Note: Descriptions are shown in the official language in which they were submitted.
1
METHOD AND APPARATUS FOR CONTROLLING A DOWNHOLE TOOL
The present invention relates to a method and apparatus for controlling a
downhole tool in a
well, and relates to a method of transmitting instructions to control a
downhole tool in a well
and more specifically but not exclusively results in multiplexing between the
outputs of at
least two downhole sensors, one of which is preferably an RFID tag reader and
another of
which is preferably a downhole fluid pressure sensor.
International PCT Publication No W02009/050517 to Petrowell(TM) Limited of
Aberdeen
discloses use of a downhole Radio Frequency IDentification (RFID) sensor
responsive to
Radio Frequency (RF) tags which are flowed past the RFID sensor in fluid or
pressure
sensors responsive to pressure signals respectively, wherein the system
operates:-
a) in RF mode (using the aforementioned RF tags) when there is circulation
of
fluid in the well (particularly fluid being pumped downhole through the
throughbore of a
tubing string); or
b) a pressure pulsing mode wherein the pressure sensor detects pulses sent
through downhole fluid when the throughbore of the tubing string is closed.
It is desirable to increase the versatility of remote communication with a
downhole tool while
conserving power.
Summary of the Invention
According to a first aspect there is provided a method of controlling a
downhole tool in a well
with a downhole processing device from the surface of the well.
The downhole tool could include (but is not limited to) any one or a
combination of the
following:
flow control devices;
chokes;
flow stimulation, enhancement or artificial lift tools or pumps;
annular isolation devices and barriers;
Date Recue/Date Received 2022-03-24
2
tubing isolation devices;
sleeves;
packers;
bridge plugs;
flapper valves;
ball valves; and
any other suitable downhole tool or tools.
The method can also include the step of controlling, changing, increasing the
flow,
restricting the flow or halting or preventing the flow of fluids downhole.
The method optionally further comprises checking the data storage device for
any stored
data received from the first downhole sensor at least once following the first
timing
operation.
The method optionally further comprises checking the data storage device for
any stored
data received from the second downhole sensor at least once following the
second timing
operation.
The method optionally further comprises storing data received from the first
downhole
sensor during the first timing operation, wherein the sensor is capable of at
least receiving a
signal sent via a first transmission mechanism.
The method optionally further comprises storing data received from the second
downhole
sensor during the second timing operation, the second sensor being capable of
at least
receiving a signal sent via a second transmission mechanism.
The method optionally further comprises controlling the downhole tool with a
downhole
processing device.
Optionally, each of the first and second timing operations is based upon the
time provided
by a clock of the downhole processing device.
Date Recue/Date Received 2021-08-11
3
Further optionally, the first and second timing operations determine when the
stored data
received from the first and second downhole sensors is checked.
Optionally, the method further comprises wirelessly transmitting the said
signals.
Optionally, the method further comprises transmitting the signals from a
location remote to
the location of the said first and second sensors.
Optionally, the method further comprises transmitting the signals from a
location remote to
the downhole location occupied by the data storage device and the downhole
processing
device.
Optionally, the method further comprises transmitting the signals from the
surface of the
well.
Optionally, there is further provided a switch that can be enabled or disabled
to switch the
first downhole sensor on or off as instructed. The switch may be comprised
with the
downhole processing device. Alternatively, the switch may be comprised with
the downhole
control device. Further alternatively, the switch may be comprised with the
first downhole
sensor.
Optionally, there is further provided a switch that can be enabled or disabled
to switch the
second downhole sensor on or off as instructed. The switch may be comprised
with the
downhole processing device. Alternatively, the switch may be comprised with
the downhole
control device. Further alternatively, the switch may be comprised with the
second
downhole sensor.
Optionally, the sensors can be any suitable sensor including but not limited
to:
electromagnetic sensors;
magnetic sensors;
acoustic sensors;
Date Recue/Date Received 2021-08-11
4
radio wave sensor;
radio-frequency sensor or receiver;
pressure sensor;
temperature sensor;
and chemical sensor;
wherein the said suitable sensor is adapted to respond to an appropriate
signal.
Optionally, the first sensor comprises a data reader mechanism and further
optionally
comprises a data antenna adapted to read data from a data containing device
that can
move with respect to the antenna and most optionally the first sensor
comprises an RFID
reader adapted to read data from and/or transmit data to a passing RFID data
containing
device such as an RFID tag. Optionally, the RFID tag travels (i.e. by gravity,
pumping or the
like or any combination thereof) down the well from the surface, further
optionally through a
throughbore of the tubing string and the RFID tag is optionally programmed at
the surface
by the operator with data to provide a signal or instructions that can be
received by the first
downhole sensor and which can provide said data to the data storage device
such that the
downhole processing device is instructed to operate or actuate at least one
downhole tool.
Optionally, the second sensor comprises a downhole environment sensor and
further
optionally comprises a downhole fluid pressure sensor adapted to sense the
pressure of
downhole fluid in communication with the sensor. Optionally, an operator can
change the
pressure of downhole fluid in the vicinity of the second downhole sensor by
changing the
pressure of fluid at the surface of the well and, further optionally, the
operator can send a
signal to the second downhole sensor via the second transmission mechanism of
the said
pressure of the downhole fluid that can be received by the second downhole
sensor and
which can provide said data to the data storage device such that the downhole
processing
device is instructed to operate or actuate at least one downhole tool.
Optionally, the downhole processing device is triggered to check the data
storage device
when the first timing operation reaches a pre-determined value and further
optionally, the
downhole processing device is triggered to check the data storage device when
the first
timing operation underflows or resets from zero to a pre-determined value that
the timing
Date Recue/Date Received 2021-08-11
5
operation will then count down to zero from. Optionally, the pre-determined
value for the
first timing operation is a relatively short predetermined value (relative to
the second timing
operation). Optionally, the said pre-determined value of the first timing
operation is in the
range of 0 seconds to 60 seconds and further optionally, the said pre-
determined value of
the first timing operation is less than 10 seconds. Yet further optionally,
the said pre-
determined value of the first timing operation is less than 1 second. Further
optionally, the
said pre-determined value of the first timing operation is less than 100
milliseconds (ms).
Further optionally, the said pre-determined value of the first timing
operation is in the range
of 10ms to 20m5 and yet further optionally, the said pre-determined value of
the first timing
operation is approximately 16ms.
Optionally, the downhole processing device is triggered to check the data
storage device
when the second timing operation reaches a pre-determined value and more
optionally, the
downhole processing device is triggered to check the data storage device when
the second
timing operation underflows or resets from zero to a pre-determined value that
the timing
operation will then count down to zero from. Optionally, the pre-determined
value for the
second timing operation is a relatively long predetermined value (relative to
the said
relatively short pre-determined value of the first timing operation).
Optionally, the said pre-
determined value of the first timing operation is in the range of 0 seconds to
60 seconds(s)
and further optionally, the said pre-determined value of the first timing
operation is in the
range of Is to 20s and preferably, the said pre-determined value of the first
timing operation
is approximately 10s.
Optionally, the first and second pre-determined values are stored in a memory
storage
device and are provided to the respective first and second timing operations
upon initiation
of the downhole processing device.
Optionally, the first timing operation comprises a timed event including a
repeating
countdown from the pre-determined time value to zero wherein said timed event
is repeated
at least once.
Date Recue/Date Received 2021-08-11
6
Optionally, the second timing operation comprises a timed event including a
repeating
countdown from the pre-determined time value to zero wherein said timed event
is repeated
at least once.
Further optionally, the point at which said timed event resets from zero to
the said pre-
determined time value comprises an underflow trigger which triggers the
checking of the
stored data received from the respective first and second downhole sensors.
Optionally, the downhole processing device comprises a first connection for
connecting to
the first downhole sensor and also optionally comprises a second connection
for connecting
to the second sensor.
Optionally, the downhole processing device is connected to at least one of the
first sensor
and the second sensor by a suitable connection such as wiring or cabling or
via an
integrated circuit board or the like and further optionally is electrically
connected to both the
first sensor and the second sensor by a suitable connection.
Optionally, the downhole processing device interprets and responds to data
stored in the
data storage device. Further optionally, the downhole processing device stores
data if
instructed to do so during predetermined time intervals determined by the
first and second
timing operations. Yet further optionally, the downhole processing device is
pre-
programmed to recognise flags represented by said stored data and/or trends
within the
stored data and is adapted to act upon said flags or said trends to for
example instruct a
downhole tool to actuate.
Optionally, the ability for the first sensor and/or the second sensor to send
data to be stored
in the data storage device may be enabled or disabled and this has the
advantage that
minimal or no power will be consumed by the first and/or second sensor if they
are disabled.
Optionally, a switch is provided to enable or disable the first and/or second
sensor. Yet
further optionally, the respective switch may be activated by a data signal
sent via the first
and/or second transmission mechanism.
Date Recue/Date Received 2021-08-11
7
Further optionally, if the respective switches are enabled for the first and
second sensors,
the downhole processing device will count the respective first and second
timing operations
in parallel but will look for valid data flag(s) in the data storage device in
series.
Embodiments of the present invention have the advantage that they effectively
enable
multiplexing between the outputs of at least two downhole sensors, one of
which is
optionally an RFID tag reader and another of which is optionally a downhole
fluid pressure
pulse sensor.
Optionally, the first and second timing operations comprise selectively
actuable respective
first and second interrupt service routines.
Optionally, the method further comprises a third or more selectively actuable
timing
operation.
Optionally, a downhole processing apparatus for controlling a downhole tool in
a well
comprises:-
a downhole processing device providing a first timing operation and a second
timing
operation;
the first timing operation being associated with a first downhole sensor
capable of at
least receiving a signal sent via a first transmission mechanism;
the second timing operation being associated with a second downhole sensor
capable of at least receiving a signal sent via a second transmission
mechanism;
a data storage device capable of storing data received from the first and
second
downhole sensors; and
the downhole processing device being adapted to be triggered by the first and
second timing operations to check the data storage device, at least once
during the
respective first and second timing operations, for data received from the
first and/or second
downhole sensors and the downhole processing device being adapted to act upon
that data
to control the downhole tool if instructed to do so.
Date Recue/Date Received 2021-08-11
8
Typically, each of the first and second timing operations is based upon the
time provided by
a clock of the downhole processing device. Typically, the first and second
timing operations
comprise respective first and second timers which optionally run from the same
clock.
Optionally, the downhole processing device is contained within a downhole
control device
that is connected to a downhole tool. Optionally, the downhole control device
further
comprises a downhole power source which is optionally a battery.
Optionally, a downhole motor is connected to and further optionally controlled
by the
downhole processing device wherein the downhole motor is capable of operating
the
downhole tool when instructed to do so by the downhole processing device.
Optionally a downhole system for controlling a downhole tool in a well
comprises:-
a downhole processing apparatus in accordance with the first aspect;
a downhole power source to provide power to at least a portion of the downhole
processing apparatus;
a first downhole sensor capable of at least receiving a signal sent by a first
transmission mechanism;
a second downhole sensor capable of at least receiving a signal sent by a
second
transmission mechanism; and
a downhole motor controlled by the downhole processing apparatus and which is
capable of operating the downhole tool.
Optionally, the downhole power source is a battery.
Optionally, the signals are sent by an operator or under an operator's
instruction. The
signals may be transmitted from a location remote from, and optionally not in
physical
connection with, the location of the said first and second sensors.
Optionally, the signals
may be transmitted wirelessly. Further optionally, the signals may be
transmitted from the
surface of the well and optionally from a location remote from the downhole
location
occupied by the downhole system.
Date Recue/Date Received 2021-08-11
9
Optionally a structure for controlling a downhole well comprises:-
a downhole tubing string for running into the well, the downhole tubing string
comprising one or more downhole systems in accordance with the second aspect
of the
present invention; and
one or more downhole tools associated with the downhole tubing string; wherein
the
one or more downhole tools are controlled by the said one or more downhole
systems.
Optionally, the one or more downhole tools associated with the downhole tubing
string are
connected in the downhole tubing string or are otherwise located downhole but
will be
associated with the downhole tubing string once it is run into the well.
Optionally, the tubing
string is a work string such as a coiled tubing string or downhole rod string
or drill pipe string
or the like. Alternatively, the tubing string is a production tubing string or
the like.
Optionally a method of transmitting instructions to control a downhole tool in
a well, the
method comprises the steps of:-
initiating a first timing operation associated with a first downhole sensor
capable of at
least receiving a signal sent via a first transmission mechanism;
initiating a second timing operation associated with a second downhole sensor
capable of at least receiving a signal sent via a second transmission
mechanism;
sending data via at least one of the first and second transmission mechanism
such
that said data is stored within a data storage device; and triggering a
downhole processing
device with the first and second timing operations to check the data storage
device, at least
once during a timed period associated with the respective first and second
timing
operations, for said data received from the said at least one of the first and
second
downhole sensors;
such that the downhole processing device acts upon that data to control the
downhole tool if instructed to do so.
The various aspects of the present invention can be practiced alone or in
combination with
one or more of the other aspects, as will be appreciated by those skilled in
the relevant arts.
The various aspects of the invention can optionally be provided in combination
with one or
Date Recue/Date Received 2021-08-11
10
more of the optional features of the other aspects of the invention. Also,
optional features
described in relation to one embodiment can typically be combined alone or
together with
other features in different embodiments of the invention. Additionally, any
feature disclosed
in the specification can be combined alone or collectively with other features
in the
specification to form an invention.
Brief Description of the drawings
Embodiments of the invention will now be described with reference to the
accompanying
Figures (Figs.), in which:-
Fig. 1 is a schematic view of a horizontal well prior to initiation of
production;
Fig. 2 is a schematic view of a horizontal well in full production;
Fig. 3 is a schematic diagram of components that form part of a downhole
apparatus
suitable for carrying out the present invention;
Fig. 4 is a flow diagram showing a general overview of some of the steps of
operation conducted by a Microprocessor Unit of the downhole apparatus of Fig.
3;
Fig. 5 is a flow diagram showing the steps of operation conducted by the
Microprocessor Unit of the downhole device of Fig. 3 during Interrupt Service
Routine (ISR)
1;
Fig. 6 is a flow diagram showing the steps of operation conducted by the
Microprocessor Unit of the downhole device of Fig. 3 during ISR 2; and
Fig. 7 is a flow diagram showing the steps of operation conducted by the
Microprocessor Unit of the downhole device of Fig. 3 during ISR 3.
Detailed Description of the Drawings
In the description that follows, like parts are marked throughout the
specification and
drawings with the same reference numerals, respectively. The drawings are not
necessarily
to scale. Certain features of the invention may be shown exaggerated in scale
or in
somewhat schematic form, and some details of conventional elements may not be
shown in
the interest of clarity and conciseness. The present invention is susceptible
to embodiments
Date Recue/Date Received 2021-08-11
11
of different forms. There are shown in the drawings, and herein will be
described in detail,
specific embodiments of the present invention with the understanding that the
present
disclosure is to be considered an exemplification of the principles of the
invention, and is not
intended to limit the invention to that illustrated and described herein. It
is to be fully
recognized that the different teachings of the embodiments discussed below may
be
employed separately or in any suitable combination to produce the desired
results.
The following definitions will be followed in the specification. As used
herein, the term
"wellbore" refers to a wellbore or borehole being provided or drilled in a
manner known to
those skilled in the art. The wellbore may be 'open hole' or 'cased', being
lined with a
tubular string. Reference to up or down will be made for purposes of
description with the
terms "above", "up", "upward", "upper" or "upstream" meaning away from the
bottom of the
wellbore along the longitudinal axis of a work string and "below", "down",
"downward",
"lower" or "downstream" meaning toward the bottom of the wellbore along the
longitudinal
axis of the work string. Similarly 'work string' refers to any tubular
arrangement for
conveying fluids and/or tools from a surface into a wellbore. In the present
invention,
production tubing is the preferred work string.
The various aspects of the present invention can be practiced alone or in
combination with
one or more of the other aspects, as will be appreciated by those skilled in
the relevant arts.
The various aspects of the invention can optionally be provided in combination
with one or
more of the optional features of the other aspects of the invention. Also,
optional features
described in relation to one embodiment can optionally be combined alone or
together with
other features in different embodiments of the invention.
Various embodiments and aspects of the invention will now be described in
detail with
reference to the accompanying figures. Still other aspects, features, and
advantages of the
present invention are readily apparent from the entire description thereof,
including the
figures, which illustrates a number of exemplary embodiments and aspects and
implementations. The invention is also capable of other and different
embodiments and
aspects, and its several details can be modified in various respects, all
without departing
from the scope of the present invention as defined by the claims.
Date Recue/Date Received 2021-08-11
12
Any discussion of documents, acts, materials, devices, articles and the like
is included in the
specification solely for the purpose of providing a context for the present
invention. It is not
suggested or represented that any or all of these matters formed part of the
prior art base or
were common general knowledge in the field relevant to the present invention.
Accordingly, the drawings and descriptions are to be regarded as illustrative
in nature, and
not as restrictive. Furthermore, the terminology and phraseology used herein
is solely used
for descriptive purposes and should not be construed as limiting in scope.
Language such
as "including", "comprising", "having", "containing" or "involving" and
variations thereof, is
intended to be broad and encompass the subject matter listed thereafter,
equivalents and
additional subject matter not recited, and is not intended to exclude other
additives,
components, integers or steps. Likewise, the term "comprising" is considered
synonymous
with the terms "including" or "containing" for applicable legal purposes.
All numerical values in this disclosure are understood as being modified by
"about". All
singular forms of elements, or any other components described herein including
(without
limitations) components of the embodiments of downhole control device 44 in
accordance
with the present invention to be described in detail subsequently are
understood to include
plural forms thereof and vice versa.
Figs. 1 and 2 show a well drilled into a formation 10. The well has a vertical
portion 12, a
horizontal portion 18, a heel 14 at the transition between the vertical
portion 12 and the
horizontal portion 18, and a toe 16 located at an end of the horizontal
portion 18. The well is
shown in Figs. 1 and 2 having tubing 42 such as production tubing 42 or work
string 42 or
wash pipe 42 inserted therein.
It should be noted that Figs. 1 and 2 are not to scale and that the horizontal
portion 18 of the
well may be many hundreds of metres or several kilometres long. However, it
should also
be noted that embodiments of the present invention to be described in detail
subsequently
are not limited to use only in horizontal wells but could be used in vertical
wells or inclined
wells that pass through the production zone at any angle.
Date Recue/Date Received 2021-08-11
13
Optionally, the production tubing 42 is formed from a plurality of individual
pipe lengths that
are interconnected and sealed to form continuous hollow tubing. The production
tubing 42
can also incorporate other downhole devices and porting as appropriate. It
should also be
noted that embodiments of the present invention to be described in detail
subsequently are
not limited to use with production tubing 42 but could instead be used during
the well
completion process and particularly could be used when fracturing a well (also
known as
fracking or fracing/frac'ing) in which case the production tubing 42 shown in
Fig. 1 would be
replaced by work string or wash pipe 42 carrying one or more packers (not
shown to isolate
the section of the well to be frac'ed.
In Fig.1 as shown, in the horizontal portion 18 of the well, the production
tubing 42
incorporates several downhole processing apparatus in accordance with the
first aspect of
the present invention in the form of downhole control devices 44 spaced at
various points
along the production tubing 42. Each control device 44 is located in close
proximity to a
respective port 26 which forms an aperture through the sidewall of the
production tubing 42
and which can be opened or closed by a respective downhole tool 100
incorporating a
moveable sleeve 100 as will be detailed subsequently but it should be noted
that the
moveable sleeve 100 and associated port 26 could be replaced by a different
sort of
downhole tool 100 (that may or may not be associated with a port 26) that
requires to be
operated by an operator.
There are three ports 26 shown in Fig. 1 and 2 denoted consecutively 26a, 26b,
26c from
the heel 14 towards the toe 16 of the well and a respective downhole device
44a, 44b, 44c
is associated with each port 26a, 26b, 26c. The control devices 44 are shown
incorporated
in part of a sand screen 24 although it should be noted that the sand screen
24 is not
essential and may or may not be included in the tubing 42 around the
respective port 26,
particularly if the wellbore is not prone to sand ingress.
As shown in Figs. 1 and 2, each control device 44 is connected to and is
capable of
controlling a respective downhole tool 100 comprising a controllable and
moveable sleeve
100 which covers a respective port 26 and again each sleeve is consecutively
denoted
Date Recue/Date Received 2021-08-11
14
100a, 100b, 100c from the heel 14 to the toe 16 of the well. In general, the
sleeves 100a,
100b, 100c are selectively controllable (by the respective control device 44
as will be
detailed subsequently) to move between the first configuration shown in Fig.1
in which they
are covering and thereby obturating the ports 26a, 26b and 26c respectively
(thus
preventing fluid flow through the ports 26a, 26b and 26c between the
throughbore 40 of the
production tubing 42 and the annulus 43 of the wellbore), and the second
configuration
shown in Fig.1 in which the sleeves 100a, 100b, 100c have been moved away from
and
have therefore uncovered the ports 26a, 26b and 26c respectively (thus
permitting fluid
communication and therefore fluid flow through the ports 26a, 26b and 26c
between the
throughbore 40 of the production tubing 42 and the annulus 43 of the
wellbore).
It should however be noted that other forms of downhole tool 100 (other than
downhole
sleeves) could be controlled by embodiments of control device 44 in accordance
with the
present invention. Additionally, any number (i.e. a plurality) of downhole
tools 100 (which
may be downhole sleeves or other forms of downhole tool 100) could be
controlled by the
one control device 44 in accordance with the present invention.
At the toe 16 of the well, the production tubing 42 has a closed end and
orifices 26d are
provided adjacent the closed end. A sleeve 100d is provided to selectively
obturate the
orifices 26d at the toe 16 of the well. In Fig. 1, the sleeve 100d is shown as
it will be
positioned when the production tubing 42 is run in, with the orifices 26d in
fluid
communication with the annulus surrounding the production tubing 42. However,
it could be
that all the orifices 26 are run into the wellbore in the closed position.
An embodiment of a downhole control device 44 is shown in Fig. 3.
As shown in Fig. 3, at the heart of the downhole control device 44 is a Micro
Controller Unit
(MCU) 202 which may be in the form of an integrated chip mounted on an
integrated circuit
board. The MCU 202 is powered by a suitable power source which is optionally a
battery 66
which outputs a DC voltage which may be in the region of 22 volts (but other
voltages could
be output) and which is supplied to the MCU 202 via suitable power
conditioning unit 204.
The power conditioning unit 204 typically supplies the specifically required
voltage to the
Date Recue/Date Received 2021-08-11
15
MCU 202 (typically 3.3 volts) and optionally can also supply the specifically
required voltage
(typically 5 volts) for other components that require power in the downhole
device 44.
The MCU 202 optionally comprises a small form computer having a memory or data
storage
facility (not separately shown), a microprocessor for processing data (not
separately
shown), a clock that provides the ability for the MCU 202 to perform at least
one or more
timing operation(s) (not separately shown) and data input/output connections
(205, 59, 211,
212).
As is further shown in schematic form in Fig. 3, each downhole device 44
comprises an
RFID reader 60 which in turn comprises an antenna 62. A preferred antenna 62
is
disclosed in W02009/050518 to Petrowell(TM) Limited of Aberdeen, UK. The
antenna 62
itself is optionally cylindrical and has a bore extending longitudinally
therethrough and is
arranged to be is accommodated co-axially within the tubing 42. The inner
surface of the
antenna 62 may be flush with an inner surface of the adjacent production
tubing 42 so that
there is no restriction in the throughbore 40 in the region of the antenna 62.
The antenna 62
optionally comprises an inner liner and a coiled conductor in the form of a
length of copper
wire that is concentrically wound around the inner liner in a helical coaxial
manner.
Insulating material optionally separates the coiled conductor from the
recessed portion (not
shown) of the sub in which the antenna is co-axially arranged within, in the
radial direction.
The liner and insulating material are formed from a non-magnetic and non-
conductive
material such as resin, fibreglass, rubber or the like. The antenna 62 is
formed such that
the insulating material and coiled conductor are sealed from the outer
environment and the
throughbore 40. The antenna 62 may be in the region of 1 metre or less in
length and more
preferably is in the region of 40 cm in length. Accordingly, RFID reader 60
comprising an
RFID antenna 62 is optionally provided within the downhole device 44 in a
manner similar to
the RFID reader disclosed in W02009/050518 to Petrowell(TM) Limited of
Aberdeen, UK, but
the RFID reader 60 and associated RFID antenna 62 could be provided as part of
a
separate downhole tool or sub-tool. In any case, the RFID reader 60 and
associated RFID
antenna 62 is connected to a power and data input/output 59 of the MCU 202 via
suitable
wiring such that the MCU 202 can both power the RFID reader 60 and/or supply
data to the
RFID reader 60 that as will be described can be used to charge up and then
transmit data to
Date Recue/Date Received 2021-08-11
16
a passing RFID tag or can read data from a passing RFID tag and transmit that
data to the
MCU 202 via the data input 59.
A pressure transducer sensor 210 is connected to a data input 211 of the MCU
202 via
suitable wiring with suitable signal conditioning 213 therebetween and, as
will be described
in more detail subsequently, the pressure transducer is arranged in the
downhole device 44
such that it can sense the pressure of downhole fluid surrounding the downhole
device 44
and supply the associated data about the pressure reading it takes to the MCU
202 either
on an automatic basis or more preferably on a controlled basis when requested
by the MCU
202 to do so.
A controllable electrical power output 205 of the MCU 202 is connected to a
motor drive 204
via suitable wiring and which when operated will mechanically drive a pump 208
to pump
hydraulic fluid to do the desired work (such as open a sleeve 100) assuming
that a spool
valve 215 is aligned in the appropriate configuration as will now be
described.
A further controllable electrical power output 212 of the MCU 202 is connected
to a second
motor drive 214 via suitable wiring and which (when operated by the MCU 202)
will
mechanically drive a spool valve 215 which can be arranged to move or
translate between
at least two positions or configurations. The spool valve has a first position
or configuration
in which the hydraulic output of the pump 208 is not in fluid communication
with the sleeve
100 and therefore the hydraulic fluid is prevented from moving downhole sleeve
100.
Furthermore, the spool valve 215 has a second position or configuration in
which the
hydraulic output of the pump 208 is in fluid communication with the sleeve 100
and therefore
the hydraulic fluid output by the pump 208 (if the latter is actuated by the
MCU 202) is
permitted to flow to the downhole tool 100 such that it does the desired work
(such as open
the sleeve 100).
The MCU 202 may additionally provide a further timing operation (not shown) so
that once
either the RFID antenna 62 or the pressure transducer 210 have read a signal
that
corresponds to an actuation command for actuating e.g. the sleeve 100 (by
means of the
Date Recue/Date Received 2021-08-11
17
pump 208 and spool valve 215), the actual step of actuation can be carried out
at a
predetermined time interval after the signal/command is received.
A suitable sliding sleeve 100 and a suitable sub containing ports 26 are
disclosed in
W02009/050518 to Petrowell(TM) Limited of Aberdeen, UK.
RFID tags (not shown) for use in conjunction with the antenna 62 described
above can be
those produced by Texas lnstruments(TM) such as a 32mm glass transponder with
the model
number RI-TRP-WRZB-20 suitably modified for use downhole. The tags should be
hermetically sealed and capable of withstanding high temperatures and
pressures. Glass or
ceramic tags are preferable and should be able to withstand pressure of 20 000
psi (138
MPa). Oil filled tags are also well suited to use downhole, as they have a
good collapse
rating. The skilled person will realise however that other suitable RFID tags
can be used.
Prior to being run into the well, the tubing 42 is made up incorporating a
plurality of
downhole devices 44. The devices 44 may be located spaced apart along the
tubing string
42 so that once run in, they will be positioned adjacent areas of the
formation 10 that
contain hydrocarbon reservoirs of interest. Once a borehole has been drilled
and the well is
ready to be completed, the tubing 42 is run downhole into the position shown
in Fig. 2. As
the tubing 42 is run downhole, the sleeves 100a, 100b, 100c of each of the
downhole
devices 44 are in the closed position, in which the sleeve 100 substantially
obturates the
respective ports 26, except for orifices 26d positioned at the end of the
tubing 42. At the
end of the tubing 42, the sleeve 100d is in the second open configuration in
which the
orifices 26d are in fluid communication with the annulus surrounding the
tubing 42.
However, the skilled person will realise that other suitable running in
configurations can be
used.
In one embodiment of a method of controlling the wellbore in accordance with
the present
invention, kill fluid is then pumped downhole into the well. The kill fluid is
optionally a high
density mud that substantially restricts egress of reservoir fluids out of the
formation 10 and
into the tubing 42 or the annulus surrounding the tubing 42. The sleeves 100a,
100b, 100c
remain in the first closed position in Fig. 2 with the ports substantially
obturated while the kill
Date Recue/Date Received 2021-08-11
18
fluid is pumped downhole. Since the sleeves 100a, 100b, 100c obturate the
respective
ports 26a, 26b, 26c, there is no access to the annulus from the throughbore 40
until the end
open orifices 26d are reached at the toe 14 of the well. As a result, an
operator can be sure
that kill fluid pumped into the throughbore 40 of the tubing 42 reaches the
toe 14 of the well
once the requisite volume of kill fluid has been pumped downhole. Therefore,
complete
circulation of kill fluid can be achieved by pumping fluid directly down the
tubing 42 since the
kill fluid cannot escape through the ports 26a, 26b, 26c. However, the skilled
person will
realise that other suitable methods of controlling the well can be employed by
the operator.
Embodiments in accordance with the present invention of the process steps that
the MCUs
202 of one, some or all of the downhole devices 44 shown in Figs. 1 and 2
follow will now
be described.
The power on stage of the MCU 202 is shown as START 300 in Fig. 4. The MCU 202
may
be powered on at stage START 300 at the surface of the well prior to the
downhole device
44 being run into the well 12 or it could be powered on by a separate timer
system switching
the MCU 202 on after a particular time has lapsed or indeed could be switched
on by a
suitable switching device for a downhole tool such as that disclosed in
W02009/109788 to
Petrowell(TM) Limited of Aberdeen, UK. Once the MCU 202 has been powered on at
stage
START 300, a first timing operation referred to as TIMER 1 is initiated at
stage 302 and that
loads a start value (for example 16 milliseconds) from a predetermined
register stored in
suitable non-volatile memory (not shown separately) associated with the MCU
202. That
start value of for example 16 ms which is delivered to TIMER 1 at stage 302
could however
be changed for instance by data that is transmitted from the switching device
that is
disclosed in W02009/109788 to Petrowell(TM) Limited of Aberdeen, UK.
Thereafter, a second timing operation referred to as TIMER 2 is initiated at
stage 304 and a
start value, for example 10 seconds, is loaded into TIMER 2 from non-volatile
memory.
A third timing operation referred to as TIMER 3 is thereafter initiated at
stage 306 and is
provided with a load start value which could be for a longer period such as
many days,
weeks or even months.
Date Recue/Date Received 2021-08-11
19
Optionally, each TIMER 1, 2 and 3 is associated with a separate task and, as
will be
described subsequently in more detail, in this example those tasks are as
follows:-
TIMER 1 = operation of an RFID reader 60;
TIMER 2 = operation of a pressure transducer 210; and
TIMER 3 = operation of a contingency action, such as instructing all
associated
downhole tools 100 to open.
The separate results of initiating TIMER 1 (at stage 302), TIMER 2 (at stage
304) and
.. TIMER 3 (at stage 306) will be detailed subsequently.
The MCU 202 then enters an endless loop at return point or stage 312.
The first stage of the endless loop comprises a step "LOOK FOR USER
INTERVENTION"
noted as 308 in Fig. 4. This stage 308 is particularly useful if the downhole
device 44 starts
(at START stage 300 in Fig. 4) with none of INTERRUPT SERVICE ROUTINES (ISR)
1, 2
or 3 enabled, as will be discussed in detail subsequently. If this is the
case, then the MCU
202 will look at the "LOOK FOR USER INTERVENTION" stage 308 for separate
specific
instructions from the user or operator of the downhole device 44 and such
separate specific
instructions can be transmitted by means of a separate data transmission
device such as
the switching device for a downhole tool disclosed in W02009/109788 to
Petrowell(TM)
Limited.
However, if no instructions are received at stage 308 to the contrary, then
the
microprocessor 202 will move to stage 310 of "DO WORK" which entails the MCU
202
looking at its associated memory buffer for valid flags. If valid flags are
present in the
associated memory buffer then the MCU 202 will suspend looking for the
interrupt created
by the ISR 1, ISR 2 or ISR 3 (as will be detailed subsequently) and will do
whatever the
valid flag instructions instruct (i.e. open downhole sleeve 100B for example).
Date Recue/Date Received 2021-08-11
20
Once the MCU 202 has completed the "DO WORK" stage 310, the MCU 202 returns to
return/entry point 312 and then starts the endless loop again by proceeding to
step "LOOK
FOR USER INTERVENTION" 308.
As discussed above, the MCU 202 is provided with an INTERRUPT SERVICE ROUTINE
(ISR) for each of the timing operations TIMER 1 (302), TIMER 2 (304) or TIMER
3 (306). In
general, the interrupt service routines ISR 1 (350), ISR 2 (400) and ISR 3
(450) can each
store flags in the memory buffer associated with the MCU 202 and in doing so
can instruct
the MCU 202 to do different work at stage DO WORK 310 depending upon the
instructions
sent from the surface by the operator of the downhole device 44 (and in the
case of ISR 3
will instruct the MCU 202 to do the pre-determined contingency action without
needing a
specific signal to be sent from the surface by the operator of the downhole
device 44).
Fig. 5 shows INTERRUPT SERVICE ROUTINE (ISR) 1 (350) and which is associated
with
stage INITIATE TIMER 1(302) of Fig. 4.
In this embodiment, stage INITIATE TIMER 1 (302) loads a start value of 16
milliseconds
into TIMER 1 and TIMER 1 counts down to zero seconds and when TIMER 1 reaches
zero
seconds, it then resets back to its start value of 16 milliseconds and counts
down again to
zero seconds and this countdown is repeated until the downhole device 44 is
switched off or
the battery 66 runs out of power.
ISR 1 (350) is arranged to observe when TIMER 1 (302) underflows and such an
underflow
condition is when TIMER 1 (302) reaches zero and then resets back to 16
milliseconds.
At the point that TIMER 1 (302) underflows, the ISR 1 (350) starts and
progresses to stage
352 "TURN OFF CHARGE". Stage 352 turns off the charge that is applied to the
RFID
antenna 62 (the antenna 62 having previously been charged).
The next stage is "LISTEN FOR TAG" 354 in which the RFID reader 60 monitors
the output
of the RFID antenna 62 and observes whether or not an RFID tag (not shown) is
present
within the RFID antenna 62, the RFID tag (not shown) having been dropped into
the fluid
Date Recue/Date Received 2021-08-11
21
being pumped down the throughbore 40 of the production tubing 42 at the
surface of the
well by the operator.
Stages 352 and 354 combined together take approximately 2 milliseconds and
therefore
mean that the RFID antenna 62 is not supplied with power from the battery 66
for those two
milliseconds and therefore have the great advantage that that battery power 66
is saved for
those two milliseconds. Considering that the RFID antenna 62 will be switched
on after
stage 354 has completed (i.e. after two milliseconds has passed) that means
that there is an
approximate 12.5% saving in the amount of power used by the RFID antenna 62
(considering that the RFID antenna 62 will be switched on for the remaining 14
milliseconds
of the 16 millisecond cycle associated with TIMER 1(302).
After stage 354 has been completed, Interrupt Service routine ISR 1 then moves
to the next
stage, "DECODE TAG" stage 356. If an RFID tag (not shown) was present within
the RFID
antenna 62 and was detected by the RFID reader 60, the MCU 202 will store a
valid flag in
its associated memory buffer along with the data transmitted by the RFID tag
and received
by the RFID reader 60 at the "DECODE TAG" stage 356.
The interrupt service routine ISR 1(350) then moves to the "RETURN TO MAIN
PROCESS"
stage 358 (and hence in essence the MCU can be considered as having completed
that
routine ISR 1 until TIMER 1 underflows again at which point ISR 1 (305)
(assuming it is
enabled) will be commended again).
Accordingly, if a valid flag was placed into the memory buffer at stage 356
during Interrupt
service routine ISR 1 (305), the MCU 202 will note that during the "DO WORK"
stage 310.
Otherwise, ISR 1 (350) will run again and interrupt service routine ISR 1
(350) is repeated
on the next underflow of TIMER 1 (and that will repeat each time TIMER 1
underflows).
Importantly, ISR 1 (350) can be switched/enabled on or off by an enable or
disable routine
351 and the enable or disable routine 351 is also controlled by the MCU 202
and can be
switched between enable or disable by instructions received from the surface
by the
Date Recue/Date Received 2021-08-11
22
operator transmitting data containing those instructions. The significant
advantages that this
feature provides will be discussed subsequently.
Interrupt service routine ISR 2 (400) is shown in Fig. 6 and is associated
with and operated
by TIMER 2 (304). Upon power up of the downhole device at stage 300 in Fig. 4,
TIMER 2
(304) is initially loaded with a start value of for example 10 seconds and
TIMER 2 counts
down from 10 seconds to zero and upon underflow wraps back round to its loaded
start
value of 10 seconds and that countdown, underflow and reset process repeats
continuously.
ISR 2 (400) monitors for when TIMER 2 underflows and at that point ISR 2 (400)
moves to
its next stage of "TAKE PRESSURE READING" 402 and which takes a pressure
reading
from the pressure transducer 210 where the pressure transducer 210 provides a
reading of
the downhole fluid pressure at its location. That pressure reading is provided
to stage 404
"RUN MATH CALCULATION" at which point the MCU 202 compares the pressure
reading
taken at stage 402 with at least the immediately previous pressure reading and
calculates
the change in pressure (that is it calculates the difference in the two
pressure values) and
also calculates if that change is positive or negative and that information is
stored in the
MCU's 202 memory buffer.
ISR 2 (400) then moves to the next stage of "RETURN TO MAIN PROCESS" 406. The
MCU 202 will therefore monitor and look for any valid flag that has been
presented into its
memory buffer by the ISR 2 (400) and if so will do the work that is associated
with that valid
flag and with the earlier stored pressure reading information, by comparing it
against stored
instructions so that the MCU 202 can then determine if an instruction has been
sent and if
so what that instruction means, during its "DO WORK" stage 310.
Consequently, operation of the MCU 202 will result in a pressure reading being
taken and
stored every 10 seconds and that will enable an operator at the surface to
pressure pulse
the downhole fluid and in a matter of minutes will enable the operator to
transmit instructions
to the MCU 202 because the MCU 202 has been previously provided with a set of
instructions to store within its non-volatile memory to for example open
sliding sleeve 100C
if there is a particular series of pressure changes (for example, a relatively
high pressure
Date Recue/Date Received 2021-08-11
23
followed by a relatively low pressure repeated 3 times) within a particular
time scale (for
example 12 minutes).
Again, and importantly, the ISR 2 (400) can be enabled or disabled by switch
401 such that
the ISR 2 (400) could for instance be disabled by an instruction sent from the
surface by the
operator by means of pressure pulsing (in that it can be instructed to switch
itself off) or
indeed such a signal could be transmitted from the surface by the operator by
another
transmission means or mechanism, e.g. by RFID tag that can be detected by ISR
1 (350)
(assuming ISR 1 is enabled at that point in time by its switch 351).
ISR 3 (450) is shown in Fig. 7 and is associated with and operated by TIMER 3
(306).
TIMER 3 (306) is initialised when the downhole device 44 is powered on START
300 and is
loaded with a start value which could be a much longer period of time such as
days, weeks
or even months and ISR 3 (450) will again monitor the underflow of TIMER 3 and
once it
detects that underflow it will move to stage 452 "DO CONTINGENCY ACTION" which
could
be for example to open all downhole sleeves 100. Once stage 452 has been
completed,
ISR 3 will move to stage 454 "RETURN TO MAIN PROCESS". Importantly, ISR 3
(450) can
again be enabled or disabled via switch 451 and therefore if the operator does
not wish to
allow ISR 3 (450) to operate, the operator can send a signal from the surface
to the
downhole device 44 to disable ISR 3 (450) via switch 451.
In practice, (assuming for example that the ISR 1 (350) is enabled via its
switch 351 and
that ISR 2 (400) is enabled via its switch 401) the MCU 202 will give the
appearance of
looking for both pressure pulsing (via ISR 2(400) and also RFID tags (via ISR
1(350)
concurrently but in actual fact is multi-plexing between the two different
transmission
mechanism because it is running ISR 1 (350) and ISR 2 (400) in parallel but
looks for the
valid flags in its memory register in series.
Importantly, in practice, the ISR 1 (350) is likely to be switched off via its
enable or disable
switch 351 for a significant amount of time that the downhole device 44 is in
use because
operating and powering the RFID antenna 62 uses approximately 10 times the
amount of
power that is used by the pressure pulse detection method operated by ISR 2
(400).
Date Recue/Date Received 2021-08-11
24
Accordingly, it is likely in practice that the operator will use ISR 2 (400)
to send instructions
via pressure pulsing to the MCU 202 to switch on ISR 1 (350) by switching on
its enable or
disable switch 351 (RFID tags being able to contain a lot more data and also
can transmit
that data at a much higher data burst rate than can be sent via the relatively
slow data rate
of the pressure pulse method).
Accordingly, in practice, the completion that is shown in Fig. 1 could be run
in with all the
downhole tools 100 closed and with ISR 1 (350) switched off via its switch
351. The
operator could then send pressure pulses with a particular code that is
detected by the
pressure transducer 210 and decoded by the MCU 202 and that code could for
instance
instruct the MCU 202 during its DO WORK stage 310 to switch on enable switch
351
immediately (or could instruct ISR 1 (350) to switch on in a number X of hours
time) and
could also instruct ISR 1 (350) to remain switched on for a number Y of hours
thereafter and
therefore look for RFID tags in that period of time when it is switched on.
Consequently, the ability to switch between the two data transmission
mechanism of RFID
Tags and pressure pulsing enables the operator to be able to choose the
highest data
transfer rate but also allows the operator to conserve the valuable battery
power.
The operator will likely keep the relatively low power pressure pulse
transmission method
switched on all the time via its enable switch 401 in order to provide at
least one data
transmission method at all times. For instance, if the operator is sending
pressure pulses to
a lower most downhole device 44C with a 3 minute pressure pulse and it does
not open its
associated downhole tool 100C for any reason, the operator can take the
decision to
abandon that downhole tool 100C and instead instruct the next highest downhole
device
44B to open its associated downhole tool 100B with, for example a 5 minute
pressure pulse.
Accordingly, by keeping ISR 2 (400) switched on all the time via its enable
switch 401, the
operator will always have the contingency of being able to send pressure
pulses (assuming
pressuring up the downhole fluid is possible).
An RFID tag (not shown) is programmed at the surface by an operator to
generate a unique
signal according to the present embodiment. Similarly, prior to being included
in the device
Date Recue/Date Received 2021-08-11
25
44 at the surface, each of the electronics packs coupled to the respective
antenna 62, is
separately programmed to respond to a specific signal. The RFID tag comprises
a
miniature electronic circuit having a transceiver chip arranged to receive and
store
information and a small antenna within the hermetically sealed casing
surrounding the tag.
One or more pre-programmed RFID tag(s) is/are then weighted if required, and
dropped or
flushed into the well with the kill fluid. Alternatively, the tag can be
circulated through the
tubing 42 to reach the devices 44 with brine or diesel flushed downhole after
the kill fluid.
After travelling through the vertical portion 12 and throughbore 40 of the
tubing 42, the
selectively coded RFID tag reaches the downhole devices 44 that the operator
wishes to
actuate. The tag passes through the throughbore 40 and the antenna 62 of each
device 44.
During passage of the RFID tag (not shown) through the throughbore 40, the
antenna 62 of
the device 44 in question is of sufficient length to charge and read data from
the tag. The
tag then transmits certain radio frequency signals, enabling it to communicate
with the
antenna 62. This data is processed by the MCU 202 in the manner described in
detail
subsequently.
According to the present example, the RFID tag has been programmed at the
surface by the
operator to transmit information instructing that a particular sliding sleeve
100a, 100b, 100c
is to be opened.
Several tags programmed with the same operating instructions for individual
devices 44 can
be added to the well, so that at least one of the tags will reach the desired
antenna 62
enabling the operating instructions to be transmitted. Once the data is
transferred to the
device 44, the other RFID tags encoded with similar data can be ignored by the
antenna 62.
In practice there are likely to be many more devices 44 spaced axially along
the tubing 42
than shown in the schematic on Figs. 1 or 2. Several devices 44 adjacent a
particular part
of the formation 10 can be opened simultaneously. Certain devices 44 can
remain in the
closed configuration if data is gathered to suggest to an operator that an
adjacent formation
10 contains mainly gas or water. Alternatively, where the downhole devices 44
are mounted
Date Recue/Date Received 2021-08-11
26
on coiled tubing and run in as part of a frac'ing operation, one or more
selected downhole
control devices 44 can be actuated depending up on the required frac'ing
operation.
According to an alternative embodiment, and particularly if a complicated
downhole tool 100
sequence of operations is required, all the ISR 2's (400) of each downhole
device 44 can be
switched on via their respective enable switches by sending the appropriate
pressure pulse
sequence and thereafter, in order to actuate a specific downhole tool 100, a
tag
programmed with a specific signal is sent downhole. Each antenna 62 is either
responsive
to the signal of a specific tag or is responsive to all tags and the decoding
is done by the
MCU 202 to determine if it is the downhole tool 100 associated with that MCU
202 that is to
be actuated. In this way tags can be used to selectively target certain
devices 44 by pre-
programming the antennas 62 or the MCU's 202 and corresponding tags. Thus,
several
different tags may be provided to target different devices 44.
The tags may also be designed to carry data transmitted from antennas 62,
enabling them
to be re-coded during passage through the tubing 42. In particular, useful
data such as
temperature, pressure, flow rate and any other operating conditions of the
device can be
transferred to the tag. The antenna 62 can emit a radio frequency signal in
response to the
radio frequency signal it receives. This can re-code the tag with information
sent from the
antenna 62.
Additionally, and as described above, signals can be sent from the surface to
the MCU 202
to operate the downhole devices 100 by sending pressure pulses through the
wellbore fluid
(either in the throughbore 40 of the tubing 42 or through the fluid located in
the annulus 43,
wherein such pressure pulses are sensed by the pressure transducer 210 of each
device
44. Additionally, or alternatively, the MCU 202 may be pre-programmed to be
responsive to
any pressure above a threshold (in the most simple form) or to be responsive
to pressure
pulses in the form of a pre-determined pressure signature, in which case the
MCU 202 is
pre-programmed to identify rates of change with a certain repetition rate of
the pressure
pulses to avoid spurious actuation.
Date Recue/Date Received 2021-08-11
27
The method of the invention does not have to be used in conjunction with every
single
specific downhole device 44 described herein. According to an alternative
embodiment, the
production tubing 42 or coiled tubing 42 may be provided with one or more
modified devices
44 containing some other form of control mechanism such as a timer for
operating a
downhole tool 100.
According to the above embodiment, the sleeves 100a, 100b, 100c, 100d are
described as
moveable between a first closed and a second open configuration. However, the
sleeves
may also be movable to a plurality of intermediate configurations in which the
sleeve 100
partially obturates the ports 26 to controllably and selectively restrict or
choke but not
completely stop the flow of fluid.
The embodiment described herein has the advantage that the MCU 202 is in
practice
always receptive to either pressure pulse signals or RFID signals rather than
the prior art
disadvantage of for example an RFID reader able to seek or read an RFID signal
only
where there is circulation of fluid or only able to sense pressure pulse
signals only when the
tubing is closed. Therefore in a situation where the tubing 42 becomes blocked
and the
capacity for flow of fluid therethrough is restricted, the MCU 202 can still
respond to
pressure pulse signals as a result of the ability of the MCU 202 to multiplex
the respective
signals.
Other methods of remote actuation of the devices can also be used in addition
to RFID tags
and associated RFID Readers 60 and/or pressure pulses and associated pressure
transducers 210. For example, the devices 44 can be provided with suitable
sensors to
.. respond to acoustic or electromagnetic signals. For example, other but
different remote
control methods of communicating could be used in one or more modified
downhole control
devices instead of RFID tags and sending pressure pulses down the completion
fluid
located in the throughbore of the production tubing 42 such as an acoustic
signalling system
such as the EDGE(TM) system offered by Baker Oil Tools(TM) of Houston, Texas,
USA or an
.. electromagnetic wave system such as the Cableless Telemetry System
(CaTS(Tm)) offered
by Expro(TM) Group of Verwood, Dorset, UK.
Date Recue/Date Received 2021-08-11
28
Modifications and improvements can be made without departing from the scope of
the
invention. The ports can be obturated by means other than a sleeve. For
example, if the
sleeve is part of a sandscreen sub, actuation of the mechanism for moving the
obturation
member between first and second configurations can cause movement of an
annular plate
rather than a sleeve to selectively obturate the ports. In addition, for
example, a downhole
power generator can provide the power source in place of the battery pack. A
fuel¨cell
arrangement can also be used as a power source.
Date Recue/Date Received 2021-08-11
