Note: Descriptions are shown in the official language in which they were submitted.
CA 02641431 2008-10-08
METHOD OF UTILIZING FLOWABLE DEVICES IN WELLBORES
BACKGROUND OF THE INVENTION
1. Field of the tnvenlion
s This Invention relates generally ta oiffield weflbores and more palticuMdriy
to
welibore systems and methods for the use of flowable devices in such wellborm.
2. Backaround of the Art
Hydrocarbons, such as oil and gas, al'e trapped in subqur(aoe forma#ions.
Hydrocarbon-bearing forrrtiations are usually riefen'ed to aa the producfng
zones or
oii and gas reservoh or "reservoirs " To obtai: hy+dnooerbons from such
fonnations,
wellbonas or boreholea are drilled from a.suriace location or "well slbe" on
land or
offshoreinto one or more such ressrvous. A welibore is usualiy forrned by
drHling
a borehole of a desired diameter or size by a drill bfl conveyed from a rig at
the - wmN
site. The driil string inciudes a hollow tubing iatteched to a drilling
assembly at its
bottom end. The driiling assembly (also referred to herein as the "bottomhole
assemby" or "BHA") Includes the dria bft tor drilHtlg the weilbole and a
nurnber of
sensors for determining a varkNy of subsurfiace or downhole parameteta. The
tubing usually is a continuous pipe made by joining relaUvely smail sections
(each
ZO'
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CA 02641431 2008-10-08
section being 30-40 feet long) of rigid metallic pipe (commonly referred to as
the
"drill pipe") or a relatively flexible but continuous tubing on a reel
(commonly referred
to as the "coiled-tubing"). When coiled tubing is used, the drill bit is
rotated by a
drilling motor in the drilling assembly. Mud rimotors are most commonly
utilized as
drilling motors. When a drill pipe is used as the tubing, the drill bit is
rotated by
rotating the drill pipe at the surface and/or by the mud motor. During
drilling of a
wellbore, drilling fluid (commonly referred to as the "mud") is supplied under
pressure from a source thereof at the surfaceithrough the drilling tubing. The
mud
passes through the driilling assembly, rotates the drilling motor, if used,
and
discharges at the drill bit bottom. The mud discharged at the drill bit bottom
retums
to the surface via the spacing between the dril`i string and the wellbore
(also referred
herein as the "annulus") carrying the rock pieces (referred to in the art as
the
"cuttings") therewith.
Most of the currently utilized drilling assemblies include a variety of
devices
and sensors to monitor and control the dri5ing process and to obtain valuable
information about the rock, wellbore conditions, and the matrix surrounding
the
drilling assembly. The devices and sensors used in a particular drilfing
assembly
depend upon the specific requirements of the well being drilled. Such devices
include mud motors, adjustable stabilizers to. provide latera) stability to
the drilling
assembly, adjustable bends, adjustable force application devices to maintain
and
to alter the drilling direction, and thrusters to apply desired amount of
force on the
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CA 02641431 2008-10-08
drill bit. The driliing assembly may include sensors for determining (a)
drilling
parameters, such as the fluid flow rate, rotational speed (r.p.m.) of the
drill bit and/or
mud motor, the weight on bit ("WOB"), and torque of the bit; (b) borehole
parameters, such as temperature, pressure, hole size and shape, and chemical
and
physical properties of the circulating fluid, inclination, azimuth, etc., (c)
driliing
assembly parameters, such as differential pressure across the mud motor or
BHA,
vibration, bending, stick-slip, whirt; and (d) formation parameters, such as
formation
resistivity, dielectric constant, porosity, density, permeability, acoustic
velocity,
natural gamma ray, formation pressure, fluid mobility, fluid composition, and
composition of the rock matrix.
During drilling, there is ongoing need to adjust the various devices in the
driil
string. Frequently, signals and data are transmitted from surface control
units to the
drilling assembly. Data and the sensor results. from the drilling assembly are
communicated to the surface. Commonly utilized telemetry systems, such as mud
pulse telemetry and acoustic telemetry systems, are relatively low data rate
transfer
systems. Consequently, large amounts of downhole measured and computed
information about the various above-noted parameters is stored in memory in
the
drilling assembly for later use. Also, relatively few instnrctions and data
can be
transmitted from the surface to the drilling assembly during the drilling
operations.
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After the well has been drilled, the well may be completed, i.e., made ready
for production. The completion of the welibore requires a variety of
operations, such
as setting a casing, cementing, setting packers, operating flow control
devices, and
perforating. There is need to send signals and data from the surface during
such
completion operations and to receive information about certain downhole
parameters. This information may be required to monitor status andlor for the
operation of devices in the welibore ("downhole devices"), to actuate devices
to
perform a task or operation or to gather data about the subsurface wellbore
completion system, information about produced or injected fluids or
information
about surrounding formation. After the well has startpd to produce, there is a
continuous need to take measurements of various downhole parameters and to
transmit downhole generated signals and data to the surface and to receive
downhole information transmitted from the surface.
The present invention provides systems and methods wherein discrete
flowable devices are utilized to communicate surface-generated information
(signals
and data) to downhole devices, measure and record downhole parameters of
interest, and retrieve from downhole devices, and to make measurements
relating
to one or more parameters of interest relating to the wellbore systems.
5
CA 02641431 2008-10-08
SUMMARY OF THE INVENTION
This invention provides a method of utilizi~g flowable devices to
communicate between surface and downhole instruments and to measure
downhole parameters of interest. In one method, one or more flowable devices
are
introduced into fluid flowing in the wellbore. The flowable device is a data
carrier,
which may be a memory device, a measurement device that can make one or more
measurements of a parameter of interest, such as temperature, pressure and
flow
rate, and a device with a chemical or biological base that provides some
useful
information about a downhole parameter or a device that can transfer power to
another device.
In one aspect of the invention, memory-type flowable devices are sent
downhole wherein a device in the wellbore reads stored information from the
flowable devices and/or writes information on the flowable device. If the
flowable
devioe is a measurement device, it takes the measurement, such as temperature,
pressure, flow rate, etc., at one or more locations in the we(lbore. The
flowable
devices flow back to the surface with the fluid, where they are retrieved. The
data
fn the flowable devices and/or the measurement inTormation obtained by the
flowable devices is retrieved for use and analysis_
During drilling of a wellbore, the flowable devices may be introduoed into the
drilling fluid pumped into the drill string. A data exchange device in the
drill string
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CA 02641431 2008-10-08
reads information from the flowable devices and/or writes information on the
flowable devices. An inductive coupiing device may be utilized for reading
information from or writing information on the flowable devices. A downhole
controller controls the information flow between the flowable device and other
downhole devices and sensors. The flowable devices return to the surface with
the
circulating drilling fluid and are retrieved. Each flowable device may be
assigned
an address for identification. Redundant devices may be utilized.
In a production well, the flowable devices may be pumped downhole via a
tubing that runs from a surface location to a desired depth in the wellbore
and then
returns to the surface. A U-shaped tubing may be utilized for this purpose.
The
flowable devices may also be carried downhole via a singie tubing or stored in
a
container or magazine located or placed at a suitable location downhole, from
which
location the flowable devices are released into the flow of the produced
fluid, which
carries the flowable devices to the surface. The release or disposal from the
magazine may be done periodically, upon command, or upon the occurrence of one
or more events. The magazine may be recharged by intervention into the
weilbore.
The tubing that carries the flowabie devices may be specifically made to
convey the
flowable devices or it may be a hydraulic line with additional functionality.
The
flowable devices may retrieve information from downhole devices and/or make
measurements along the wellbore. A plurality of flowable devices may be
present
in a welibore at any given time, some of which may be designed to communicate
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with other flowable device or other downhole device, thereby providing a
communication network in the wellbore. The flowable devices may be
intentionally implanted in the wellbore wall to form a communication link or
network in the wellbore. A device in the wellbore reads the information
carried by
the flowable devices and provides such Information to a downhole controller
for
use. The information sent downhole may contain commands for the downhole
controller to perform a particular operation, such as operating a device. The
downhole controller may also send information back to the surface by writing
information on the flowable devices. This may be information from a downhole
system or confirmation of the receipt of the information from surface.
Accordingly, in one aspect of the present invention there is provided a
method of utilizing flowable devices in a wellbore wherein a working fluid
provides
a fluid flow path for moving said flowable devices from a first location of
introduction of said devices into the flow path to a second location of
interest,
said method comprising:
selecting at least one flowable device constituting a data carrier that is
adapted to be moved in the wellbore at least in part by the working fluid;
introducing the at least one flowable device into the fluid flow path at the
first location to cause the working fluid to move the at least one flowable
device to
the second location of interest; and
providing a data exchange device in the fluid flow path for effecting data
exchange with the at least one flowable device.
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CA 02641431 2008-10-08
According to another aspect of the present invention there is provided a
method of utilizing discrete devices in a wellbore wherein a working fluid
provides
a fluid flow path for moving said discrete devices from a first location of
introduction of said devices into the flow path to a second location of
interest,
said method comprising:
(a) introducing a plurality of flowable discrete devices comprising data
carriers
that are adapted to be moved in the wellbore at least in part by the working
fluid
and forming a network of flowable devices in the wellbore;
(b) introducing at least one flowable discrete device into the fluid flow path
at
the first location to cause the working fluid to move the at least one
flowable
device to the second location of interest; and
(c) providing a data exchange device in the fluid flow path for effecting data
exchange with the at one flowable discrete device.
Examples of the more important features of the invention have been
summarized rather broadly in order that the detailed description thereof that
follows may be better understood, and in order that the contributions to the
art
maybe appreciated. There are, of course, additional features of the invention
that
will be described hereinafter and which will form the subject of the claims
appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed understanding of the present invention, reference should be
made to the following detailed description of the preferred embodiment, taken
in
8a
CA 02641431 2008-10-08
conjunction with the accompanying drawings, in which like elements have been
given like numerals, wherein:
Figure 1 is a schematic illustration of a drill string in a wellbore during
drilling
of a wellbore, wherein flowable devices are pumped downhole with the drilling
fluid.
Figure 2 is a schematic illustration of a wellbore during drilling wherein
flowable devices are implanted In the borehole wall to form a communications
line
in the open hole section and wherein a cable is used for communication in the
cased hole section.
Figure 3 is a schematic illustration of a wellbore wherein flowable devices
are pumped downhole and retrieved to the surface via a U-shaped hydraulic or
fluid
line disposed in the welibore.
Figure 4 is a schematic illustration of a production well wherein flowable
devices are released in the flow of the produced fluid at a suitable location.
Figure 5 is a schematic illustration of a multi-lateral production wellbore
wherein flowable devices are pumped down through a hydraulic line and released
into the fluid flow of the first lateral and where information is communicated
from the
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CA 02641431 2008-10-08
first lateral to the second lateral through the earth formition and wherein
flowable
devices may also be released into the fluid flow of the second lateral to
carry such
devices to the surface.
Figure 6 is a block functional diagram of a flowable device according to one
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention utilizes "flowable devices" in wellbores to perform one
or more functions downhole. For the purpose of this disclosure, a flowable
device
means a discrete device which is adapted to be moved at least in part, by a
fluid
flowing in the wellbore. The flowable device according to this invention is
preferably
of relatively small size (generally in the few millimeters to a centimeter
range in
outer dimensions) that can perform a useful function in the wellbore. Such a
device
may make measurements downhole, sense a downhole parameter, exchange data
with a downhole device, store information therein, andlor store power. The
flowable
device may communicate data and signals with other flowable devices and/or
devices placed In the wellbore ("downhole devices"). The flowable device may
be
programmed or coded with desired information. An important feature of the
flowable devices of the present invention is that they are sufFciently small
in size so
that they can circulate with the drilling fluid without impairing the drilling
operations.
Such devices preferably can flow with a variety of fluids in the wellbore. In
another
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CA 02641431 2008-10-08
aspect of the invention, the devices may be installed in the wellbore wall
either
permanently or temporarily to form a network of devices for providing selected
measurement of one or more downhole parameters. The various aspects of the
present invention are described below in reference to Figures 1-6 utilizing
exemplary weilbores.
In a preferred embodiment, the flowable device may include a sensor for
providing measurements relating to one or more parameters of interest, a
memory
for storing data andlor instructions, an antenna for transmitting and/or
receiving
signals from other devices and/or flowable devices in the wellbore and a
control
circuit or controller for processing, at least in part, sensor measurements
and for
controlling the transmission of data from the device, and for processing data
received from the device. The device may include a battery for supplying power
to
its various components_ The device may also include a power generation device
due to t~e turbulence in the wellbore fluid flow. The generated power may be
utilized to charge the battery in the device.
i=igure 1 is an illustration of the use of flowable devices during drilling of
a
wellbore, which shows a wellbore 10 being drilled by a drill string 20 from a
surface
location 11. A casing 12 is placed at an upper section of the wellbore 10 to
prevent
collapsing of the wellbore 10 near the surface 11. The drilling string 20
includes a
tubing 22, which may be a drill pipe made from joining smaller sections of
rigid pipe
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CA 02641431 2008-10-08
or a coiled tubing, and a drilling assembly 30 (also refen-ed to as a bottom
hole
assembly or "BHA") attached to the bottom end 24 of the tubing 22.
The drilling assembly 30 carries a drill bit 26, which is rotated to
disintegrate
the rock formation. Any suitable drilling assembly may be utilized for the
purpose
of this invention. Commonly used drilling assemblies include a variety of
devices
and sensors. The drilling assembly 30 is shown to include a mud motor section
32
that includes a power section 33 and a bearing assembly section 34. To drill
the
wellbore 10, drilling fluid 60 from a source 62 is supplied under pressure to
the
tubing 22. The drilling fluid 60 causes the mud motor 32 to rotate, which
rotates the
drill bit 26. The bearing assembly section 34 includes bearings to provide
lateral and
axial stability to a drill shaft (not shown) that couples the power section 33
of the
mud motor 32 to the driil bit 26. The drilling assembly 30 contains a
plurality of
direction and position sensor 42 for determining the position (x, y and z
coordinates)
with respect to a known point and inclination of the drilling assembly 30
during
drilling of the wellbore 10. The sensors 42 may include, accelerometers,
inclinometers, magnetometers, and navigational devicds. The drilling assEmbly
further includes a variety of sensors denoted herein by numeral 43 for
providing
information about the borehole parameters, drilling parameters and driiling
assembly condition parameters, such as pressure, temperature, fluid flow rate,
differential pressure across the mud motor, equivalent circulatory density of
the.
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drilling fluid, drill bit and/or mud motor rotationai speed, vibration, weight
on bit, etc.
Formation evaluation sensors 40 (also referred to as the "FE" sensors) are
included
in the drilling assembly 30 to determine properties of the formations 77
surrounding
the welibore 10. The FE sensors typically incliide resistivity; acoustic,
nuclear and
nuclear magnetic resonance sensors which alone provided measurements that are
used alone or in combination of measurements from other sensors to calculate,
among other things, formation resistivity, water saturation, dielectric
constant,
porosity, permeability, pressure, density, and vther propgrties or
characteristics of
the formation 77. A two-way telemetry unit 44 communicates data/signals
between
the drilling assembly 30 and a surface control unit or processor 70, which
usually
includes a computer and associated equipment.
During drilling, according to one aspect of the present invention, flowable
devices 63 are introduced at one or more suitable locations into the flow of
the
drilling fluid 60. The flowable devices 63 travel with the fluid 60 down to
the BHA
30 (forward flow), wherein they are channeled into a passage 69. A data
exchange
device 72, usually a readlwrite device disposed adjacent to or in the passage
69,
which can read information stored in the devices 63 (at the surface or
obtained
during flow) and can write on the devices 63 any information that needs to be
sent
back to the surface 11. An inductive coupling unit or another suitable device
may
be used as a readNvrite device 72. Each flowable device 63 may be programmed
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CA 02641431 2008-10-08
at the surface with a unique address and specific or predetermined
information.
Such information may include instructions for the controller 73 or other
electronic
circuits to perform a selected function, such as activate ribs 74 of a force
application
unit to change drilling direction or the information may include signals for
the
controlier 73 to transmit values of certain downhole measured parameters or
take
another action. The controller 73 may include a microprocessor-based circuit
that
causes the read/write unit 72 to exchange appropriate information with the
flowable
devices 63. The controller 73 process downhole the information received from
the
flowable devices 63 and also provides information to the devices 63 that is to
be
carried to the surface. The read/write device 72 may write data that has been
gathered downhole on the flowable devices 63 leaving the passage 69. The
devices 63 may also be measurement or sensing devices, in that, they may
provide
measurements of certain parameters of interest such as pressure, temperature,
flow
rate, viscosity, composition of the fluid, presence of a particular chemical,
water
i5 saturation, composition, corrosion, vibration,. etc. The devices 63 return
to the
surface 11 with the fluid circulating through the annulus 13 between the
wellbore 10
and drill string 22.
The flowable devices returning to the surface designated herein for
convenience by numeral 63a are received at the surface by a recovery unit 64.
The
returning devices 63a may be recovered by filtering magnetic force or other
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CA 02641431 2008-10-08
techniques. The information contained in the returning devices 63a is
retrieved,
interpreted and used as appropriate. Thus, in the drilling mode, the flowable
devices 63 flow downhole where they perform an intended function, which may be
taking measurements of a parameter of interest or providing information to a
downhole controller 73 or retrieving information from a downhole device. The
devices 63a return to the surface (the return-destination) via the annulus 13_
During drilling, some of the devices may be lost in the flow process or get
attached or stuck to the wall of the wellbore 10. Redundant devices may be
supplied to account for such loss. Once the controller 73 has communicated
with
a device having a particular address, it may be programmed to ignore the
redundant
device. Alternatively, the controller 73 may cause a signal to be sent to the
surface
confirming receipt of each address. If a particular address Is not received by
the
downhole device 72, a duplicate device may be sent. The devices 63a that get
attached to the wellbore wall 10a (see Figure 2), may act as sensors or
communication locations in the wellbore 10. A stuck device may communicate
with
another flowable device stuck along the wall 10a or with devices passing
adjacent
the stuck device, thereby forming a communications network. The retuming
devices
63a can retrieve information from the devices stuck in the well 10. Thus, the
flowable devices in one aspect, may form a virtual network of devices which
can
pass datalinformation to the surface. Altematively, some of the devices 63 may
be
CA 02641431 2008-10-08
adapted or designed to lodge against or deposited on the wellbore wall 10a,
therebjr
providing permanent sensors and/or communication devices in the wellbore 10.
In
one embodiment, the flowable devices may be designed to be deposited on the
borehole wall during the drilling process. As one flowable device can
communicate
with another neighboring flowable device, a plurality of flowable devices
deposited
on the wellbore wall may form a communications network. As drilling of new
formation continues new flowable devices are constantly deposited on the
borehole
wall to maintain the network. When drilling of'the section is completed, the
flowabte
devices may be retrieved from the borehole wall for use in another
application. The
devices 63 may include a movable element that can generate power due to
turbulence in the welibore fluid, which power can be used to change a resident
battery in the flowable devices. Further, the devices 63 may include a
propulsion
mechanism (as more fully explained in reference to Figure 6) that aids these
devices in flowing with or in the fluid 60. The devices 63 usually are
autonomous
devices and may include a dynamic ballast that can aid such devices to flow in
the
fluid 60.
Flowable devices may also be periodically planted in the wellbore wall in a
controlled operation to form a communication line along the weitbore, as
opposed
to randomly depositing flowable devices using the hydraulic pressure of the
drilling.
fluid. An apparatus may be constructed as part of the downhole assembly to
mechanically apply a force to press or screw the flowable device into the
wellbore
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CA 02641431 2008-10-08
wall. In this operation, the force required to implant the device may be
measured,
either by sensors within the flowable device itself or sensors within the
implanting
apparatus. This measured parameter may be communicated to the surface and
used to investigate and monitor rock mechanical properties. The flowable
devices
may be pumped downhole to the planting apparatus, or kept in a magazine
downhole to be used by the planting apparatus. In this case the flowable
devices
may be permanently installed. Figure 2 which is a$chematic illustration of a
wellbore, wherein devices made in accordance with the present invention are
implanted in the borehole wall during drilling of the wellbore 10 to form a
communication network. Figure 2 shows a well 10 being drilled by drill bit 26
at the
bottom of a drilling assembly 80 carried by .a drilling tubing 81. Driliing
fluid 83
supplied under pressure through the tubing 81 discharges at the bottom of the
drill
bit 26. Flowable devices 63 are introduced or pumped into the fluid 83 and
captured
or retrieved by a device 84 in the driiling assembly 80. The drilling assembly
$0
includes an implanting device 85 that implants the retrieved flowable devices
63 via
a head 86 into the borehole wall 10a. The devices which are implanted during
the
drilling of the wellbore 10 are denoted by numeral 63b. The devices 63 may be
pumped downhole through a dedicated tubing 71 placed in the drilling tubing
81.
If coiled tubing is used as the tubing 81, the tubing 71 for carrying the
flowable
devices 63 to the implanter 85 may be built inside or outside the coiled
tubing.
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CA 02641431 2008-10-08
Altematively, the devices to be implanted may be stored in a chamber or
magazine 83, which deliver them to the implanter 85. The implanted flowable
devices 63b in the well 10 can exchange data with each other and/or other
flowable
devices returning to the surface via the annuius 13 and/or with other devices
in the
drill string as described above in reference to Figure 1. A communication
device
88 may be disposed in the well at any suitali le location, such as below the
upper
casing 12 to communicate with the implanted devices 63b. The communication
device 88 may communicate with one or more nearby flowable devices 63b such
as a device denoted by numeral 63b, which device then communicates with next
device and so forth down the line to the remaining implanted devices 63b.
Similariy,
the implanted devices 63b communicate uphole up to the devices 63b which
communicates with the device 88, thus establishing a two-way communication
link
or line along the wellbore 10. The device 88 can read data from and write data
on
the devices 63b. It is operatively coupled to a receiver/transmitter unit 87
and a
processor 89 at the surface by a conductor or link 91. The link 91 may be an
electrical conduct or a fiber optic link. The processor 89 processes the data
received by the receiver/transmitter unit 87 fiom the devices 63b and also
Bends
data to the devices 63b via the receiver/transrriitter 87. The implanted
devices 63b
may be used to take measurements for one or more selected downhole parameters
during and after the driiiing of the wellbore 10.
18
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Figure 3 illustrates an alternative method of transporting the devices 63 to
a downhole location. Figure 3 shows a wellbore 101 formed to a depth 102. For
simplicity and ease of understanding, normal equipment and sensors placed in a
wellbore are not shown. A fluid conduit 110 is disposed In the wellbore. The
conduit 110 runs from a fluid supply unit 112,; forms a U-return 111 and
returns to
the surface 11. Flowable devices 63 are pumped into the conduit 110 by the
supply
unit 112 with a suitable fluid. A downhole device 72a retrieves information
from the
flowable devices 63 passing through a channel 70a and/or writes information on
such devices. A controller 73a receives the information from the flowable
devices
63 and utilizes it for the intended purpose. Controller 73a also controls the
operation of the device 72a and thus can cause it to transfer the required
information onto the flowable devices 63. The flowable devices 63 then return
to
the surface via the return segment 110a of the tubing 110. A retrieval unit
120 at
the surface recovers the retuming flowable devices 63a, which may be analyzed
by
a controller 122 or by another method. The devices 63 may perform sensory and
other functions described above in references to Figure 1.
Figure 4 is a schematic illustration of a production well 200 wherein flowable
devices 209 are released into the produced fluid or formation fluid 204, which
carries these devices to the surface. Figure 4 shows a well 201 that has an
upper
casing 203 and a well casing 202 installed therein. Formation fluid 204 flows
into
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CA 02641431 2008-10-08
the well 201 through perforations 207. The fluid 204 enters the wellbore and
flows
to the surface via a production tubing 210. For simplicity and ease of
understanding, Figure 4 does not show the:various production devices, such as
flow control screens, valves and submersible pumps, etc. A plurality of
flowable
devices 209 are stored or disposed in a suitabie container at a selected
location 211
in the wellbore 201. The devices 209 are selectively released into the flow of
the
produced fluid 204, which fluid carries these devices, the released devices
are
designated by numeral 209a to the surface. The devices 209a are retrieved by a
retrieval unit 220 and analyzed. As noted above in reference to Figures 1 and
3,
the flowable devices 209a may be sensor devices or information containing
devices
or both_ Periodic release of sensory devices can provide-information about the
downhole conditions. Thus, in this aspect of the invention, the flowable
devices are
released in the well 201 to transfer downhole information during the
production
phase of the well 201.
Communication in open-hole sections may be achieved using flowable
devices in the drilling mud deposited on the borehole wall, or by using
implanted
flowable devices as described above. In cased hole sections often found above
open-hole sections, communications may be achieved in several ways; through
flowable devices deposited in the mud filter cake or implanted in the borehole
wall
during the drilling process, or through flowable devices mixed in the cement
which
CA 02641431 2008-10-08
fills the annulus between the borehole watUmud filter cake and the casing, or
through a communication channel installed as part of the casing. The latter
may
include a receiver at'the bottom of the casing to pick up information from the
devices, and a transmitter to send this information to the surface and vice
versa.
The communication device associated with the casing could be an electrical or
fibre-
optic or other type of cable, an acoustic signal or an electromagnetic signal
carried
within the casing or within the earth, or other methods of communication. In
conclusion, a communication system based on the use of flowable devices may be
used in combination with other communication methods to cover different
sections
of the wellbore, or to communicate over distances not covered by a welfbore.
Another example of using flowable devices in combination with other
communication systems is a multilateral well. One or more laterals of the well
may
have a two-way communication system with:flowable devices, while one or more
laterals of the same well may not have a full two-way communication system
with
the flowable devices. In one embodiment: of the invention, the first lateral
Is
equipped with a single tube or a U-tube that allows flowabie devices
containing
Information from surface to travel to the bottom of the first lateral. The
second
lateral is not equipped with a tubing, but has flowable devices stored in a
downhole
magazine. A message to the second lateral is pumped into the first lateral.
From
the receiver station in the first lateral, information such as a command to
release a
flowable device in the second lateral, is transmitted from the first lateral
to the
21
CA 02641431 2008-10-08
second lateral through acoustic or electromagnetic signals through the earth.
Upon
receipt of this information in the second lateral, the required task, such as
writing to
and releasing a flowable device or initiating some action downhole is
performed.
Provided the distance and formation characteristics allow transmission of
signal
through the earth formation, the same concept can be used to communicate
between individual wellbores.
Figure 5 is an exemplary schematic illustration of an muttiiatera) production
well 300, wherein flowable devices are pumped into one branch or lateral and
then
utilized for communication between the laterals. Figure 5 shows a main well
section 301 having two branch welis or laterals 301a and 301b. In the
exemplary
lateral wellbore configuration of Figure 5, both wells 301a and 301b are shown
to
be production wells. Well 301a and 301b produce fluids (hydrocarbons) which
are
shown by arrow 302a and 302b, respectively. Flowable devices 63 are pumped
into
the first lateral 301a via a tubing 310 from a supply unit 321 at the surface
11. The
devices 63 are discharged at a known depth 303a where a receiver unit 370a
retrieves data from the devices 63. The devices return to the surface with the
produced fluid 302a. The returning devices from wellbore 301 are denoted by
63d.
A transmitter unit 380 transmits signals 371 in response to information
retrieved
from the flowable devices 63. A second receiver 370b in the second latera1301
b
receives signals 371. A controller unit or processor 382 utilizes the received
signals
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CA 02641431 2008-10-08
to perform an intended function or operation, which may include operating a
device
downhole, such as a valve, a sliding sleeve, or a pump, etc. Flowable devices
63c
may be disposed in magazine 383 in the second Iatera1301b and released into
the
fluid flow 302b by the controller 382. The devices 63d and 63c flowing uphole
are
retrieved at the surface by a receiver unit 320 !and the data carried by the
flowable
devices 63c and 63d is processed by the processor 322. It should be noted that
Figure 6 is only one example of utilizing the flowable devices in multiple
wellbores.
The wells selected for intercommunication may be separate wells in a field.
The
signals 371 may be received by instruments in one or more wells and/or at the
surface for use in performing an intended task.
Figure 6 shows a block functional diagram of a flowable device 450
according to one embodiment of the present invention. The device 460 is
preferably
encapsulated in a material 452 that is suitable for downhole environment such
as
ceramic. and includes one or more sensor elements 464, a control circuit or
controller 456 and a memory unit 458. A resident power supply 460 supplies
power
to the sensor 454, controller 456, memory 458 and any otheir electrical
component
of the device 450. The controller 456 may include a processor that interacts
wiith
one or more programs in the device to process the data gathered by the device
and/or the measurements made by the device to compute, at least partly, one or
more parameters of interest, including results or answers. For example, the
device
23
CA 02641431 2008-10-08
450 may calculate a parameter, change its future function and/or transmit a
signal
in response to the calculated parameter to cause an action by another flowable
device or a device in the welibore. For example, the device may determine a
detrimental condition downhole, such as presence of water and then send a
signal
to a fluid flow control device in the wellbore to shut down a production zone
or the
well. The device may be designed to have sufficient intelligence and
processing
capability so it can take any number of different actions in the wellbore. A
power
generation unit that generates electrical power due to the turbulence in the
flow may
be incorporated in the device 450 to charge a battery (resident power supply)
460.
An antenna 4f2 is provided to transmit andlor receive signals, thereby
providing
one-way or two-way communication (as desir.ed) between the flowable device 450
and another device, which may be a flowable device or a device located
downhole
or at the surface. The device 450 may be programmed at the surface or downhole
to carry data and instructions. The surface information pi=ogrammed into a
flowable
device is read by a device in the wellbore while the downhole programmed
information may be read at the surface or by reading devices downhole. The
device
450 may transmit and receive signals in the wellbore and thus communicate with
other devices. Such a flowable device can transfer or exchange information
with
other devices, establish communication link.along the welibore, provide two-
way
communication between surface and downhole devices, or between different
wellbores in a field or laterals of a wellbore system, and establish a
communication
network in the wellbore and/or between the surface instrumentation and
downhole
24
CA 02641431 2008-10-08
devices. Each such device may be coded with an identification number or
address,
which can be utilized to confirm the receipt or transfer of information by the
devices
deployed to receive the information from the flowable device 460. In one
method,
the flowable device 450 may be sequentially numbered and introduced into the
fluid
flow to be received at a target location. If the;receiving device receives a
flowable
device, it can cause a signal to be sent to the sending Io6ation, thereby
confirming
the arriva( of a particular device. If the receiving device does not confirm
the arrival
of a particular device, a second device carrying the same information and the
address may be sent. This system will provide a closed loop system for
transferring
information between iocations.
In another aspect of the invention, the flowable device may contain a
chemical that alters a state in response to a downhole parameter, which
provides
a measure of a downhole parameter. Other devices, such as devices that contain
biological mass or mechanical devices that are designed to carry information
or
sense a parameters may also be utilized. In yet another aspect, the flowable
devioe
may be a device carrying power, which may be received by the receiving device.
Thus, specially designed flowable devices may be utilized to transfer power
from
one location to another, such as from the surface to a downhole device.
The flowable device 450 may include a ballast 470 that can be released or
activated to alter the buoyancy of the device 450. Any other method also may
be
CA 02641431 2008-10-08
utilized to make the device with variable buoyancy. Additionally, the device
450
may also include a propulsion mechanism 480 that can be selectively activated
to
aid the device 450 to flow within the fluid path. The propulsion mechanism may
be
self-activated or activated by an event such as the location of the device 450
in the
fluid or its speed.
Whiie the foregoing disclosure is directed to the preferred embodiments of
the invention, various modifications wiil be apparent to those skilled in the
art. It is
intended that all variations within the scope and spirit of the appended
claims be
embraced by the foregoing disclosure.
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