U.S. patent application number 11/693147 was filed with the patent office on 2008-03-20 for adjustable testing tool and method of use.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Nicolas Adur, Cosan Ayan, Antonio Castilho, Arne Richard Pedersen, Gustavo Andreolli Ribeiro, Ricardo Vasques.
Application Number | 20080066535 11/693147 |
Document ID | / |
Family ID | 40512899 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080066535 |
Kind Code |
A1 |
Vasques; Ricardo ; et
al. |
March 20, 2008 |
Adjustable Testing Tool and Method of Use
Abstract
Methods and systems for testing a subterranean formation
penetrated by a wellbore are provided. A testing tool has a
plurality of packers spaced apart along the axis of the tool, and
at least a testing port. The testing tool is positioned into the
wellbore and packers are extended into sealing engagement with the
wellbore wall, sealing thereby an interval of the wellbore. In some
embodiments, the wellbore interval sealed between two packers is
adjusted downhole. In one embodiment, the location of the testing
port is adjusted between two packers. The methods may be used to
advantage for reducing the contamination of the formation fluid by
fluids or debris in the wellbore.
Inventors: |
Vasques; Ricardo; (Sugar
Land, TX) ; Ribeiro; Gustavo Andreolli; (Tupa-SP,
BR) ; Ayan; Cosan; (Istanbul, TR) ; Adur;
Nicolas; (Santiago del Estero, AR) ; Pedersen; Arne
Richard; (Tolvsrod, NO) ; Castilho; Antonio;
(Macae-RJ, BR) |
Correspondence
Address: |
SCHLUMBERGER OILFIELD SERVICES
200 GILLINGHAM LANE, MD 200-9
SUGAR LAND
TX
77478
US
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Sugar Land
TX
|
Family ID: |
40512899 |
Appl. No.: |
11/693147 |
Filed: |
March 29, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60845332 |
Sep 18, 2006 |
|
|
|
Current U.S.
Class: |
73/152.17 |
Current CPC
Class: |
E21B 33/1246 20130101;
E21B 49/081 20130101; E21B 49/08 20130101 |
Class at
Publication: |
73/152.17 |
International
Class: |
E21B 49/00 20060101
E21B049/00 |
Claims
1. A method for testing a subterranean formation penetrated by a
wellbore, the method comprising: positioning the testing tool in
the wellbore, the testing tool comprising a tool body, a plurality
of packer elements spaced apart from one another along the
longitudinal axis of the tool body, and at least one port on the
tool body located between two of the plurality of packer elements;
selecting in situ the length of an interval of the wellbore to be
sealed; extending at least two packer elements into sealing
engagement with the wellbore wall; sealing the interval of the
wellbore with the two packer elements; and flowing fluid between
the sealed interval and the testing tool through the port.
2. The method of claim 1 wherein selecting in situ the length of an
interval on the wellbore wall to be sealed comprises sliding a
packer element along the longitudinal axis of the tool body.
3. The method of claim 1 wherein the downhole tool further
comprises at least three packer elements; and selecting in situ the
length of an interval on the wellbore wall to be scaled comprises
selectively enabling the extension of a first and a second packer
elements.
4. The method of claim 1 wherein the downhole tool further
comprises a plurality of ports associated to a plurality of valves;
and the method further comprises selectively opening a valve to
establish the fluid communication through the port associated with
this valve.
5. The method of claim 3 further comprising extending a third
packer element into sealing engagement with the wellbore wall.
6. The method of claim 5 wherein the third packer element is
located between the first and second packer elements.
7. The method of claim 6 wherein the downhole tool further
comprises a plurality of ports associated to a plurality of valves;
and the method further comprises selectively opening a valve to
establish the fluid communication through the port associated with
this valve.
8. The method of claim 1 wherein the selecting in situ the length
of an interval on the wellbore wall to be sealed is based on the
value of a measured property by a downhole tool.
9. The method of claim 1 further comprising pulverizing particles
carried by the fluid flowed through the port.
10. A method for testing a subterranean formation penetrated by a
wellbore, the method comprising: positioning a testing tool in the
wellbore, the testing tool comprising a tool body, a plurality of
packer elements spaced apart from one another along the
longitudinal axis of the tool body, and at least one port on the
tool body located between two of the plurality of packer elements;
extending at least two packer elements into sealing engagement with
the wellbore wall; sealing a first interval of the wellbore;
flowing fluid between the first sealed interval and the testing
tool through the port; extending a third packer element into
sealing engagement with the wellbore wall; and sealing a second
interval of the wellbore.
11. The method of claim 10 further comprising flowing fluid from
the second sealed interval into the testing tool through the
port.
12. The method of claim 10 wherein the second interval being
comprised in the first interval.
13. The method of claim 10 wherein the downhole tool further
comprises a plurality of ports; the method further comprises
flowing fluid from the second sealed interval into the testing tool
through another port.
14. The method of claim 10 wherein the downhole tool further
comprises a cavity in fluid communication with the port on tool
body, the cavity carrying a material; and flowing fluid between the
first sealed interval and the testing tool through the port
comprises releasing the material in the wellbore.
15. The method of claim 10 wherein the downhole tool further
comprises a cavity in fluid communication with the port on tool
body; and flowing fluid between the first sealed interval and the
testing tool through the port comprises drawing fluid into the
cavity.
16. The method of claim 10 wherein the downhole tool further
comprises a sensor; and the method further comprises monitoring a
property with the sensor.
17. The method of claim 16 further wherein extending another packer
element into sealing engagement with the wellbore wall is triggered
by the monitored property.
18. The method of claim 10 further comprising pulverizing particles
carried by the fluid flowed through the port.
19. A method for testing a subterranean formation penetrated by a
wellbore, the method comprising: adjusting a port on a testing
tool, the testing tool comprising a tool body, a plurality of
packer elements spaced apart from one another along the
longitudinal axis of the tool body, and at least a port on the tool
body located between two of the plurality of packer elements;
positioning the testing tool in the wellbore; extending at least
two packer elements into sealing engagement with the wellbore wall;
sealing an interval of the wellbore; and draining fluid from the
sealed interval into the testing tool through the adjusted
port.
20. The method of claim 19 wherein the testing tool further
comprises a screen filter; and the method further comprises
adjusting a characteristic of the screen filter.
21. The method of claim 19 further comprising reducing the fluid
volume trapped in the sealed interval by selecting the outer
diameter of the snorkel assembly.
22. The method of claim 19 wherein adjusting a port comprises
adjusting the location of the port within a packer interval.
23. The method of claim 19 wherein adjusting a port on a testing
tool comprises adapting a snorkel assembly on the testing tool, the
snorkel assembly comprising a snorkel port and a fluid
communication between the port on the tool body and the snorkel
port, the snorkel port and the tool port being substantially offset
from each other.
24. A system for testing a subterranean formation penetrated by a
wellbore, the system comprising: a testing tool comprising a tool
body, a plurality of packer elements spaced apart from one another
along the longitudinal axis of the tool body, and at least a port
on the tool body located between two packer elements; and a snorkel
assembly adaptable on the testing tool comprising a snorkel port
and a fluid communication between the port on the tool body and the
snorkel port, the snorkel port and the tool port being
substantially offset from each other.
25. The system of claim 24 further comprising a screen filter.
26. The system of claim 24 wherein the snorkel port is located at a
different level with respect to the longitudinal axis of the tool
body than the port on the tool body.
27. The system of claim 24 wherein the snorkel port extends around
the circumference of the tool.
28. The system of claim 24 further comprising: a flow line in the
testing tool, the flow line being in fluid communication with the
port on the tool; and an ultrasonic transmitter for emitting a wave
in the flow line.
29. The system of claim 24 further comprising: a flow line in the
testing tool, the flow line being in fluid communication with the
port on the tool; and a laser diode for emitting a wave in the flow
line.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a non-provisional application of
co-pending provisional application No. 60/845,332 filed on Sep. 18,
2006, and relates to co-pending and commonly assigned U.S. patent
application Ser. No. 11/562,908 filed Nov. 22, 2006; U.S. patent
application No. 60/882,701 filed Dec. 29,2006; and U.S. patent
application No. 60/882359 filed Dec. 28, 2006, the disclosures of
which are hereby incorporated herein by reference for all
purposes.
TECHNICAL FIELD
[0002] The present invention relates to well testing tools and
method of use. More particularly, the invention relates to testing
tools having a plurality of packer elements and at least a testing
port on the tool body.
BACKGROUND OF THE INVENTION
[0003] Advanced formation testing tools have been used for example
to capture fluid samples from subsurface earth formations. The
fluid samples could be gas, liquid hydrocarbons or formation water.
Formation testing tools are typically equipped with a device, such
as a straddle or dual packer. Straddle or dual packers comprise two
inflatable sleeves around the formation testing tool, which makes
contact with the earth formation in drilled wells when inflated and
seal an interval of the wellbore. The testing tool usually
comprises a port and a flow line communicating with the sealed
interval, in which fluid is flown between the packer interval and
in the testing tool.
[0004] Examples of such tools are schematically depicted in FIGS.
1A to 1D. FIG. 1A shows an elevational view of a typical
drill-string conveyed testing tool 10a . Testing tool 10a is
conveyed by drill string 13a into wellbore 11 penetrating a
subterranean formation 12. Drill string 13a has a central
passageway that usually allows for mud circulation from the
surface, then through downhole tool 10a, through the bit 20 and
back to the surface, as known in the art. Testing tool 10a may be
integral to one of more drill collar(s) constituting the bottom
hole assembly or "BHA". Testing tool 10a is conveyed among (or may
itself be) one or more measurement-while-drilling or logging while
the tool(s) known to those skilled in the art. In some cases, the
bottom hole assembly is adapted to convey a casing or a liner
during drilling. Optionally, drill string 13a allows for two-way
mud pulse telemetry between testing tool 10a and the surface. A mud
pulse telemetry system typically comprises surface pressure sensors
and actuators (such as variable rate pumps) and downhole pressure
sensors and actuators (such as a siren) for sending acoustic
signals between the downhole tool and the surface. These signals
are usually encoded, for example compressed, and decoded by surface
and downhole controllers. Alternatively any kind of telemetry known
in the art may be used instead of mud pulse telemetry, such as
electro-magnetic telemetry or wired drill pipe telemetry. Tool 10a
may be equipped with one or more packer(s) 26a, that are preferably
deflated and maintained below the outer surface of tool 10a during
the operations. When testing is desired, a command may be sent from
the surface to the tool 10a via the telemetry system. Straddle
packer 26a can be inflated and extended toward the wall of wellbore
11, achieving thereby a fluid connection between the formation 12
and the testing tool 10a across wellbore 11. As an example, tool
10a may be capable of drawing fluid from formation 12 into the
testing tool 10a, as shown by arrows 30a. Usually one or more
sensor(s) located in tool 10a, such as pressure sensor, monitors a
characteristic of the fluid. The signal of such sensor may be
stored in downhole memory, processed or compressed by a downhole
processor and/or send uphole via telemetry. Note that in some
cases, part of tool 10a may be retrievable if the bottom hole
assembly becomes stuck in the wellbore, for example by lowering a
wireline cable and a fishing head.
[0005] FIG. 1B shows an elevational view of a typical drill-stem
conveyed testing tool 10b. Testing tool 10b is conveyed by tubing
or drill pipe string 13b into wellbore 11 penetrating a
subterranean formation 12. Tubing string 13b may have a central
passageway that usually allows for fluid circulation (wellbore
fluids or mud, treatment fluids, or formation fluids for example).
The passageway may extend through downhole tool 10b, as known in
the art. Tubing or drill string 13b may also allow for tool
rotation from the surface. Testing tool 10b may be integral to one
or more tubular(s) screwed together. Testing tool 10b is conveyed
among (or may be itself) one or more well testing tool(s) known to
those skilled in the art, such as perforating gun. The testing tool
10b may be lowered in an open hole as shown, or in a cased
wellbore. In some cases, tubing string 13b allows for two-way
acoustic telemetry between testing tool 10b and the surface, or any
kind of telemetry known in the art may be used instead, including
conductive tubing or wired drill pipe. Tool 10b may be equipped
with one or more packer(s) 26b that is usually retracted (deflated)
during tripping of testing tool 10b. When testing is desired, tool
10b may be set into testing configuration, for example by
manipulating flow in tubing string 13b. Extendable packer 26b can
be extended (inflated) toward the wall of wellbore 11, achieving
thereby a fluid connection between an interval of formation 12 and
the testing tool 10b across wellbore 11. As an example, tool 10b
may be capable of drawing fluid from formation 12 into the testing
tool 10b, as shown by arrows 30b. Usually one or more sensor(s)
located in tool 10b, such as pressure or flow rate sensor,
monitor(s) a characteristic of the fluid. The signal of such sensor
may be stored in downhole memory, processed or compressed by a
downhole processor and/or send uphole via telemetry. Note that in
some cases part of tool 10b may be a wireline run-in tool, lowered
for example into the tubing string 13b when a test is desired.
[0006] FIG. 1C shows an lavational view of a typical wireline
conveyed testing tool 10c. Testing tool 10c is conveyed by wireline
cable 13cinto wellbore 11 penetrating a subterranean formation 12.
Testing tool 10c may be an integral tool or may be build in a
modular fashion, as known to those skilled in the art. Testing tool
10c is conveyed among (or may be itself) one or more logging
tool(s) known to those skilled in the art. Preferably the wireline
cable 13c allows signal and power communication between the surface
and testing tool 10c. Testing tool 10c may be equipped with
straddle packers 26c, that are preferably recessed below the outer
surface of tool 10c during tripping operations. When testing is
desired, straddle packer 26c can be extended (inflated) toward the
wall of wellbore 11 achieving, thereby, a fluid connection between
an interval of formation 12 and the testing tool across wellbore
11. As an example, tool 10c may be capable of drawing fluid from
formation 12 into the testing tool 10c, as shown by arrows 30c.
Examples of such tools can be found U.S. Pat. No. 4,860,581 and
U.S. Pat. No. 4,936,139, both assigned to the assignee of the
present invention, and incorporated herein by reference. Note in
some cases that wireline tools (and wireline cable) may be
alternatively conveyed on a tubing string, or by a downhole tractor
(not shown). Note also that the wireline tool may also be used in
run-in tools inside a drill string, such as the drill string shown
in FIG. 1A. In these cases, the wireline tool 10c usually sticks
out of hit 20 and may perform measurements, for example when the
bottom hole assembly is pulled out of wellbore 11.
[0007] FIG. 1D shows an elevational view of another typical
wireline conveyed testing tool 10d. Testing tool 10d is conveyed by
wireline cable 13d into wellbore 11 penetrating a subterranean
formation 12. This time wellbore 11 is cased with a casing 40.
Testing tool 10d may be equipped with one or more extendable
(inflatable) packer(s) 26d, that are preferably recessed (deflated)
below the outer surface of tool 10d during tripping operations.
Tool 10d is capable of perforating the casing 40, usually below at
least one packer (see perforation 41), for example, the tool could
include one or more perforating gun(s). In FIG. 1D, the testing
tool 10d is shown drawing fluid from formation 12 into the testing
tool 10d (see arrows 30d). Usually one or more sensor(s) is located
in tool 10d, such as a pressure sensor, monitors a characteristic
of the fluid. The signal of such sensor is usually send uphole via
telemetry. Note that in some cases, tools designed to test a
formation behind a casing may also be used in open hole. Note also
that cased formations may be evaluated by downhole tool conveyed by
other means that wireline cables.
[0008] Typical tools are not restricted to two packers. Downhole
systems having more than two packers have been disclosed for
example in patents U.S. Pat. No. 4,353,249, U.S. Pat. No.
4,392,376, U.S. Pat. No. 6,301,959 or U.S. Pat. No. 6,065,544.
[0009] In some situations, a problem occurs when fluid is drawn
into the tool through openings along the tool body. Formation
fluids, wellbore fluids and other debris from the wellbore may
occupy the volume between the upper sealed packer and the lower
sealed packer. This causes various fluids to enter the same
openings (or similar openings) located in the sealed volume.
Moreover, when the density of the wellbore fluid is larger than the
density of the formation fluid, it is very difficult to remove all
of the wellbore fluid since there will be a residual of wellbore
fluid that resides between the lowest opening and the lowest
packer, even after a log pumping time. Thus, these wellbore fluids
can contaminate the formation fluid entering the tool.
[0010] Downhole systems facilitating the adjustment of the flow
pattern between the formation and the interior of the tool have
been disclosed for example in patent application US 2005/0155760.
These systems may be used to reduce the contamination of the
formation fluid by mud filtrate surrounding the wellbore. Note that
methods applicable for reducing the contamination by mud filtrate
surrounding the wellbore are not always applicable for reducing the
contamination by fluids and other debris from the wellbore.
[0011] Despite the advances in formation testing, there is a need
for improved testing methods utilizing a tool having plurality of
packers spaced apart along the axis of the tool, and at lest a port
on the tool body located between two packer elements. Such methods
are preferably capable of reducing the contamination of the
formation fluid by fluid or debris in the wellbore. These methods
may comprise adjusting in situ the length of a sealed interval
between two packer elements. Alternatively, these methods may
comprise adjusting the location of the port within a packer
interval.
SUMMARY OF THE INVENTION
[0012] Methods and systems for testing a subterranean formation
penetrated by a wellbore are provided. A testing tool has a tool
body, a plurality of packer elements spaced apart from one another
along the longitudinal axis of the tool body, and at least a
testing port on the tool body located between two packer elements.
The testing tool is positioned into the wellbore and packers are
extended into sealing engagement with the wellbore wall, sealing
thereby an interval of the wellbore. Fluid is flown between the
sealed interval and the testing tool through the testing port.
[0013] In at least one aspect, the invention relates to a method
that comprises the steps of selecting in situ the length of an
interval of the wellbore to be sealed, and extending at least two
packer elements. The length of the interval of the wellbore that is
sealed by extending the packer elements is substantially equal to
the selected length.
[0014] In another aspect, the invention relates to a method that
comprises the step of extending at least two packer elements into
sealing engagement with the wellbore wall, sealing thereby a first
interval of the wellbore. The method also comprises the step of
extending another packer element into sealing engagement with the
wellbore wall, sealing thereby a second interval of the
wellbore.
[0015] In yet another aspect, the invention relates to a method
that comprises the step of adjusting a port on a testing tool.
[0016] In yet another aspect, the invention relates to a system for
testing a subterranean formation penetrated by a wellbore. The
system comprises a testing tool and a snorkel assembly adaptable on
the testing tool. The snorkel assembly comprises a snorkel port and
a fluid communication between the port on the tool body and the
snorkel port, the snorkel port and the tool port being
substantially offset from each other.
[0017] The foregoing has outlined rather broadly the features and
technical advantages of the present invention in order that the
detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention
will be described hereinafter which form the subject of the claims
of the invention. It should be appreciated by those skilled in the
art that the conception and specific embodiment disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
invention. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the invention as set forth in the appended claims. The
novel features which are believed to be characteristic of the
invention, both as to its organization and method of operation,
together with further objects and advantages will be better
understood from the following description when considered in
connection with the accompanying figures. It is to be expressly
understood, however, that each of the figures is provided for the
purpose of illustration and description only and is not intended as
a definition of the limits of the present invention.
BRIEF DESCRIPTION Of THE DRAWINGS
[0018] For a more complete understanding of the present invention,
reference is now made to the following descriptions taken in
conjunction with the accompanying drawings, in which:
[0019] FIGS. 1A-1D are elevation views showing typical examples of
downhole testing tools, where the testing tool is drill string
conveyed in FIG. 1A, tubing string conveyed in FIG. 1B, and
wireline conveyed in FIGS. 1C and 1D.
[0020] FIG. 2 is a schematic showing one embodiment of a testing
tool capable of scaling wellbore intervals of various lengths;
[0021] FIG. 3 is a schematic illustrating the selective length
adjustment of a sealed wellbore interval with a tool having a
plurality of spaced apart packer elements;
[0022] FIG. 4 is a schematic illustrating the selective adjustment
the length of a sealed wellbore interval with a tool having a
slidable packer element;
[0023] FIGS. 5A-5B are cross sectional views showing embodiments of
a snorkel assembly adapted to a testing tool;
[0024] FIGS. 6A-6B show a flow chart describing the steps involved
in one embodiment of a method for testing a subterranean
formation;
[0025] FIGS. 7A-7D are schematics illustrating a method for testing
a subterranean formation;
[0026] FIGS. 8A-8D are schematics illustrating another a method for
testing a subterranean formation; and
[0027] FIGS. 9A-9B are schematics illustrating yet another method
for testing a subterranean formation.
DETAILED DESCRIPTION
[0028] Certain examples are shown in the above identified figures
and described in detail below. In describing these examples, like
or identical reference numbers are used to identify common or
similar elements. The figures are not necessarily to scale and
certain features and certain view of the figures may be shown
exaggerated in scale or in schematic for clarity and/or
conciseness.
[0029] FIG. 2 shows one embodiment of a testing tool capable of
sealing wellbore intervals of various lengths. The testing tool 10
is conveyed within wellbore 11 created in formation 12 via
conveyance mean 13. The testing tool 10 can be conveyed downhole
using a wireline cable after the well has been drilled and the
drill string removed from the wellbore. Alternatively, the testing
tool can be conveyed downhole on the drill string used to drill the
wellbore. Any conveyance mean known in the art can be used to
convey the tool 10. Optionally, the conveyance mean allows for two
ways communication between tool 10 and the surface, typically a
surface monitor (not shown), via a telemetry system as known by
those skilled in the art. When used with some conveyance means,
tool 10 may accommodate for mud circulation through the tool (not
shown), as well known by those skilled in the art. As shown in FIG.
2, the testing tool 10 is build in a modular fashion, with
telemetry/electronics module 154, packer module 100, downhole fluid
analysis module 151, pump module 152, and carrier module 153.
Telemetry/electronics module 154 may comprise a controller 140, for
controlling the tool operation, either from instructions programmed
in the tool and executed by processor 140a and stored in memory
140b, or from instruction received from the surface and decoded by
telemetry system 140c. Controller 140 is preferably connected to
valves, such as valves 110, 111, 112, 113, 114, 115 and 116 via one
or more bus 190 running through the modules of tool 10 for
selectively enabling the valves. Controller 140 may also control a
pump 130, collect data from sensors (such as optical analyzer 131),
store data in memory 140b or send data to surface using telemetry
system 140c. the fluid analysis module 151 may include an optical
analyzer 131, but other sensors such as resistivity cells, pressure
gauges, temperature gauges, may also be included in fluid analysis
module 151 or in any other locations in tool 10. Pump module 152
may comprise the pump 130, which may be a bidirectional pump, or an
equivalent device, that may be used to circulate fluid along the
tool modules via one or more flow line 180. Carrier module 153 can
have a plurality of cavities, such as cavities 150-1, 150-2, to
150-n to either store samples of fluid collected downhole, or
transport materials from the surface, as required for the operation
of tool 10. Packer elements 102, 103, 104 and 105 are shown
uninflated and spaced along the longitudinal axis of packer module
100. Although not shown, the packers extend circumferentially
around tool 100 so that when they are inflated they will each form
a seal between the tool and a wellbore wall 15.
[0030] Also shown on FIG. 2 are particle breaking devices 160, 161,
or 162. These particle breaking devices could be focused ultrasonic
transducers or laser diodes. Particle breaking devices are
preferably used to pulverize sand, or other particles passing into
the flow lines, into smaller size particle, for example, for
avoiding plugging of component of the testing tool. These devices
may use different energy/frequency levels to target various grain
sizes. For example, particle breaking device 162 may be used to
break produced sand during a sampling operation. In some cases, the
readings of downhole sensor 131 will be less affected by pulverized
particles than larger size particles. In another example, particle
breaking device 163 may be used to break particles in suspension in
the mud during an injection (fracturing) operation. In some cases,
pump 130 will be able to handle pulverized particles more
efficiently and will not plug, leak or erode as fast as with larger
size particles in the mud. Particle breaking devices may be used
for other applications, such as transferring heat to the flow line
fluid.
[0031] While testing tool 10, as shown in FIG. 2, is build in a
modular fashion, those skilled in the art will appreciate that all
the components of tool 10 may be packaged in a single housing.
Also, the arrangement of the modules in FIG. 2 may be modified. For
example, fluid analysis module 151 shown above pump module 152 may
alternatively be located between pump module 130 and carrier module
153. In some situation, tool 10 can have additional (or fewer)
operational capabilities beyond what is discussed herein. The tool
can be used for a variety of testing, sampling and/or injection
operations using the selectively enabled packer elements as
discussed herein.
[0032] FIG. 3 shows in more details an embodiment of packer module
200 similar to module 100 of FIG. 2, where two of the four packer
elements have been inflated. Packer module or tool portion 200 may
comprise one or more flow line 280, similar to flow line 180 in
FIG. 2. Flowline 280 is selectively connected to one or more
port(s) in the tool, such as ports 252, 253a, 253b and 254 via
associated valves 242, 243a, 243b and 244 respectively, allowing
fluid to flow from or into flow line 280. Each interval between
packer elements 262, 263, 264 and 265 has preferably at least one
port. Although shown on the same side of the tool, ports may be
located anywhere around the tool. Packer module or tool portion 200
may also comprise packer inflation devices 212, 213, 214 and 215
for selectively inflate or deflate packers 262, 263, 264, and 265
respectively. Other means to extend packers into sealing engagement
with the wellbore wall may also be used without departing from the
invention. Inflation devices 212, 213, 214 and 215 may consist of
one or more pump(s), controlled by a controller (not shown) via bus
290, similar to bus 190 of FIG. 2.
[0033] Note that testing tool 10 may not be modular. In this
eventuality FIG. 3 would represent a portion of testing tool 10.
Note also that the concepts discussed herein are not limited to
four packer elements. Any number of packer elements may be deployed
on a tool and selectively inflated depending on desired results and
the operations to be performed. Also note that the packer elements
need not be all of the same type or spaced equidistant from each
other.
[0034] Each of the packers 262, 263, 264 and 265 can be inflated so
that the packers radially expand and contact wellbore wall 15 of
formation 12. By expanding at least two of the packers sufficiently
to contact the wellbore wall, the interval of the wellbore between
the two inflated packers can be sealed off from the rest of the
wellbore. Thus, as shown in FIG. 2, packers 263 and 265 have been
selectively inflated to form a sealed interval 221 between packers
263 and 265. The sealed interval allows, for example, formation
fluid to be drawn into the tool for testing. The selective enabling
of each packer can be, for example, by expanding the packer under
the control of inflation devices 212, 213, 214 and 215 by hydraulic
lines extending into the packer element. Note that while each
packer is shown with an individual inflation device, a device
common to each packer can be used. Also, the force for enabling the
packers can come from the surface or from another tool, if
desired.
[0035] Other packers may be selectively extended to seal wellbore
intervals of various lengths. An interval length may be selected
downhole, for example by analyzing measurements performed by
sensors of tool 10 or from another tool in the tool string. A
measurement that may be used in some cases could be a wellbore
resistivity image. By way of example, the longest testing interval
may be selected. Sampling a long interval of wellbore wall in this
way could result in a lower drawdown pressure. The user (or some
logic implemented downhole) would then enable packers 262 and 265,
for example by activating inflation devices 212 and 215 through bus
290. Packers 262 and 264 would not be enabled and would remain
retracted (deflated). By extending packers 262 and 265, the
wellbore interval between top packer 262 and bottom packer 265
would be sealed. Testing would follow. For example, this may
include injecting or drawing fluid from any of the ports 252, 253a,
253b or 254 by opening any of the associated valves 242, 243a, 243b
or 244 respectively. Alternatively, a short testing interval may be
selected. Sampling a short interval of wellbore wall in this way
could result in a more homogenous fluid. For example, it may be
desirable to only test an interval having a length almost equal to
the distance between packers 263 and 264. This can be done by
extending packers 263 and 264 toward the wellbore wall and sealing
the corresponding interval. Note that by having non-equal spacings
between three or more packers, the user can choose among a variety
of interval length to be sealed and test the formation.
[0036] In some testing applications, monitoring the flow of fluids
in the formation (injected from the tool or drawn into the tool)
maybe desirable. In some situations, it can be advantageous to have
sensors, such has sensors 201, close the wellbore wall 15. In one
embodiment, sensors 201a, 201b, 201c and 201d may be located
directly on the packers. These sensors can measure various
formation or fluid properties while the tool is in the wellbore.
For simplification. FIG. 3 illustrates sensors 201a -201d only on
packers 263 and 265. However, the sensors may also be located on
any or all of the packers. In addition to locating the sensors on
the packers, other sensors 202, such as sensors 202a, 202b, and
202c, may be located on or within the tool at any location. Some of
these sensors 201, 202 may measure fluid properties (such as
pressure, optical densities) while others may measure formation
properties (such as resistivity, sigma, carbon-oxygen ratio, sonic
travel time). Data gathered by sensors 201a-d and 202a-c (and other
sensors) may be communicated via bus 290 to a controller (not
shown) similar to the controller 140 of FIG. 2. The data sent to
the controller may further by processed downhole by a processor,
similar to the processor 140a of FIG. 2. The controller may further
adjust operations of the tool 10, for example modify the pumping
rate of pump 130 or modifying the length of the sealed interval,
based on the processed data. Data gathered by sensors 201, 202 may
also be stored downhole into a memory, similar to the memory 140b
of FIG. 2, or sent uphole for analysis by an operator via a
telemetry system, similar to the telemetry system 140c of FIG.
2.
[0037] Perforation may be desirable for some testing applications.
Thus, the formation may further be perforated at a point within the
sealed off interval of the wellbore, for example, for altering the
fluid flow from the formation to the sealed interval of the
wellbore between the two inflated packers. Any kind of perforation
device may be mounted between two inflatable packers, such as
perforation guns 230 and 231. For example, a bullet fired from a
perforating gun 230 may be used to perforate formation 12 as shown
in FIG. 3 to create a perforation 222. The bullet may hold a sensor
capable of sending data to tool 10, for example using an
electromagnetic wave communication.
[0038] FIG. 4 shows another embodiment of a testing tool capable of
selecting in situ the length of an interval to be sealed. Thus,
FIG. 4 illustrates the selective length adjustment of a sealed
wellbore interval by sliding a packer element along the length of
the tool to vary the distance between two packer elements.
Referring to FIG. 4, packer module 300 similar to packer module 100
of FIG. 2 is shown. Packer module 300 is shown with three packer
elements 360, 361 and 362 but any number of packers could be
employed. These three packer modules are operatively coupled with
three inflation devices 310, 311 and 312 respectively for
selectively extending (inflating) and recessing (deflating) the
three packer elements. The inflation devices 310, 311 and 312 may
be communicatively coupled to a downhole controller via a bus 390,
similar to bus 190. In the embodiment of FIG. 4, the middle packer
361 is shown to be slidably movable along the longitudinal axis of
the tool 10. Packer element 361 is coupled to piston actuator 302
which may be utilized to slide packer 361 up or down the length of
the tool body. For example, actuator 302 could be used to move
packer 361 to position 361. The fluid for inflating/deflating the
packer could be delivered by inflation device 311 to packer 361,
for example, via hydraulic line located in ram 303 (not shown).
[0039] In operation, testing tool 10 of FIG. 4 would be lowered
into formation 12 traversed by wellbore 11. The length of an
interval of wellbore 11 to be sealed can be determined in situ. For
example, a Nuclear Magnetic Resonance measurement can be used to
estimate the viscosity of the formation fluid surrounding tool 10,
and the length of the interval to be sealed for a sampling
operation may be adjusted therefrom. The piston actuator 302 may
then be activated for sliding packer element 361 along the tool
body for adjusting the distance between packer element 360 and
packer element 361. For example, once the length is selected
(packer element 361 is moved to position 361' on FIG. 4), packer
elements 360 and 361 may be extended (inflated) toward the wellbore
wall 15 by inflation devices 310 and 311, sealing thereby an
interval of the wellbore which length is substantially equal to the
selected length. Testing may then begin. For example, fluid may be
drawn into the tool through port 351. The testing step may involve
manipulating valves, such as valve 341. Fluid may be flown into
flowline 380 (similar to flowline 180 in FIG. 2). When testing is
finished, packers are usually deflated below the outer surface of
the testing tool.
[0040] The embodiment shown in FIG. 4 can be combined with the
embodiment shown in FIG. 2 or FIG. 3, such that packers 102, 103,
104 and 105 (FIG. 2) may all be slidably moved along the tool such
that it is possible to vary the vertical distance between any two
packers. As an example, it may be desirable to test a region of an
earth formation larger than that covered by the area between
packers 102 and 103 but not as large as the areas covered by
packers 102 and 104. In this case, packer 102 could be moved upward
in the vertical directional along the tool to expand the top area,
or packer 103 may be moved downward in the vertical direction along
the tool to expand the area downward. The ability to selectively
move packers in the vertical direction along the tool provides an
infinite number of testing regions within the well.
[0041] Note that some packers may be slidable and some may not, as
shown in FIG. 4 by non slidable packer 360 and 362, and slidable
packer 361. Note also that slidable and non slidable packers may be
arranged in various combinations. Although the operation of testing
tool 10 of FIG. 4 has been described using packer element 360 and
361 to seal an interval with a length selected downhole, packer 361
and 362 may be used instead, and fluid may alternatively be flown
through port 352 (and open valve 342) on tool 10.
[0042] FIGS. 5A-5B show embodiments of a snorkel assembly 401 (FIG.
5A) and 401' (FIG. 5B) adapted to a testing tool 10. The snorkel
assembly may be used to advantage for bringing a port of the
sampling tool to a more effective relative position with respect to
the packer elements. FIG. 5A-5B show a packer module 400 adapted on
a testing tool 10 lowered in a wellbore 11 penetrating a formation
12. Note that the testing tool is shown partially, and may be
similar to the testing tool of FIG. 2. The testing tool 10 may
include controller bow springs 480 and 481 as known in the art. The
packer module 400 comprises packer elements 462 and 463 for sealing
an interval of the wellbore 11 by extending (inflating) the packer
elements into sealing engagement with the wellbore wall 15, for
example with inflation devices 412 and 4l3 respectively. The packer
module 400 may further comprise a port 450 on the tool body and an
associated valve 451. The port allows for fluid communication
between a flow line 490 in the downhole tool, similar to flow line
180 in FIG. 2, and a sealed interval of the wellbore. In the
examples of FIGS. 5A-5B two different snorkel assemblies 401 and
401' respectively, are adapted on the testing tool 10. The snorkel
assembly 401 or 401' may comprise a filter 423, an adapter 422, a
snorkel 421 (FIG. 5A) or 421' (FIG. 5B), and a ring 420. Note that
the snorkel assembly may comprise additional parts, such as
sensors, for providing other functionalities. Note also that the
snorkel assembly may comprise fewer parts. For example the filter
423, the ring 420, may be optional.
[0043] The snorkel assembly is preferably adaptable on the testing
tool 10. For example, while the packer module 400 is disconnected
from the testing tool 10, and the packer element 462 is not mounted
on the packer module, the adapter 422 may slide around the packer
module body and rest on the mounted packer 463. When the adapter
422 is in place, the port 450 of the tool is fluidly connected to
annular groove 431 of the adapter 422. Then the snorkel 421 or 421'
is slid on top of the adapter 422. Snorkel 421 (421') comprises one
or more fluid communication(s) 440 (440') between a snorkel port
430 (430') and annular groove 431 via one or more passageway 441.
In the example of FIGS. 5A-5B, fluid communication(s) 440 comprise
a plurality of flow lines, for example eight, distributed around
the circumference of the snorkel. A screen filter 423 may then
slide around the snorkel and may be held in place with screws 470
or other fasteners. The filter 423 preferably covers the snorkel
port 430 (430'). A ring 420 may finally be slid on the tool mandrel
and locked in place before the packer element 462 is mounted. The
packer module 400 is further included into testing tool 10. The
testing tool 10 may be lowered into a wellbore to perform a test on
a subterranean formation.
[0044] Different snorkel designs may have different snorkel port
configurations. The snorkel design that is adapted on tool 10 is
preferably chosen such that the snorkel port configuration is
adjusted for a particular testing operation. In the example of FIG.
5A, the snorkel port 430 is shown higher than the snorkel port 430'
of FIG. 5B. Also the snorkel port shape may be adjusted from one
snorkel design to another. Thus, if a snorkel port configuration
such as shown by 430 is desirable for testing, an operator may
adapt the snorkel 421 to the testing tool 10, adjusting thereby the
initial configuration of the port on the testing tool 450 to the
desired configuration of the snorkel port 430. In other cases, a
different snorkel port configuration, such as shown by 430', may be
desirable for testing. Here again, an operator may adapt a
different snorkel to the testing tool 10, adjusting thereby the
initial configuration of the port on the testing tool 450 to the
different configuration of the snorkel port 430'.
[0045] Screen filters with various characteristics can be assembled
in the snorkel assembly. In some cases, the screen filter may
comprise two or more screens. In some cases, the screens may be
separated by a small gap. Also the screens can be reinforced, for
example by vertical strips. The screen filter characteristics are
preferably adjusted for the testing operation the tool is intended
to perform.
[0046] Note that a snorkel assembly can be adapted to any kind of
testing tool, such as the testing tool of FIG. 2, 3 or 4. Note also
that the snorkel in the snorkel assembly could be made telescopic
and may be adjusted downhole using an actuator.
[0047] FIGS. 6A-6B describe one embodiment of a method 500 for
testing a subterranean formation. The method 500 preferably
utilizes a testing tool having a tool body, a plurality of packer
elements spaced apart from one another along the longitudinal axis
of the tool body, and at least a testing port on the tool body
located between two packer, as is the described herein. However,
the method 500 may be used with any testing tool having
selectively-activated packer elements and capable of formation
testing.
[0048] In optional step 505, a snorkel assembly is placed on the
testing tool. The snorkel assembly is capable of adjusting a port
on a testing tool. The snorkel assembly may also be capable of
adjusting the characteristic of a filter screen. The snorkel may
further be capable of reducing the volume trapped in the sealed
interval. For example, the testing tool may be intended to sample
formation fluid in an unconsolidated formation, and the formation
fluid is expected to have a lower density than the borehole fluid.
The testing tool may also be intended for a large diameter
wellbore. Such sampling situation is illustrated in FIG. 9A-9B for
explanatory purposes. Note that in step 505 of method 500, the
testing tool is not yet lowered into the borehole, and FIG. 9A-9B
are used therebelow to explain how the testing tool is expected to
perform in the sampling situation discussed above, based on a prior
knowledge of the sampling conditions, and how the adjustment of
step 505 may be performed.
[0049] Referring to FIG. 9A, a portion of testing tool similar to
testing tool 10 of FIG. 2 is shown in a wellbore 11 traversing a
formation 12 during a sampling operation. Packer elements 862 and
863 are shown in an extended position, and engaged with the
wellbore wall 15 for sealing a wellbore interval therebetween. In
the example of FIG. 9A, the testing tool 10 has drained fluid from
the wellbore into flowline 890 (similar to flow line 180 of FIG. 2)
through tool port 850 and open valve 851. The fluid drained from
the wellbore has been partially replaced by formation fluid 842,
and sand or debris 840 produced from the formation. Note that some
wellbore fluid may still be present in the sealed interval, as
shown by wellbore fluid 841. The illustration of FIG. 9A assumes
that debris, wellbore fluid and formation fluid have segregated in
the order as shown, because of the density contrast between these
materials. However segregation may occur in a different order.
During the sampling operation shown in FIG. 9A, sand or debris may
enter tool port 850 and plug, clog or erode various components in
the testing tool 10, such as pumps, or valves. Also, debris may
cause noise at a fluid property sensor. Finally, the volume of the
sealed interval may be large, because the testing tool is run in a
wellbore of large diameter. Because of this large volume, the
sampling operation may require a log time before formation fluid
enters in the testing tool and is available for capture in a
cavity. This long sampling time may increase the probability of the
testing tool to become stuck in the wellbore.
[0050] Turning now to FIG. 9B, a snorkel assembly 800 is shown in a
wellbore 11 traversing a formation 12 during a sampling operation
similar to the sampling operation shown in FIG. 9A. Ib FIG. 9B the
location of the tool port 850 has been adjusted for this particular
operation by adapting a snorkel assembly to the testing tool prior
to lowering it into the borehole. Fluid is now drawn from the
wellbore at the snorkel port 830. Snorkel port 830 is located above
the debris that have segregated on top of the lower packer element
863, reducing thereby the probability of components of the tool 10
being plugged by debris entering the testing tool 10. Note also
that the snorkel port is located close to the upper packer element
862, reducing thereby the volume and the time needed to draw into
the tool formation fluid that has segregated above the wellbore
fluid. In the example of FIG. 9B, the snorkel assembly also
comprises a filter screen 823, whose characteristics such as the
area, the screen mesh size, the number of screen layers or the
screen collapse resistance may have bene adjusted to the sampling
operation. For example, the screen filter 823 may be chosen to be a
double layer filter, or may be reinforced by vertical stripes
between the layers to insure a high collapse resistance. The
snorkel port 830 may further extend around the entire circumference
of the tool, increasing thereby the area of the intake adjacent to
the filter screen, which may be advantageous for avoiding plugging
of the filter screen. In the example of FIG. 9B, the outside
diameter of the snorkel module has been selected so that the
trapped volume of fluid between packer element 862 and 863 is
reduced with respect to FIG. 9A. Specifically, the outside diameter
is selected just below the wellbore diameter. Reducing the trapped
volume of fluid may decrease the volume of fluid needed to be
pumped before formation fluid enters the tool and decreases the
time needed to capture a formation fluid sample. Note that the
volume may also be reduced by using rings, such as ring 820.
[0051] Turning back to FIGS. 6A-6B, the testing tool is lowered in
the wellbore in step 510. As mentioned before, the testing tool may
be conveyed on a drill string, a tubing string, a wireline cable or
any other means known by those skilled in the art. Lowering the
downhole tool may comprise drilling or reaming the wellbore. The
wellbore may be open to the formation or may be cased. If the
wellbore is cased, the testing tool preferably comprises
perforation devices, such as the shafts or perforating guns, for
example located between two packer elements. The testing tool may
be lowered in the wellbore with other tools, such as formation
evaluation tools known by those skilled in the art. The conveyance
means preferably comprises a telemetry system capable of sending
information collected by a downhole tool to the surface, and
receiving commands from the surface for controlling operation of
the testing tool. A downhole controller executing instructions
stored in a downhole memory in the testing tool may also control
operations of the testing tool.
[0052] Step 515 in FIGS. 6A-6B determines the length of the
wellbore interval to be tested. This can be achieved downhole, for
example using a processor and data collected by sensors. This can
alternatively be achieved under control of a user operating from
the surface, for example, using a camera or other sensing tools,
not shown, which are part of the downhole tool string. This can be
alternatively achieved by any other methods and/or sensors
mentioned therein. Other methods and/or sensors may also be used
without departing from this invention. The method 500 may comprise
the optional step 520, that determines whether cleaning is desired
within the testing interval. Cleaning may comprise delivering
materials conveyed from the surface in one of the cavity of testing
tool 10, such as cavity 150-1 of FIG. 2, into the wellbore, for
example for dissolving locally the mudcake on the wellbore wall 15.
This material could be water, steam, acid solution, solvent or any
combination thereof. If cleaning is desired, optional step 525
determines the length of a cleaning interval to be sealed, usually
comprising the testing interval so that the cleaning material can
be fully removed from the testing interval as further discussed
below. The cleaning interval length may be selected by enabling the
extension of two packer elements from the plurality of the packer
elements carried by the testing tool in step 530. Note that the
adjustment of the testing interval length may alternatively be
achieved by sliding packer elements along the axis of the tool
prior to extending the packer element toward the wellbore wall, as
previously discussed with respect to FIG. 4.
[0053] As a way of example, FIGS. 7A-7D show a portion of a testing
tool similar to testing 10 of FIG. 2, lowered in a wellbore 11
traversing a formation 12. The testing tool 10 comprises packer
elements 602, 603, 604 and 605, and ports 652, 653, and 654. In the
example of FIGS. 7A-7D, the extension of packer elements 602, 603,
604 or 605 can be selectively enabled, for example using the
apparatus described in more details with respect to FIG. 3. As a
way of example, the length of the wellbore interval to be sealed
determined in step 515 may be represented by interval 610 on FIGS.
7A-7D. As a way of example, the length of the wellbore interval to
be sealed determined in step 525, may be represented by interval
611 on FIGS. 7B-7D.
[0054] Turning back to FIGS. 6A-6B, packer elements of the testing
tool are extended toward the wellbore wall in step 535 if cleaning
is desired. A first interval, the cleaning interval, is sealed from
the rest of the wellbore in step 540. Note that in some cases it
may be advantageous to bypass one of the sealing packer element
with a flow line (not shown) in the testing tool that establishes a
fluid communication between the sealed interval in step 540 and
another part of the system, for example the wellbore outside the
sealed cleaning interval. Optional cleaning or treatment is
performed in step 545.
[0055] In the example of FIGS. 7B and 7C, the interval length may
be selected by enabling the extension of two selected packer
elements from a plurality of packer elements carried by the testing
tool. Packers 602 and 604 are first enabled and then extended
(inflated) in step 535 of the method shown in FIGS. 6A-6B. By
extending toward the wellbore wall, packers 602 and 604 seal the
cleaning interval 611 which length is roughly equivalent to the
determined length in step 525 of the method 500 shown in FIGS.
6A-6B. A cleaning fluid 660 may then be injected through port 652
or 653 into the wellbore in step 545 of the method shown in FIGS.
6A-6B. Preferably the cleaning fluid 660 will occupy a large
portion of the cleaning interval, as indicated by cleaning fluid
660 in FIG. 7B. Sensors, similar to sensors 202a-c or 201a -d shown
in FIG. 3, or other sensors, may optionally monitor the cleaning
process, and the cleaning process may be controlled based on the
sensor signals. Step 545 may further comprise draining the cleaning
fluid 660, for example in port 653 as shown in FIG. 7C. This
cleaning fluid may be dumped into the wellbore outside the sealed
interval, for example at port 163 of FIG. 2, or stored in a cavity
in the testing tool, such cavity 150-2 of FIG. 2. Usually, draining
through port 653 will not efficiently remove the cleaning fluid 660
located between the lower packer element of the sealed interval 604
and the draining port 653. Note that in the example of FIG. 7C, it
is assumed that the density of the cleaning fluid and/or cleaning
debris is larger than the density of the formation fluid. It is
further assumed that the testing tool 10 is operated such that
formation fluid is drawn from the surrounding formation as cleaning
fluid is drained outside the cleaning interval, as shown by
formation fluid 661. Thus, formation fluid and cleaning fluid may
segregate by gravity as shown in FIG. 7C. In the case the formation
fluid density is higher than the cleaning fluid and/or cleaning
debris density, the sequence of formation fluid, cleaning fluid,
and/or cleaning debris may be different. Note also that this
invention is not limited to the presence of two segregated fluids
in the sealed interval.
[0056] Turning back to FIGS. 6A-6B, the testing interval length may
be selected by enabling the extension of two packer elements from
the plurality of the packer elements carried by the testing tool in
step 550. Note that the adjustment of the testing interval length
may alternatively be achieved by sliding packer elements along the
axis of the tool prior to extending the packer element toward the
wellbore wall, as previously discussed with respect to FIG. 4.
Packer elements of the testing tool are extended toward the
wellbore wall in step 555. Note that if a first cleaning interval
has already been sealed, it may be advantageous in some cases to
maintain the first interval sealed while sealing a second interval,
the testing interval. Thus, it may be advantageous to bypass one of
the sealing packer element with a flow line (not shown) in the
testing tool that establishes a fluid communication between the
cleaning interval and another part of the system, for example the
wellbore outside the sealed cleaning interval. This would allow for
the fluid displaced by the extension of a third packer element in
the sealed interval to be vented out of the sealed interval. A
testing interval is sealed from the rest of the wellbore in step
560. Testing of the formation is performed in step 565, for example
injection, sampling, or local interference test (also known as
interval pressure transient test or IPTT) is preferably performed
in a manner known in the art.
[0057] Continuing with the example of FIG. 7D, the testing interval
610 is selected by enabling the extension (inflation) of packer
element 603 between already extended packer elements 602 and 603
(step 550 of the method in FIGS. 6A-6B). Note, that in this
scenario packer element 602 would be enabled for both sealing the
testing volume and the cleaning volume. The testing interval 610 is
sealed once the packer element 603 reaches the wellbore wall. Thus,
the testing interval 610 is now isolated from the residual cleaning
material and/or debris 660 above the lower packer 604. The residual
cleaning material and/or debris 660 is retained below expanded
packer 603 and is trapped, so as not to contaminate the fluid
contained in the testing interval 610. However, if desired, packer
604 can be retracted (deflated) thereby allowing the residual
cleaning material to disburse downhole if desired. Testing may then
begin. Formation fluid may be drawn from interval 610 into the port
652. Note that cleaning fluid 660 was drained during the cleaning
period through port 653 and formation fluid 661 is now drawn
through port 652 during the testing period. This may be achieved by
associating port 652 and 653 with valves (not shown), similar to
valves 242 and 243 associated respectively to ports 252 and 253 in
FIG. 3.
[0058] Turning back to FIGS. 6A-6B, one or more additional interval
may be sealed if needed, including the option of selecting of the
length of these additional intervals, as shown by step 570. Also,
additional testing may be performed as shown by step 575. At any
time, the operator or internal logic may decide to abort the cycle
and terminate the test. All the packer elements are preferably
retracted (deflated) in step 580 and the testing tool is free to
move in the wellbore. Other methods than method 500 may also
benefit from sealed interval of adjustable length. These methods
include, but are not limited to, injecting materials into the
formation, or formation testing to determine for example pressure
and mobility of hydrocarbons in a reservoir. As mentioned above, a
local interference test (also known as interval pressure transient
test of IPTT) may benefit from sealed interval of adjustable
length. The pressure in sealed intervals of variable length may be
pulsed. The pressure pulse may be detected at a probe located above
or below the sealed interval (similar to probe 16c in FIG. 1C),
that is in pressure communication with the formation.
[0059] FIGS. 8A-8D show another illustration of a method for
testing a subterranean formation according to one aspect of this
invention. FIGS. 8A-8D show a portion of a testing tool similar to
testing tool 10 of FIG. 2, lowered in a wellbore 11 traversing a
formation 12, as taught by step 510 of method 500. Testing tool 10
comprises packer elements 702, 703, 704 and 705, and ports 752,
753, 754 and 755. In the example of FIGS. 8A-8D, packer elements
703 is slidable, for example using the apparatus described in more
details with respect to FIG. 4.
[0060] As a way of example, the length of the wellbore interval to
be sealed determined in step 515 of method 500 may be represented
by interval 770 on FIGS. 8A-8D. As taught by step 550 of method
500, the testing interval length may then be selected by sliding
packer element 703 as indicated by arrow 730 on FIG. 8A. The
movement of packer element may be controlled by a downhole
controller (not shown), either automatically according to
instructions executed by the downhole controller, or under the
supervision of a surface operator sending a command to the testing
tool. The command sent to the testing tool could comprise a value
of the testing interval length determined by the operator, for
example in view of information recorded by downhole sensors (not
shown) and sent uphole by a telemetry system (not shown).
[0061] FIG. 8B illustrate a first testing operation. In the example
of FIG. 8B, packer elements 702 and 703 have been extended into
sealing engagement with the wellbore wall 15 (step 555 of method
500) and the testing interval 770 is isolated (step 560 of method
500). The testing operation (step 565 of method 500) may comprise
the optional step of perforating the formation as shown by tunnel
722 in formation 12. Perforation may be achieved by perforating
guns, such as perforating gun 231 of FIG. 3, or by any other method
known by those skilled in the art. Note that the perforation of the
formation 12 about the testing interval 770 may be performed before
or after inflation of the packer elements 702 and 703. The testing
operation shown in the example of FIG. 8B comprises injecting
material through the port 752, for example steam, hot water, acid
or solvent, into the testing interval 770 and the formation 12.
Injection of steam, hot water or solvent may be desirable for
example to lower viscosity of heavy hydrocarbon in formation 12
prior to sampling. Injection may also be desirable for testing the
compatibility of the injected fluid with the formation or reservoir
fluid. The injected material may be conveyed downhole in a cavity
(not shown), similar to cavity 150-1 in FIG. 2, or may also be
conveyed from the surface into the conveyance mean 13b, as
explained above with respect to FIG. 1B. The testing operation
preferably allows for the injected material to diffuse in the
formation 12, as indicated by arrows 731. During this soaking
period, various sensors (not shown) may measure formation of fluid
properties, such as fluid temperature, fluid pressure, or formation
resistivity profile along the radial, axial or azimuthal direction
of the wellbore.
[0062] FIGS. 8C and 8D illustrate an optional testing operation
following the injection described in FIG. 8B. The length of a
second testing interval can be selected, for example from the set
of the distance between packer element 703 and 704, the distance
between packer 703 and 705 or the distance between packer 704 and
705. In the example of FIG. 8C, a second testing interval 771
between packer elements 705 and 703 is sealed, as taught by step
570 of method 500. Alternatively, packer element 704 may have been
enabled instead of packer element 705, sealing thereby a second
testing interval with a shorter length. The testing tool may start
drawing fluid from interval 771 may be replaced by sand 763,
produced by an unconsolidated formation, and formation fluid 762,
as indicated by arrows 732. Note that in the example of FIG. 8C, it
is assumed that the density of the formation fluid 762, for example
heavy oil, is larger than the density of the wellbore fluid 761,
for example water. Note also that formation fluid 762 may be
contaminated by injection materials or other materials.
[0063] FIG. 8D shows the continuation of the sampling process
started in FIG. 8C. In FIG. 8D, an alternate fluid communication
with the testing tool is established through port 754 by
selectively opening a valve (not shown) associated with port 754,
for example a valve similar to valve 243b of FIG. 3, and by closing
a valve (not shown) associated with port 753, for example a valve
similar to valve 243a of FIG. 3. This operation may be initiated by
a surface operator, for example in view of fluid properties
measured by the testing tool, for example by a sensor similar to
sensor 131 of FIG. 2, and send uphole via telemetry. This operation
may alternatively be initiated by a downhole controller. Thus,
formation fluid 762 may enter the testing tool through port 754,
indicated by arrows 733. In the example of FIG. 8D, packer element
704 has not been inflated, increasing thereby the risk of
particles, such as sand or other debris, to enter the testing tool
via port 754. In some cases, there may still be particles in
suspension in formation fluid 754. It may be advantageous to
pulverize these particles with particle breaking devices, such as
particles breaking devices 160, 161 or 162 on FIG. 2. Formation
fluid may then be analyzed by one or more sensor in the testing
tool and/or captured in a cavity in the testing tool and brought to
the surface for further analysis, as known by those skilled in the
art.
[0064] In the example of FIG. 8C, the second testing interval 771
is located below the first interval, for example to take advantage
of gravity during a sampling operation of a heavy hydrocarbon in
formation 12. It will be appreciated by those skilled in the art
that a second testing interval may have alternatively be chosen
above the first interval, for example by extending initially packer
elements 704 and 705 for sealing the first testing interval.
Alternatively, the second testing interval may comprise the first
testing interval, for example by extending packer element 704 and
retracting packer element 703.
[0065] Although the present invention and its advantages have been
described in detail, it should b understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the invention as defined by the
appended claims. Moreover, the scope of the present application is
not intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present invention, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present invention. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
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