Note: Descriptions are shown in the official language in which they were submitted.
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Downhole Tool Deployment
Field of the invention
The invention relates to tools for use in downhole or wellbore environments,
for
example in the oil and gas industry. More specifically, the invention relates
to
downhole tools for use in well intervention or workover operations, and in
specific
arrangements may relate to self-propelled and/or autonomous downhole tools..
Background
In the oil and gas industry, well boreholes ("wellbores") are drilled in order
to access
subsurface hydrocarbon-bearing formations. In order to control production from
a given
wellbore, a valve arrangement known as a Christmas tree is typically disposed
on the
wellhead, the valve arrangement comprising a number of flow control valves and
safety
valves configured amongst other things to control production, permit well
isolation and
control access of downhole tools and equipment into/from the wellbore.
During the operational life of a given well, it may be necessary to access the
wellbore
in order to perform remedial operations, known generally in the industry as
intervention
or workover operations.
However, while necessary, intervention operations pose a number of challenges
for
operators. For example, wellbores may be located in remote or relatively
inaccessible
locations, making them difficult and time consuming to access, particularly
for
intervention operations which require significant man-power to operate and/or
which
require equipment which by virtue of size or weight may be restricted or
prevented by
local infrastructure laws. Wel!bores may also be located in areas of
particular scientific
or environmental sensitivity. The given location may also pose challenges in
terms of
how to protect the environment, intervention equipment and personnel.
An operator may wish to carry out intervention operations a number of times in
order to
mitigate deferred production or otherwise maintain production at optimal
levels. One
such intervention operation involves the removal of paraffin wax, asphaltenes
and/or
other solids, residues and the like which can accumulate in the wellbore over
time and
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which reduce production or otherwise reduce the optimal operation of the well.
In
some instances, a given field may include a significant number of wells, some
fields
having hundreds of wells, making intervention operations difficult and in some
cases
prohibitively expensive to carry out regularly given the above factors and
demands on
personnel and equipment.
A number of intervention operations may be carried out using tools deployed on
slickline. Typically, a tool is introduced to the well on a slickline through
a stuffing box,
which is designed to seal around the slickline to prevent well fluids and
gases
escaping. In known arrangements, the stuffing box includes a sheave or pulley
assembly with a number of pulley wheels for guiding the slickline into the
well. The
slickline may be used to deploy the tool into the wellbore and/or to retrieve
the tool from
the wellbore.
Summary
According to the invention in an aspect, there is provided an apparatus for
fitting to a
wellbore. The apparatus may comprise a self-propelled downhole tool for
deployment
within the wellbore. The self-propelled downhole tool may be configured to
propel itself
along at least part of a length of the wellbore. The apparatus may comprise a
lubricator for fitting to a wellhead of the wellbore. The lubricator may be
fitted to the
wellhead via a valve system providing communication between the lubricator and
the
wellbore. The lubricator may be for housing the self-propelled downhole tool
when in a
stowed position. The lubricator may comprise an input port for receiving data
from a
remote unit. The input port may be in electrical communication with the self-
propelled
downhole tool when in the stowed position. The received data may comprise
instructions for operating the self-propelled downhole tool.
Optionally, the lubricator is configured to transfer the received data
communications to
the self-propelled downhole tool when in the stowed position.
Optionally, the input port comprises an electrical connector for connection to
the self-
propelled downhole tool when in the stowed position for creating an electrical
connection between the input port and the self-propelled downhole tool.
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Optionally, electrical connector and/or the self-propelled downhole tool are
configured
such that the electrical connection is broken when the self-propelled downhole
tool is
not in the stowed position. Optionally, electrical connector and/or the self-
propelled
downhole tool are configured such that the electrical connection may be broken
at a
point during deployment of the self-propelled downhole tool. Such a point
during
deployment may be at the time the downhole tool leaves the stowed position,
and in
some arrangements may be later. After the electrical connection is broken, the
self-
propelled downhole tool may operate autonomously for part of or all of the
deployment.
Optionally, the wellbore may form part of a flowing or producing well.
Accordingly, the
self-propelled downhole tool may be deployed in the flowing or producing well.
The
self-propelled downhole tool is able to drive itself into the wellbore against
the flow.
Optionally, communications data is received by the input port and is
transmitted to the
self-propelled downhole tool via the electrical connection.
Optionally, the apparatus further comprises at least one sensor configured to
sense
one or more downhole parameters during deployment of the self-propelled
downhole
tool. The at least one sensor may comprise one or more of a camera or other
light-
based sensor, a temperature sensor and a pressure sensor. The skilled person
will
envisage other sensors that may be used. Accordingly, the one or more downhole
parameters may comprise one or more of an image or light-based representation
of the
wellbore, a temperature sensed in the wellbore and a pressure sensed in the
wellbore.
The one or more parameters may be associated with a depth or other position in
the
wellbore and/or a time.
Optionally, the lubricator further comprises an output port for transmitting
sensor data
corresponding to the one or more sensed downhole parameters to the, or a
separate,
remote unit. Optionally, the output port comprises an electrical
connector for
connection to the self-propelled downhole tool when in the stowed position for
creating
an electrical connection between the output port and the self-propelled
downhole tool.
The output port may comprise at least part of the input port.
Optionally, the received data comprising instructions for operating the self-
propelled
downhole tool comprises one or more instructions based on the one or more
sensed
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downhole parameters. Such instructions may have been determined by the, or a
separate, remote unit receiving the sensor data. In this sense, "remote"
encompasses
a feature external to the wellbore and/or external to the output (or input)
port.
Optionally, the received data communications comprise data instructing the
self-
propelled downhole tool to deploy within the wellbore. Such instruction may be
arranged to be enacted immediately or at a later time.
Optionally, the data communications comprise one or more instructions setting
deployment parameters for a deployment of the self-propelled downhole tool.
The
deployment parameters may comprise one or more of a depth to which the self-
propelled downhole tool will be driven, a speed of drive of the self-propelled
downhole
tool, a sensor reading to take, an operation to undertake and a timing of any
of the
above or another deployment parameter. The skilled person will envisage other
deployment parameters.
Optionally, the self-propelled downhole tool comprises a processor configured
to store
the one or more instructions and/or one or more preloaded instructions.
Optionally, the processor is configured to control the self-propelled downhole
tool to
undertake the one or more instructions and/or the one or more preloaded
instructions.
Optionally, the processor is configured to determine one or more autonomous
instructions based at least in part on the one or more sensed downhole
parameters.
That is, the processor may be configured to determine one or more deployment
parameters (or instructions) without transmitting data associated with the
sensed
downhole parameters to a remote unit. The deployment parameters (or
instructions)
determined by the processor may relate to the current deployment and/or to
future
deployments.
Optionally, the processor is configured to control the self-propelled downhole
tool
autonomously.
Optionally, the one or more instructions comprise a plurality of instructions.
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Optionally, the plurality of instructions comprise a complete operation within
the
wellbore, including returning the self-propelled downhole tool to the stowed
position.
Optionally, after deployment, the self-propelled downhole tool is configured
to operate
5 autonomously.
Optionally, after deployment, the self-propelled downhole tool has no direct
and/or
physical connection to the remote unit.
Optionally, the self-propelled downhole tool comprises a battery to provide
power for
propelling the self-propelled downhole tool and/or to provide power to the
processor
and/or sensors.
Optionally, the input port is further configured to receive electrical power
from the, or a
further, remote unit.
Optionally, the battery is chargeable when the self-propelled downhole tool is
in the
stowed position.
Optionally, the apparatus further comprises a sealed end cap fitted to a
distal end of
the lubricator, and the input port forms part of the end cap. The sealed end
cap means
that the lubricator, and therefore the wellbore, is sealed and is therefore at
a lower risk
of leaks.
Optionally, the input port comprises an electrical connector for fitting to an
external
cable.
According to the invention in an aspect, there is provided a self-propelled
downhole
tool for deployment within a wellbore. The self-propelled downhole tool may
comprise
a drive mechanism for propelling the self-propelled downhole tool along at
least part of
a length of the wellbore. The self-propelled downhole tool may comprise a
receiver for
electrical communication with an input port of a lubricator when the self-
propelled
downhole tool is in a stowed position. The self-propelled downhole tool may be
configured to receive data communications from a remote unit for operating the
self-
propelled downhole tool.
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According to the invention in an aspect, there is provided a lubricator for
fitting to a
wellhead of a wellbore. The lubricator may be for fitting via a valve system
providing
communication between the lubricator and the wellbore. The lubricator may be
for
housing a self-propelled downhole tool when in a stowed position. The self-
propelled
downhole tool may be for deployment within the wellbore and may be configured
to
propel itself along at least part of a length of the wellbore. The lubricator
may comprise
an input port for receiving data from a remote unit, and for electrical
communication
with a receiver of the self-propelled downhole tool when in the stowed
position. The
received data may comprise instructions for operating the self-propelled
downhole tool.
According to the invention in an aspect, there is provided a method for
operating a self-
propelled downhole tool within a wellbore. The self-propelled downhole tool
may be
configured to propel itself along at least part of a length of the wellbore.
The method
may comprise stowing the self-propelled downhole tool in a stowed position. In
the
stowed position, the self-propelled downhole tool may be received within a
lubricator
fitted to a wellhead of the wellbore. The lubricator may be fitted via a valve
system
providing communication between the lubricator and the wellbore. The method
may
comprise transmitting, from a remote unit, data communications for operating
the self-
propelled downhole tool. The method may comprise receiving, at an input port
of the
lubricator, the transmitted data communications, the input port being in
electrical
communication with the self-propelled downhole tool. The method may comprise
deploying the self-propelled downhole tool based on the received data
communications.
According to the invention in an aspect, there is provided a method for
operating a self-
propelled downhole tool within a wellbore. The self-propelled downhole tool
may be
configured to propel itself along at least part of a length of the wellbore.
The method
may comprise sensing, by at least one sensor, one or more downhole parameters.
The method may comprise determining, based on the sensed downhole parameters,
one or more instructions setting deployment parameters for a deployment of the
self-
propelled downhole tool. The method may comprise deploying the self-propelled
downhole tool based on the determined instructions. The one or more
instructions may
be determined by a processor of the self-propelled downhole tool.
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The one or more instructions may be determined by a remote unit. Accordingly
the
method may comprise transmitting data relating to the sensed downhole
parameters to
the remote unit. The method may comprise stowing the self-propelled downhole
tool in
a stowed position. In the stowed position, the self-propelled downhole tool
may be
received within a lubricator fitted to a wellhead of the wellbore. The
lubricator may be
fitted via a valve system providing communication between the lubricator and
the
wellbore. The method may comprise, while the self-propelled downhole tool is
stowed,
transmitting, from the self-propelled downhole tool to a remote unit, the data
relating to
the sensed downhole parameters. The method may comprise determining, by the
remote unit, one or more instructions setting deployment parameters for a
deployment
of the self-propelled downhole tool. The method may comprise transmitting,
from the
remote unit, data communications comprising the determined instructions. The
method
may comprise receiving, at an input port of the lubricator, the transmitted
data
communications, the input port being in electrical communication with the self-
propelled
downhole tool.
Brief description of the drawings
Figure 1 shows an isometric view of a wellhead with a lubricator fitted
thereto;
Figure 2 shows an isometric view of a wellhead with a lubricator fitted
thereto along
with a plurality of remote units;
Figure 3a shows a section through part of a wellhead including a self-
propelled
downhole tool stowed within a lubricator;
Figure 3b shows a section through part of a wellhead including a self-
propelled
downhole tool during deployment; and
Figure 4 is a flow diagram of a method for operating a self-propelled downhole
tool
within a wellbore.
Detailed description
Referring first to Figure 1 of the accompanying drawings, there is shown an
apparatus
(e.g. an intervention system) 10 configured to perform an intervention
operation in a
wellbore 12. In the illustrated arrangement, the wellbore 12 is land-based
having a
wellhead valve arrangement in the form of a Christmas tree 14 disposed on a
wellhead
16.
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The intervention system 10 is configured to deploy an intervention tool into
the
wellbore 12. In the illustrated arrangement, the intervention tool comprises a
paraffin
wax removal tool for cleaning paraffin deposits from the wellbore 12 and
associated
infrastructure and equipment. However, it will be recognised that the
intervention
system 10 may be configurable to perform a number of different intervention
operations
using a suitable intervention tool. In such cases, the intervention tool is
typically be
deployed on a slickline or wireline through a stuffing box, as with the tool.
As shown in Figure 1, the intervention system 10 comprises a tool housing in
the form
of a lubricator 20. In the illustrated arrangement, the lubricator 20
comprises a stand of
three connected heavy wall tubing sections, the interior of the lubricator 20
defining a
tool storage compartment configured to house the intervention tool.
As shown in Figure 1, the lubricator 20 is coupled to and disposed on top of
the
Christmas tree 14. The lubricator 20 is fitted to the wellhead via a valve
system 22,
which in the illustrated arrangement forms part of the lubricator 20. The
valve system
may also include the Christmas tree. The valve system 22 permits selective
communication of tools and fluid between the lubricator 20 and the wellbore
12.
The exemplary valve system 22 shown has an upper control valve 24 and a lower
control valve 26, which can be controlled independently. The valve system 22
provides
a dual barrier between the lubricator 20 and the wellhead valve arrangement
14, and
permits an upper valve 28 of the Christmas tree 14 to be maintained in an open
condition.
The intervention system 10 is configurable between a tool stowed configuration
in
which the lubricator 20 is isolated from the wellbore 12 by the valve system
22 and an
activated configuration in which the valve system 22 is open and the
lubricator 20
communicates with the Christmas tree 14 and/or the wellbore 12 to permit
deployment
of the intervention tool by a tool deployment arrangement 30, as will be
described
below.
The tool deployment arrangement 30 is provided for deploying the intervention
tool into
the wellbore 12. The tool deployment arrangement 30 comprises a conveyance in
the
form of slickline or wireline 32 which is coupled to the intervention tool and
which
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extends through an upper end portion of the lubricator 20 via stuffing box 34
¨ in the
illustrated arrangement a dual chamber stuffing box - to ensure pressure
integrity of the
lubricator 20 and monitor any fluid/gas wire bypass.
The tool deployment arrangement 30 further comprises sheaves or pulleys 36, 38
for
supporting the wireline 32. In the illustrated arrangement shown in Figure 1,
pulley 36
is disposed on the lubricator 20 above the stuffing box 34 and pulley 38 is
tied to
wellhead 16, although it will be recognised that the pulleys 36, 38 may be
disposed at
other suitable locations.
Figure 2 shows an exemplary setup of an intervention apparatus or system at a
wellhead. The Christmas tree, lubricator and valve system arrangement of
Figure 2
may be the same or similar to that of Figure 1. A winch is provided as part of
a wireline
unit 40 and is operatively coupled to a drive which in the illustrated
arrangement takes
the form of a direct drive electric motor. In use, the drive rotates the winch
in order to
pay out the wireline 32 when it is desired to deploy the intervention tool 18
into the
wellbore 12, and to reel in the wireline 32 when it is desired to retrieve the
intervention
tool from the wellbore 12. That is, the tool is deployed and retrieved using
the wireline.
In addition, weight bars may be positioned on the tool to drive it into the
wellbore 12
when the wireline 32 is paid out. The weight bars take up considerable space
in the
lubricator 20.
As shown in Figure 2, the illustrated arrangement of an intervention apparatus
further
comprises a wireline power unit 42, a control power unit 44 and other
ancillary
equipment.
In Figure 1 (and similarly in Figure 2) a support arrangement in the form of
support
mast 58 supports the Christmas tree 14 and the lubricator 20.
In some arrangements, the intervention tool may form part of a self-propelled
downhole
tool for use in the wellbore 12. The self-propelled downhole tool may be
configured to
drive itself into the wellbore, powered by one or more motors. The one or more
motors
may be electric motors and may be provided with electrical power via a power
supply
similar to that shown in Figure 2. The self-propelled downhole tool may
comprise a
plurality of drive wheels. The drive wheels may be extendable on arms from a
main
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body of the self-propelled downhole tool to engage an inner wall of the
wellbore (or
production tubing or casing). The drive wheels may be electrically or
hydraulically
driven.
5 Figures 3a and 3b show an apparatus 300 for deploying a self-propelled
downhole tool
302 into a wellbore 304. In the example of Figure 3, the self-propelled
downhole tool
302 is not deployed on a slickline or wireline. The self-propelled downhole
tool 302 is
configured to operate autonomously.
10 As used herein, the term "autonomous" in respect of operation of the
self-propelled
downhole tool 302 encompasses a self-propelled downhole tool that is
instructed to
deploy and undertake a task, and then requires no further instruction during
that task in
order to complete it. Completion of the task may include the self-propelled
downhole
tool returning to a start position, such as the stowed position. In some
arrangements,
an autonomous self-propelled downhole tool may also require no power (e.g.
electrical
power and/or hydraulic power) after deployment in order to complete the task.
Accordingly, the self-propelled downhole tool may be configured, after
deployment, to
have no direct connection to any remote unit providing instructions to the
self-propelled
downhole tool. Direct connection in this context encompasses any communication
of
instructions, electrical power and/or hydraulic power to the self-propelled
downhole tool
from a remote unit via a physical medium, such as a wireline or slickline. The
downhole tool 302 may also gather data using sensors and use that gathered
data for
control of the tool 302 without assistance from other apparatus outside the
wellbore
304, e.g. from surface.
Figure 3a shows a top part of a Christmas tree 306, however a Christmas tree
need not
be used in all arrangements. Below the Christmas tree 306 and not shown in
Figure 3a
is the wellbore 304.
A valve system 308 is fitted to the Christmas tree 306 by a plurality of bolts
309,
although other fixings may be used. As in Figures 1 and 2, the valve system
308
provides communication between the Christmas tree 306 and/or the wellbore 304,
and
a lubricator 310, which is fitted to a distal end of the valve system 308. The
lubricator
310 is fitted to the valve system 308 by a plurality of bolts 311, although
other fixings
may be used. Communication between the lubricator 310 and the Christmas tree
306
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may be fluid communication and/or communication allowing the self-propelled
downhole tool 302 to pass from the lubricator 310 to the wellbore 304 and/or
from the
wellbore 304 to the lubricator 310. As in Figures 1 and 2, the valve system
308
comprises an upper valve 312 and a lower valve 314 that are controllable
independently. In some arrangements, the valve system 308 may form part of the
lubricator 310. In some arrangements, the valve system 308 may comprise a
different
number of valves, for example 1 or 3 valves. The Christmas tree may form part
of the
valve system 308.
As used herein, the term "distal" encompasses a feature of an apparatus that
is
positioned further away from the wellbore 304. The term "proximal" encompasses
a
feature that is positioned closer to the wellbore 304. For example, the valve
system
308 is generally elongate and has a proximal end fitted to the Christmas tree
306 and a
distal end fitted to the lubricator 310.
An end cap 316 is fitted to a distal end of the lubricator 310 by a plurality
of bolts 317,
although other fixings may be used. The end cap 316 is sealed. The end cap 316
comprises static features that form the seal. That is, the end cap 316 does
not include
a stuffing box or any mechanism through which a slickline or wireline can be
passed
and which a seal must be formed around. The end cap 316 comprises an input
port
318 through which data communications and/or electrical power may be received.
In
the example shown in Figure 3, the input port comprises an electrical
connector
configured to be connected to an external cable 320. The electrical connector
is
secured to the end cap 316 so as to form a seal. The external cable 320 may be
further connected to one or more remote units (not shown). The one or more
remote
units may be configured to supply data communications and/or electrical power
to the
apparatus 300 via the external cable 320. In other arrangements, the input
port 318
may comprise one or more wireless communications devices. In some
arrangements,
the one or more wireless communications devices may be positioned elsewhere
within
the apparatus 300. It is also noted that the input port 318 may also be
configured as
an output port or a separate output port may be provided on the apparatus. An
output
port may be arranged to transmit data communications from the self-propelled
downhole tool 302 and/or the lubricator 310 to one or more remote units.
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The lubricator 310 is configured to house the self-propelled downhole tool 302
when it
is stowed. That is, the lubricator 310 is configured to house the self-
propelled
downhole tool 302 before deployment and/or after completion of a task or
operation,
such as an intervention operation.
The self-propelled downhole tool 302 may further comprise an electrical
connector 322
that is configured for electrical connection to the input port 318. The input
port 318
may comprise an electrical connector 324, which is configured to connect with
the
electrical connector 322 of the self-propelled downhole tool 302. Accordingly,
an
electrical connection may be established between the input port 318 and the
self-
propelled downhole tool 302. The lubricator 310, and in the specific
arrangement of
Figure 3a, the input port 318, is able to receive data communications and/or
electrical
power from one or more remote units (not shown) and may pass those data
communications and/or the electrical power to the self-propelled downhole
tool. In the
example shown, the electrical connection is provided by the electrical
connectors 322,
324 although other arrangements, e.g. a wireless data link, may be used. The
data
communications received by the lubricator 310, via the input port 318,
comprise data
for operation of the self-propelled downhole tool 302, as explained below.
The self-propelled downhole tool 302 may comprise a battery pack 326, which is
configured to receive electrical power from the one or more remote units and
store it.
When the self-propelled downhole tool 302 is in the stowed position and
electrical
communication between the input port 318 and the self-propelled downhole tool
302 is
established, the battery pack 326 may be configured to receive electrical
power from
the one or more remote units to charge it. The self-propelled downhole tool
302 may
also comprise a memory 329 configured to store data received in the data
communications from the one or more remote units. When the self-propelled
downhole
tool 302 is in the stowed position, the data communications may be transferred
to the
memory 329 of the self-propelled downhole tool 302 over the electrical
connection via
the input port 318.
The lubricator 310 may include one or more cleaning apparatus 330. The
cleaning
apparatus 330 may be positioned at a point in the lubricator 310 such that the
self-
propelled downhole tool 302 must pass the cleaning apparatus 330 when being
deployed and/or when returning to the stowed position after deployment. That
is, the
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cleaning apparatus 330 may be positioned at a more proximal location than the
self-
propelled downhole tool 302 when the self-propelled downhole tool 302 is in
the
stowed position. The cleaning apparatus may comprise one or more brushes or
scrapers.
The lubricator 310 may have a reduced length over known lubricators. For
example,
the lubricator 310 may be short enough to fit between two decks of an offshore
rig.
This is possible at least partly because the weight bars used for known tool
deployments are not required in exemplary arrangements disclosed herein, as
deployment is made possible by the self-propulsion system of the downhole
tool.
Figure 3a shows the self-propelled downhole tool 302 in the stowed position
and
received within the lubricator 310. The self-propelled downhole tool 302 is
configured
to propel itself along at least part of a length of the wellbore 304. That is,
the self-
propelled downhole tool 302 may propel itself along the wellbore 304 without
receiving
further electrical power and/or data communications from a remote unit during
at least
part of a time period when it is deployed. Accordingly, the self-propelled
downhole tool
302 comprises a drive mechanism. The drive mechanism may comprise a motor. The
drive mechanism may comprise one or more wheels 328 and/or caterpillar tracks,
for
example (although other means for propelling the self-propelled downhole tool
will be
clear to the skilled person). The motor may be an electric motor and may be
powered
by the battery pack 326. The motor may be configured to drive the one or more
wheels
328, caterpillar tracks or other means. Further, the wheels 328, caterpillar
tracks or
other means may be positioned on arms extendable from a main body of the self-
propelled downhole tool 302. The arms may extend until the wheels 328,
caterpillar
tracks or other means are in contact with a sidewall of the wellbore, which
may
comprise tubing, casing or an open hole.
The self-propelled downhole tool 302 may comprise docking features that engage
with
corresponding docking features 332 on the lubricator 310. The docking features
332
are arranged to retain the self-propelled downhole tool 302 in the lubricator
310 when
stowed. Accordingly, the docking features 332 may comprise one or more detent
mechanisms. The skilled person will be aware of a number of detent mechanisms
and
any may be used.
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As mentioned above, the self-propelled downhole tool 302 may comprise an
electrical
terminal 322 that is configured to communicate electrically with a
corresponding
electrical terminal 324 on the input port 318. When the self-propelled
downhole tool
302 is stowed, the electrical terminal 322 of the self-propelled downhole tool
302 is
able to communicate with the electrical terminal 324 of the input port 318.
The
electrical terminals 322, 324 may comprise electrical connectors configured to
engage,
antennas configured to communicate wirelessly, or another type of electrical
terminal.
The transfer of electrical power and/or data communications to the self-
propelled
downhole tool 302 may be via the electrical communication provided by the
electrical
terminals 322, 324.
In exemplary arrangements, the electrical terminals 322, 324 may form at least
part of
the docking features and/or detent mechanism. That is, the docking features
may form
an electrical connection between the self-propelled downhole tool 302 and the
input
port 318 and/or may control at least partly operation of the electrical
terminals 322, 324
when the self-propelled downhole tool 302 is stowed. In exemplary
arrangements, the
electrical communication between the self-propelled downhole tool 302 and the
input
port 318 (or lubricator 310) is broken after deployment of the self-propelled
downhole
tool 302, e.g. after the detent mechanism is overcome.
As mentioned above, the self-propelled downhole tool 302 may comprise a
battery
pack 326. The battery pack 326 of the self-propelled downhole tool 302 may be
charged by the electrical power received from the remote unit and passed to
the self-
propelled downhole tool 302 via the electrical terminals 322, 324. The battery
pack
326 of the self-propelled downhole tool 302 may provide electrical power to
the motor
to drive the wheels 328, caterpillar tracks or other drive means, and/or to
any sensors
or other electrical equipment fitted to the self-propelled downhole tool 302.
The self-propelled downhole tool 302 may also comprise a processor 334. The
processor 334 may be configured to control operation of one or more tools on
the self-
propelled downhole tool 302. For example, the self-propelled downhole tool 302
may
include one or more of a camera, a temperature sensor, a pressure sensor or
any other
tool used in downhole operations. In a specific arrangement, the self-
propelled
downhole tool 302 may include a wax removal tool for the removal of paraffin
wax
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build-up. The processor may also be configured to control the drive mechanism
of the
self-propelled downhole tool 302.
More specifically, the processor 334 may be configured to receive data
5 communications from the lubricator 310, which may be via the input port
318, and to
store the data in a memory for use during deployment to control the self-
propelled
downhole tool 302 and/or one or more tools located on the self-propelled
downhole tool
302.
10 In some arrangements, the memory 329 may be configured to store data
relating to
one or more downhole parameters and sensed by the one or more sensors on the
self-
propelled downhole tool 302, such as a camera, a temperature sensor, a
pressure
sensor. When the self-propelled downhole tool 302 is in the stowed position
and
electrical communication is established with the input port 318, the self-
propelled
15 downhole tool 302 may transmit the stored sensor data to the one or more
remote
units. The data communications received from the remote unit may be based on
the
transmitted sensor data. In other arrangements, the processor 334 may be
configured
to determine one or more instructions for operating the self-propelled
downhole tool
302 based on the sensor data. For example, during deployment the one or more
sensors may measure an internal diameter of a casing or tubing of the wellbore
704. If
the diameter is found not to be as expected in a particular area, the
processor 334 of
the self-propelled downhole tool 302 (and/or the remote unit if the sensed
diameter is
transmitted thereto) may determine that more wax cleaning (e.g. greater time)
should
be focused on that area. This may be done by the processor 334 without human
intervention and/or the intervention of apparatus outside of the wellbore 304.
The processor 334 may be configured to control the self-propelled downhole
tool 302
autonomously, e.g. without receiving any further data or instruction from the
lubricator
310 or the remote unit for at least part of the period of deployment.
In specific arrangements, the self-propelled downhole tool 302 may be
configured to
undertake one or more well intervention or workover tasks. For example, the
self-
propelled downhole tool 302 may be configured deploy within the well bore and
the
paraffin wax removal tool may remove paraffin wax deposits from the wellbore
12 and
associated infrastructure and equipment.
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16
In the exemplary arrangement shown in Figure 3a, the self-propelled downhole
tool
302 also comprises a fishing neck 336 for removal of the self-propelled
downhole tool
dock 322 and self-propelled downhole tool 302 using a fishing tool, if
necessary.
Figure 3b shows the system of Figure 3a with the self-propelled downhole tool
302
shortly after deployment.
In exemplary arrangements, the self-propelled downhole tool 302 may be
configured to
transmit data (e.g. sensor data) to surface and/or to receive data from
surface using, at
least in part, wireless EM communication and/or wireless acoustic
communication.
Figure 4 shows a flow diagram of a method for operating a self-propelled
downhole tool
302 within a wellbore 304. The self-propelled downhole tool 302 may be as
described
above. Accordingly, the self-propelled downhole tool 302 is configured to
propel itself
along at least a part of the length of the wellbore 304.
The method comprises stowing 400 the self-propelled downhole tool 302 in a
stowed
position. This may comprise docking the self-propelled downhole tool 302 in
the
lubricator 310, e.g. using the docking features discussed above. In stowing
the self-
propelled downhole tool 302, the docking feature of the self-propelled
downhole tool
302 may engage with the corresponding docking features 332 of the lubricator
310.
The detent mechanism may be engaged. Further, electrical communication is
possible
between the input port 318 and the self-propelled downhole tool 302 by way of
the
electrical terminals. In exemplary arrangements, the electrical terminals
comprise
electrical connectors 322 on the self-propelled downhole tool 302 that are
configured to
engage with electrical connectors 324 on the input port 318.
In this configuration, the upper and lower control valves 312, 314 may be in
their closed
configurations, thereby providing a dual barrier between the lubricator 310
and the
Christmas tree 306/wellbore 304. The provision of the dual barrier
beneficially permits
the upper control valve of the Christmas tree 306 to be maintained in an open
configuration.
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17
The method may include charging the battery pack 326 of the self-propelled
downhole
tool 302 when the self-propelled downhole tool 302 is in the stowed position.
This may
be done by electrical power received from one or more remote units via the
input port
318 of the end cap 316.
The method further comprises transmitting 402 data communications from a
remote
unit and receiving 404 the transmitted data communications at the self-
propelled
downhole tool 302.
The data communications may include instructions for deployment of the self-
propelled
downhole tool 302 within the wellbore 304. More specifically, the data
communications
may include a plurality of instructions for the self-propelled downhole tool
302 to
complete a task, such as an intervention or workover task. The instructions
may
comprise a set parameters for the completion of the task. For example, the
data
communications may include a plurality of instructions for the self-propelled
downhole
tool 302 to undertake a paraffin wax removal task, which may include operating
the
drive mechanism of the self-propelled downhole tool 302 to move the self-
propelled
downhole tool 302 to a required position within the wellbore 304, operating
the paraffin
wax removal tool, and operating the drive mechanism to return the self-
propelled
downhole tool 302 to the lubricator 310. In such circumstances, the parameters
of the
deployment may include a depth to which the self-propelled downhole tool 302
should
travel, a type of operation to be conducted at that depth and/or the time for
which the
operation should be undertaken.
The plurality of instructions may be stored in the memory 329 of the self-
propelled
downhole tool 302, such that they may be implemented, e.g. by the processor
334,
after the self-propelled downhole tool 302 has been deployed and there is no
communication with the lubricator 310 or the remote unit. That is, the self-
propelled
downhole tool 302 may operate autonomously.
In some arrangements, a monitoring arrangement is provided, as illustrated in
Figure 1.
The exemplary monitoring arrangement comprises a flow sensor 60 and a pressure
sensor 62. However, it will be recognised that in other arrangements the
monitoring
arrangement may comprise one or other of the flow sensor 60 and the pressure
sensor
62, or other sensors alone or in combination. The monitoring arrangement also
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18
comprises a visual monitoring system in the form of a camera 64 which in the
illustrated arrangement is disposed on the support mast 58. In use, the camera
64
may facilitate remote visual monitoring of the tool deployment arrangement.
The
monitoring arrangement may sense data, such as flow rate and/or pressure and
provide the sensed data to the remote unit and/or the processor 334. The
processor
334 and/or the remote unit may use the sensed data to determine instructions
setting
one or more deployment parameters, as discussed above.
In some arrangements, the instructions for undertaking a task may be preloaded
into
the memory 329 of the self-propelled downhole tool 302 before being fitted
into the
apparatus 300. In some arrangements, the instructions for undertaking a task
may be
determined by the processor 334, e.g. based on sensor data. In such
arrangements,
the data communications may include amendments to the preloaded instructions
or
processor determined instructions.
It will be appreciated that a plurality of different sets of instructions may
be stored in the
processor 334 of the self-propelled downhole tool 302 to allow the self-
propelled
downhole tool 302 to undertake a plurality of tasks.
The data communications may also include an instruction to deploy the self-
propelled
downhole tool 302. That is, the data communications may include an instruction
to
begin a deployment of the self-propelled downhole tool 302. Such a deployment
may
be one of one or more deployment programs stored in the memory 329.
Instructions
may be determined and sent manually, or may be determined and sent based on an
intervention system configured to receive data, some of which may be sensor
data
from the wellbore, wellhead and/or vicinity of the wellhead, and determine
whether the
self-propelled downhole tool 302 should be deployed. Accordingly, the method
may
further comprise deploying 406 the self-propelled downhole tool 302 into the
wellbore
304.
The data communications may also include instructions for operation of one or
more
other components of the apparatus 300, such as the valve system 308.
For example, on identifying that an activation event has occurred (e.g. a
sensor
detecting that the well flow rate has dropped below a threshold valve) the
intervention
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19
system may enter an activated configuration to permit deployment of the self-
propelled
downhole tool 302 into the wellbore 304 by opening the lower and upper control
valves
312, 314. The intervention system may ensure that the control valves 312, 314
have
opened correctly and that pressure integrity has been maintained. The
intervention
system 300 may then transmit data communications to the lubricator 310, and
then on
to the self-propelled downhole tool 302 to deploy the self-propelled downhole
tool 302
into the wellbore 304. The instructions may include data identifying a
particular
operation to be undertaken.
On completion of the operation by the self-propelled downhole tool 302, which
may be
indicated by the self-propelled downhole tool 302 returning to the stowed
position in the
lubricator 310, the intervention system 300 may reconfigure from the activated
configuration to a tool storage configuration by closing the upper and lower
control
valves 312, 314. Well pressure may then be vented from the lubricator 20.
It should be understood that embodiments described herein are merely exemplary
and
that various modifications may be made thereto without departing from the
scope of the
invention.
For example, while in the described embodiments the systems and methods are
directed to the removal of paraffin wax from a wellbore and associated
infrastructure
and equipment, it will be understood that the systems and methods may be used
to
perform any suitable intervention operation, including not exclusively well
logging
operations.
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