for cleaning, or for sampling the oil.
[0044] Fig. 6 shows still another way for assisting the cleaning of a flow
line. In the
illustrated example, a flow line 620 is made of a shape memory alloy. Sampling
is performed
while the flow line 620 has a small diameter. When cleaning is desired, it is
assisted by
increasing the diameter of at least a portion 625 of the flow line 620, as
indicated by the arrows
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in Fig. 6. This may be achieved by modifying the temperature of the alloy
forming the flow line
620. Increasing the diameter of the flow line 620 may facilitate the removal
of viscous oil from
the inner walls of the flow line 620. Circulating a fluid may further evacuate
any remaining oil
film.
[0045] Although many embodiments may be described above in the context of
a wireline
apparatus, aspects of the present disclosure are also applicable or readily
adaptable to while-
drilling implementations, such as measurement-while-drilling (MWD) and logging-
while-
drilling (LWD), among others. More generally, some aspects of the present
disclosure may be
implemented in conjunction with any mode of conveyance of a downhole tool.
Similarly, while
many embodiments described above are discussed in the context of a probe tool,
other tools may
also be implemented with one or more aspects of the present disclosure, such
as a dual packer
tool. Furthermore, although a sampling tool having a guard line and a sample
line has been
shown, a conventional sampling tool may also be used (such as the MDT,
trademark of
Schlumberger).
[0046] Moreover, while the hydraulic cleaning operation has been described
as taking place
just before a second sampling operation, in some cases, the cleaning operation
may be initiated
just after a first sampling operation, or elsewhere in a reservoir sampling
program. For example,
the formation fluid may still be hot just after the first sampling operation,
such that the cleaning
of the flow line may thereby be facilitated. It should be appreciated that the
cleaning processes
of the present disclosure may also be used in combination. Similarly, while an
open hole
sampling tool has been described above, a cased hole sampling tool (e.g., a
sampling tool similar
to the Cased Hole Dynamics Tester, trademark of Schlumberger) may also be
provided with
means for cleaning hydraulic components according to one or more aspects of
the present
disclosure.
[0047] The foregoing outlines features of several embodiments so that
those skilled in the art
may better understand the aspects of the present disclosure. Those skilled in
the art should
appreciate that they may readily use the present disclosure as a basis for
designing or modifying
other processes and structures for carrying out the same purposes and/or
achieving the same
advantages of the embodiments introduced herein. Those skilled in the art
should also realize
that such equivalent constructions do not depart from the scope of the present
13
CA 02702868 2012-10-23
79350-299
disclosure, and that they may make various changes, substitutions and
alterations herein without
departing from the scope of the present disclosure.
14
