AU2015363810B2

AU2015363810B2 - Subsea manifold system

Info

Publication number: AU2015363810B2
Application number: AU2015363810A
Authority: AU
Inventors: Bjorgulf Haukelidsæter Eidesen; Knut Sveberg
Original assignee: Equinor Energy AS
Current assignee: Equinor Energy AS
Priority date: 2014-12-19
Filing date: 2015-12-18
Publication date: 2020-04-30
Anticipated expiration: 2035-12-18
Also published as: BR112017012754A2; AU2015363810A1; RU2721204C2; WO2016099291A1; GB2536763A; GB2536763B; GB201522425D0; NO20171165A1; MX2017007818A; US20180258742A1; RU2017125498A; RU2017125498A3; CA2970442A1

Abstract

A modular, subsea hydrocarbon production hub 36 comprises a primary manifold 22 and a plurality of co-located extension structures 26, 30, 34. The primary manifold 22 has first connections 23 for connection a top-side facility 21, second connections 27, 35 for connection to at least one extension structure 26, 34, and third connections 25 for connection to at least one well 24. The extension structures 26, 30, 34may comprise a secondary manifold 26, 30, having first connections 27, 31 for connection to the primary manifold 22 or another secondary manifold 26, 30, second connections 31 for connection to at least one further extension structure 26, 30, 36, and third connections 28, 31 for connection to further wells 29, 32. The extension structures 26, 30, 34 may also comprise one or more functional units, such as a pumping unit 34 or a separator unit 51.

Description

Subsea Manifold System

The present invention relates to a subsea hydrocarbon production hub, and to a subsea hydrocarbon production system incorporating such a hub, which are particularly useful when oil or gas is to be produced from a plurality of fields where at least one is a remote “satellite” field.

It is well-known that when hydrocarbons (oil and/or gas) are to be produced from a sub-sea reservoir, a top-side facility, such as a production platform or vessel is provided on the surface and well-head is provided on the sea bed. The well-head is located at the top of the well, through which oil and/or gas may flow from the underground reservoir. The well-head is equipped to control the well and has valve and arrangements to prevent leakage from the reservoir.

The well-head is connected to the top-side facility by means of a production and/or injection flow line running along the sea bed, often for tens of kilometers, and a riser extending upwardly to the top-side facility, also referred to as a platform. Through these, the oil/gas flows to the top-side facility. Also, from the top-side facility, risers for gas lift, gas injection or water injection are connected to the well-head, either via subsea manifolds or directly to the dedicated wells.

In addition, dedicated umbilicals provide power, control and communications, as well as the supply of chemicals, such as hydraulic fluids and MEG (mono ethylene glycol), which is used as anti-freeze to prevent the formation of hydrates.

There will typically be a number of well-heads grouped comparatively close together. Rather than having separate risers leading to each, a manifold is normally provided on the sea bed. This will have risers connecting it to the top-side facility to provide the previously-mentioned services. In turn, there are separate connections from the manifold to each of a plurality of well-heads. One example of such a manifold system is disclosed in US 2011/0132615.

Another known situation is for a so-called satellite field to be developed and produced from the same topside facility. When this is to be done, it can either be achieved by a daisy-chained solution via other templates or by connecting each new satellite field directly to the topside facility. The conventional arrangement is to provide a so-called riser base in association with each wellhead and for the riser base to be connected to the topside facility.

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Figure 1 illustrates such a conventional arrangement where a topside facility, in this case the platform, is connected to a standard manifold and to a number of satellite fields.

Referring to that figure, the platform 1 is shown schematically as preferably having two regions, 2 and 3. Region 2 provides for connection to standard manifold 4 by means of umbilical 5 which includes various conduits. (In the diagram, C indicates conduits for control, power and fluids (hydraulic, chemicals and barrier fluids). Wl indicates water or gas injection, and LP/ HP indicate low pressure/ high-pressure production respectively.) Manifold 4 is in turn connected to a number of wells 6 (shown here as nos. 1,2 and 3) by means of connectors 7.

Preferably, platform 1 also has a region 3 for connection to satellite fields. These fields will typically have been developed subsequent to the initial fields. The satellite fields are shown adjacent to the other fields in the figure, but in reality, they will be dispersed over a large area of the seabed, often tens of kilometers away. Each satellite field has a riser base 8, 9, 10 connected to the platform by means of risers and umbilicals 11, 12, 13. The riser bases are in turn connected to various satellite fields 14, 15 and 16 by means of connections 17,18 and 19.

It will be understood from the figure that each satellite field normally requires dedicated riser(s) between the satellite field and the topside facility, which each must include production lines and provide for injection of gas and water. In addition, there must be umbilical(s), providing conduits for control, power, MEG and various fluids. Accordingly, between two and four riser slots are needed at the topside facility for each satellite field.

Taking these factors together, the result is that for each single new field, very significant new costs are involved. Whilst these costs may be economically justifiable where the satellite fields in question contain significant reserves of producible hydrocarbons, the development of more marginal fields will not be commercially attractive. In addition, there is a physical limit on the number of available riser slots at the top site facility.

The present invention aims to address this problem in order to enable production from more marginal satellite fields.

Viewed from a first aspect of an embodiment of the invention, there is provided a modular, subsea hydrocarbon production hub comprising a primary manifold and at least one co-located extension structure, the primary manifold having first connections for connection to at least a riser and an umbilical from a top-side facility, and second

2015363810 07 Apr 2020 connections for connection to at least one extension structure, wherein the at least one extension structure is within one hundred meters of the primary manifold, wherein the least one extension structure comprises a secondary manifold having first connections connected to the second connections of the primary manifold, second connections for connection to at least one further extension structure, and third connections for connection to at least one wellhead or template, the secondary manifold providing for a flow of produced hydrocarbon from the at least one wellhead or template to the top-side facility via the primary manifold and the riser, and facilitating electrical and/or hydraulic control from the top-side facility via the primary manifold and the umbilical.

The use of such a modular hub facilitates communication between a large number of subsea wells and the surface platform via a small number of risers and umbilicals. Furthermore, the modular configuration means that if additional capacity or functionality is required, for example to produce from new satellite wells or to provide additional subsea processing, then this can be provided simply by connecting further extension structures to the hub. For example, extension manifolds or processing equipment may be connected directly to on spare connections on the primary manifold or an extension structure.

In the present context, the term “co-located” is intended to mean that the modular components of the hub (the primary manifold and the extension structures) are located in a group or cluster proximate one another in the context of an offshore hydrocarbon production facility, e.g. below a platform. Thus, they are proximate at least relative to a satellite well site, which will be remotely located, often tens of kilometers away. In various embodiments, this could for example be understood to include components within the safety zone surrounding the riser (typically a 100 meter radius around the riser base, or primary manifold in this case). More typically the components of the hub will be closer together and the distance between individual components would typically be well under 100m, and usually under 50m. In some embodiments, the components may be directly adjacent and/or mechanically inter-connected (in addition to the fluid/control connections), e.g. bolted together or rigidly connected in some other manner.

In various embodiments, the primary manifold may provide connection to the secondary manifold (or other extension structure) in respect of any or all of the following services, which will typically connect to the riser: hydrocarbon production, water injection, gas injection, gas lift. Additionally (or alternatively) it may provide any or all of

2015363810 07 Apr 2020 the services provided via the umbilical, such as control, power and/or service fluids (hydraulic, chemicals, barrier fluids).

Typically, the primary manifold will itself be connected to a wellhead and/or template and indeed, either or both manifolds may be connected to a plurality of wellheads and/or templates. Thus, the primary manifold may also have third connections for connection to at least one wellhead or template. In some implementations, the hub may be installed at an initial well site, and then expanded using extension structures to connect subsea to new satellite sites as they are found or become viable.

The facilitation of control is preferably provided by the provision of conduits and/or conductors within the riser/umbilical/connector that distribute one or more (and preferably all of) the following services: injection gas and water, electrical power, electrical control signals, communication, chemicals and/or hydraulic power. Corresponding conduits and connections may then be provided within the primary manifold to allow distribution of these services to the secondary manifold(s). Most preferably, each of these services is provided to the hub.

Thus, by means of an embodiment ofthe invention, satellites can be added to the overall production system without any increase in the number of risers connected to the top-side facility. Alternatively, where a large number of satellite fields are added, the increase in the number of risers/umbilicals is significantly reduced compared to the prior art. This minimises the number of topside modifications and reduces the overall cost of producing from such satellite fields.

Preferably, the at least one extension structures include a plurality of secondary manifolds. As discussed above, the modular configuration permits simple enlargement of the capacity of the hub to permit new well sites to be connected and produced. The modular hub is not limited to any specific configuration, and in various embodiments at least two of the secondary manifolds may be connected to the primary manifold or to another extension structure in series, i.e. as a daisy chain, or in parallel, e.g. in as spokes. The specific configurations available will of course depend upon the individual design of the components of the hub and how many ports are available for the second connections on each modular component.

The hub, and particularly the primary manifold of the hub, preferably also provides valving arrangements so that flow of each of the various production lines may be controlled. (Likewise, switching arrangements may be provided for electrical power, communications and control.) This may be necessary, either to open and close

2015363810 07 Apr 2020 connection ports when secondary manifolds are connected/disconnected, or for control purposes during operation. Such valves may be remotely operated from the surface, automatically operated (e.g. safety cut-off systems) or operable by ROV. Preferably each conduit within the hub may be closed by means of a valve and preferably a valve is provided in association with each connection port thereof.

An embodiment of the invention of course also extends to the hub when installed. Thus, in a second aspect, an embodiment of the invention also provides a hydrocarbon production system comprising a top-side production platform connected by means of a riser and an umbilical to a hub on the sea floor as described above, the hub being in turn connected subsea to one or more wells, wherein hydrocarbons produced from each of the wells flow to the platform via a secondary manifold of the hub, the primary manifold of the hub, and the riser, and wherein one or more of service fluids, electrical control signals, electrical power and injection fluids are transmitted to each of the wells via first the primary manifold and then a secondary manifold.

It will therefore be seen that, in a particularly preferred embodiment, there is provided a production platform connected by means of a riser and an umbilical to a primary manifold on the sea floor. The primary manifold is in turn connected to one or a plurality of secondary manifolds that expand the capacity of the hub. The secondary manifolds are themselves connected to wellheads and hydrocarbons produced from those wellheads flows via the secondary manifold, the primary manifold and then, via a riser, to the platform. At the same time, fluid, electrical control signals, electrical power and/or injection fluids are transmitted to the wellhead via first the primary manifold and then via the secondary manifold.

Optionally, the primary manifold, a secondary manifold or one or more of the other extension structures may provide ancillary services. Such services may include: processing of produced fluids, such as separation of oil from water and/or gas, oil, gas and water treatment; boosting the fluid by means of a pump or compressor; measuring one or more of the different fluid streams.

For example, an external pumping unit may be provided in an extension structure which may be used to increase the pressure of produced fluids in order to maintain or increase the production from the satellite field. The pumping unit may be connected to second connections of the primary manifold or an extension structure.

In another example, one of the extension structures may comprise a separator unit. The separator unit may be connected to second connections of the primary manifold or an extension structure. The separator unit may separate water from a

2015363810 07 Apr 2020 hydrocarbon stream before the hydrocarbon stream is passed to the riser. This reduces the quantity of water raised unnecessarily to the surface. The separated water may be discharged to sea or may be re-injected into a well. The separator unit may additionally or alternatively separates a hydrocarbon gas phase from a hydrocarbon liquid phase. The gas phase can be used to provide gas lift. The liquid phase can be used as a driving medium for an ejector. Alternatively, the gas and liquid phases may be separated to facilitate pumping to the surface as separate phases, which may simplify the pumping equipment required.

Preferably, means is provided for connection of an external pump/pressure module (to boost pressure of production from satellite fields). To achieve this, most preferably, the second connections include ports that are suitable both for connection to secondary manifold and also for connection to such units.

Although an embodiment of the invention has been described in the context of both a riser and umbilical being provided between the top-side facility and the subsea manifold, other aspects of an embodiment of the invention may involve only a riser or an umbilical, or pluralities of one or the other.

An embodiment of the invention also extends to a method of hydrocarbon production comprising the use of the system, or hub of any of the above aspects of an embodiment of the invention.

Viewed from a third aspect, an embodiment of the invention also provides a method of connecting a subsea wellhead to a top-side production platform via a modular, subsea hydrocarbon production hub connected to the platform via a riser and an umbilical, the method comprising: connecting a secondary manifold to the subsea hub; and connecting the wellhead subsea to the extension manifold of the hub such that hydrocarbons produced from the wellhead flow to the platform via the hub and the riser, and one or more of service fluids, electrical control signals, electrical power and injection fluids are transmitted to the wellhead via the hub and the umbilical.

In accordance with this method, a new satellite well or template can be added to an existing subsea hydrocarbon production facility by simply installing a modular extension structure to the hub and connecting the new satellite to the extension structure. This avoids the need for new dedicated risers and umbilicals to be connected from the platform to the site, thereby reducing costs and tie-offs required at the platform, and potentially making new sites economically viable.

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The method may further comprise (remotely) controlling a valving arrangement and/or switching equipment within the hub to permit flow of hydrocarbons and/or control to and from the new extension structure.

The method may further comprise connecting one of more functional units to the hub, for example to enable processing of the hydrocarbons produced by the satellite well. This may be required where the satellite well has a different composition to existing wells and may require different processing to existing wells, e.g. a higher water or acid gas composition or the like.

Embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings:Figure 1 is a of view of a conventional system for producing hydrocarbons from main and satellite fields;

Figure 2 is schematic view of the first embodiment of the invention showing a primary manifold connected to two secondary manifolds and a pumping unit;

Figure 3 is a schematic view of another of embodiment of the invention which differs from that of figure 2 in that a further pumping unit is shown in the position of one of the extension structures;

Figure 4 is a schematic view of a still further embodiment in which a separator is provided in connection with the primary manifold;

Figure 5 a schematic diagram of a possible application of an embodiment of the invention to a complex oil field situation;

Figure 6 is a schematic view of the network and valves in the primary manifold;

Figure 7 is a perspective view corresponding to figure 6;

Figure 8 is a perspective view of a hub including the primary manifold and a pumping unit; and

Figures 9 is a sectional view of an umbilical for use with the hubs of the various embodiments.

With reference to figure 2, there is shown a first embodiment of the invention 20. A host platform 21, at the surface, is connected to a subsea hub 36, on the seabed, by means of risers and umbilicals 23. These correspond to the risers/umbilicals 5 in figure 1. Accordingly, they provide for control, power and fluids (hydraulic, chemicals and/or barrier) (C), low pressure production (LP), high pressure production (HP) and injection of water (or gas) injection (Wl). Gas lift may also be provided (not shown). The hub 36 comprises a primary manifold or “mother structure” 22 that receives the risers and umbilicals 23 from the surface. The primary manifold 22 is in turn connected to a

2015363810 07 Apr 2020 plurality of wells 24 (nos. 1,2 and 3) by means of connectors 25, again similarly to figure

1. These are shown as providing production (P), water injection (Wl) and control (C), though any or all of the above-mentioned services may also be provided.

The present embodiment 20 differs significantly from the prior art system shown in figure 1 in that the hub 36 has a modular configuration and can be extended after installation using extension structure that increase the capacity or capabilities of the primary manifold 22.

In figure 2, the hub 36 comprises two secondary or extension manifolds 26, 30, which are examples of such extension structures. The first extension manifold 26 is connected to the primary manifold 22 by means of connections 27. The first extension structure 26 is adjacent to the primary manifold 22, generally within about 50 meters and in some cases physically adjoining the primary manifold 22 with preferably rigid connections 27. The first extension manifold 26 provides connections to wells 29 (nos. 4 and 5) by means of connections 28. These correspond to connections 25 and 7, thus providing production P, water injection Wl and control C, though any of the other abovementioned services may be provided.

The first extension manifold 26 is in turn connected to an adjacent second extension manifold 30 by means of connections 31, which can be identical to connections 27. The second extension structure 30 is in turn connected to further satellite wells 32 by means of connections 33.

Only two extension manifold are shown in figure 2. However, it will be appreciated that a third extension manifold may be connected to the second extension manifold 30. Likewise further such structures may be daisy-chained together, or connected in parallel.

In addition to being connected to the extension manifold, primary manifold 22 is shown as being connected to a pumping unit 34 by means of conduits 35. The pumping unit 24 is an extension structure that serves to pressurise the produced fluids to enable them to be transported to the platform 21 in cases where one more of the produced wells is at insufficiently high pressure.

As will be discussed further below, the primary manifold 22 and extension structures 26, 30, 34, have ports, which are used for connection to various connectors, in a standard manner. Accordingly a modular system is provided whereby standardised extension structures, may be connected to the subsea hub 36 as desired.

The hub 36 thus provides for communication between a large number of subsea wells 24, 29, 32 and the surface platform 21 via a small number of risers and umbilicals

2015363810 07 Apr 2020

23. If additional capacity or functionality is required, for example to produce from new satellite wells, then this can be provided by simply connecting further extension manifolds or other functional units to the hub 36.

The provision of additional subsea functionality is illustrated in figure 3 where a second embodiment 40 is shown. This corresponds to the first embodiment except that in place of second extension manifold 30, the hub 36 is provided with a further pumping unit 41. Thus, the primary manifold 22 is connected both to the second pumping unit 41 (indirectly via the first extension manifold 26) and to the first pumping unit 42.

Another example of the provision of additional subsea functionality is illustrated in figure 4, where the third embodiment 50 is shown. This differs from the second embodiment 40 in that, in place of first pumping unit 42, the hub 36 is provided with a separator unit 51. The use of a subsea separator unit 51 permits improved efficiency of the hub in this embodiment 50.

Produced hydrocarbons often contain substantial amounts of water. This may include formation water that was trapped in the reservoir, or water injected during production. The separator unit 51 separates water from produced fluids so that water is not wastefully transported to the platform 52. This both relieves the riser, as a smaller quantity of fluid must be transported to the surface, as well as reducing the amount of topside water processing required at the processing platform, where space is often limited. The water can be either discharged into the sea (subject to appropriate processing, for example using a further extension structure), or re-injected into an injection well.

As pure phases of liquid and/or gas are more controllable with respect to throttling, boosting and transporting than a two-or three phase mixture, the separator unit 51 can also separate liquid phase and gas phase hydrocarbons from one another. The gas phase may be pressurized as used as lift gas to increase production from a well. Alternatively or in addition, the preferably gas-free liquid phase may be used as a driving medium for an ejector. Ejectors can be used to boost production of an existing well or to restart a “dead” well.

Note that in any of figures 2 to 4, the ancillary unit(s) may be provided in addition to the plural extension structures shown in figure 2; for clarity only a limited number of components are illustrated.

Figure 5 shows a possible application of an embodiment of the invention to areas having a number of hydrocarbon producing fields connected to the platform.

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Here, production platform 61 is above the original well site and is connected directly to the initial subsea template 62 in a conventional manner. Previously, the platform 61 would have been connected directly to the satellite subsea templates 63 and 64 (for example, with reference to figure 1, manifold 4 might have been at the initial site and riser bases 8, 9 and 10 might have been at satellite sites A, B and C). However, implementing an embodiment of the invention has the result that a subsea hub 65 is instead provided in direct connection with the platform 61. The satellite templates 63 and 64 connect subsea to the hub 65, instead of being connected directly to the platform.

This facilitates a reduction in the number of risers and umbilicals required to connect these templates 63, 64 to the platform 61. Additionally, an embodiment of the invention enables satellite fields C, D, E, which would previously have been economically unviable, to be produced. Using an embodiment of the invention, an extension manifold and any other required extension structures can be added to the hub 65, and production templates 66, 67 and 68 can be installed and connected to the extension manifold of the hub 65. Field C is to be produced initially, with fields D and E being added later (hence they are shown in phantom).

The application of an embodiment of the invention to this oil field provides a number of the advantages described previously. In particular, there is a reduced need for riser hang-offs at the production platform 61. It also makes it easier to provide subsea water separation and pressure boosting, again as previously described. Furthermore, the use of a modular construction permits the capacity of the hub 65 to be increased to allow further satellite wells to be produced, without the need for new risers or umbilicals to directly connect the satellite well to the platform 61.

Details of the primary manifold and extension structures are described now with reference to figures 6 to 8.

Schematic pipework diagram 6 shows a hub 70 having a primary manifold 71, an extension manifold 72 and a pumping unit 73. The physical arrangement of the pipework and valves, etc. may be seen from figures 7 and 8.

The arrows at the upper part of figure 6 represent connections to the umbilical and riser which lead to the production platform. Produced oil is shown at 81 and 86, electrical control inputs at 82 and 83, water input at 84, and hydraulic control input at 85.

The connections to the various external units are shown at the lower part of the figure. Production input is at 87, 89 and 93, hydraulic fluid at 88 and 92, with water

2015363810 07 Apr 2020 outlets at 90 and 91. It will also be seen that there are provided flow paths between each of the respective inputs and outputs and that control valves are provided in each line.

Connections 94 and 95 permit the connection of an external pump 73, with connections 96, 97 and 98 providing injection water, hydraulic and production connections for future use.

Pumping unit 73 comprises an input and output conduit for connection to the primary manifold 71, plus an internal pump and a control valve.

Figure 8 shows the pipework of figure 7 mounted to a support cradle and connected to the external pumping unit 73, thus corresponding to figures 6 and 7.

Figure 9 illustrates a cross-section through an umbilical used to connect the hub to the platform. It provides the following services:36x MEG tubes

6x low pressure hydraulic fluid tubes

6x high pressure hydraulic fluid tubes

6x chemicals tubes

2x barrier fluid tubes

4x spares hydraulic fluid tubes

33x FO cables

10x electrical quads (3-phase and earth)

4x spares electrical quads

2x HV triads 12 kV, 120 mm²

In use, the various control valves provided at the hub and elsewhere will normally be operated by remotely operated vehicles. However, certain safety critical valves may be controlled remotely and all by means of automatic operation based at the hub.

In this specification, the terms “comprise”, “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that a system, method or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia or elsewhere.

Claims

Claims

1. A modular, subsea hydrocarbon production hub comprising:

a primary manifold and at least one co-located extension structure(s), the primary manifold having first connections for connection to at least a riser and an umbilical from a top-side facility, and second connections for connection to at least one extension structure, wherein the at least one extension structure is within one hundred meters of the primary manifold, wherein the at least one extension structure comprises a secondary manifold having first connections connected to the second connections of the primary manifold, second connections for connection to at least one further extension structure, and third connections for connection to at least one wellhead or template, the secondary manifold providing for a flow of produced hydrocarbon from the at least one wellhead or template to the top-side facility via the primary manifold and the riser, and facilitating electrical and/or hydraulic control from the top-side facility via the primary manifold and the umbilical.
2. A hub according to claim 1, wherein the second connections of the primary manifold provide services in respect of water injection and/or gas injection to the secondary manifold.
3. A hub according to claim 1 or 2, wherein the second connections of the primary manifold provide power to the secondary manifold.
4. A hub according to any one of the preceding claims, wherein the primary manifold has third connections for connection to at least one wellhead or template.
5. A hub according to any one of the preceding claims, wherein the at least one colocated extension structure comprises a plurality of extension structures, and the extension structures comprise a plurality of secondary manifolds.
6. A hub according to claim 5, wherein at least two of the secondary manifolds are connected to the primary manifold in series.

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7. A hub according to claim 5 or 6, wherein at least two of the secondary manifolds are connected to the primary manifold or to another secondary manifold in parallel.
8. A hub according to any one of the preceding claims, wherein the primary manifold comprises a valving arrangement so that flow within various production lines of the primary manifold may be controlled and/or a switching arrangement for distribution of electrical power, communications and control.
9. A hub according to any one of the preceding claims, wherein the at least one extension structure comprises a service unit connected to the second connections of the primary manifold or an extension structure, wherein the service unit provides an ancillary service, and preferably provides one or more ofthe following: processing of produced fluids, such as separation of oil from water and/or gas, oil, gas and water treatment; boosting of fluid by means of a pump or compressor; and measuring the flow of one or more fluid streams.
10. A hub according to any one of the preceding claims, wherein the at least one extension structure comprises a separator unit connected to second connections of the primary manifold or another extension structure.
11. A hub according to claim 10, wherein the separator unit is configured to separate water from a hydrocarbon stream before the hydrocarbon stream is passed to the riser.
12. A hub according to claim 10 or 11, wherein the separator unit is configured to separate a hydrocarbon gas phase from a hydrocarbon liquid phase, and wherein the gas phase is used to provide gas lift and/or the liquid phase is used as a driving medium for an ejector.
13. A hydrocarbon production system comprising a top-side production platform connected by means of a riser and an umbilical to a hub on the sea floor according to any one of the preceding claims, the hub being in turn connected subsea to one or more wells, wherein hydrocarbons produced from each of the wells flow to the platform via a secondary manifold of the hub, the primary manifold of the hub, and the riser, and wherein one or more of service fluids, electrical control signals, electrical power and

2015363810 07 Apr 2020 injection fluids are transmitted to each of the wells via first the primary manifold and then a secondary manifold.
14. A method of connecting a subsea wellhead to a top-side production platform via a modular, subsea hydrocarbon production hub connected to the platform via a riser and an umbilical, the method comprising:

connecting a secondary manifold to the subsea hub, wherein the secondary manifold is within one hundred meters of the subsea hub; and connecting the wellhead subsea to the secondary manifold of the hub such that hydrocarbons produced from the wellhead flow to the platform via the hub and the riser, and one or more of service fluids, electrical control signals, electrical power and injection fluids are transmitted to the wellhead via the hub and the umbilical.