Bore access spool apparatus and method

Abstract

The present invention relates to a bore access spool assembly comprising a housing (2) having a longitudinal axis, an upper end (3) of the housing being configured for connection to a riser, a lower end (4) of the housing being configured for connection to a subsea well assembly. The housing further comprises an upper bore (5) located at the upper end, and a plurality of lower bores (6, 6a) located at the lower end, a chamber (7) extending along the longitudinal axis linking the upper and lower bores. A diverter sleeve (11) is provided for introduction into the housing chamber (7) through the upper bore (5), the diverter sleeve (11) being open at its upper end to allow access into a sleeve interior from the upper bore (5), and having an angled kick surface (17) at a lower end of its interior, the diverter sleeve (11) and housing (2) having respective guide formations. The diverter sleeve (11) is configured to be received within the chamber (7) and guided into position through interaction of the guide formations to a deployed state to block a first one (6a) of the plurality of lower bores (6a, 6b), and to divert communication of the upper bore (5) instead to be with a second one (6b) of the plurality of bores.

Description

[0001] BORE ACCESS SPOOL APPARATUS AND METHOD

[0002] Background of the Invention

[0003] The present invention relates in general to subsea well equipment and in particular to a bore access spool apparatus and a related method of operation.

[0004] In this regard, access to a multi-bore subsea well often requires the use of a multibore riser extending from the well to the surface facility. Multi-bore risers add significant expense and time to such a well installation.

[0005] An alternative is therefore to use a mono-bore subsea riser. To direct lowered tools into different bores of a well, devices have conventionally been taken back to surface, reconfigured and re-run (round-tripped), which is a time-consuming activity.

[0006] An improved option to such arrangements to avoid round-tripping is to provide a bore access spool to direct access to the different bores in a multi-bore subsea well. For example, a bore access spool can allow access to a production bore or an annulus bore. The bore access spool enables access to the multiple bores whilst the equipment remains subsea, avoiding retrieving components back to the surface. One such known access spool is disclosed in US9234393.

[0007] However, known bore selector assemblies suffer from issues involving high maintenance, low reliability and low flexibility of operation and it is an object of the present invention, to seek to provide a simple and reliable bore access spool apparatus and related method of operation.

[0008] Summary of the Invention

[0009] According to a first aspect of the present invention, there is provided a bore access spool assembly comprising:- a housing having a longitudinal axis, an upper end of the housing being configured for connection to a riser, a lower end of the housing being configured for connection to a subsea well assembly, the housing further comprising:- an upper bore located at the upper end, and a plurality of lower bores located at the lower end, a chamber extending along the longitudinal axis linking the upper and lower bores; and a diverter sleeve for introduction into the housing chamber through the upper bore, the diverter sleeve being open at its upper end to allow access into a sleeve interior from the upper bore, and having an angled kick surface at a lower end of its interior, the diverter sleeve and housing having respective guide formations; wherein the diverter sleeve is configured to be received within the chamber and guided into position through interaction of the guide formations to a deployed state to block a first one of the plurality of lower bores, and to divert communication of the upper bore instead to be with a second one of the plurality of bores.

[0010] Such an arrangement provides a reliable and controllable bore access spool apparatus. Where the first lower bore is used with a production bore and the second lower bore is used with an annulus bore, the assembly allows switching access to either the production bore or the annulus bore without the need to retrieve components back to the surface.

[0011] The diverter sleeve is dimensioned to be received by the upper bore, so that in use it can be deployed from the surface, passing down the riser drill string.

[0012] Preferably, the diverter sleeve and upper bore have inter-engaging profiles for guiding the diverter sleeve into a deployed orientation within the housing.

[0013] Preferably, the inter-engaging profiles involve a helical profile for rotating and axially lowering the diverter sleeve within the housing. The use of helical formations, such as for example a helical profile in surface of the upper bore of the housing and an associated key on the diverter sleeve, provides a controlled rotational and axial movement.

[0014] Optionally, the chamber has at a lower end of the housing a land-out shoulder for receiving the diverter sleeve. The land-out shoulder can be tailored for specific applications. As such different shoulder profiles can be incorporated into a standard housing, allowing for using a standard housing with tailored diverter sleeve a shoulder sets. Preferably, the land-out shoulder includes bores aligned with the plurality of lower bores. In this way, the shoulder can be tailored to specific requirements, for example for each lower bore.

[0015] Optionally, the land-out shoulder includes a bore aligned with the first one of the plurality of lower bores.

[0016] Optionally, the land-out shoulder has a seating profile for receiving a bottom surface of the diverter sleeve.

[0017] Preferably, an upper end of the diverter sleeve has one or more latch fingers for locking the diverter sleeve in position within the housing when at the correct orientation. In this way the diverter sleeve can be securely positioned within the housing.

[0018] Preferably, the upper bore is axially aligned with one of the lower bores.

[0019] Optionally, the one or more of the lower bores includes an isolation valve. Preferably, the second lower bore has an isolation valve allowing controlled access through to the annulus.

[0020] Rather than to an isolation valve, one or more of the lower bores may be provided with an isolation plug.

[0021] In a further embodiment, a sliding sleeve may be provided in the chamber, the sliding sleeve blocking a second one of the lower bores before the diverter sleeve is deployed, wherein deployment of the diverter sleeve into the housing pushes the sliding sleeve downwardly to allow the diverter sleeve access to the lower bore.

[0022] Optionally, the assembly further comprises a latching mechanism configured to releasably lock the diverter sleeve in position within the housing, the latching mechanism comprising: a latch coupled to the diverter sleeve for axial movement relative to the diverter sleeve, the latch being biased along the diverter sleeve; wherein at different axial positions of the latch along the diverter sleeve, one or more dog heads of the latch align axially with either a deployment recess or a retrieval recess provided on the diverter sleeve, allowing the one or more dog heads to move into the deployment recess or the retrieval recess, thereby reducing the radial extent of the latch such the diverter sleeve can move axially relative to the housing; wherein the housing is provided with a dual bore seal sub having a locking recess into which the one or more dog heads of the latch is receivable to lock the diverter sleeve within the housing; and wherein a shear pin is provided for coupling the latch to the diverter sleeve, the shear pin being configured to restrict an extent of axial movement of the latch when the shear pin is intact; wherein the pin has to be sheared to allow the latch to move sufficiently axially to align with the retrieval recess.

[0023] Optionally, the dual bore seal sub has a tapered face configured, on engagement with the one or more dog heads, to guide the latch into the deployment recess and wherein the one or more dog heads, deployment recess, locking recess and retrieval recess each have tapered faces for guiding the one or more dog heads into and out of the recesses.

[0024] Optionally, the latch comprises a collar element having a plurality of resilient fingers, each having a dog head profile at their free end.

[0025] Optionally, the latch is biased downwardly towards an end of the diverter sleeve, and wherein the shear pin restricts the extent of axial movement of the latch so that when the shear pin is intact, the one or more dog ends are at the maximum axial displacement positioned on a section of the diverter sleeve between the deployment recess and retrieval recess.

[0026] Optionally, the latch is connected to a lower end (e.g. the free end) of the diverter sleeve. Optionally the latch is coupled to the diverter sleeve via a biasing mechanism (i.e. a spring) configured to bias the latch downwardly towards the lower end (optionally the free end) of the diverter sleeve.

[0027] Optionally, the land-out shoulder is formed in the dual bore seal sub provided in the housing.

[0028] According to a further aspect of the present invention there is provided a method of operating a bore access spool assembly, the bore access spool assembly comprising a housing configured for connection between a riser and subsea well assembly, the housing having a upper bore and a plurality of lower bores; the bore access spool assembly further comprising a diverter sleeve for introduction into the housing through the upper bore, wherein the method comprises:- connecting the housing between the riser and the subsea well assembly: conveying the diverter sleeve down the riser and into the housing interior through the upper bore; guiding the diverter sleeve to lock into position blocking a first of the lower bores, the diverter sleeve having a kick surface configured to divert communication of the upper bore to be away from the first lower bore and instead to be with a second of the lower bores.

[0029] Preferably, guiding the diverter sleeve comprises lowering and rotating it to the correct axial and rotational orientation within the housing, this being controlled through guide formations between the diverter sleeve and housing defining a helical path for the diverter sleeve within the housing.

[0030] Optionally, wherein the chamber has at a lower end of the housing a land-out shoulder for receiving the diverter sleeve, the land-out shoulder having a seating profile for receiving a bottom surface of the diverter sleeve.

[0031] Optionally, the diverter sleeve is locked in its deployed position by way of one or more latch fingers.

[0032] Preferably, the upper bore is axially aligned with the first lower bore to provide a production bore before deployment of the diverter sleeve, and wherein once deployed the upper bore communicates with the second lower bore to provide an annulus bore for receiving a tool string.

[0033] Optionally, once in its deployed position an isolation valve is opened in the second lower bore allowing access between the upper bore through the diverter sleeve to the second lower bore. Alternatively, an isolation plug provided in the second lower bore is retrieved using a retrieval tool to allow access between the upper bore through the diverter sleeve to the second lower bore.

[0034] In a further embodiment a sliding sleeve is provided in the chamber, the sliding sleeve blocks or covers a second one of the lower bores before the diverter sleeve is deployed, wherein deployment of the diverter sleeve into the housing pushes the sliding sleeve downwardly to allow the diverter sleeve access to the lower bore.

[0035] Optionally, the diverter sleeve is locked in a deployed position by way of a latching mechanism, the latching mechanism comprising: a latch coupled to the diverter sleeve for axial movement relative to the diverter sleeve, the latch being biased along the diverter sleeve; wherein at different axial positions of the latch along the diverter sleeve, one or more dog heads of the latch align axially with either a deployment recess or a retrieval recess provided on the diverter sleeve, allowing the one or more dog heads to move into the recess, thereby reducing the radial extent of the latch such the diverter sleeve can move relative to the housing; wherein in order to lock the diverter sleeve in the deployed position, the diverter sleeve is run into a dual bore seal sub provided to the housing, engagement of the one or more dog heads of the latch with the dual bore seal sub moving the latch axially along the diverter sleeve until the one or more dog heads aligns with the deployment recess allowing the radial extent of the latch to be reduced as the one or more dog heads is received in the deployment recess, whereby the diverter sleeve can move further into the housing, until the one or more dog heads align with a locking recess in the dual bore seal sub, at which point the one or more dog heads move into the locking recess to lock the diverter sleeve within the housing.

[0036] Optionally, a shear pin is provided for coupling the latch to the diverter sleeve, the shear pin being configured to restrict an extent of axial movement of the latch when intact; wherein in order to retrieve the diverter sleeve the diverter sleeve is jarred upwardly to shear the pin, allowing the latch to move axially along the diverter sleeve sufficiently to align and engage the one or more dog heads in the retrieval recess.

[0037] According to a further aspect of the present invention there is provided a latching mechanism configured to releasably lock a sleeve in position within a housing, the latching mechanism comprising: a latch coupled to the sleeve for axial movement relative to the sleeve, the latch being biased along the sleeve; wherein at different axial positions of the latch along the sleeve, one or more dog heads of the latch align axially with either a deployment recess or a retrieval recess provided on the sleeve, allowing the one or more dog heads to move into the deployment recess or the retrieval recess, thereby reducing the radial extent of the latch such the sleeve can move axially relative to the housing; wherein a dual bore seal sub provided to the housing has a locking recess into which the one or more dog heads of the latch is receivable to lock the sleeve within the housing; and wherein a shear pin is provided for coupling the latch to the sleeve, the shear pin being configured to restrict an extent of axial movement of the latch when the shear pin is intact; wherein the pin has to be sheared to allow the latch to move sufficiently axially to align with the retrieval recess.

[0038] Optionally, the dual bore seal sub has a tapered face configured, on engagement with the one or more dog heads, to guide the latch into the deployment recess and wherein the one or more dog heads, deployment recess, locking recess and retrieval recess each have tapered faces for guiding the one or more dog heads into and out of the recesses.

[0039] Optionally, the latch comprises a collar element having a plurality of resilient fingers, each having a dog head profile at their free end.

[0040] Optionally, the latch is biased downwardly towards an end of the sleeve, and wherein the shear pin restricts the extent of axial movement of the latch so that when the shear pin is intact, the one or more dog ends are at the maximum axial displacement positioned on a section of the sleeve between the deployment recess and retrieval recess. Optionally, the shear pin is provided on one of the latch and sleeve and moves within an axially orientated slot on the other of the latch and sleeve.

[0041] Brief Description of the Figures

[0042] Certain embodiments of the present invention will now be described by way of example and with reference to Figures 1 to 12F of the accompanying drawings, of which:-

[0043] Figures 1 and 2 show exterior perspective views of a bore access spool assembly according to a first embodiment of the present invention;

[0044] Figure 3 shows a pre-deployment cross-sectional view of the bore access spool assembly of Figure 1 ; Figure 4 shows a deployed cross-sectional view of the bore access spool assembly of Figure 1 with a diverter sleeve in a deployed state;

[0045] Figure 5 shows an enlarged view of an orientation guide of the present invention;

[0046] Figure 6 shows an enlarged view of a first latching mechanism of the present invention; Figure 7 shows an enlarged view of a diverter sleeve land-out shoulder of the present invention;

[0047] Figures 8A to 8E show operational sequence views of the bore access spool assembly of the first embodiment of the present invention;

[0048] Figures 9A and 9B show a second embodiment of the present invention;

[0049] Figures 10A to 10E show operational sequence views of the second embodiment

[0050] Figures 11A and 11B show a third embodiment of the present invention;

[0051] Figure 11C shows a detailed view of a latching mechanism of the third embodiment; and

[0052] Figures 12A - 12F show operational sequences of the latching mechanism of the third embodiment.

[0053] Detailed Description

[0054] Turning to the drawings, Figures 1 to 3 show a first embodiment of a bore access spool assembly 1 comprising a housing / spool 2 having a longitudinal axis, an upper end 3 of the housing being configured for connection to a riser or the like, a lower end 4 of the housing being configured for connection to a subsea well assembly.

[0055] As shown in Figure 3, the assembly 1 has an upper bore 5 located at the upper end, and a plurality of lower bores 6a, 6b located at the lower end 4 of the housing spaced from each other.

[0056] The upper bore 5 opens into a chamber 7 extending along the longitudinal axis of the housing 2.

[0057] A land-out shoulder 8, in the form of a dual bore seal sub 8 is provided at the bottom of the chamber 7. The dual bore seal sub has through bores 9 and 10 aligned with respective ones of the lower bores. As shown, the upper bore 5 is aligned axially with the one of the shoulder through bores 9 and a lower bore 6a to thereby form a straight through “production bore” from the top of the housing 2, namely through upper bore 5, through chamber 7, through dual bore seal sub bore 9 and through lower bore 6a, to the bottom of the housing. The lower bore 6a is in this respect optionally intended to connect with a production bore in a subsea Christmas tree assembly.

[0058] In Figure 3, the second lower bore, provides an “annulus” bore 6b, spaced from the “production” bore 6a. Figure 3 shows the annulus bore 6b of this example being isolated due to a isolation valve 21 (in this example, a 2 inch (5.08 cm) isolation valve 21). As such, the assembly shown in Figure 3 is in a straight through production state.

[0059] Figure 4 shows a deployed state of a diverter sleeve 11. As will be described in more detail below, the diverter sleeve 11 is deployed when there is a requirement to isolate the production bore 6a and to connect the riser to the surface with the annulus bore 6b.

[0060] In this event, the diverter sleeve 11 is introduced through the upper bore 5 into the chamber 7. As shown in Figure 5, an orientation guide, preferably a helical slot 12 in the upper bore 5 engages with a suitable profile on the diverter sleeve 11 to rotate the diverter sleeve 11 into the correct orientation, from which the diverter sleeve 11 engages a seating profile 14 of the dual bore seal sub 8. Latch fingers 13, shown in detail in Figure 6, are provided to the diverter sleeve lock the diverter sleeve in position when at the correct orientation. Whilst a helical slot is shown, it will be appreciated that alternative means for lowering and orientating the diverter sleeve in a controlled fashion are possible.

[0061] Figure 7 shows detail of the land-out shoulder 8 formed in the dual bore seal sub, including the seating profile 14 for receiving the end of the diverter sleeve 11.

[0062] From Figure 4, it will be appreciated that the diverter sleeve 11 is open at an upper end 15 to allow access. One side 16 of the diverter sleeve 11 is moreover open to allow access into chamber 7, with a lower end of the diverter 11 including an inclined kick surface 17. When deployed, the diverter sleeve 11 covers or blocks the production bore 6a and, by way of the kick surface 17, directs any tooling / fluids towards the annulus bore 6b.

[0063] Figures 8A to 8E show an operational sequence for the bore access spool assembly.

[0064] The bore access spool assembly shown in Figure 8A is in a deployed state for production runs with the annulus bore 6a isolated by a isolation valve (in this example, a 2” (5.08cm) isolation valve). The diverter sleeve 11 is yet to be deployed.

[0065] Then in Figure 8B, when downhole scopes have been completed, a 577” (10.27cm / 17.78cm) downhole plug is inserted to isolate production. The production bore is as such isolated downhole.

[0066] As shown in Figure 8C, the diverter sleeve 11 is then deployed, for example on a production tool string with a pulling tool (in this example, a 7” (17.78cm) GS pulling tool). The diverter sleeve 11 is orientated and locked into the housing 2. The diverter sleeve 11 has a key, which locates with the orientation slot 12 to rotate it into the correct position. Once in the correct position, the diverter is locked into place using the latch fingers 13 that latch to the inside of the housing.

[0067] Figure 8D shows the next step where the 2” (5.08cm) isolation valve is in the open position. The isolation vale is preferably opened through hydraulics.

[0068] Figure 8E shows the process of completing downhole scopes on a slickline 18. The tool string is then deployed, and as it passes through the diverter sleeve 11 it is kicked off the kick surface 17 to access the annulus bore for operations. The 2” (5.08cm) downhole annulus plug is set (jar down on the plug to set the dogs) so that the production and annulus bores are isolated downhole.

[0069] In this connection, whilst the specific embodiment above shows a method of operation which includes an isolation valve on the second lower bore coupled to the annulus, this may for example be replaced with an isolation plug provided in the second lower bore in an alternative arrangement. In this connection, once the diverter sleeve has been deployed, the isolation plug can be retrieved by way of a plug retrieval tool on a slickline in order to allow access to the second lower bore. Moreover, as shown in Figures 9A and 9B, in a second embodiment of the bore access spool assembly, a sliding sleeve 110 is provided in the housing 100. Figures 9A and 9B respectively show pre-deployed and deployed states of the diverter sleeve 111 of this second embodiment whose operational sequence is discussed below in relation to Figures 10A to 10E.

[0070] In this respect, during a production run, the sliding sleeve 110 blocks or covers the second lower annulus bore 106b, as shown in Figures 9A and 10A. Figure 10B then shows the situation where downhole scopes are completed and a downhole plug is set to isolate production so that the production bore 106a is isolated downhole.

[0071] In Figure 10C, the diverter sleeve 111 is deployed on a slickline, the diverter sleeve 111 landing on the sliding sleeve 110. Then Figure 10D, the sliding sleeve 110 is pushed through the production bore 106a with the diverter sleeve 111 , and the sliding sleeve 110 lands on a shoulder 114 in the housing 100. As with the first embodiment, the diverter sleeve 111 has guide formations to correctly lower and rotate the diverter sleeve 111 into the correct position where it is locked in place with latch fingers 113.

[0072] Figure 10E then shows how a toolstring is deployed with an annulus downhole plug (in this example, a 2” (5.08cm) annulus downhole plug), which is set (jar down to set locking dogs). As such, the production and annulus bores are isolated downhole.

[0073] Figures 11A-11C show a third embodiment of a bore access spool assembly 201. This third embodiment differs from the first embodiment in that instead of having latch fingers 13 provided on the upper end of the diverter sleeve 11 to lock the diverter sleeve 11 in position, the third embodiment of the bore access spool 201 comprises a latching mechanism 220 with a latch 222 connected to a lower end of the diverter sleeve 211. As best seen in Figure 11C, the latch 222 of this example comprises a collar or sleeve with a plurality of downward extending latch fingers each having a dog head 224. Additionally, each of the latch fingers are compressible such that each of the dog heads 224 are radially moveable relative to the diverter sleeve 211.

[0074] Figure 12A shows the latch 222 of this example connected to a lower end of the diverter sleeve 211 by a biasing mechanism 226, which in this example is a spring 226. The latch 222 of this example is axially moveable relative to the diverter sleeve 211 , with the spring 226 urging the latch 222 downwards. In this example, a shear pin 228 is connected to the latch 222 and configured to abut against a lower end of a shear slot or groove 230 disposed on the diverter sleeve 211 such that downward axial movement of the latch 222 is prevented beyond a certain axial position relative to the diverter sleeve 211 while the shear pin 228 is unsheared.

[0075] Figures 12A-12F show an operational sequence the latching mechanism 220. Starting at Figure 12A, the diverter sleeve 211 is lowered into the seating profile 214 of the dual bore seal sub 208. At this position, the latch 222 is not in contact with the seating profile 214.

[0076] Figure 12B shows a lower tapered face 224I of the dog head 224 engaged with a tapered portion 232 of the seating profile 214. As the diverter sleeve 211 continues to be lowered, this engagement will cause the spring 226 to compress and allows the latch 222 to move upwards relative to the diverter sleeve 211. This engagement additionally urges the resilient dog heads 224 radially inwards. This continues until the latch 222 reaches an upper axial position relative to the diverter sleeve 211, where the dog heads 224 are moved into and received by a deployment recess or groove 234 disposed on the diverter sleeve 211 and having tapered faces 234u, 234I for guiding the dog heads 224 into and out of the deployment recess / groove 234 (see Figure 12C).

[0077] While the dog heads 224 are within the deployment recess 234, the diverter sleeve 211 is able to continue moving downwards. This lowering is continued until the diverter sleeve 211 reaches its operational position, as seen in Figure 12D. At this point, the dog heads 224 are aligned with a locking recess 236 disposed in the seating profile 214 of the dual bore seal sub 208 and move radially outwards such that they are received in the locking recess 236. In this example, the locking recess 236 has tapered faces 236u, 236I for guiding the dog heads 224 into and out of the locking recess 236.

[0078] The unsheared shear pin maintains the axial position of the diverter sleeve 211 , thereby locking the diverter sleeve 211 in its operational position.

[0079] When the diverter sleeve 211 is to be retrieved from the housing 202 / dual bore seal sub 208, an operator may cause the diverter sleeve 211 to jar upwards to shear the shear pin 228. Afterwards, the operator will action the lifting of the diverter sleeve 211 . As seen in Figure 12E, this lifting will allow the spring 226 to extend and the latch 222 to move downwards relative to the diverter sleeve 211 . As the diverter sleeve 211 is lifted, an upper tapered face 224u of the dog heads 224 engages with an upper tapered face 236u of the locking recess 236, urging the dog heads 224 radially inwards. This continues until the latch 222 reaches a lower axial position relative to the diverter sleeve 211 , where the dog heads 224 are moved into and received by a retrieval recess 240 disposed on the diverter sleeve 211. In this example, the retrieval recess 240 has a tapered face 240u for guiding the dog heads 224 into and out of the retrieval recess 240. From this position, the diverter sleeve 211 is lifted off the dual bore seal sub 208, out of its operation position and out of the housing 202.

[0080] It will be understood that the various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

[0081] Various aspects of the invention are described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

[0082] Language such as "including", "comprising", "having", "containing", or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word “comprise” or variations thereof such as “comprises” or “comprising” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

Claims:-1. A bore access spool assembly comprising:- a housing (2; 100; 202) having a longitudinal axis, an upper end (3) of the housing being configured for connection to a riser, a lower end (4) of the housing being configured for connection to a subsea well assembly, the housing further comprising:- an upper bore (5) located at the upper end, and a plurality of lower bores (6, 6a; 106a, 106b) located at the lower end, a chamber (7) extending along the longitudinal axis linking the upper and lower bores; and a diverter sleeve (11 ; 111 ; 211) for introduction into the housing chamber (7) through the upper bore (5), the diverter sleeve (11 ; 111 ; 211) being open at its upper end to allow access into a sleeve interior from the upper bore (5), and having an angled kick surface (17) at a lower end of its interior, the diverter sleeve (11 ; 111 ; 211) and housing (2; 100; 202) having respective guide formations; wherein the diverter sleeve (11 ; 111 ; 211) is configured to be received within the chamber (7) and guided into position through interaction of the guide formations to a deployed state to block a first one (6a; 106a) of the plurality of lower bores (6a, 6b; 106a, 106b), and to divert communication of the upper bore (5) instead to be with a second one (6b; 106b) of the plurality of bores.

2. A bore access spool assembly as claimed in claim 1, wherein the guide formations comprise inter-engaging profiles on the diverter sleeve (11 , 111 , 211) and upper bore (5) of the housing (2; 100; 202) for guiding the diverter sleeve (11; 111 ; 211) into a deployed orientation within the housing (2; 100; 202).

3. A bore access spool assembly as claimed in claim 2, wherein the interengaging profiles involve a helical profile for axially lowering and rotating the diverter sleeve (11 , 111 , 211) within the housing (2, 100, 202).

4. A bore access spool assembly as claimed in any preceding claim, wherein the chamber (7) has at a lower end of the housing (2; 202) a land-out shoulder (8, 208) for receiving the diverter sleeve (11 ; 211).

5. A bore access spool assembly as claimed in claim 4, wherein the land-out shoulder (8; 208) includes bores (9, 10) aligned with the plurality of lower bores (6a, 6b).

6. A bore access spool assembly as claimed in claim 4 or 5, wherein the land-out shoulder (8; 208) has a seating profile (14; 214) for receiving a bottom surface of the diverter sleeve (11 ; 211).

7. A bore access spool assembly as claimed in any preceding claim, wherein an upper end of the diverter sleeve (11 ; 111) has one or more latch fingers (13) for locking the diverter sleeve (11 ; 111) in position within the housing (2; 100) when at the correct orientation.

8. A bore access spool assembly as claimed in any preceding claim, wherein the diverter sleeve (11 ; 111 ; 211) is dimensioned to be received by the upper bore (5).

9. A bore access spool assembly as claimed in any preceding claim, wherein the upper bore (5) is axially aligned with one of the lower bores (6a).

10. A bore access spool assembly as claimed in any preceding claim, wherein one or more of the lower bores (6b) includes an isolation valve (21).

11. A bore access spool assembly as claimed in any one of claims 1 to 9, wherein one or more of the lower bores (6b) has an isolation plug.

12. A bore access spool assembly as claimed in any one of claims 1 to 9, wherein a sliding sleeve (110) is provided in the chamber, the sliding sleeve (110) blocking a second one of the lower bores (106b) before the diverter sleeve (111) is deployed, wherein deployment of the diverter sleeve (111) into the housing (100) pushes the sliding sleeve (110) downwardly to allow the diverter sleeve (111) access to the lower bore (106b).

13. A bore access spool assembly as claimed in any preceding claim, further comprising a latching mechanism (220) configured to releasably lock the diverter sleeve (211) in position within the housing (202), the latching mechanism (220)comprising: a latch (222) coupled to the diverter sleeve (211) for axial movement relative to the diverter sleeve (211), the latch being biased along the diverter sleeve (211); wherein at different axial positions of the latch (222) along the diverter sleeve (211), one or more dog heads (224) of the latch (222) align axially with either a deployment recess (234) or a retrieval recess (240) provided on the diverter sleeve (211), allowing the one or more dog heads (224) to move into the deployment recess (234) or the retrieval recess (240), thereby reducing the radial extent of the latch (222) such the diverter sleeve can move axially relative to the housing; wherein the housing (202) is provided with a dual bore seal sub (208) having a locking recess (236) into which the one or more dog heads of the latch (222) is receivable to lock the diverter sleeve within the housing (202); and wherein a shear pin (228) is provided for coupling the latch (222) to the diverter sleeve (211), the shear pin (228) being configured to restrict an extent of axial movement of the latch (222) when the shear pin (228) is intact; wherein the pin (228) has to be sheared to allow the latch (222) to move sufficiently axially to align with the retrieval recess (240).

14. A bore access spool assembly as claimed in claim 13, wherein the dual bore seal sub (208) has a tapered face (232) configured, on engagement with the one or more dog heads (224), to guide the latch (222) into the deployment recess (234) and wherein the one or more dog heads (224), deployment recess (234), locking recess (236) and retrieval recess (240) each have tapered faces (224u, 224I, 234u, 234I, 236u, 236I, 240u) for guiding the one or more dog heads (224) into and out of the recesses (234, 236, 240).

15. A bore access spool assembly as claimed in claim 13 or 14, wherein the latch (222) comprises a collar element having a plurality of resilient fingers, each having a dog head profile at their free end.

16. A bore access spool assembly as claimed in any one of claims 13 to 15, wherein the latch (222) is biased downwardly towards an end of the diverter sleeve (211), and wherein the shear pin (228) restricts the extent of axial movement of the latch (222) so that when the shear pin (228) is intact, the one or more dog ends (224) are at the maximum axial displacement positioned on a section of the diverter sleeve (211) between the deployment recess (234) and retrieval recess (240).

17. A method of operating a bore access spool assembly, the bore access spool assembly comprising a housing (2; 100; 202) configured for connection between a riser and subsea well assembly, the housing (2; 100; 202) having a upper bore (5) and a plurality of lower bores (6a, 6b; 106a, 106b); the bore access spool assembly further comprising a diverter sleeve (11; 111 ; 211) for introduction into the housing (2; 100; 202) through the upper bore (5), wherein the method comprises:- connecting the housing (2; 100; 202) between the riser and the subsea well assembly: conveying the diverter sleeve (11 ; 111; 211) down the riser and into the housing interior through the upper bore (5); guiding the diverter sleeve (11 ; 111 ; 211) to lock into position blocking a first of the lower bores (6a; 106a), the diverter sleeve (11 ; 111; 211) having an angled kick surface (17) configured to divert communication of the upper bore (5) to be away from the first lower bore (6a; 106a) and instead to be with a second of the lower bores (6b; 106b).

18. A method as claimed in claim 17, wherein guiding the diverter sleeve (11 ; 111 ; 211) comprises lowering and rotating it to the correct axial and rotational orientation within the housing (2; 100; 202), this being controlled through guide formations between the diverter sleeve (11 ; 111 ; 211) and housing (2; 100; 202) defining a helical path for the diverter sleeve (11; 111; 211) within the housing (2; 100; 202).

19. A method as claimed in any one of claims 17 or 18, wherein the chamber (7) has at a lower end of the housing (2, 202) a land-out shoulder (8, 208) for receiving the diverter sleeve (11, 211), the land-out shoulder (8, 208) having a seating profile (14, 214) for receiving a bottom surface of the diverter sleeve (11 , 211).

20. A method as claimed in any one of claims 17 to 19, wherein the diverter sleeve (211) is locked in a deployed position by way of a latching mechanism (220), the latching mechanism (220) comprising: a latch (222) coupled to the diverter sleeve (211) for axial movement relative to the diverter sleeve (211), the latch (222) being biased along the diverter sleeve (211); wherein at different axial positions of the latch (222) along the diverter sleeve (211), one or more dog heads (224) of the latch aligns axially with either a deploymentrecess (234) or a retrieval recess (240) provided on the diverter sleeve, allowing the one or more dog heads (224) to move into the deployment recess (234) or the retrieval recess (240), thereby reducing the radial extent of the latch (222) such the diverter sleeve (211) can move relative to the housing (202); wherein in order to lock the diverter sleeve (211) in the deployed position, the diverter sleeve (211) is run into a dual bore seal sub (208) provided to the housing (202), engagement of the one or more dog heads (224) of the latch (222) with the dual bore seal sub moving the latch (222) axially along the diverter sleeve (211) until the one or more dog heads (224) aligns with the deployment recess (234) allowing the radial extent of the latch to be reduced as the one or more dog heads (224) is received in the deployment recess (234), whereby the diverter sleeve (211) can move further into the housing (202), until the one or more dog heads (224) align with a locking recess (236) in the dual bore seal sub (208), at which point the one or more dog heads (224) move into the locking recess (236) to lock the diverter sleeve (211) within the housing (202).

21. A method as claimed in claim 20, wherein a shear pin (228) is provided for coupling the latch (222) to the diverter sleeve (211), the shear pin (228) being configured to restrict an extent of axial movement of the latch (222) when intact; wherein in order to retrieve the diverter sleeve (211) the diverter sleeve (211) is jarred upwardly to shear the pin (228), allowing the latch (222) to move sufficiently axially to align and engage in the retrieval recess (240).

22. A latching mechanism (220) configured to releasably lock a sleeve (211) in position within a housing (202), the latching mechanism (220) comprising: a latch (222) coupled to the sleeve (211) for axial movement relative to the sleeve (211), the latch (222) being biased along the sleeve (211); wherein at different axial positions of the latch (222) along the sleeve (211), one or more dog heads (224) of the latch (222) align axially with either a deployment recess (234) or a retrieval recess (240) provided on the sleeve (211), allowing the one or more dog heads (224) to move into the deployment recess (234) or the retrieval recess (240), thereby reducing the radial extent of the latch (222) such the sleeve (211) can move axially relative to the housing (202); wherein a dual bore seal sub (208) provided to the housing (202) has a locking recess (236) into which the one or more dog heads (224) of the latch (222) is receivable tolock the sleeve (211) within the housing (202); and wherein a shear pin (228) is provided for coupling the latch (222) to the sleeve (211), the shear pin (228) being configured to restrict an extent of axial movement of the latch (222) when the shear pin (228) is intact; wherein the pin (228) has to be sheared to allow the latch (222) to move sufficiently axially to align with the retrieval recess (240).

23. A latching mechanism as claimed in claim 22, wherein the dual bore seal sub (208) has a tapered face (232) configured, on engagement with the one or more dog heads (224), to guide the latch (222) into the deployment recess (234) and wherein the one or more dog heads (224), deployment recess (234), locking recess (236) and retrieval recess (240) each have tapered faces for guiding the one or more dog heads (224) into and out of the recesses (234, 236, 240).

24. A latching mechanism as claimed in claim 22 or 23, wherein the latch (222) comprises a collar element having a plurality of resilient fingers, each having a dog head profile at their free end.

25. A latching mechanism as claimed in any one of claims 22 to 24, wherein the latch (222) is biased downwardly towards an end of the sleeve (211), and wherein the shear pin (228) restricts the extent of axial movement of the latch (222) so that when the shear pin (228) is intact, the one or more dog ends (224) are at the maximum axial displacement positioned on a section of the sleeve (211) between the deployment recess (234) and retrieval recess (240).

26. A latching mechanism as claimed in any one of claims 22 to 25, wherein the shear pin (228) is provided on one of the latch (222) and sleeve (211) and moves within an axially orientated slot (230) on the other of the latch (222) and sleeve (211).

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