U.S. patent application number 14/780085 was filed with the patent office on 2016-02-18 for downhole apparatus, system and method.
This patent application is currently assigned to Halliburton Manufacturing and Services Limited. The applicant listed for this patent is INTELLIGENT WELL CONTROLS LIMITED. Invention is credited to William Brown-Kerr, Bruce Hermann Forsyth McGarian.
Application Number | 20160047237 14/780085 |
Document ID | / |
Family ID | 49081157 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160047237 |
Kind Code |
A1 |
Brown-Kerr; William ; et
al. |
February 18, 2016 |
DOWNHOLE APPARATUS, SYSTEM AND METHOD
Abstract
An example apparatus for generating downhole fluid pressure
pulses includes a tubular housing defining an internal fluid flow
passage and providing a housing wall having an internal surface and
an external surface. The apparatus also includes a device for
selectively generating a fluid pressure pulse, the device being
mounted in an aperture defined in the housing wall and being
movable between a retracted position, where the device is seated
within the aperture, and a radially extended position, where the
device extends at least partially beyond the external surface.
Inventors: |
Brown-Kerr; William; (Aboyne
Aberdeenshire, GB) ; McGarian; Bruce Hermann Forsyth;
(Stonehaven Aberdeenshire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTELLIGENT WELL CONTROLS LIMITED |
Dyce Aberdeenshire |
|
GB |
|
|
Assignee: |
Halliburton Manufacturing and
Services Limited
London
GB
|
Family ID: |
49081157 |
Appl. No.: |
14/780085 |
Filed: |
July 9, 2014 |
PCT Filed: |
July 9, 2014 |
PCT NO: |
PCT/GB2014/052096 |
371 Date: |
September 25, 2015 |
Current U.S.
Class: |
166/250.01 ;
166/316; 166/317; 166/319; 166/373 |
Current CPC
Class: |
E21B 47/18 20130101;
E21B 47/01 20130101; E21B 47/00 20130101 |
International
Class: |
E21B 47/18 20060101
E21B047/18; E21B 47/00 20060101 E21B047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 11, 2013 |
GB |
1312465.6 |
Claims
1. An apparatus for generating downhole fluid pressure pulses,
comprising: a tubular housing defining an internal fluid flow
passage and providing a housing wall having an internal surface and
an external surface; and a device for selectively generating a
fluid pressure pulse, the device being mounted in an aperture
defined in the housing wall and being movable between a retracted
position, where the device is seated within the aperture, and a
radially extended position, where the device extends at least
partially beyond the external surface.
2. The apparatus of claim 1, wherein the aperture extends between
the internal and external surfaces of the housing wall.
3. The apparatus of claim 1, wherein, when in the retracted
position, the device extends at least partially into the internal
fluid flow passage and beyond the internal surface.
4. The apparatus of claim 1, further comprising a mounting block
movably disposed within the aperture, wherein the device is mounted
to the mounting block and the mounting block moves between the
retracted and radially extended positions.
5. The apparatus of claim 4, wherein the mounting block is secured
in the retracted position using one or more latch elements.
6. The apparatus of claim 4, wherein the mounting block is secured
in the radially extended position using one or more latch
elements.
7. The apparatus of claim 6, wherein the one or more latch elements
are shearable to permit release of the mounting block for movement
from the radially extended position back to the retracted
position.
8. The apparatus of claim 1, wherein the device is movable from the
retracted position to the radially extended position by imparting
an expansion force on the tubular housing at or adjacent the
aperture.
9. The apparatus of claim 8, wherein the tubular housing comprises
at least one deformation zone configured to deform so that the
device can move from the retracted position to the radially
extended position.
10. The apparatus of claim 9, wherein the at least one deformation
zone defines at least one corrugation arranged to be at least
partially extended upon assuming the expansion force.
11. The apparatus of claim 1, wherein the device is movable from
the retracted position to the radially extended position via at
least one of a pressure differential between the internal fluid
flow passage and external to the tubular housing, and application
of a mechanical force that serves to move the device.
12. The apparatus of claim 1, further comprising at least one
sensor communicably coupled to the device for measuring a downhole
parameter, wherein data relating to the downhole parameter measured
by the at least one sensor is transmitted to a surface location via
fluid pressure pulses generated by the device.
13. The apparatus of claim 12, wherein the downhole parameter is
selected from the group consisting of pressure, temperature, a
geological feature, density, weight on bit, torque on bit, strain,
stress, acceleration, and a wellbore geometry feature.
14. A method, comprising: introducing a downhole assembly into a
wellbore, the downhole assembly including a tubular housing
defining an internal fluid flow passage and providing a housing
wall having an internal surface and an external surface, and a
device mounted in an aperture defined in the housing wall;
conveying the downhole assembly within the wellbore on a tubing
string with the device being in a retracted position, where the
device is seated within the aperture; locating the device at a
desired position in the wellbore; operating the device to generate
fluid pressure pulses to transmit data relating to at least one
downhole parameter to a surface location; and moving the device
from the retracted position to a radially extended position, where
the device extends at least partially beyond the external
surface.
15. The method of claim 14, wherein moving the device from the
retracted position to the radially extended position precedes
operating the device to generate fluid pressure pulses to transmit
data relating to at least one downhole parameter to a surface
location.
16. The method of claim 14, wherein the device is arranged within a
mounting block movably disposed within the aperture, and wherein
moving the device from the retracted position to the radially
extended position comprises moving the mounting block from the
retracted position to the radially extended position.
17. The method of claim 16, further comprising securing the
mounting block in the retracted position using one or more latch
elements.
18. The method of claim 16, further comprising securing the
mounting block in radially extended position using one or more
latch elements.
19. The method of claim 14, wherein moving the device from the
retracted position to the radially extended position comprises:
imparting an expansion force on the tubular housing at or adjacent
the aperture; and deforming at least one deformation zone in the
tubular housing in response to the expansion force and thereby
moving the device from the retracted position to the radially
extended position.
20. The method of claim 14, wherein moving the device from the
retracted position to the radially extended position comprises
introducing a pressure differential between the internal fluid flow
passage and external to the tubular housing.
21. The method of claim 14, wherein moving the device from the
retracted position to the radially extended position comprises
applying a mechanical force to the device.
22. The method of claim 21, wherein the device is arranged within a
mounting block movably disposed within the aperture, and wherein
applying the mechanical force to the device comprises applying the
mechanical force on the mounting block.
23. The method of claim 14, further comprising measuring the at
least one downhole parameter with at least one sensor arranged in
the downhole assembly and communicably coupled to the device, the
downhole parameter being is selected from the group consisting of
pressure, temperature, a geological feature, density, weight on
bit, torque on bit, strain, stress, acceleration, and a wellbore
geometry feature.
Description
BACKGROUND
[0001] The present invention relates to apparatus for use in
generating a fluid pressure pulse downhole comprising a tubular
housing defining an internal fluid flow passage and a device for
selectively generating a fluid pressure pulse located in a wall of
the housing. The present invention also relates to a downhole data
acquisition and telemetry system comprising such an apparatus, and
at least one sensor. The present invention also relates to a method
of measuring at least one parameter downhole in a wellbore and of
transmitting data relating to the at least one parameter to
surface.
[0002] In the oil and gas exploration and production industry, a
wellbore is drilled from surface utilizing a string of tubing
carrying a drill bit. Drilling fluid known as drilling `mud` is
circulated down through the drill string to the bit, and serves
various functions. These include cooling the drill bit and
returning drill cuttings to surface along an annulus formed between
the drill string and the drilled rock formations.
[0003] It is well known that the efficiency of oil and gas well
drilling operations can be significantly improved by monitoring
various parameters pertinent to the process. For example,
information about the location of the borehole is utilized in order
to reach desired geographic targets. Additionally, parameters
relating to the rock formation can help determine the location of
the drilling equipment relative to the local geology, and thus
correct positioning of subsequent wellbore-lining tubing. Drilling
parameters such as Weight on Bit (WOB) and Torque on Bit (TOB) can
also be used to optimize rates of penetration.
[0004] For a number of years, measurement-whilst-drilling (MWD) has
been practiced using a variety of equipment that employs different
methods to generate pressure pulses in the mud flowing through the
drill string. These pressure pulses are utilized to transmit data
relating to parameters that are measured downhole, using suitable
sensors, to surface. Systems exist to generate `negative` pulses
and `positive` pulses.
[0005] Many previous methods have involved placing some, or all, of
the apparatus in a probe, and locating the probe down the center of
the drill-pipe. This leads to inevitable wear and tear on the
apparatus, primarily through the processes of erosion, and also
often through excessive vibration experienced during the drilling
operation. The cost of operating MWD equipment is therefore often
determined by the required flow rates and types of mud employed
during the drilling process. Furthermore, as the pipe is obstructed
by the MWD equipment, it is impossible to pass through other
equipment such as is often required for a variety of purposes.
Examples of this include logging tools for the method commonly
referred to as `through bit logging`. Other examples such as
diverting valves can be activated by dropping activation devices
through the thru bore MWD equipment (these activation devices are
commonly balls of a variety of diameters).
[0006] Apparatus has been developed for generating a fluid pressure
pulse downhole in which a pulse generating device is located at
least partly in a space provided in a wall of an elongate,
generally tubular housing. Apparatus of this type is disclosed in
the Applicant's International Patent Publication No.
WO-2011/004180. The apparatus disclosed in WO-2011/004180 offers
significant advantages over prior apparatus and methods, in that
locating the pulse generating device in the space in the wall of
the tubular housing reduces exposure of the device to fluid flowing
through the housing, and thereby erosion of components of the
apparatus, particularly the pulse generating device. Additionally,
location of the device in the space facilitates the passage of
fluid or other downhole objects (such as downhole tools, or
actuating devices such as balls or darts) along the fluid flow
passage defined by the housing.
[0007] There is a desire to further improve upon the apparatus
disclosed in WO-2011/004180. In particular, the device disclosed in
WO-2011/004180 typically requires that the wall of the tubular
housing be of greater thickness than uphole/downhole portions of
the housing, in order to provide a sufficiently large space to
receive the device. In one instance this can be achieved by forming
an `upset` or shoulder, which typically either extends outwardly
from an external surface of the housing, or inwardly into the
internal tubing bore (or possibly both). In another instance this
can be achieved my mounting the apparatus in a constant external
diameter tubular (or `slick OD` tubular) of sufficient wall
thickness, such as a drill collar.
[0008] It is preferable to form an upset on the external surface of
the housing, so as to avoid restricting the internal tubing bore.
However, this requires that the downhole tubing (or wellbore) into
which the apparatus is deployed be of sufficiently large diameter
all the way down to the placement point for the apparatus. This
diameter might be larger than would otherwise be dictated by the
overall well design, or features of other components deployed into
the well. Furthermore, in certain scenarios, such as where a
restriction exists in the wellbore uphole of the desired placement
point for the apparatus, it may not be possible to provide the
required clearance.
[0009] As a result, an internal upset is employed, extending into
the internal tubing bore. Following completion of a downhole
procedure involving the measuring of a downhole parameter or
parameters, and the transmission of data to surface employing the
pulse generating device, there is a desire to provide full bore
access through the tubular member. The full bore might be required
for the passage of tools or equipment to a position downhole of the
apparatus, and for improving fluid flow.
[0010] One proposal is to mill away the components of the apparatus
protruding into the internal bore, and so: the upset; at least part
of the pulse generating device; and associated control/power
equipment. This is undesirable for various reasons, including: the
milling operation can take time as the pulse generating device
comprises components made from relatively hard materials; the
debris from the milling operation can cause problems downhole; and
milling batteries in the device (typically lithium based) may not
be acceptable either from an environmental or safety perspective.
Indeed, for safety reasons it is advisable that the batteries be
mounted beyond the milling path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The following figures are included to illustrate certain
aspects of the present disclosure, and should not be viewed as
exclusive embodiments. The subject matter disclosed is capable of
considerable modifications, alterations, combinations, and
equivalents in form and function, without departing from the scope
of this disclosure.
[0012] FIG. 1 is a schematic longitudinal sectional view of a
downhole assembly, comprising apparatus for generating a fluid
pressure pulse downhole, in accordance with an embodiment of the
present invention, the apparatus shown in use during the completion
of a well in preparation for the production of well fluids;
[0013] FIG. 2 is an enlarged, perspective view of the apparatus
shown in FIG. 1;
[0014] FIG. 3 is a longitudinal cross-sectional view of the
apparatus of FIG. 2, taken in the direction B-B;
[0015] FIG. 4 is an enlarged, highly schematic view of parts of the
apparatus of FIG. 2, taken in the direction A-A;
[0016] FIG. 5 is a detailed longitudinal sectional view of the
apparatus of FIG. 2, showing a pulse generating device of the
apparatus in more detail;
[0017] FIG. 6 is a further enlarged view of part of the device
shown in FIG. 5;
[0018] FIG. 7 is a further enlarged view of part of the device
shown in FIG. 5;
[0019] FIG. 8 is a further enlarged perspective view of part of the
apparatus shown in FIG. 5, with certain internal components shown
in ghost outline;
[0020] FIG. 9 is an enlarged view of part of a wellbore of the well
shown in FIG. 1, which has been underreamed, showing the apparatus
located in the underreamed section;
[0021] FIG. 10 is a sectional view through part of an apparatus for
generating a fluid pressure pulse downhole in accordance with
another embodiment of the present invention, with a device of the
apparatus shown in a retracted position;
[0022] FIG. 11 is a further enlarged view of part of the apparatus
shown in FIG. 10; and
[0023] FIG. 12 is a view of the apparatus of FIG. 10, with the
device shown in a radially extended position.
DETAILED DESCRIPTION
[0024] According to a first aspect of the present invention, there
is provided apparatus for use in generating a fluid pressure pulse
downhole, the apparatus comprising:
[0025] a tubular housing defining an internal fluid flow passage,
the housing having a housing wall; and
[0026] a device for selectively generating a fluid pressure pulse,
the device mounted in a space in the wall of the tubular housing
for movement between:
[0027] a retracted position; and
[0028] a radially extended position.
[0029] Mounting the pulse generating device for movement between
such retracted and extended positions provides the advantage that a
maximum width dimension (e.g. diameter) described by the apparatus
can be arranged to be less when the device is in the retracted
position, facilitating deployment of the apparatus along a wellbore
to a desired placement point. Following location at the desired
placement point, the device can be moved to the radially extended
position. Advantageously therefore, the invention provides the
ability to open up access through the tubular housing (and so
through the apparatus) when the device is in the extended
position.
[0030] The retracted position may be an operating position of the
device, in which the device can be employed to generate fluid
pressure pulses representative of at least one parameter measured
downhole in the well. The device may be moved to the extended
position following operation to generate such fluid pressure
pulses. However, it will be understood that the device may be
equally (or alternatively) capable of generating fluid pressure
pulses when in the extended position. In the extended position, an
outer surface of the device may be disposed beyond the external
surface of the housing.
[0031] In the radially extended position, at least part of the
device may extend beyond an external surface of the housing. The
tubular housing may have an internal surface and an external
surface, and the space may be defined by an aperture in the wall of
the housing extending between the internal surface and the external
surface. The aperture may have an opening in the internal surface
of the tubular housing, and an opening in the external surface of
the tubular housing which communicates with the opening in the
internal surface. The openings may be of similar or different
dimensions, profile and/or shape. The aperture may communicate with
the internal passage, and may open on to the passage.
[0032] In the retracted position, the pulse generating device may
not extend beyond the external surface of the tubular housing. The
device may therefore be retracted into the space, and may not
protrude beyond the external surface out of the space.
Advantageously therefore, the invention provides the ability to
navigate a wellbore without requiring that the wellbore be larger
than might otherwise be the case, to accommodate the apparatus. In
the retracted position, the device may extend a first distance
beyond the external surface of the tubular housing; and in the
extended position, the device may extend a second distance beyond
the external surface of the tubular housing which is greater than
said first distance.
[0033] In the retracted position, the pulse generating device may
extend beyond the internal surface of the tubular housing and into
the internal fluid flow passage. In the extended position, the
device may not extend beyond the internal surface of the tubular
housing and so may not extend into the internal fluid flow passage.
Advantageously therefore, the invention provides the ability to
open full bore access through the tubular housing (and so through
the apparatus) when the device is in the extended position. In the
retracted position, the device may extend a first distance beyond
the internal surface of the tubular housing and into the internal
fluid flow passage; and in the extended position, the device may
extend a second distance beyond the internal surface of the tubular
housing and into the internal fluid flow passage, said second
distance being smaller than said first distance.
[0034] The pulse generating device may be releasably mounted to the
tubular housing in the space.
[0035] The apparatus may comprise a mounting member (such as a
mounting block) which receives the device, the mounting member
mounted for movement between the retracted and extended positions.
Mounting of the device in the mounting member may thus facilitate
movement of the device between its retracted and extended
positions. The device may comprise or may take the form of a
cartridge which can be: a) releasably movably mounted in the space;
or b) releasably mounted in the mounting member. The mounting
member may be a floating mounting member (and may in particular be
a floating block), mounted for floating movement in the space under
applied fluid pressure. In the extended position, part of the
mounting member may extend beyond the external surface of the
housing. In particular, an outer surface of the mounting member may
be disposed beyond the external surface of the housing.
[0036] The device may be initially restrained in the retracted
position. The device may be initially restrained by at least one
latch element, which may be a dog or pin. Said latch element may be
actuable to release the device for movement to the extended
position. Said latch element may be movable between an engaging
position where it restrains the device and a release position where
the device is released for movement to the extended position. Said
latch element may be shearable or breakable to release the device
for movement to the extended position. Where the apparatus
comprises a mounting member for the device, said latch element may
cooperate with the mounting member for restraining the device.
[0037] The apparatus may be arranged so that the device can be
restrained in the extended position. The apparatus may be arranged
to automatically restrain the device in the extended position
following movement to said position. The device may be restrained
by at least one latch element, which may be a dog or pin. Said
latch element may be actuable to restrain the device in the
extended position. Said latch element may be movable between: a
release position, in which movement of the device to the extended
position is permitted; and an engaging position where it restrains
the device in the extended position. Said latch element may be
shearable or breakable to permit release of the device for movement
from the extended position back to the retracted position. Where
the apparatus comprises a mounting member for the device, said
latch element may cooperate with the mounting member for
restraining the device.
[0038] Said latch elements may be provided in the tubular housing,
in the device (such as in the mounting member), or optionally latch
elements may be provided in both the housing and the device.
Actuation options for the latch elements described above may
include mechanical, electrical, electromechanical, hydraulic and
combinations thereof.
[0039] The device may be mounted in the space in such a way that
movement of the device within or relative to the tubular housing,
in particular the space, is restricted. The space may be a recess
or pocket defined in the wall of the housing. The apparatus may be
configured so that the device is movable from the retracted
position to the radially extended position by imparting an
expansion force on the tubular housing, in particular on a part of
the tubular housing defining the space. Movement to the extended
position may therefore be achieved by expansion of the tubular
housing (or part thereof).
[0040] The device may form part of an external surface of the
housing, or may be located in a portion of the housing which
defines part of the external surface, and which surface part may be
moved radially outwardly when the device is moved to the extended
position. The tubular housing may be configured so that it is
expandable to thereby permit movement of the device to the extended
position. The tubular housing may comprise at least one deformation
zone which is configured to deform so that the device can move to
the extended position. The deformation zone may be provided between
a part of the tubular housing which defines the space, and a
further part of the tubular housing, which may be a main part or
majority of the housing. There may be a zone or zones of
deformation bordering the space around an entire perimeter of the
space.
[0041] The deformation zone may be a region of the tubular housing
which is shaped so that it can deform to permit radially outward
movement of the device, to its extended position. The tubular
housing may be shaped to define at least one corrugation, fold (or
the like) in the deformation zone, said corrugation arranged so
that it can be at least partially opened out or extended on
exertion of an expansion force, so that the device can move to the
extended position. The space may be elongate in a direction along a
longitudinal axis of the housing, and there may be at least one of
said corrugations bordering lateral sides of the space and
extending in a direction along said longitudinal axis.
[0042] The at least one deformation zone may comprise a material
having at least one material property which differs from a
corresponding property of a remainder or majority of the housing,
and in particular from the part of the housing defining the space.
The material property may be yield strength, and the at least one
deformation zone may comprise a material having a lower yield
strength than the remainder/majority of the housing. This may
encourage the tubular housing to deform in the deformation zone on
application of an expansion force. The at least one deformation
zone may comprise portions which are formed from different
materials.
[0043] The apparatus may comprise at least one sensor for measuring
a downhole parameter, data relating to the parameter measured by
the sensor being transmitted to surface via fluid pressure pulses
generated by the pulse generating device. Said sensor may be
provided as part of the device, or separately and coupled to the
device. Where the apparatus comprises a mounting member for the
pulse generating device, the sensor may be provided on or in the
mounting member.
[0044] The device may be movable under applied fluid pressure, e.g.
by creating a pressure differential between fluid in the internal
fluid flow passage relative to fluid externally of the tubular
housing. The aperture may define a cylinder which receives the
device, and the device may form a piston which is movable within
the cylinder by the application of fluid pressure. Suitable seals
may be provided between the piston and a wall or walls of the
aperture. Where the apparatus comprises a mounting member, the
mounting member may define the piston. The tubular housing may be
deformable in the at least one deformation zone by applied fluid
pressure. The device may be movable from the retracted position to
the extended position by applied fluid pressure. The device may be
movable from the extended position to the retracted position by
applied fluid pressure.
[0045] The device may be movable from the retracted position to the
extended position via application of a mechanical force, such as by
passing an expansion tool or element through the internal fluid
flow passage, the tool imparting a force on: a) the device located
in the aperture, to urge it to the extended position; or b) the
part of the tubular housing defining the space, to thereby deform
the housing in the at least one deformation zone. The device may be
movable from the extended position back to the retracted position
via application of mechanical force, such as via contact between
the device and a feature in the wellbore. The feature may be a
dedicated feature (such as an upset or profile) provided in the
wellbore for imparting a force on the device.
[0046] The apparatus may comprise a plurality of devices for
generating a fluid pressure pulse. Each device may be located in a
respective space. A plurality of devices may be located in one
space. Where the apparatus comprises a mounting member, the
mounting member may receive a plurality of pulse generating
devices.
[0047] The tubular housing may define an external upset which forms
at least part of the external surface of the housing. The tubular
housing may define an internal upset which forms at least part of
the internal surface of the housing.
[0048] The apparatus may further comprise an operating unit
arranged to operate the device. The operating unit may comprise a
source or sources of electrical power (such as a battery), a data
acquisition system, sensor(s) and a connector element which serves
for electrically coupling the power source(s) to the device and for
communicating with the device. The operating unit may be mounted in
the or a space. Where the apparatus comprises a mounting member,
the operating unit may be mounted on or in the mounting member.
[0049] The device may be for controlling the flow of fluid along a
flow path which communicates with the internal fluid flow passage,
to generate a fluid pressure pulse. The device may comprise a valve
having a valve element and a valve seat, the valve being actuable
to control the flow of fluid along the flow path. This may be
achieved by moving the valve element into or out of sealing
abutment with the valve seat. The device may comprise an actuator
element which is operable to move the valve element to thereby
control the flow of fluid through the flow path. The actuator
element may be electrically operated (and may for example be a
solenoid or motor) and coupled to the source of electrical power in
the operating unit. Positive or negative fluid pressure pulses may
be generated by the device. Positive pulses may be generated by
operating the device to close the respective flow path, and
negative pulses by operating the devices to open the flow path. The
device may be in the form of a cartridge or insert. The cartridge
may house the valve. The device may define at least part of the
flow path. The device may define the outlet. The inlet of each flow
path may open on to the internal fluid flow passage. The outlet may
open on to an exterior of the housing. The outlet may open on to
the internal fluid flow passage at a position which is spaced
axially along a length of the housing from the inlet.
[0050] The apparatus may comprise a carrier mounted in the space,
and one or more of: the fluid pressure pulse generating device; a
source of electrical power (e.g. battery); electronics and sensors
or sensor assemblies may be mounted in the carrier.
[0051] According to a second aspect of the present invention, there
is provided a downhole data acquisition and telemetry system
comprising:
[0052] apparatus for use in generating a fluid pressure pulse
downhole according to the first aspect of the invention; and
[0053] at least one sensor for measuring a downhole parameter, data
relating to the parameter measured by the sensor being transmitted
to surface via fluid pressure pulses generated by the pulse
generating device.
[0054] Further features of the apparatus and sensor forming part of
the system of the second aspect of the invention are defined above
in relation to the first aspect of the invention.
[0055] It will be understood that a sensor or sensors may be
provided which are capable of measuring a wide range of different
parameters in a wellbore, including but not restricted to: pressure
(e.g. in the internal bore and/or externally of the tubular
housing); temperature; geological features (e.g. rock resistivity,
background radiation); density; force (e.g. an axially directed
force such as a weight applied to a component in the wellbore,
which might be weight on bit (WOB), or a rotationally directed
force or torque applied to a component in the wellbore, which might
be torque on bit (TOB) or in wellbore tubing); strain; stress;
acceleration; and wellbore geometry features (e.g. rotational
orientation or `azimuth`, inclination, the depth of a particular
component or feature).
[0056] According to a third aspect of the present invention, there
is provided a method of measuring at least one parameter downhole
in a wellbore and of transmitting data relating to the at least one
parameter to surface, the method comprising the steps of:
[0057] mounting a device for generating a fluid pressure pulse
within a space in a wall of a tubular housing which defines an
internal fluid flow passage;
[0058] running the housing into the wellbore with the device in a
retracted position, and locating the device at a desired position
in the wellbore;
[0059] following location of the device at the desired position,
operating the device to generate fluid pressure pulses to transmit
data relating to at least one downhole parameter to surface;
and
[0060] moving the pulse generating device from the retracted
position to a radially extended position.
[0061] The step of moving the pulse generating device to the
extended position may take place following transmission of said
data to surface. The step of moving the pulse generating device to
the extended position may take place prior to transmission of said
data to surface.
[0062] The method may comprise the further step of subsequently
moving the device from the extended position back to the retracted
position.
[0063] The space may take the form of an aperture extending between
an internal surface of the housing and an external surface of the
housing, and the method may comprise movably mounting the device
within the aperture, and locating the device in a retracted
position in the aperture (which is the retracted position defined
above). In the radially extended position, at least part of the
device may extend beyond an external surface of the housing.
[0064] The device may be moved to the extended position by
expansion of the tubular housing, or part thereof, in particular a
part defining the space. The device may be moved to the extended
position by deforming the tubular housing in a deformation zone or
zones.
[0065] The step of moving the device to the extended position may
comprise applying fluid pressure to the device to urge it to the
extended position. This may involve creating a pressure
differential between fluid in the internal fluid flow passage
relative to fluid externally of the tubular housing. The method may
comprise the further step of subsequently moving the device from
the extended position back to the retracted position by applying
fluid pressure to the device.
[0066] The step of moving the device to the extended position may
comprise applying a mechanical force to the device to urge it to
the extended position. This may involve passing an expansion tool
or element through the internal fluid flow passage (which may be
actuable e.g. under fluid pressure), the tool imparting a force on
the device to urge it to the extended position. The device may form
part of an external surface of the housing, or may be located in a
portion of the housing which defines part of the external surface,
and which surface part may be moved radially outwardly when the
device is moved to the extended position. The method may comprise
the further step of subsequently moving the device from the
extended position back to the retracted position, by applying a
mechanical force to the device. This may involve bringing the
device into contact with a feature in the wellbore.
[0067] The method may comprise initially restraining the device in
the retracted position. The device may be initially restrained by
at least one latch element. Said latch element may be actuated to
release the device for movement to the extended position. Said
latch element may be sheared or broken to release the device for
movement to the extended position, such as via the application of a
mechanical force.
[0068] The method may comprise restraining the device in the
extended position. The device may be restrained using at least one
latch element. Said latch element may be selectively actuated to
restrain the device in the extended position. Said latch element
may be sheared or broken to permit release of the device for
movement from the extended position back to the retracted
position.
[0069] Further features of the method of the third aspect of the
invention may be derived from or with respect to the text set out
above relating to the apparatus and/or system of the first/second
aspect of the invention.
[0070] Turning firstly to FIG. 1, there is shown a downhole
assembly indicated generally by reference numeral 10, the assembly
comprising an apparatus for generating a fluid pressure pulse
downhole in accordance with an embodiment of the present invention,
and which is indicated generally by reference numeral 12. As will
be described in more detail below, the apparatus 12 has a
particular utility in transmitting data relating to one or more
parameters measured in a downhole environment to surface.
[0071] In the illustrated embodiment, the assembly 10 takes the
form of a tubing string and is shown in use, during the completion
of a wellbore or borehole 14. In the drawing, a main portion 16 of
the wellbore 14 has been drilled from surface, and lined with
wellbore-lining tubing known as casing 18, which comprises lengths
or sections of tubing coupled together end-to-end. The casing 18
has been cemented in place at 20, in a known fashion. The wellbore
14 has then been extended, as indicated by numeral 22, by drilling
through a section of tubing 24 at the bottom of the wellbore (known
as a casing `shoe`) and through a cement plug 26 which surrounds
the casing shoe.
[0072] A smaller diameter wellbore-lining tubing known as a liner
28 has then been installed in the extended portion 22 of the
wellbore, suspended from the casing 18 by means of a liner hanger
30. The liner 28 is shown prior to cementing in place, cement used
to seal the liner (not shown) passing up an annulus 32 defined
between a wall 34 of the drilled wellbore and an external surface
36 of the liner. The cement passes up along the annulus 32 and into
the casing 24, at a level which is below (i.e. deeper in the well)
the liner hanger 30. The liner hanger would then be set by
conventional methods. A sealing device known as a packer 38 can
then be operated to seal the upper end 40 of the liner 28 (i.e.
that which is further uphole towards the surface). The liner 28 is
run into the extended portion 22 of the well by means of the tubing
string 10 which, in the illustrated embodiment, is a liner running
string 10. The running string 10 also provides a pathway for the
passage of cement into the liner 28 to seal the annulus 32, and for
actuating the liner hanger 30 and packer 38.
[0073] The apparatus 12 of the present invention is incorporated
into the string 10, and so run into the wellbore 14 with the liner
28. As will be described below, the apparatus 12 serves for sending
data relating to one or more downhole parameter to surface
real-time, to facilitate completion of the well (by installing the
liner 28), and preparation of the well for production. In the
illustrated embodiment, the data which is recovered to surface
relates to the orientation of a window 41 in the liner 28, through
which a lateral wellbore (not shown) is to be drilled, extending
from the main wellbore 14. As will be understood by persons skilled
in the art, data relating to the orientation of the wellbore 14,
and indeed other parameters, is vital to ensuring correct drilling
and completion of the well shown, for accessing a subterranean
formation containing well fluids (oil and/or gas).
[0074] To this end and as shown in the enlarged perspective view of
FIG. 2 and the longitudinal cross-sectional view of FIG. 3, the
apparatus 12 also carries a sensor acquisition system 42 which is
provided in an operating unit 44 of the apparatus. The apparatus
may include orientation sensors associated with the acquisition
system 42, for measuring directional positioning information, and
may include suitable strain sensors (not shown) of known types, for
measuring the compressive load on the casing 28 having the window
41. As will be described below, the sensors are provided in the
sensor acquisition system 42, but may be separate and mounted in an
elongate, generally tubular housing 46 of the apparatus 12. The
operating unit 44 includes suitable electronics which stores the
data, relays the data to the transmitting device 50, and provides
power for operation of the apparatus 12. In this way, the data
measured by the sensors in the system 42 can be transmitted to
surface via the apparatus 12. As will be described below, separate
sensors may be provided and coupled to the apparatus 12, for
transmitting data relating to various downhole parameters to
surface. The sensors may be provided in separate components in the
string 10 and coupled to the apparatus 12. The apparatus 12
including the sensor forms a downhole data acquisition and
telemetry system according to the invention.
[0075] Parts of the apparatus 12 are also shown in the highly
schematic view of FIG. 4. The apparatus 12 is also shown in more
detail in the longitudinal sectional view of FIG. 5, and the
enlarged views of FIGS. 6 and 7. The apparatus 12 comprises the
tubular housing 46, which defines an internal fluid flow passage or
bore 48. A pulse generating device 50 is mounted in the housing 46,
and serves for controlling the flow of fluid along a flow path 52
which communicates with the internal fluid flow passage 48, to
generate a fluid pressure pulse.
[0076] In the embodiment of the invention shown in FIGS. 2 and 3,
the tubular housing 46 has a housing wall 60, an internal surface
61 and an external surface 63. A space 65 is provided in the wall
60 of the housing 46, and takes the form of an aperture which
extends between the internal surface 61 and the external surface
63, and opens on to the internal passage 48. The aperture 65 has
internal and external openings which communicate with one another,
and which are of similar dimensions. The pulse generating device 50
is mounted in the aperture 65 for movement between a retracted
position and a radially extended position. The device 50 is shown
in the retracted position in solid outline in FIG. 3, and in the
extended position in broken outline. FIG. 5 also shows the device
50 in the extended position. In the extended position, part of the
device 50 extends beyond the external surface 63 of the housing. In
particular, an external surface 51 of the device 50 is located
beyond the housing surface 63.
[0077] Mounting the pulse generating device 50 for movement between
such retracted and extended positions provides the advantage that a
maximum width dimension (in particular a diameter) described by the
apparatus 12 can be arranged to be less when the device 50 is in
the retracted position, facilitating deployment of the apparatus 12
along the wellbore 14 to a desired placement point. This may in
particular facilitate passage of the apparatus 12 through or past a
restriction in the casing 18 (such as upsets or profiles in the
casing 18). This may provide the advantage that it is not necessary
to make the wellbore 14 larger than might otherwise be the case, to
accommodate the apparatus 12. It is of note that it is not uncommon
for a wellbore to be enlarged using an underreamer to allow passage
of larger tubulars. There may also be a restriction or a restricted
bore that the tool needs to pass through such that it can be placed
in a hole location that has been enlarged/underreamed, or left
conventionally sized consistent with that required to run the
original casing into.
[0078] In the illustrated embodiment, the placement point for the
device 50 is determined by the required position for the liner 28,
as shown in FIG. 1, the apparatus 12 carrying the device 50 being
located downhole of the window 41 in the liner. Following location
at the desired placement point, the device 50 can be moved to the
radially extended position. Advantageously therefore, the invention
provides the ability to open up access through the tubular housing
46 (and so through the apparatus 12) when the device 50 is in the
extended position. This can be appreciated from FIG. 1, which shows
the device 50 in the retracted position, where it impedes the
internal passage 48 of the tubular housing 46. Optionally, the
apparatus 12 may be located in a portion of a wellbore which has
been underreamed, to provide sufficient clearance for movement of
the device 50 to the extended position. This is shown in FIG. 9,
where the extended portion 22 of the wellbore has been underreamed,
as shown at 23 in the drawing.
[0079] Typically, the retracted position will be an operating
position of the device 50, in which the device is employed to
generate fluid pressure pulses representative of at least one
parameter measured downhole in the well. The device 50 is moved to
the extended position following operation to generate fluid
pressure pulses to send data to surface. However, it will be
understood that the device 50 may be equally be capable of
generating fluid pressure pulses when in the extended position.
Indeed, an operating position of the device 50 may be the extended
position, rather than the retracted position.
[0080] In the retracted position, the pulse generating device 50
does not extend beyond the external surface 63 of the tubular
housing 46. The device 50 is therefore retracted into the aperture
65, and does not protrude beyond the external surface out of the
aperture. This facilitates passage of the apparatus 12 along the
wellbore 14, navigating past any restrictions in the wellbore. In
the retracted position, the pulse generating device 50 extends
beyond the internal surface 61 of the tubular housing 46 and into
the internal fluid flow passage 48. In the extended position, the
device 50 does not extend beyond the internal surface 61, and so
does not extend into the internal fluid flow passage 48. This may
provide the ability to open full bore access through the tubular
housing 46 when the device 50 is in the extended position. This may
be particularly desirable in order to allow subsequent deployment
of tools/equipment into the wellbore downhole of the apparatus 12,
and in terms of maximizing fluid flow through the apparatus.
[0081] The apparatus 12 also comprises a mounting member, which
takes the form of a mounting block 67, which receives the device
50. The mounting block 67 is mounted for movement between the
retracted and extended positions, carrying the device 50, and so
serves for moving the device between said positions. The pulse
generating device 50 is mounted in the block 67 in such a way that,
when the block is moved to an extended position, at least part of
the device 50 protrudes beyond the external surface 63 of the
housing 46.
[0082] Effectively, the mounting block 67 forms a floating mounting
block or piston which is mounted in the aperture 65, and which is
sealed relative to the wall 60 via suitable seals 71. The aperture
65 thereby effectively defines a cylinder in which the mounting
block 67 is mounted for movement between the retracted and extended
positions, under applied fluid pressure, which will be discussed
below. A flange or stop 83 can be provided on the mounting block 67
for restricting outward movement of the block. Following the
teachings of WO-2011/004180, the disclosure of which is
incorporated herein by way of reference, the pulse generating
device 50 takes the form of a cartridge which is releasably mounted
in the mounting block 67. The operation of the device 50 will be
discussed in more detail below.
[0083] The device 50 is initially restrained in the retracted
position, by at least one latch element. In the illustrated
embodiment, there are two such latch elements, one of which is
shown (FIG. 3) and given the reference numeral 73. The latch
element 73 takes the form of a dog or pin, and is actuable to
release the device 50 for movement to the extended position. The
dogs 73 are movable between engaging positions, where they restrain
the device 50, and a release position, where the device 50 is
released for movement to the extended position. The dogs 73 are
arranged to engage the mounting block 67 to thereby restrain the
device 50.
[0084] The apparatus 12 is also arranged so that the device 50 can
be restrained in the extended position, again by means of at least
one latch element. In the illustrated embodiment, there are two
such latch elements, one of which is shown and indicated by
reference numeral 75. The latch element 75 takes the form of a dog
or pin, and is actuable to engage the device 50. The dogs 75 are
movable between a release position, so that movement of the device
50 to the extended position is permitted, and an engaging position
where they restrain the device 50 in the extended position. The
dogs 75 may be shearable or breakable to permit release of the
device 50, for movement from the extended position back to the
retracted position. Again, the dogs 75 are arranged to engage the
mounting block 67 to thereby restrain the device 50.
[0085] Actuation options for the dogs 73 and 75 include mechanical,
electrical, electromechanical, hydraulic and combinations
thereof.
[0086] As mentioned above, the device 50 is movable from its
retracted position to its extended position under applied fluid
pressure. This is achieved by creating a pressure differential
between fluid in the internal fluid flow passage 48 relative to
fluid externally of the tubular housing 46, in the annulus 32. For
example, the pressure of the fluid in the internal passage 48 may
be raised using a pump at surface, so that the fluid pressure force
acting on an internal piston face defined by the mounting block 67
is greater than that acting on an external piston face (that
resulting from the pressure of fluid in the annulus 32). However,
the device 50 may be movable from the retracted position to the
extended position via application of a mechanical force, such as by
passing an expansion tool or element (not shown) through the
internal fluid flow passage 48, the tool imparting a force on the
device to urge it to the extended position. The device 50 is
similarly movable from the extended position back to the retracted
position by applied fluid pressure, in this case by raising the
pressure in the annulus 32, or by allowing the pressure of the
fluid in the passage 48 to fall.
[0087] The tubular housing 46 defines an external upset 77 which
forms or defines part of the external surface 63 of the housing 46.
The tubular housing 46 may, however, be arranged to define an
internal upset which forms at least part of the internal surface 61
of the housing 46, and so which may protrude into the internal
passage 48 to some extent.
[0088] Optionally, the apparatus 12 can comprise a plurality of
pulse generating devices, and FIG. 4 illustrates an option where
the apparatus 12 comprises the device 50, plus a second similar
such device 54. Both of the devices 50 and 54 are mounted in the
mounting block 67, and so movable between retracted and extended
positions in unison. The devices 50 and 54 can be operated in
various different ways, and can, for example, be employed to issue
separate or combined pressure pulse signals. In a further
variation, the apparatus 12 may comprise only a single pulse
generating device 50, and associated operating/power and sensor
equipment may be arranged differently from that described above.
For example and referring to FIG. 4, a battery or other power
source for operating the pulser 50 may be provided in the location
indicated by the numeral 54; the sensor assembly 42 may be provided
in the location indicated by the numeral 54; or the operating unit
44 may be provided in the location indicated by the numeral 54.
[0089] Operation of the devices 50 and 54 is achieved in a similar
fashion, and will now be described.
[0090] The operating unit 44 is arranged to operate the device 50,
or both the first and second devices 50 and 54 where provided,
simultaneously or individually, as required. The operating unit 44
is shown in more detail in FIG. 8, which is a further enlarged
perspective view of part of the apparatus shown in FIG. 5, with
certain internal components shown in ghost outline and showing the
operating unit during insertion into the mounting block 67. The
operating unit 44 includes an electronics section 66 which
comprises the sensor acquisition system 42, first and second
electrical power sources in the form of batteries 69a and 69b,
first and second electrical connector elements 68a, 68b and a
suitable data storage device (not shown). The batteries 69a and 69b
provide power for actuation of the devices 42, 50 and 54,
respectively, although a single battery may be utilized. The
connector elements 68a, 68b provide electrical connection with the
devices 50 and 54 so that they can be operated to transmit data
relating to parameters measured by the sensors in or associated
with the sensor acquisition system 42 to surface.
[0091] The first and second devices 50 and 54 each comprise a
valve, one of which is shown and given the reference numeral 74.
The valves 74 comprise a valve element 76 and a valve seat 78, the
valves being actuable to control the flow of fluid along the
respective flow paths 52. This is achieved by moving the respective
valve elements 76 into or out of sealing abutment with the valve
seats 78. The devices 50 and 54 also each include respective
actuators 70 coupled to the valve elements 76, to thereby control
the flow of fluid through the respective flow paths 52. The
actuators 70 are electrically operated, and take the form of
solenoids or motors having shaft linkages 81. The actuator shaft
linkages 81 are coupled to the valve elements 76 to control their
movement, and provide linear or rotary inputs for operation of the
valve elements, the latter being via a suitable rotary to linear
converter.
[0092] Power for operation of the actuators 70 is provided by the
battery packs 69a, 69b via the connector elements 68a, 68b. As
shown in FIGS. 6 and 8, the connector elements 68 are located
within seal bore assemblies 90 mounted within bores 92 of the
devices 50, 54. Ends 98 of the connector elements 68a, 68b make
electrical connection with sockets 99, which transmit power to the
actuators 70. Operation of the actuators 70 causes the actuator
shaft linkage 81 to translate the valve elements 76 out of sealing
engagement with the valve seat 78. When it is desired to return the
valves 74 to their closed positions, the actuators 70 are
deactivated and return springs (not shown) urge the valve elements
76 back into sealing abutment with their valve seats 78.
[0093] The structure and operation of both the valves 74 and
actuators 66 are in most respects similar to that disclosed in
WO-2011/004180, the disclosure of which is incorporated herein by
way of reference. Accordingly, these components will not be
described in further detail herein.
[0094] The first and second devices 50 and 54 are mounted in
respective spaces 80 and 82 provided in the floating mounting block
67. The operating unit 44 is similarly mounted in a space 84 in the
mounting block 67, which is separate from the spaces 80, 82 in
which the first and second devices 50, 54 are mounted but which
opens on to them. As shown, the devices 50, 54 and the operating
unit 44 are mounted entirely within the respective spaces 80, 82
and 84.
[0095] The first and second devices 50, 54 and indeed the operating
unit 44 are in the form of cartridges or inserts which can be
releasably mounted in the mounting block 67, in the spaces 80, 82
and 84. Whilst shown as pockets or recesses, the spaces 80, 82
and/or 84 could take the form of bored chambers in the mounting
block 67.
[0096] The cartridges of the first and second devices 50, 54 and
operating unit 44 are shaped so that they are entirely mounted
within the respective spaces 80, 82 and 84. The cartridges of the
first and second devices 50, 54 house the respective valves 74. The
first and second devices 50 and 54 also define part of the
respective flow paths 52, the flow paths extending from the inlets
58 in the housing wall 60, through the valves 74 to outlets 62.
Operation of the valves 74 thereby controls the flow of fluid along
the flow paths 52 from the inlets 58 to the respective outlets 62
to generate pulses. Positive or negative fluid pressure pulses may
be generated by the devices 50, 54. Positive pulses are generated
by operating the devices 50, 54 to close the respective flow paths
52, 56, and negative pulses by operating the devices to open the
flow paths.
[0097] Turning now to FIG. 10, there is shown a sectional view
through part of an apparatus for generating a fluid pressure pulse
downhole in accordance with another embodiment of the present
invention, the apparatus indicated by reference numeral 12'. Like
components of the apparatus 12' with the apparatus 12 of FIGS. 1 to
9 share the same reference numerals, with the addition of the
suffix `.
[0098] The apparatus 12` is of similar construction to the
apparatus 12, and only the significant differences will be
described herein. The apparatus 12' is shown in FIG. 10 sectioned
transverse to a main longitudinal axis of a housing 46' in the
region of a device 50' for generating a fluid pressure pulse. The
device 50' is shown in FIG. 10 in a retracted position. FIG. 11 is
a further enlarged view of part of the apparatus 12', in particular
of part of a wall 60' of the housing 46'. FIG. 12 is a view of the
apparatus 12' with the device 50' in a radially extended
position.
[0099] In this embodiment, the device 50' is mounted in a space 65'
in the wall 60' which takes the form of a recess or pocket. The
device 50' is mounted in the space 65' in such a way that movement
of the device within the space is restricted. The apparatus 12' is,
in this embodiment, configured so that the device 50' is movable
from the retracted position to the radially extended position by
imparting an expansion force on the tubular housing 46', in
particular on the part which defines the space 65'. The tubular
housing 46' is therefore configured so that it is expandable to
permit movement of the device 50' to the extended position. In this
embodiment, the device 50' forms part of an external surface 63' of
the housing 46', or is located in a portion of the housing 46'
which defines part of the external surface 63', and which surface
part is moved radially outwardly when the device 50' is moved to
the extended position.
[0100] In the illustrated embodiment, the tubular housing 46'
comprises a plurality of deformation zones 102, which are
configured to deform so that the device 50' can move to the
extended position. The deformation zones 102 are provided between a
part 104 of the tubular housing 46' which defines the space 65',
and a main part 106 of the housing 46'. The space 65' is elongate
in a direction along a longitudinal axis of the housing 46', and
the zones 102 border the lateral sides of the space, extending in a
direction along the longitudinal axis. Effectively however, there
are zones of deformation bordering the space 65' around its entire
perimeter, although only two are shown in the drawings. Any
suitable number of deformation zones may be provided to permit the
desired movement of the device 50'.
[0101] The deformation zones 102 are regions of the tubular housing
46' which are shaped so as to permit the required radially outward
movement of the device 50' to its extended position. In the
illustrated embodiment, the tubular housing 46' is shaped to define
at least one corrugation or fold 108 in the deformation zones 102,
the corrugations arranged so that they can be at least partially
opened out or extended on exertion of an expansion force, so that
the device can move to the extended position. This is shown in FIG.
12.
[0102] The deformation zones 102 comprise a material having at
least one material property which differs from a corresponding
property of a majority of the housing, and in particular from the
part 104 of the housing defining the space 65'. The material
property is typically the yield strength, and the deformation zones
102 comprise a portion 112 of a material having a lower yield
strength than the remainder of the housing 46'. This may encourage
the tubular housing 46' to deform in the deformation zones 102, on
application of an expansion force. By way of example, a majority of
the housing 46' (in particular the main part 106 and the part 104
defining the space 65') may be of a steel alloy having a higher
yield strength than that of the portion 112, so that deformation
occurs in the portion 102, which includes the corrugation 108.
Deformation may be achieved by applied fluid pressure or mechanical
expansion, such as using an expansion tool, following the
techniques described above. For example and as shown in FIG. 10,
hydraulic rams 110 may be actuated to impart a force on the portion
104 defining the space 65'.
[0103] Whilst the apparatus of the present invention has been shown
and described in the transmission of data to surface relating to
compressive load applied to a wellbore-lining tubing, it will be
understood that the apparatus has a wide range of uses including in
the drilling and production phases, or indeed in an intervention
operation (e.g. to perform remedial operations in the well
following commencement of production). Accordingly, the apparatus
may have a use in transmitting data relating to other parameters
pertinent to the drilling, completion or production phases and/or
in an intervention. Such may include but are not limited to
pressure (e.g. in the internal bore and/or externally of the
tubular housing); temperature; geological features (e.g. rock
resistivity, background radiation); density; force (e.g. an axially
directed force such as a weight applied to a component in the
wellbore, which might be weight on bit (WOB), or a rotationally
directed force or torque applied to a component in the wellbore,
which might be torque on bit (TOB) or in wellbore tubing); strain;
stress; acceleration; and wellbore geometry features (e.g.
rotational orientation or `azimuth`, inclination, the depth of a
particular component or feature). Sensors appropriate for the
measurement of the required parameter(s) may be provided.
[0104] Various modifications may be made to the foregoing without
departing from the spirit or scope of the present invention.
[0105] In the retracted position, the device may extend a first
distance beyond the external surface of the tubular housing; and in
the extended position, the device may extend a second distance
beyond the external surface of the tubular housing which is greater
than said first distance.
[0106] In the retracted position, the device may extend a first
distance beyond the internal surface of the tubular housing and
into the internal fluid flow passage; and in the extended position,
the device may extend a second distance beyond the internal surface
of the tubular housing and into the internal fluid flow passage,
said second distance being smaller than said first distance.
[0107] The device may comprise or may take the form of a cartridge
which can be releasably movably mounted in the aperture.
[0108] Said latch element may be shearable or breakable to release
the device for movement to the extended position.
[0109] The latch elements may be provided in the tubular housing,
in the device (such as in the mounting member), or optionally in
both the housing and the device.
[0110] The device may be movable from the extended position to the
retracted position via application of mechanical force, such as via
contact between the device and a feature in the wellbore. The
feature may be a dedicated feature, such as an upset or profile,
provided in the wellbore for imparting a force on the device.
[0111] The apparatus may comprise a plurality of devices for
generating a fluid pressure pulse. Each device may be located in a
respective aperture. A plurality of devices may be located in one
aperture. Where the apparatus comprises a mounting member, the
mounting member may receive a plurality of pulse generating
devices.
[0112] The aperture openings may be of different dimensions,
profile and/or shape.
[0113] The apparatus may be arranged to automatically restrain the
device in the extended position following movement to said
position. For example, the latch element may be sprung or otherwise
biased.
* * * * *