GB2298667A - Manifold for well production system - Google Patents

Description

A MANIFOLD This invention relates to a manifold for production systems for underwater wells, particularly (but not exclusively) underwater oil and gas wells, and water or gas inspection wells.

It is known to use subsea satellite production systems remote from a parent platform in which a plurality of individual wells are connected to a central manifold.

Oil or gas produced by the individual wells is fed from the central manifold to a platform terminal or shore terminal and, similarly, control signals and water to be pumped into individual wells are received at the central manifold.

Whilst such satellite facilities provide a certain level of production flexibility, the central manifolds are massive, complex structures which must be built to order to suit each individual application and are difficult and expensive to construct and install.

Furthermore, once installed, these facilities are difficult to adapt to new requirements or configurations.

According to one of its aspects, the present invention provides a manifold for production systems for wells whereby, the manifold is connectable to one or more remote individually supported well head apparatus, in which the manifold is adapted to be coupled to a conductor pile.

In use, the conductor pile is secured at the surface through which one or more well heads are or are to be sunk. Where the manifold is used for offshore applications, the conductor pile is secured at the sea bed.

The conductor pile may be dedicated for securing a particular manifold or the manifold may be secured to a pre-existing conductor pile which may previously have been used for some other purpose. The manifold is preferably attached releasably to the conductor pile to facilitate its subsequent removal and possible reuse elsewhere. Preferably, a quick fit connector is used to connect the manifold to the conductor pile.

One particular advantage of the present invention is the ease, efficiency and convenience with which the manifold may be coupled to the conductor pile, and the manifold itself may be installed using a conventional drill rig. In offshore applications, this obviates the need and associated expense of using special barges and lifting apparatus which have previously been required to install known manifolds. With the present invention, it is possible for a drill rig which is used to drill individual well heads to install the manifold before leaving the well head site.

The conductor pile may be provided with an extension above the manifold. The extension may be of a length extending above the sea surface, and support an elevated platform.

The well head apparatus connected to the manifold may be used to introduce a fluid into a well and/or to receive fluid extracted from a well. Fluid intended for introduction into a well may be received at the manifold from where it may be distributed to one or more of the connected well head apparatus. Fluid recovered from the well at one or more of the connected well head apparatus may be received at the manifold from where it may be distributed to a platform terminal or shore terminal. Control signals intended to control one or more functions of one or more of the connected well head apparatus may also be received at the manifold from which they may be distributed to a relevant well head apparatus.

Where the manifold is used for oil and/or gas production, one or more of the well head apparatus may be provided by conventional Christmas tree assemblies.

In a preferred embodiment, the manifold is adapted for connection to four individual well head apparatus.

However, alternative embodiments may be provided in which the manifold is adapted for connection to one, two, three, five, six, seven, eight, nine, ten, eleven, twelve or more individual well head apparatus. In use, the manifold may be connected to fewer well head apparatus than the maximum number to which it is adapted to be connected.

The manifold of the present invention facilitates flexible and cost-effective subsea production. The manifold may be produced as a standard mass produced unit to help minimise unit costs compared with known individually designed and manufactured manifolds.

Attachment by means of a connector pile provides for quick, flexible and cost-effective installation and subsequent removal if desired. Furthermore, as a well site develop, the flexibility provided by the manifold permits the number, configuration, and use of well head sites to be easily modified.

According to a further aspect, the present invention provides a method of extracting a fluid from or introducing a fluid into a well in which a manifold is coupled to a conductor pile.

Fluid passing to or from a remote individually supported well head apparatus associated with the manifold is preferably received at the manifold for passage between the well head apparatus and a platform or shore terminal.

One particular embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1: shows a perspective view of a manifold connected to a parent platform; Figure 2: shows a perspective view of the manifold secured to the seabed; Figure 3: shows a schematic plan view of a modular development of an oil field using a number of manifolds; Figure 4: illustrates an example of modular development over time using the manifolds; Figure 5: shows a plan view of an arrangement with a manifold associated with a number of well head apparatus; Figure 6: shows a plan view of an alternative arrangement with a manifold; and Figure 7: shows a side elevation of a modified manifold.

Figure 1 shows a manifold 1 positioned on the seabed.

Four individual well head apparatus, each provided in this example by individual christmas tree assemblies 10, 11, 12, 13, are positioned remotely from the manifold 1 and secured individually to the seabed.

Each christmas tree assembly has a well head jumper which provides a well head pipe 3 through which fluid extracted at that assembly is fed to the manifold 1. A main flowline 5 transfers fluid extracted at each well head from the manifold 1 to a platform terminal 2. A control umbilical 6 is also provided between the manifold 1 and the platform terminal; control signals passed from the platform terminal 2 through the control umbilical 6 are received at a control device 7 at the manifold. The control signals control the functioning of the manifold. Control signals are also supplied from the control device 7 to the individual well head apparatus via well head control lines 8 as shown in detail in Figure 2.

The manifold 1 is shown in more detail in Figure 2. It comprises conventional pipe and valve arrangements supported by, and in this embodiment enclosed substantially within a structural frame 15. Each well head pipe 3 is connected to the main flowline 5 through a ROV actuated valve 9. A quick fit connector 16 attached to the frame 15 is used to connect the manifold 1 to a conductor pile 17 which is secured at the seabed.

Figure 3 shows one way in which the manifold can be used in association with a platform terminal 2. The platform 2 has a maximum drilling reach indicated at 20 and a number of manifolds are used to exploit wells beyond this reach.

In a first area 21, a pair of manifolds 22, 23 are used to provide a water injection system to enhance main field production. In a second area 24, one or more manifolds (not shown) may be used to supplement main field production. In a third area 25, a pair of manifolds 26, 27 are used to provide a subsea production system separate from the main field production. Manifold 26 is connected to four well heads 28, 29, 30, 31 each of which introduces water into the well; the water is supplied to each well head via the manifold 26 from a main flowline 32. Manifold 27 supplies water to two well heads 33, 34 to which it is connected and collects fluid extracted from the well from a further two well heads 35, 36 to which it is also connected. A control umbilical 38, water flowline 39 and extracted fluid flowline 37 connect manifold 27 to the platform terminal 2.

Fluid extracted from the well heads and collected at the platform terminal 2 is exported via trunkline pipelines 40.

Each of the areas shown in Figure 3 lies within the step out reach 41 of the platform terminal 2.

The flexibility and modular development facilitated by the present invention is illustrated schematically in Figure 4. In the illustrated example, manifolds are added to the production site at successive stages as production and requirement develop.

At a first stage in the example illustrated in Figure 4, a first manifold 51 is used to introduce water into three associated well heads apparatus 59 remote from a parent platform 50. A water flowline 55 supplies water from the parent platform 50 to the first manifold 51 from where it is distributed to the associated well head apparatus 59 via well head pipes 62 and hence into the well heads. A control umbilical 54 links the parent platform 50 with the first manifold 51 and is used to pass control signals to control the first manifold 51 and its associated well head apparatus 59.

This first stage may be completed during the first year of production.

In a second stage of development, which may be completed during the third year of production, a second manifold 52 is added to the installation. The second manifold 52 is used to recover fluid from four well heads each of which is capped with a well head apparatus 60. Fluid received at each of these associated well head apparatus 60 is passed through respective well head pipes 62 to the second manifold 52 and is subsequently fed through a first production flowline 56 from the manifold 52 to the parent platform 50.

A third stage of development, which may be completed during the sixth year of production, comprises adding a third manifold 53 to the installation. The third manifold 53 is a production manifold arranged in a similar way to the second manifold 52. Fluid received at four associated well head apparatus 61 is passed from the third manifold 53 via a second production flowline 57 to the parent platform 50. There may be a "round trip" link 58 between the second and third manifolds.

The arrangement shown in Figure 5 is used to supply fluid to four well head apparatus 71, 72, 73, 74 from a remote parent platform (not shown). The fluid is supplied from the parent platform to a manifold 75 via a main flowline 76. The fluid is distributed to the associated well head apparatus 71, 72, 73, 74 at the manifold 75 by means of respective well head pipes 77 which link each well head apparatus to the manifold 75.

A control umbilical 78 is received at a control device 79 from the parent platform. Individual well head control lines 80 connect each well head apparatus to the control device. In this example, the control device 79 is positioned at the manifold 75, within a frame 81 surrounding the manifold.

The arrangement of Figure 6 is similar to that shown in Figure 5 and the same reference numerals have been used where appropriate. In this arrangement, the manifold 75 is associated with five well head apparatus.

Furthermore, the control device 79 is positioned remotely from the manifold within its own control device frame 82.

Figure 7 illustrates a modification in which the conductor pile 17 supporting the manifold 1 is provided with an extension 71 supporting a platform 72 which carries a warning beacon 73 powered by a powerpack 74 which suitably incorporates solar panels. This modification provides warning of the presence of seabed equipment. The extension 71 may support pipework 75 from the manifold 1 which may, for example, provide an emergency vent, or a conduit for emergency control or power to the manifold 1. A boarding ladder 76 is provided to enable access to the platform 72 by boat.

Modifications and variations of the above described embodiment can be adopted without departing from the scope of the invention.

Claims (16)

1. A manifold for production systems for wells whereby the manifold is connectable to one or more remote individually supported well head apparatus, in which the manifold is adapted to be coupled to a conductor pile.

2. A manifold according to claim 1 wherein, in use, the conductor pile is secured at the surface through which one or more well heads are or are to be sunk.

3. A manifold according to claim 1 or 2 wherein, when the manifold is used for offshore applications, the conductor pile is secured at the sea bed.

4. A manifold according to any of the preceding claims wherein the manifold is releasably attachable to the conductor pile.

5. A manifold according to any of the preceding claims wherein the conductor pile is provided with an extension above the manifold.

6. A manifold according to claim 5 wherein the extension extends above the sea surface and supports an elevated platform.

7. A manifold according to any of the preceding claims wherein fluid is introduced and/or extracted from a well through the well head apparatus.

8. A manifold according to claim 7 wherein fluid intended for introduction into a well is received at the manifold from which the fluid is distributed to one or more of the connected well head apparatus.

9. A manifold according to claim 7 wherein fluid recovered from the well at one or more of the connected well head apparatus is received at the manifold from which the fluid is distributed to a platform terminal or shore terminal.

10. A manifold according to any of the preceding claims wherein control signals intended to control one or more functions of one or more of the connected well head apparatus are received at the manifold from which the control signals are distributed to a relevant well head apparatus.

11. A manifold according to claim 3 wherein one or more of the well head apparatus are provided by Christmas tree assemblies.

12. A manifold according to any of the preceding claims wherein the manifold is adapted for connection to four individual well head apparatus.

13. A manifold substantially herein before described with reference to the accompanying drawings.

14. A method of extracting a fluid from or introducing a fluid into a well in which a manifold is coupled to a conductor pile, and the manifold is connectable to one or more remote individually supported well head apparatus.

15. A method according to claim 14 wherein fluid passing to or from a remote individually supported well head apparatus associated with the manifold is received at the manifold for passage between the well head apparatus and a platform or shore terminal.

16. A method substantially as hereinbefore described with reference to the accompanying drawings.