Imaging apparatus for visualising downhole operations

Abstract

A method for providing an imaging device for imaging the interior of an access fitting in a well top installation, for example to visualise fishing operations, is disclosed. The access fitting has an axial passage allowing access to a wellbore and a side passage that intersects the axial passage, and the well top installation including a side arm comprising one or more side arm fittings connected to the side passage. The method comprises installing an imaging device in the side arm, such that an imaging window of the imaging device faces the access fitting and the axial passage of the access fitting is in a field of view of the imaging window.

Description

[0001] IMAGING APPARATUS FOR VISUALISING DOWNHOLE OPERATIONS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to imaging assemblies suitable for visualising downhole operations, for example by imaging the interior of an access fitting in a well top installation; imaging devices for use in such imaging assemblies; and methods for providing an imaging device in a well top installation.

[0004] BACKGROUND

[0005] In hydrocarbon production operations it is occasionally necessary to retrieve objects from a wellbore, using a procedure known in the art as “fishing”. In a fishing operation, a suitable specialised fishing tool is passed into the wellbore, through the wellhead (i.e. the top of the wellbore), to locate and capture the downhole object (known as the “fish”). The fishing tool is then pulled out of the wellbore. If the fishing operation has been successful, the fish is attached to the fishing tool and can then be retrieved.

[0006] Fishing operations are often performed with a well top installation installed on the wellhead, particularly when performed on wells in production. A well top installation is an assembly of valves, fittings and pipework used to manage access to and flow from the wellbore through the wellhead, and may for example include a blowout preventer and a Christmas tree (production tree) providing flow control. In such cases, the fishing tool may be inserted and removed from the wellbore through the Christmas tree and the blowout preventer, which can complicate fishing operations. For instance, if a fishing operation is performed through an opened blowout preventer valve, it is important that the valve is closed only at the appropriate time in the procedure, for example once the fish has been fully extracted from the wellhead. It may however be difficult to determine that the bottom of a fish has cleared the valve or that there is no detritus hanging from the fish, and if the valve is closed prematurely in such cases there is a risk that the fishing operation will fail, leaving objects to fall downhole.

[0007] In another example, for certain operations, such as the retrieval of wireline cables and objects connected to wireline cables, it is necessary to pause the fishing operation once the fished cable has been brought to the surface, so that the fished cable can be connected to a drum and subsequently spooled to retrieve the remainder of the fished cable and any object connected to it. In one approach, the blowout preventer valve is closed and sealed on the fished cable once it emerges from the wellhead to clamp the fished cable while the transfer of the fished cable to a spool takes place. In such cases, difficulties in closing the blowout preventer can arise if the fished cable has not been brought to the surface, or if the fished cable is tangled or is otherwise non-uniform.

[0008] It is desirable to minimise the risk of any difficulties occurring during fishing operations. Even when successful, fishing operations can result in substantial amounts of nonproduction time. Unsuccessful fishing attempts can significantly increase the production time lost, and increase the chance of equipment damage (for example to the fishing tools, the fish, and / or the well equipment).

[0009] It is against that background that the present invention has been devised.

[0010] SUMMARY OF THE INVENTION

[0011] In a first aspect, the present disclosure provides a method for providing an imaging device for imaging the interior of an access fitting in a well top installation, the access fitting having an axial passage allowing access to a wellbore and a side passage that intersects the axial passage, and the well top installation including a side arm comprising one or more side arm fittings connected to the side passage. The method comprises installing an imaging device in the side arm, such that an imaging window of the imaging device faces the access fitting and the axial passage of the access fitting is in a field of view of the imaging window.

[0012] The present inventors have recognised that, by installing an imaging device in a side arm of a well top installation, an imaging device can be provided to visualise downhole operations such as fishing operations without the need to remove or disturb the whole of a well top installation. For instance, where the well top installation is a Christmas tree mounted on a blowout preventer, tools and objects can be visualised as they pass through the access fitting (embodied, for example, by a riser block) by installing the imaging device in a side arm of the Christmas tree. Installing the imaging device in a side arm (preferably a non-production side arm) avoids the need to remove the Christmas tree from the wellhead or to disturb the connections between the wellhead, the blowout preventer and the Christmas tree, resulting in a significant cost and time saving and improving safety. Furthermore, the imaging device can be accommodated without adding to the height of the well top installation.

[0013] By installing the imaging device in the side arm, the imaging device (and in particular the imaging window) need not extend into the axial passage of the access fitting. Therefore the imaging device does not interfere with fishing operations or other downhole operations.

[0014] Installing the imaging device may comprise mounting the imaging device or an imaging assembly comprising the imaging device between two side arm fittings or between a side arm fitting and the access fitting.

[0015] The method may comprise attaching a first end of a spacer fitting to the access fitting to align a spacer passage of the spacer fitting with the side passage of the access fitting, and attaching the imaging device to a second end of the spacer fitting by coupling a first side of a mounting element of the imaging device to the spacer fitting, such that the imaging window of the imaging device is disposed in the spacer passage of the spacer fitting.

[0016] The side arm fitting or at least one of the side arm fittings may comprise a valve fitting, in which case the method may comprise attaching the valve fitting to a second side of the mounting element of the imaging device.

[0017] The mounting element may be a mounting flange, a tubular, or any another suitable element to which one or more adjacent fittings can be connected.

[0018] The method may comprise providing power and / or signal connection to the imaging device by inserting an elongate connector rod through the valve fitting, so as to connect a first connector disposed on the second side of the mounting element to a second connector disposed at a distal end of the connector rod.

[0019] The spacer fitting may comprise a service passage that intersects the spacer passage, in which case the method may comprise passing a cleaning agent through the service passage to clean the imaging window. The well top assembly may be a Christmas tree, in which case the imaging device may be provided in a non-production arm of the Christmas tree.

[0020] The imaging device may be a camera for providing still images and / or a video feed of the interior of the access fitting. The imaging device may comprise a sensor housing, and the sensor housing may comprise at least one illumination window and a light source for providing illumination for a field of view of the camera through the illumination window.

[0021] The steps in the method of providing an imaging device for imaging the interior of an access fitting in a well top installation may be performed in any suitable order.

[0022] In a second aspect, the disclosure provides an imaging assembly for imaging the interior of an access fitting in a well top installation, the access fitting having an axial passage allowing access to a wellbore and a side passage that intersects the axial passage. The imaging assembly comprises an imaging device having a mounting flange with a first side and an opposite second side, and an imaging window, wherein the imaging window is disposed on a first side of the mounting flange, and a spacer fitting for connection between the first side of the mounting flange and the access fitting, the spacer fitting comprising a spacer passage. When installed, the imaging window is disposed in the spacer passage of the spacer fitting, and the spacer passage is coaxial with the side passage of the access fitting such that the axial passage of the access fitting is in a field of view of the imaging window. The second side of the mounting flange is configured to connect with a valve fitting of the well top installation.

[0023] With this arrangement, the imaging device can be used to provide real-time or still images of the interior of an access fitting, for example during fishing operations, to allow an operator to visualise the fishing operation and confirm the status of the fishing tool and / or the fish within the access fitting in the well top installation. The access fitting may for example be a cross or riser block of a Christmas tree (production tree), through which access is provided to the wellbore via a blowout preventer mounted between the access fitting and a wellhead. Advantageously, the imaging device can be installed in a non-production side arm (also known as a kill arm or kill wing) of the well top assembly, with the imaging device and spacer fitting installed between the access fitting one or more valve fittings mounted to the second side of the mounting flange. In this way, it is possible still to provide kill valves in the non-production side arm for emergency use, despite the presence of the imaging device.

[0024] To that end, the well top installation may be a Christmas tree, and the access fitting may be a cross of the Christmas tree through which fishing operations can be conducted. However, the well top installation may be any other arrangement of pipes, valves and / or fittings that is installed above or is otherwise connected to a wellbore, either directly or via another installation such as a blowout preventer. The access fitting may be any suitable component that has an axial passage that allows access to the wellbore and an intersecting side passage (such as a tee, or a pipe with a collar and flange).

[0025] The spacer fitting may comprise a service passage extending through the spacer fitting and intersecting the spacer passage to define an intersecting region. Preferably, when installed, the imaging window is disposed in the intersecting region of the spacer fitting, and the service passage may provide a flow path to allow a cleaning agent to flow across the imaging window in use. To that end, the imaging assembly may comprise a fluid flow arrangement connected to at least one end of the service passage and arranged to pump the cleaning agent through the service passage.

[0026] The imaging device may comprise a connector disposed on the second side of the mounting flange, for example for providing power and / or signal connections to the imaging device from an external control unit. In this case, the imaging assembly may further comprise an elongate connector rod, the connector rod having a distal end and a second connector at the distal end. The second connector may be arranged to releasably connect with the connector of the imaging device for providing power and / or signal connections to the imaging device. In use, the second connector can preferably be connected and disconnected from the connector of the imaging device by insertion and withdrawal respectively of the connector rod through the valve fitting. With this arrangement, in an emergency situation, the connector rod can be withdrawn, allowing the valve fitting to be closed.

[0027] The imaging device provided in the method of the first aspect of the disclosure may be the imaging device of the imaging assembly according to the second aspect of the disclosure. A third aspect of the disclosure provides an imaging device comprising a mounting flange having a first side and a second side and comprising a through-bore. The imaging device also comprises a sensor housing projecting from the first side of the mounting flange, the sensor housing having a sensor housing coupler to couple the sensor housing to the mounting flange, an imaging window disposed at a distal end of the sensor housing, and a connector projecting from the second side of the mounting flange, the connector having a connector coupler to couple the connector to the mounting flange. At least one of the sensor housing coupler and the connector coupler extend into the through-bore and form a seal with the mounting flange at a wall of the through-bore.

[0028] The imaging device of the third aspect of the disclosure, which may be suitable for use in the method of the first aspect of the disclosure and / or the imaging assembly of the second aspect of the disclosure, provides a pressure-sealed device that can be used to image the interior of a pressurised fitting, for example in a hydrocarbon production or similar environment.

[0029] Preferably, both the sensor housing coupler and the connector coupler extend into the through-bore. At least one of the sensor housing coupler and the connector coupler may comprise an o-ring seal for sealing with the mounting flange at a wall of the through-bore.

[0030] The sensor housing coupler and / or the connector coupler may be secured to the respective first or second side of the mounting flange by fasteners that engage with a collar of the respective coupler to secure the collar against the mounting flange.

[0031] The first and / or the second side of the mounting flange may comprise sealing means for forming a seal with an adjacent flange when installed. The mounting flange could be sandwiched between two fittings in use, such as a spacer fitting or pipe flange and a valve fitting.

[0032] In an embodiment, the imaging device is a camera for providing still images and / or a video feed, for example for imaging of the interior of an access fitting of a well top assembly. In this case, the sensor housing may comprise at least one illumination window and a light source for providing illumination for a field of view of the camera through the illumination window. In a fourth aspect, the present disclosure provides an imaging assembly for visualising downhole operations, the imaging assembly comprising an imaging device comprising a mounting flange, a sensor housing projecting from the first side of the mounting flange, and an imaging window disposed at a distal end of the sensor housing; and a spacer fitting comprising a spacer passage extending through the spacer fitting and a service passage extending through the spacer fitting and intersecting the spacer passage to define an intersecting region. The spacer fitting is connectable to the mounting flange of the imaging device such that the imaging window is disposed in the intersecting region.

[0033] Preferably, the service passage provides a flow path to allow a cleaning agent to flow across the imaging window in use. To that end, the imaging assembly may further comprise a fluid flow arrangement connected to at least one end of the service passage and arranged to pump the cleaning agent through the service passage.

[0034] In a fifth aspect, the disclosure provides a sensor assembly for use in a well top installation comprising at least one valve fitting, the sensor assembly comprising a sensor device having a mounting element, a sensor disposed on or facing towards a first side of the mounting element, and a first connector disposed on a second side of the mounting element; and an elongate connector rod, the connector rod having a distal end and a second connector at the distal end, the second connector being arranged to releasably connect with the first connector for providing power and / or signal connections to the sensor device. In use, the second side of the mounting element is connectable to the valve fitting of the well top installation, such that the second connector can be connected and disconnected from the first connector by insertion and withdrawal respectively of the connector rod through the valve fitting.

[0035] The sensor assembly may comprise cooperating first and second guide formations to guide the second connector into engagement with the first connector upon insertion of the connector rod. For example, the first guide formation may comprise a frustoconical socket, and the second guide formation may comprise a frustoconical or cylindrical plug for cooperation with the socket. The first guide formation may be associated with the first connector, and the second guide formation may be provided at the distal end of the connector rod. Alternatively, the second guide formation may be associated with the first connector, and the first guide formation may be provided at the distal end of the connector rod.

[0036] Preferably, the connector rod comprises at least one centraliser for centring the connector rod in the valve fitting during insertion and withdrawal.

[0037] The sensor device may be an imaging device for imaging the interior of an access fitting in a well top installation.

[0038] Preferred and / or optional features of each aspect of the disclosure may also be used, alone or in appropriate combination, in the other aspects also.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which like reference signs are used for like features, and in which:

[0041] Figure 1 shows an imaging assembly according to an embodiment of the invention, installed in well top assembly;

[0042] Figure 2 is a cross-sectional view of part of the well top installation and imaging assembly of Figure 1 ;

[0043] Figure 3 is a perspective view of an imaging device of the imaging assembly of Figures 1 and 2, showing a first side of a mounting flange of the imaging device;

[0044] Figure 4 is another perspective view of the imaging device of Figure 3, showing a second side of the mounting flange;

[0045] Figure 5 is a cross-sectional view of the imaging device of Figure 3;

[0046] Figure 6 is a perspective view of a connector rod for use in the imaging assembly of Figure 1 ; Figure 7 is a cross-sectional view of part of the connector rod of Figure 6;

[0047] Figure 8 is sectional view showing parts of a connector rod and an imaging device connector for use in an imaging assembly according to another embodiment of the invention in a disconnected configuration; and

[0048] Figure 9 is sectional view showing the connector rod and imaging device connector of Figure 8 in a connected configuration.

[0049] DESCRIPTION OF THE EMBODIMENTS

[0050] Figure 1 shows a well top installation 10 including an imaging assembly 100 according to an embodiment of the invention. In this example, the well top installation 10 is part of a Christmas tree (production tree), and includes a production arm 12, a nonproduction arm 14, and an access fitting in the form of a cross 16 (also known as a riser block).

[0051] The production arm 12 includes a first production gate valve 18a connected to a production side flange 20 of the cross 16 and a second production gate valve 18b connected to the first production gate valve 18a on one side and to other components (not shown) of the well top installation on the other side.

[0052] Referring additionally to Figure 2, which omits the production arm 12, the imaging assembly 100 comprises a spacer fitting 110 and an imaging device 120 having a mounting element in the form of a flange 122. The spacer fitting 110 is cross-shaped, and has a horizontally-extending spacer passage 112 and a vertically-extending service passage 114 that intersect at a central intersecting region 116. The spacer fitting 110 is connected on one side to a non-production side flange 22 of the cross 16. The other side of the spacer fitting 110 is connected to a first side 124 of the mounting flange 122 of the imaging device 120, so that the spacer fitting 110 is disposed between the imaging device 120 and the cross 16. A first kill gate valve 24a is connected to a second side 126 of the mounting flange 122 of the imaging device 120, and a second kill gate valve 24b is connected to the first kill gate valve 24b. In this way, the spacer fitting 110 and imaging device 120 are incorporated into the nonproduction arm 14 between the kill gate valves 24a, 24b and the cross 16. The cross 16 includes a lower flange 26 which in this example is connected to a blowout preventer (not shown), that is in turn connected to a wellhead to provide access to a wellbore. An upper flange 27 of the cross 16 may be connected to other components (such as other Christmas tree components). As can be seen in Figure 2, an axial passage 28 of the cross 16 provides access vertically through the cross 16, for example for fishing tools.

[0053] A side passage 30 of the cross 16 extends horizontally between the production and non-production side flanges 20, 22 and intersects the axial passage 28. In this example, the intersection between the axial and side passages 28, 30 is enlarged to provide a box-shaped cavity 31 . During production, the side passage 30 provides a fluid flow path, via the axial passage 28, between the wellbore, the production arm 12, and the non-production arm 14.

[0054] The imaging device 120 is shown in more detail in Figures 3, 4 and 5. A sensor housing 130 projects from the first side 124 of the mounting flange 122 (see Figures 3 and 5), and a connector 132 projects from the second side 126 of the mounting flange 122 (see Figures 4 and 5). Each of the first and second sides 124, 126 of the mounting flange 122 are provided with a sealing ring 134 (shown in Figures 3 and 4 and omitted from Figure 5). Each sealing ring 134 seats in a groove 136 (see Figure 5) on the corresponding face of the mounting flange 122, and the sealing rings 134 provide sealing means that allow the first side 124 of the mounting flange 122 to seal with the spacer fitting 110 and the second side 126 of the mounting flange 122 to seal with the first kill gate valve 24a.

[0055] As shown most clearly in Figure 5, the sensor housing 130 houses an imaging sensor 140 which, in this example, is a visible light camera sensor. The imaging sensor 140 is positioned behind a viewport or imaging window 142 provided at the distal end 144 of the sensor housing 130. The imaging window 142 may for example be a sapphire element, suitably sealed in an opening in the sensor housing 130. An imaging lens 146 is disposed between the imaging window 142 and the imaging sensor 140. The imaging lens 146 may be a fixed lens, or may be a lens system providing focal point and / or focal length adjustment.

[0056] The imaging window 142 and imaging lens 146 are disposed in a reduced-diameter tip portion 148 at the distal end 144 of the sensor housing 130. The tip region 148 meets a remaining body portion 150 of the sensor housing 130 at an annular shoulder 152, in which a plurality of illumination ports or illumination windows 154 are provided (shown most clearly in Figure 3), which again may comprise sapphire elements suitably sealed in openings in the sensor housing 130. Referring back to Figure 5, a light source 156 (such as an LED light source array) is provided in the body portion 150 of the sensor housing 130, behind the illumination windows 154, to illuminate the field of view of the imaging sensor 140 beyond the imaging window 142. The body portion 150 also houses control electronics 158 for the imaging sensor 140 and the light source 156.

[0057] The mounting flange 122 forms a base or bulkhead part of the imaging device 120, to which the sensor housing 130 is mounted, and includes a central through-bore 128 to allow power and / or signal connections to pass through the mounting flange 122.

[0058] The sensor housing 130 is coupled to the mounting flange 122 by a sensor housing coupler 160. The generally tubular sensor housing coupler 160 includes an annular collar 162 that abuts the first side 124 of the mounting flange 122. The collar 162 is fixed to the face of the mounting flange 122 by a plurality of fasteners 164 (see Figures 3 and 5). A tubular sealing portion 166 of the sensor housing coupler 160 extends from the collar 162 into the through-bore 128. The sealing portion 166 carries a pair of O- rings 168 to form a seal against the wall of the through-bore 128. A tubular projecting portion 170 of the sensor housing coupler 160 extends from the collar 162 into the sensor housing 130 and is suitably attached to and sealed with the sensor housing 130.

[0059] A similar arrangement is provided to couple the connector 132 to the mounting flange 122. In this case, a generally tubular connector coupler 172 includes an annular collar 174 that abuts the second side 126 of the mounting flange 122 and is secured to the face of the mounting flange 122 by a plurality of fasteners 176 (see Figure 4). A tubular sealing portion 178 of the connector coupler 172 extends from the collar 174 into the through-bore 128 towards the sealing portion 166 of the sensor housing coupler 160. The sealing portion 178 carries a pair of O-rings 180 to form a seal against the wall of the through-bore 128. A tubular projecting portion 182 of the connector coupler 172 extends from the collar 174 into a generally tubular shroud 184 of the connector 132. The projecting portion 182 is suitably affixed to the shroud 184. The shroud 184 of the connector 132 houses a male connector element 186. The male connector element 186 (in this case an electrical connector) is disposed in a straightwalled section of the shroud 184, and the shroud 184 tapers outwardly to form a frustoconical guide formation 188 (or socket) of the shroud 184 that extends beyond the male connector element 186 and protects a plurality of pins 190 of the male connector element 186. A seal arrangement 192 is provided between the male connector element 186 and the connector coupler 172, to seal the interior of the connector coupler 172 (and, in turn, the interior of the sensor housing coupler 160 and the sensor housing 130). The pins 190 of the male connector element 186 are electrically connected to the control electronics 158 in the sensor housing 130 by suitable wires (indicated schematically at 194) and one or more internal connectors (one of which is indicated at 196).

[0060] The seals formed between the sensor housing coupler 160 and the connector coupler 172 on the one hand and the mounting flange 122 on the other hand provide a primary pressure seal that, in use, guards against fluid leakage past or through the mounting flange 122 of the imaging device 120, allowing the imaging device to be operated while the interior of the spacer fitting 110 and the cross 16 are under pressure (as would be the case during fishing operations, where the cross 16 is in fluid connection with the wellbore). The primary seal is preferably rated for at least 10,000 psi (approx. 70 MPa), and more preferably 20,000 psi (approx. 140 MPa). The seal arrangement 192 between the male connector element 186 and the connector coupler 172 provides a secondary pressure seal that guards against pressure loss and fluid leakage through the interior of the imaging device 120, for example in the event that the sensor housing 130 or another component of the imaging device is compromised. The secondary pressure seal is preferably rated for at least 5,000 psi (approx. 35 MPa).

[0061] Referring back to Figure 2, and additionally to Figures 6 and 7, electrical connections (for power and signals) are provided to the imaging device 120 by an elongate connector rod 200. Figure 6 shows the whole of the connector rod 200, and Figure 7 is a sectional view of a first, distal end of the connector rod 200. The distal end of the connector rod 200 is provided with a female connector element 202 configured to mate with the male connector element 186 of the imaging device connector 132. A rigid tubular elongate body 204 of the connector rod 200 extends from the female connector element 202 to a second end, which is provided with a main cable connector 206 (see Figure 6) for connection to a main cable (not shown). Wires (not shown) extend along the body 204 to form electrical connections between the main cable connector 206 and the female connector element 202.

[0062] As shown most clearly in Figure 7, the female connector element 202 has a cylindrical shape, and is configured to pass into the frustoconical guide formation 188 of the shroud 184 of the imaging device connector 132 to mate with the male connector element 186. The male and female connector elements 186, 202 (and / or the shroud 184) may be provided with cooperating key features to assist with correct orientation.

[0063] Referring again to Figure 2, the connector rod 200 is long enough to extend through the first and second kill gate valves 24a, 24b. Thus, with the imaging device 120 installed and the kill gate valves 24a, 24b open, the connector rod 200 can be inserted from the end of the second kill gate valve 24b and pushed into engagement with the connector 132 of the imaging device 120, assisted by the guide formation 188 of the shroud 184. To further assist with insertion of the connector rod 200, the connector rod body 204 is provided with one or more centralisers 208 (two in this example, see Figure 6). The centralisers 208 are spaced apart along the connector rod body 204 and are arranged to keep the connector rod 200 approximately central and coaxial with the bores of the kill gate valves 24a, 24b. In the illustrated example, the centralisers 208 are embodied as part-circular baffles, although any suitable alternative structure could be used.

[0064] To disconnect the connector rod 200 from the imaging device 120, the connector rod 200 can be pulled to withdraw it from the kill gate valves 24a, 24b. In this way, the first and second kill gate valves 24a, 24b can be quickly brought into use in an emergency situation.

[0065] Figures 8 and 9 illustrate an alternative embodiment of the connector rod 200’ and imaging device connector 132’. Figure 8 shows the components in a disconnected configuration, and Figure 9 shows the components in-situ and in a connected configuration. In this embodiment, the imaging device connector 132’ comprises a male connector element 186’ that is surrounded by a frustoconical plug formation 185 that tapers inwardly towards the pin end of the male connector element 186’, and the female connector element 202’ of the connector rod 200’ carries a frustoconical shroud 210 that tapers outwardly moving distally toward the end of the connector rod 200’. An orientation key 212 is provided on the interior of the shroud 210 for cooperation with a corresponding slot (not shown) on the plug formation 185. The shroud 210 provides a socket formation that receives the plug formation 185 when the connector rod 200’ is inserted for connection with the imaging device 120, guiding the male and female connector elements 186’, 202’ into mating connection as shown in Figure 8. It will be appreciated that, in any embodiment, the male and female connector elements could be reversed.

[0066] Referring back to Figure 2, when installed, the sensor housing 130 of the imaging device 120 extends along the spacer passage 112 of the spacer fitting 110. The spacer fitting is dimensioned so that the imaging window 142 is disposed in the intersecting region 116 of the spacer fitting 110. By connecting suitable fittings and equipment to the spacer fitting 110, the service passage 114 of the spacer fitting 110 can be used to pass a cleaning agent (such as water or a gas) through the spacer fitting 110 when required, so that the imaging window 142 can be cleaned. A suitable fluid flow arrangement (not shown) may be provided to supply the cleaning agent to one end of the service passage 114 and optionally to collect the cleaning agent from the other end of the service passage 114. The provision of the service passage 114 in the spacer fitting 110 thereby allows fogging or debris to be cleared from the imaging window 142 as necessary in use. When not required for cleaning, the service passage can be closed and sealed using suitable valves or blanking plates attached to the spacer fitting 110.

[0067] In an example, the spacer fitting 110 and the imaging device 120 are dimensioned such that the imaging window 142 is disposed approximately 600 mm from the central vertical axis of the axial passage 28 of the cross 16.

[0068] Installation and use of the imaging assembly 100 in one example application will now be described. In this example, the starting point is a well top installation in the form of a Christmas tree including all of the components shown in Figure 1 without the imaging assembly 100. Thus the cross 16 is fitted to a blowout preventer, the first production gate valve 18a of the production arm 12 is connected to the production side flange 20 of the cross 16, and the first kill gate valve 24a of the non-production arm 14 is connected directly to the non-production side flange 22 of the cross 16. In this configuration, the well may be performing production operations. In the event that it becomes necessary to perform a fishing operation, the imaging assembly 100 can be installed by removing the first and second kill gate valves 24a, 24b, mounting the spacer fitting 110 on the non-production side flange 22 of the cross 16, mounting the imaging device 120 with the first side 124 of the mounting flange 122 against the spacer fitting 110, then reinstalling the kill gate valves 24a, 24b by first mounting the first kill gate valve 24a on the second side 126 of the mounting flange, and then mounting the second kill gate valve 24b to the first kill gate valve 24a.

[0069] The distal end of the connector rod 200 is then inserted into the second kill gate valve 24b and pushed through the first kill gate valve 24a and into engagement with the connector 132 of the imaging device 120, thereby arriving at the configuration shown in Figure 1 . The main cable connector 206 of the connector rod is then connected to control and logging equipment (not shown). Operation of the imaging device 120 can then be tested, for example by confirming that a stable video signal is obtained, and that the lighting is sufficient for illuminating the interior of the cross 16. The ability of the control and logging equipment to capture high-resolution still images and to record video clips may also be confirmed.

[0070] Various pressure tests may then be performed. For example, the imaging device 120 may be powered down and the connector rod 200 removed. The cross 16 may then be pressurised so that any pressure leakage past the imaging device 120 can be observed, and the first and second kill gate valves 24a, 24b may be closed and checked for correct operation.

[0071] Having verified that there is no pressure leakage associated with the imaging assembly 100 and that the kill gate valves 24a, 24b are operable in an emergency, the connector rod 200 is re-inserted to provide power and signal connections to the imaging device 120. The cross 16 may then be re-pressurised and the system checked again for pressure loss and for correct imaging device performance.

[0072] At this time, a cleaning test may also be performed, in which water (or another suitable cleaning agent) is pumped through the service passage 114 of the spacer fitting 110. The video feed from the imaging device 120 can be monitored during and after the test to ascertain that the cleaning agent flows over the imaging window 142 and that a clear image is subsequently restored after cleaning. The imaging device 120 can then be used to visualise the interior of the cross 16 during fishing or other operations. Once the operation has been complete and imaging is no longer required, the imaging assembly 100 can be removed in the reverse order of installation.

[0073] It will be understood that the imaging assembly and the imaging device described herein could be used for many different imaging tasks in hydrocarbon production operations and other applications, and are not limited to providing imaging of fishing operations. For instance, the imaging device could be used for inspection of downhole tools, inspection of fittings, inspection of valves, monitoring of well operations, visualisation and monitoring of pipelines and so on. The imaging device may be installed in a production tree (i.e. a Christmas tree or frac tree), as described above, in a pipeline, or in a different well top installation such as those used during drilling or other pre-production operations. The imaging assembly and the imaging device may be used in geothermal operations, carbon-capture wells, water injectors and so on.

[0074] It is conceivable that the imaging device could be used without a spacer fitting, in which case the imaging window could be located directly in a cross, a tee, a riser block, a pipeline or any other fitting associated with a hydrocarbon production operation. Where a spacer fitting is used, the spacer fitting may be a separate fitting or may be part of another component, such as the access fitting (i.e. the spacer fitting and the access fitting may be integrally formed).

[0075] Several variations of the spacer fitting are possible. For example, a spacer fitting without a service passage may be used (for example in applications where fouling of the imaging window is not expected). When a service passage is provided, the service passage could be oriented vertically (as in the above-described examples), or horizontally, or could intersect the spacer passage at a different angle. The service passage need not be straight, but could instead comprise for example a vertically- oriented part and a horizontally-oriented part that intersect at the intersecting region. The spacer fitting may be formed integrally with or permanently connected (e.g. as by welding) to the mounting flange, so that the spacer fitting and mounting flange together provide a tubular housing.

[0076] The imaging sensor used in the imaging device is for most applications a visible light camera sensor. However, other imaging sensors could be used. Examples include non-visible light camera sensors, thermal imaging sensors, acoustic (e.g. ultrasonic) imaging sensors, depth imaging sensors and so on.

[0077] The imaging window may take any suitable form. For example, the imaging window could be a lens, a viewing window, a filter and so on. Taken broadly, the imaging window could be any element or structure through which imaging signals (including electromagnetic waves, acoustic / ultrasonic waves and so on) can pass between the imaging sensor and the area to be imaged.

[0078] In the above-described examples, the imaging device receives power and transmits and receives data signals through an electrical connector. It will be appreciated that data signals could instead by transmitted for example by a fibre optic cable, in which case the connectors provided on the imaging device and the connector rod may facilitate fibre optic connections.

[0079] In some cases, it is not necessary to provide the imaging device with electrical power. For example, the imaging device may be battery powered. In such cases, the imaging device and the connector rod may provide electrical and / or fibre optic connections only for signals. Alternatively, or in addition, the imaging device may have a wireless transmitter / receiver for communicating with a control unit, in which case signal connections are not required. In cases where it is not necessary to provide either power or signal connections, the connector of the imaging device (and the connector rod) can be omitted. In such cases, the through-hole of the mounting flange could also be omitted and a solid flange used instead.

[0080] It is also conceivable that an imaging device without a mounting flange could be used. For example, the imaging device may be provided within a valve fitting, spacer fitting or other generally tubular fitting to be installed in a well top installation, for example in a side arm. In such cases, the tubular body of the fitting may provide a mounting element to which adjacent fittings can be connected. In another example, the imaging device is a stand-alone device that can be temporarily inserted into a valve fitting, spacer fitting or other fitting. In such cases, the imaging device can be inserted without the need to disconnect any of the components of the side arm.

[0081] Various aspects of the imaging assembly disclosed herein can be used independently of others. For example, the connector arrangement comprising a first connector on one side of a mounting flange and a second connector at the distal end of a connector rod could be used with a sensor device other than an imaging device (e.g. a sensor device that lacks an imaging window). Examples include pressure and temperature sensors, gas sensors, fluid flow sensors and so on.

[0082] In another example, an imaging device and optionally a spacer fitting as described above could be used in arrangements in which no further components are mounted to the second side of the mounting flange. In such cases, when present, the spacer fitting may include or omit a service passage for admitting a cleaning agent.

[0083] It will be understood that, while components such as fittings may be described herein as a single structure, element or part, it is also possible that such components could be formed from more than one structure, element or part suitably joined or connected. Similarly, where components are described as assemblies of two or more structures or parts, it is possible that such components could be formed from a single structure, element or part.

[0084] Further modifications and variations of the various aspects of the present invention not explicitly described above can also be contemplated without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS1 . A method for providing an imaging device for imaging the interior of an access fitting in a well top installation, the access fitting having an axial passage allowing access to a wellbore and a side passage that intersects the axial passage, and the well top installation including a side arm comprising one or more side arm fittings connected to the side passage, the method comprising: installing an imaging device in the side arm, such that an imaging window of the imaging device faces the access fitting and the axial passage of the access fitting is in a field of view of the imaging window.

2. A method according to Claim 1 , wherein installing the imaging device comprises mounting the imaging device or an imaging assembly comprising the imaging device between two side arm fittings or between a side arm fitting and the access fitting.

3. A method according to Claim 1 or Claim 2, wherein installing the imaging device comprises: attaching a first end of a spacer fitting to the access fitting to align a spacer passage of the spacer fitting with the side passage of the access fitting; and attaching the imaging device to a second end of the spacer fitting by coupling a first side of a mounting element of the imaging device to the spacer fitting, such that the imaging window of the imaging device is disposed in the spacer passage of the spacer fitting.

4. A method according to Claim 3, wherein the side arm fitting or at least one of the side arm fittings comprises a valve fitting, and the method comprises attaching the valve fitting to a second side of the mounting element of the imaging device.

5. A method according to Claim 4, comprising providing power and / or signal connection to the imaging device by inserting an elongate connector rod through the valve fitting, so as to connect a first connector disposed on thesecond side of the mounting element to a second connector disposed at a distal end of the connector rod.

6. A method according to any of Claims 3 to 5, wherein the spacer fitting comprises a service passage that intersects the spacer passage, and wherein the method comprises passing a cleaning agent through the service passage to clean the imaging window.

7. A method according to any of Claims 1 to 6, wherein the imaging device is a camera for providing still images and / or a video feed of the interior of the access fitting.

8. A method according to Claim 7, wherein the imaging device comprises a sensor housing, and wherein the sensor housing comprises at least one illumination window and a light source for providing illumination for a field of view of the camera through the illumination window.

9. An imaging assembly for imaging the interior of an access fitting in a well top installation, the access fitting having an axial passage allowing access to a wellbore and a side passage that intersects the axial passage; the imaging assembly comprising: an imaging device having a mounting flange with a first side and an opposite second side, and an imaging window, wherein the imaging window is disposed on a first side of the mounting flange; and a spacer fitting for connection between the first side of the mounting flange and the access fitting, the spacer fitting comprising a spacer passage; wherein, when installed, the imaging window is disposed in the spacer passage of the spacer fitting, and the spacer passage is coaxial with the side passage of the access fitting such that the axial passage of the access fitting is in a field of view of the imaging window; and wherein the second side of the mounting flange is configured to connect with a valve fitting of the well top installation.

10. An imaging assembly according to Claim 9, wherein the well top installation is a Christmas tree, and the access fitting is a cross of the Christmas tree through which fishing operations can be conducted.

11. An imaging assembly according to Claim 9 or Claim 10, wherein the spacer fitting comprises a service passage extending through the spacer fitting and intersecting the spacer passage to define an intersecting region and wherein, when installed, the imaging window is disposed in the intersecting region of the spacer fitting.

12. An imaging assembly according to Claim 11 , wherein the service passage provides a flow path to allow a cleaning agent to flow across the imaging window in use.

13. An imaging assembly according to Claim 12, further comprising a fluid flow arrangement connected to at least one end of the service passage and arranged to pump the cleaning agent through the service passage.

14. An imaging assembly according to any of Claims 9 to 13, wherein the imaging device comprises a connector disposed on the second side of the mounting flange for providing power and / or signal connections to the imaging device.

15. An imaging assembly according to Claim 14, further comprising an elongate connector rod, the connector rod having a distal end and a second connector at the distal end, the second connector being arranged to releasably connect with the connector of the imaging device for providing power and / or signal connections to the imaging device; wherein, in use, the second connector can be connected and disconnected from the connector of the imaging device by insertion and withdrawal respectively of the connector rod through the valve fitting.

16. A sensor assembly for use in a well top installation comprising at least one valve fitting, the sensor assembly comprising: a sensor device having a mounting element, a sensor disposed on or facing towards a first side of the mounting element, and a first connector disposed on a second side of the mounting element; andan elongate connector rod, the connector rod having a distal end and a second connector at the distal end, the second connector being arranged to releasably connect with the first connector for providing power and / or signal connections to the sensor device; wherein, in use, the second side of the mounting element is connectable to the valve fitting of the well top installation, such that the second connector can be connected and disconnected from the first connector by insertion and withdrawal respectively of the connector rod through the valve fitting.

17. A sensor assembly according to Claim 16, further comprising cooperating first and second guide formations to guide the second connector into engagement with the first connector upon insertion of the connector rod.

18. A sensor assembly according to Claim 17, wherein the first guide formation comprises a frustoconical socket, and the second guide formation comprises a frustoconical or cylindrical plug for cooperation with the socket.

19. A sensor assembly according to any of Claims 16 to 18, wherein the connector rod comprises at least one centraliser for centring the connector rod in the valve fitting during insertion and withdrawal.

Images