Patent Description:
In the field of hydrocarbon production it is known to use acoustic telemetry to transmit real-time data to the surface in order to monitor oil and gas well and reservoir performance. For example, <CIT>, discloses a gauge hanger which is used to support an acoustic telemetry device that is designed to measure wellbore pressure in real-time.

The measurements are converted into encoded acoustic wave data and sent to surface as a vibration inside the steel wall of the wellbore tubing. These acoustic waves are detected by an accelerometer that is bolted to the wellhead. In this way, the device can provide real-time data about wellbore pressure during production.

During oil well construction it is sometimes necessary to install wide points, known as side pocket mandrels, in the production tubing. These provide a place to install equipment within the tubing but off to one side so as not to obstruct the main bore. Two typical uses are to install measurement instrument or to install a valve connecting the outside to the inside of the tubing. The measurement instrument might be wired to surface or it might have a memory that can be downloaded when it is subsequently retrieved. Typically, the measurement instrument would be installed and retrieved with a cable deployed tool.

<CIT>, discloses a system including a power generator and a wireless communications transmitter which can be deployed in a side pocket mandrel. An acoustic generator may be used to provide acoustic energy as digital bits that travel to the surface using fluid, production tubing or the like.

A problem in the arrangement disclosed in <CIT> is that the setting and retrieving of such a system in the side pocket mandrel is complex due to the constraints of borehole geometry and the mechanical coupling requirements of acoustic transmission. In particular, the acoustic source must be properly acoustically coupled to the tubing in order for acoustic communication to be effective. This may limit or prevent the setting and then subsequent retrieval of the system in an existing side pocket mandrel.

It would therefore be desirable to provide a mechanism for installing and/or retrieving an acoustic instrument in a side pocket mandrel or similar locating profile, and allowing it to communicate effectively.

<CIT> discloses a system for sealing a wellbore. The system comprises a control sub-assembly and a packer sub-assembly. The control sub-assembly monitors a sealing efficiency of the system by comparing a first pressure up-hole of the packing element and a second pressure downhole of the packing element. The packer sub-assembly includes a hydraulic power unit connected to a packer slip. Once the hydraulic power unit has received a signal to activate the packer sub-assembly, it moves a wedged-shaped mandrel towards the packer slip. The wedge-shaped mandrel causes the packer slip to extend radially outward from the packer sub-assembly towards the wall of the wellbore.

<CIT> discloses a down-hole packer for positioning in a wellbore to establish a seal. The packer includes a sealing element that is responsive to compression by a setting piston to radially expand into the wellbore. An actuator is provided to longitudinally move the setting piston in response to a telemetry signal received by the down-hole packer. The actuator can include a hydraulic pump, an electromechanical motor or valves operable to control hydraulic energy to apply a down-hole force to the setting piston.

<CIT> discloses a lock mandrel for selectively locking a well tool at a desired landing nipple in a well bore, and a running tool for installing the lock mandrel. The lock mandrel includes an upwardly operable expander sleeve for locking the mandrel responsive to an upward force and a selector key assembly for landing the lock mandrel at a landing nipple having a selector profile compatible with the profile on the selector keys of the lock mandrel. The running tool includes a latch key assembly for coupling the running tool with the lock mandrel and an operator lug assembly for operating the lock mandrel. The running tool also includes a non-load bearing shear pin for holding the running tool in a running mode and an emergency release apparatus for releasing the lock mandrel in the well bore and retrieving the lock mandrel with the running tool in the event that the locking mechanism of the lock mandrel is not fully operable in the well bore.

<CIT> discloses a wellbore intervention tool having one or more packing elements. The intervention tool comprises a mandrel. The mandrel houses on its outer surface a packing element and a slip setting cone. Compression of the intervention tool moves the cone into contact with the slips, and the slips are urged radially outwards to contact the inner surface of a second of black casing.

According to one aspect of the present invention there is provided a coupling mechanism as defined in claim <NUM>.

Preferred features of the invention are recited in the dependent claims.

The present invention may provide the advantage that the coupling mechanism can be used to set the communication device in a location which may be constrained by wellbore geometry, such as a side pocket mandrel. The coupling mechanism can be used to set the acoustic communication device and to acoustically couple the acoustic communication device to the wellbore.

The coupling body and the anchoring unit may be arranged such that relative movement between the two is in an axial direction. For example, the coupling mechanism may further comprise a shaft, and at least one of the coupling body and the anchoring unit may be arranged to slide axially along the shaft. This may help to ensure that relative movement between the coupling body and the anchoring unit is in the required direction.

Preferably, the relative movement between the coupling body and the anchoring unit is such that the coupling body moves inside the anchoring unit. This may facilitate expansion of the anchoring unit and biasing of the anchoring unit against the locating profile.

The tapered outer surface of the coupling body may be provided at one end of the coupling body. In this case, the other end of the coupling body may be arranged to connect to the communication device. For example, the coupling body may comprise a screw thread or any other appropriate connecting means for connecting the coupling body to the communication device.

Preferably the tapered outer surface of the coupling body is substantially frustoconical. The tapered inner surface of the anchoring unit may also be substantially frustoconical. This can allow the two surfaces to oppose each other in such as way as to allow radially expansion of the anchoring unit as the coupling body moves inside the anchoring unit. This may facilitate expansion of the anchoring unit and help to ensure that the anchoring unit is biased against the locating profile. However, the tapered surfaces do not need to be frustoconical, and could for example be flat or curved in some other way.

The anchoring unit may comprise a plurality of anchor slips each of which may have a tapered inner surface. For example, each anchor slip may have a partially frustoconical inner surface and/or a partially cylindrical outer surface. The anchoring slips may be arranged circumferentially around the tapered part of the coupling body and/or a shaft. This may provide a convenient mechanism by which the anchoring unit can be expanded radially. In one embodiment, three anchor slips are provided, although any other appropriate number, such as two, four or more, could be used.

The anchoring unit preferably comprises means for elastically retaining the anchor slips. The retaining means may be, for example, a snap ring or any other suitable elastic or other energy storage device. The retaining means may be arranged to expand to allow expansion of the anchoring unit in the locating profile. Furthermore, the retaining means may be arranged to apply a contracting force to the expanded anchoring unit. This can allow the anchoring unit to expand as the coupling body enters, and then subsequently to contract as the anchoring unit retracts. Thus, this arrangement may facilitate the setting and then subsequent removal of the coupling mechanism.

The coupling mechanism is preferably arranged to prevent relative movement between the coupling body and the anchoring unit as it is lowered into the wellbore. To help achieve this, the coupling mechanism may further comprise means for connecting the anchoring unit to the coupling body. The connecting means may be arranged to prevent relative movement between the anchoring unit and the coupling body as the coupling mechanism is lowered in the wellbore. Preferably, the connecting means is arranged to disengage when the coupling mechanism lands in the locating profile, for example, upon application of a predetermined force. This may help to ensure that the anchoring unit only expands when it is in the locating profile.

The connecting means may comprise, for example, a shear pin or similar weak point, which may be arranged to shear upon the application of a predetermined force. In this case, the coupling mechanism may be arranged to shear the shear pin as it lands in the locating profile. This may be achieved, for example, by force of gravity and/or a wireline jar such as a slide hammer which may be connected to the coupling mechanism.

The coupling mechanism may further comprise means for biasing the anchoring unit against the locating profile. The biasing means may be arranged to bias the anchoring unit against the locating profile so as to allow acoustic energy to be transmitted between the communication device and the wellbore through the coupling body and the anchoring unit.

In a preferred embodiment the biasing means comprises a spring. The coupling mechanism may be arranged to hold the spring in compression or tension as it is lowered in the wellbore. In this case, the coupling mechanism may be arranged to release the spring when the coupling mechanism lands in the locating profile. This can allow the spring to store mechanical energy as it is being lowered, and then release mechanical energy when the coupling mechanism lands in the locating profile. This may facilitate expansion of the anchoring unit and help to ensure that the anchoring unit is firmly biased against the locating profile. However, any other appropriate biasing means which is capable of storing mechanical energy may be used instead of a spring. Alternatively, a hammer action and/or gravity on the tapered surfaces may be sufficient to bias the anchoring unit against the locating profile.

Where the coupling mechanism comprises means for connecting the anchoring unit to the coupling body, the connecting means may be arranged to prevent relative movement between the anchoring unit and the coupling body and to hold the spring in compression or tension as the coupling mechanism is lowered in the wellbore. In this case, the connecting means may be arranged to disengage the anchoring unit from the coupling body and to release the spring when the coupling mechanism lands in the locating profile. This may help to reduce complexity of the coupling mechanism by allowing a single device, such as a shear pin, to release the spring as well as to disengage the anchoring unit from the coupling body, thereby allowing the anchoring unit to expand into the locating profile.

Where the coupling mechanism comprises a shaft, the spring may be located on the shaft. This may help to hold the spring in place and allow it to apply a biasing force against the anchoring unit. The spring may be, for example, a helical spring which may be held in compression on the shaft.

The coupling mechanism may further comprise a collar on the shaft between the spring and the anchoring unit. The collar may help to transfer mechanical energy from the spring to the anchoring unit.

The collar may comprise means for preventing reverse movement of the anchoring unit along the shaft. For example, the collar may comprise an annular groove on its inner surface, which may be arranged to receive an elastic device such as a snap ring. A corresponding annular groove may be provided on the outer surface of the shaft. The collar and the shaft may be arranged such that, as the collar moves along the shaft, the elastic device moves into the groove in the shaft. This may help to prevent the anchoring unit from sliding back along the shaft once it has expanded. This in turn may help to ensure that the anchoring unit remains in place and/or facilitate removal of the coupling mechanism.

Preferably the coupling mechanism comprises retention means for retaining the coupling body inside the anchoring unit once the anchoring unit has expanded. This may help to ensure that the anchoring mechanism remains in place, with the anchoring unit biased against the locating profile.

In a preferred embodiment, the coupling mechanism is arranged such that, after setting in the locating profile, it can be subsequently removed. This may be achieved by arranging the retention means to be disengagable. This may allow the coupling body to withdraw from the anchoring unit, thereby allowing the anchoring unit to contract.

For example, the retention means may comprise a shear pin which may be arranged to shear upon the application of a predetermined force. Where the coupling mechanism comprises a first shear pin for connecting the anchoring unit to the coupling body, the retention means may comprise a second shear pin, and the second shear pin may require a greater shearing force than the first shear pin. This can allow the anchoring unit to be released in order to expand into the locating profile upon application of a first force when the coupling mechanism lands in the locating profile, and the coupling body to be withdrawn to allow contraction of the anchoring unit on application of a second, higher force. The second, higher force may be provided for example through a wireline connected to the coupling mechanism. Thus this arrangement can facilitate the setting and subsequent removal of the coupling mechanism in the locating profile.

The wireless communication device is an acoustic communication device, and is arranged for acoustic communication through the wellbore.

The locating profile is preferably arranged such that it is able to receive the coupling mechanism, and to provide an area into which the anchoring unit can expand. Thus, the locating profile may comprise a first section with an inner radius sufficiently large to allow passage of the coupling mechanism in an unexpanded state but not in an expanded state, and a second section with an inner radius greater than that of the first section. The radius of the second section is preferably such that it can allow the anchoring unit to bear against it in the expanded state. This may facilitate secure anchoring of the coupling mechanism in the locating profile.

Preferably the coupling mechanism further comprises a third section with an inner radius less than that of the first section and/or the second section. This may provide a restriction against which the coupling mechanism can land as it is lowered into the wellbore. This in turn may allow the anchoring unit to be released so as to expand into the locating profile, for example by severing a shear pin.

The locating profile may be in a side pocket mandrel, for example, in a production tubing, or it may be present in the main wellbore, or elsewhere.

According to another aspect of the invention there is provided an assembly comprising a coupling mechanism in any of the forms described above, and an acoustic communication device. The acoustic communication device is arranged for acoustic communication through the wellbore, via the coupling body and the anchoring unit. Any appropriate data and/or commands, such as pressure and/or temperature data, may be transmitted or received. The assembly may further comprise a measurement device for measuring one or more parameters to be transmitted.

Corresponding methods may also be provided. Thus, according to another aspect of the invention, there is provided a method as defined in claim <NUM>.

The wireless communication device is an acoustic communication device. The method may further comprise biasing the anchoring unit against the locating profile, thereby allowing acoustic energy to be transmitted between the acoustic communication device and the wellbore through the coupling body and the anchoring unit.

Features of one aspect of the invention may be provided with any other aspect. Apparatus features may be provided with method aspects and vice versa.

Preferred embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:.

<FIG> is a radial cross section through parts of a coupling mechanism in an embodiment of the invention. Referring to <FIG>, the coupling mechanism <NUM> comprises main body <NUM>, anchoring unit <NUM>, collar <NUM>, spring <NUM> and shaft <NUM>. The coupling mechanism <NUM> has a generally cylindrical outer profile, which allows it to be accommodated in a locating profile having a generally cylindrical internal surface. The coupling mechanism extends in an axial direction, with a longitudinal axis <NUM> running through its centre.

The main body <NUM> comprises a cylindrical portion <NUM> with a substantially cylindrical outer surface, and a conical portion <NUM> with a substantially frustoconical outer surface. The cylindrical portion <NUM> and conical portion <NUM> are both hollow, with cylindrical inner surfaces. The shaft <NUM> runs through the centre of the conical portion <NUM> and partially into the cylindrical portion <NUM>.

The inner surface of the conical portion <NUM> has a radius which is sufficient to allow the main body <NUM> to slide along the shaft <NUM>, while minimising any play between the two. The inner surface of the cylindrical portion <NUM> has a radius which is larger than that of the conical portion <NUM>. The inner radius of the cylindrical portion <NUM> is sufficient to accommodate a nut <NUM> screwed onto an end of the shaft <NUM> and to allow axial movement thereof. A shoulder <NUM> at the interface of the cylindrical portion <NUM> and the conical portion <NUM> prevents entry of the nut <NUM> into the conical portion <NUM>. The end of the cylindrical portion <NUM> away from the conical portion <NUM> has an internal thread <NUM> which is used to connect the main body <NUM> to an acoustic transceiver.

The anchoring unit <NUM> comprises a plurality of anchor slips spaced circumferentially around the shaft <NUM> and the end of the conical portion <NUM>. Each of the anchor slips has a partially cylindrical outer surface, and a tapered (partially frustoconical) inner surface. The tapered inner surfaces oppose the frustoconical outer surface of the conical portion <NUM> of the main body <NUM>. The anchoring unit <NUM> includes an annular groove <NUM> for a snap ring which is used to retain the anchor slips. A hole <NUM> passes through the anchoring unit <NUM> and into the conical portion <NUM> of the main body <NUM>. The hole <NUM> is used to hold a shear pin. The shear pin, when in position, holds the main body <NUM> and the anchoring unit <NUM> together and prevents relative movement between the two.

The collar <NUM> is in the form of a hollow cylinder, with an inner surface sized to allow the collar to slide along the shaft <NUM>, while minimising any play between the two. The collar <NUM> has a first end surface which abuts the anchoring unit <NUM>, and a second end surface with a recess <NUM> which receives one end of the spring <NUM>. The collar <NUM> also includes an annular groove <NUM> on its inner surface. This groove <NUM> is used to accommodate a second snap ring, as will be explained later.

The shaft <NUM> runs in an axial direction through the centre of the main body <NUM>, anchoring unit <NUM>, collar <NUM> and spring <NUM>. The main body <NUM>, anchoring unit <NUM>, collar <NUM> and spring <NUM> are each arranged such that, in the appropriate circumstances, they are able to slide axially along the shaft <NUM>. A cap <NUM> is securely fixed to the end of the shaft <NUM> and provides a shoulder against which the spring <NUM> can bear. The nut <NUM> is screwed onto the other end of the shaft, inside the main body <NUM>. The shaft <NUM> also includes a hole <NUM> which can accommodate a second shear pin. The hole <NUM> is located inside the cylindrical portion <NUM> of the main body <NUM>. The dimensions of the hole <NUM> are such that it is able to receive a shear pin requiring a greater shear force than that of the hole <NUM>.

<FIG> shows parts of the anchoring unit <NUM> in more detail. In this embodiment, the anchoring unit comprises three anchor slips <NUM> spaced circumferentially around the shaft <NUM>. Each of the anchor slips <NUM> has a partially cylindrical outer surface, and a tapered (partially frustoconical) inner surface. The direction of the taper opposes that of the outer surface of the conical portion <NUM> of the main body <NUM>. The anchor slips <NUM> include grooves <NUM>, which are used to locate a snap ring which holds the anchor slips together. One or more holes <NUM> are provided, which are used to locate a shear pin which holds the anchoring unit <NUM> and the main body <NUM> together. <FIG> shows an end view of the anchoring unit <NUM>, and <FIG> shows a radial cross section through the anchoring unit.

The coupling mechanism is assembled as follows. First a shear ring is inserted in the hole <NUM> in the shaft <NUM>, and the bolt <NUM> is screwed onto the end of the shaft. The shaft is then inserted into the main body <NUM> through the end with the screw thread <NUM>. The shaft is passed through the centre of the main body <NUM> until the shear pin in the hole <NUM> comes into contact with the shoulder <NUM> between the cylindrical portion <NUM> and the conical portion <NUM>, preventing further passage. The anchoring unit <NUM> is then assembled by placing anchor slips <NUM> around the shaft <NUM> and the end of the conical portion <NUM>. The anchor slips are held in place with a slip ring in the groove <NUM>. A shear pin is inserted in the hole <NUM> to prevent relative movement between the anchoring unit <NUM> and the main body <NUM>. The collar <NUM> is then slid onto the shaft <NUM> to abut the end of the anchoring unit <NUM>. The spring <NUM> is then inserted on the shaft <NUM>. The spring is compressed, and the compressed spring in held in place with the cap <NUM>. The cap <NUM> is fixed securely to the shaft <NUM>, for example by screwing an internal thread in the cap onto an external thread on the shaft.

<FIG> shows the coupling mechanism in the assembled state. The anchoring unit <NUM> and the main body <NUM> are held together by means of a shear pin <NUM> in the hole <NUM>. The spring <NUM> is in compression and bears against the cap <NUM> at one end and the collar <NUM> at the other end. A snap ring <NUM> is located around the anchoring unit <NUM>. The snap ring <NUM> holds the anchoring unit in an unexpanded state, with an outer radius substantially the same as that of the main body <NUM>. A second shear pin <NUM> is located in the hole <NUM> in the shaft <NUM>, inside the cylindrical portion <NUM> of the main body <NUM>. The second shear pin <NUM> is sized to withstand a larger shearing force than the first shear pin <NUM>.

The assembled coupling mechanism is connected to the bottom of an acoustic transceiver <NUM> and associated measuring instruments (not shown). This is achieved by screwing the acoustic transceiver <NUM> into the thread <NUM> in the main body <NUM>. The entire assembly (coupling mechanism, acoustic transceiver and measuring instruments) is then lowered into the well on a mechanical cable (as known as a slickline or wireline). No electrical communication is needed.

As the assembly is lowered into the wellbore, it eventually reaches a locating profile in the wellbore. This locating profile may be in a side pocket mandrel in a production tubing, or it may be present in the main wellbore. If appropriate, means for pushing the assembly laterally into a side pocket mandrel may be provided, such means being known in the art.

<FIG> shows the coupling mechanism as it lands in the locating profile. The locating profile <NUM> is a female receiving profile with substantially cylindrical (or partially cylindrical) inner surfaces. The locating profile has three sections, each of which has an inner surface with a different radius. The top section <NUM> of the locating profile has an inner radius which is sufficient to allow passage of the coupling mechanism <NUM> in the unexpanded state shown in <FIG> and <FIG> (but not in the expanded state). The middle section <NUM> of the locating profile has an inner radius which is slightly larger than that of the top section <NUM>. The bottom section <NUM> of the locating profile has an inner radius which narrower than that of the other two sections. The inner radius of the bottom section <NUM> is such that it is able to accommodate the collar <NUM> but not the anchoring unit <NUM> (in either unexpanded or expanded state).

As the coupling mechanism <NUM> reaches the locating profile <NUM>, the anchoring unit <NUM> lands on the restriction created by the bottom section <NUM>. This causes the first shear pin <NUM> to shear. In some embodiments, the shear pin <NUM> may shear due to the jolt of the assembly landing in the locating profile. Alternatively, the equipment screwed on to the coupling mechanism may include a jarring device, such as a slide hammer, which may be actuated as the assembly lands to impart a jolt sufficient to shear the shear pin <NUM>.

When the shear pin <NUM> severs, the main body <NUM> slides downwards into the anchoring unit <NUM>. This action takes place partially under the force of gravity due to the mass of the main body, acoustic transceiver and measuring equipment. However, the severing of the shear pin <NUM> also releases the spring <NUM>, which applies a counterforce to the anchoring unit <NUM> via the collar <NUM>. This counterforce assists in providing relative movement between the anchoring unit <NUM> and the main body <NUM>.

As the main body <NUM> slides downwards into the anchoring unit <NUM>, the outer surface of the conical portion <NUM> slides against the inner taper of the anchoring unit <NUM>. This provides a wedging action which urges the anchor slips <NUM> outwards. The force of this action is sufficient to overcome the retaining force of the snap ring <NUM>, causing the anchoring unit <NUM> to swell. This causes the anchoring unit <NUM> to engage with the middle section <NUM> of the locating profile with a high force.

<FIG> shows the coupling mechanism after expansion of the anchoring unit <NUM> in the locating profile. In this state the sprung snap ring <NUM> has stretched allowing expansion of the anchoring unit <NUM> into the middle section <NUM> of the locating profile. Downward movement of the anchoring unit is prevented by the bottom section <NUM> of the locating profile. Upward movement of the anchoring unit <NUM> is prevented by the lip between the middle section <NUM> and the top section <NUM> of the locating profile. The compression spring <NUM> has lengthened but remains in compression. This causes the collar <NUM> to bear against the lower surface of the anchoring unit <NUM>. This assists the process of driving the anchoring unit <NUM> along the conical portion <NUM> of the main body <NUM> and then keeping it there under force.

When the anchoring unit <NUM> is in the expanded state, it jams in place in the middle section <NUM> of the locating profile. The action of the spring <NUM> in combination with the outward wedging force of the conical portion <NUM> creates a high force metal to metal contact between the anchoring unit <NUM> and the wall of the locating profile <NUM>. This is key to the transmission of acoustic energy between the instruments above, through the main body <NUM>, the anchoring unit <NUM> and into the wellbore tubing (the locating profile). Other instruments at surface or further up or down the well may now communicate with sonic pulses to this assembly. Communication may be in either or both directions.

<FIG> show optional features of the collar <NUM>. In <FIG> the anchoring unit <NUM> is in the unexpanded state. The collar <NUM> comprises a recess <NUM> on its end surface, which receives one end of the spring <NUM>. The collar <NUM> also includes an annular groove <NUM> on its inner surface, which receives a snap ring <NUM>. In this state the snap ring <NUM> is under tension (swollen) around the shaft <NUM>. The inner radius of the collar <NUM> between the groove <NUM> and the recess <NUM> is larger than the radius of the shaft <NUM>, but less than the combined radius of the shaft and the snap ring <NUM>. This provides a lip <NUM> which bears against the snap ring <NUM> when it is in the swollen state. The lip <NUM> causes the snap ring <NUM> to slide along the shaft <NUM> with the collar <NUM> as the anchoring unit <NUM> expands.

<FIG> shows a detail of the collar <NUM> when the anchoring unit <NUM> is in the expanded state. In this state, the collar <NUM> has moved axially along the shaft <NUM> under the force of the spring <NUM>. As the collar <NUM> moves axially along the shaft, the snap ring <NUM> encounters an annular groove <NUM> in the shaft <NUM>. At this point the snap ring <NUM> snaps into the groove <NUM>. The dimensions of the groove <NUM> are such that, once the snap ring is in the groove, the lip <NUM> is able to pass over the snap ring <NUM>. However, downward movement of the collar is prevented by the narrower radius of the collar above the groove <NUM>. Thus the snap ring <NUM> prevents the collar <NUM> (and hence the anchoring unit <NUM>) from travelling back in the opposite direction.

However, the coupling mechanism described above may function without requiring a specific mechanism to prevent reverse travel. Thus, in an alternative embodiment, the optional features described with reference to <FIG> are dispensed with.

Typically the wireline that deployed the assembly is removed by shearing pins above the acoustic transceiver and instruments. The acoustic transceiver and instruments are left in the well hole to record and transmit data.

To retrieve the assembly at a later date, first a wireline is run into the wellbore and engaged with the top of the instruments. Various latching and guide mechanisms are commonly available for this purpose. A jarring device is then used to impart a high shearing force upward on the assembly. This force breaks the second shear pin <NUM>, allowing the main body <NUM> to slide axially along the shaft <NUM> until restricted by the nut <NUM>. This leaves the anchoring unit <NUM> free to collapse under the compressive force of the snap ring <NUM>, thereby allowing the assembly to move upwards beyond the lip of the middle section <NUM> of the locating profile. The entire assembly can then be drawn upwards through the wellbore.

Claim 1:
A coupling mechanism (<NUM>) arranged to acoustically couple an acoustic communication device (<NUM>) to a locating profile (<NUM>) in a wellbore, the coupling mechanism comprising:
a coupling body (<NUM>) arranged to be connected to the acoustic communication device (<NUM>), the coupling body comprising a tapered outer surface; and
an anchoring unit (<NUM>) comprising a tapered inner surface arranged to oppose the tapered outer surface of the coupling body (<NUM>),
wherein the coupling body and the anchoring unit are configured for relative movement to cause the anchoring unit to expand radially to grip the locating profile (<NUM>), so as to allow the transmission of acoustic energy between the acoustic communication device (<NUM>) and the wellbore, through the coupling body (<NUM>) and the anchoring unit (<NUM>), thereby to acoustically couple the acoustic communication device (<NUM>) to the wellbore.