US20010040034A1

US20010040034A1 - Conductor supported pulltube bundle

Info

Publication number: US20010040034A1
Application number: US09/266,117
Authority: US
Inventors: Paul Louis Dorgant; Mark Christian Hansen; Dale Marion Gallaher; Carl Gottlieb Langner; Michael John Coyne
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-11
Filing date: 1999-03-11
Publication date: 2001-11-15

Abstract

A flowline system is disclosed installed within a bottom founded offshore platform having a plurality of conductor guides which are vertically aligned within a wellbay interior and structurally connected to a jacket of the platform. A conductor is supported by the jacket in the wellbay at the conductor guides. A plurality of flowlines are each connected to a remote well and run, together, within the conductor which provides lateral support to the flowlines.

Description

BACKGROUND OF THE INVENTION

Offshore development of hydrocarbon reserves requires substantial investments into both well development and infrastructure. Further, project economics increasingly demand the best utilization of equipment. In this development, the production facilities of a bottom founded platform may be useful for initial processing of hydrocarbons produced from wells not drilled and completed from the platform, e.g., from satellite subsea wells or from minimal platforms not providing such initial processing capabilities. Platforms with such processing capabilities then become central hubs upon which the minimal facilities depend for economic development of a region.

Providing this support to these remote wells requires that the wells be connected to the platform facilities by pipeline along the ocean floor and through vertical flowlines.

In the conventional practice, flowlines are run within or exteriorly aside legs of the platform and require frequent support points interconnecting the flowlines to the vertical legs of the platform. This can require that the jacket be designed with additional legs to accommodate the flowlines, increasing the cost of materials (more steel) and increasing installation weight. This also requires a more complicated deck and facility design because produced fluids are conducted to the initial processing facilities from the exterior legs as well as from the central well bay. Such complications can substantially impact the economics of developing the region substantially more than the incremental cost of providing greater processing facilities.

Thus there is a need for alternative techniques for tying such remote production into a platforms processing facilities with minimal impact on the structure itself.

SUMMARY OF THE INVENTION

The present invention is a flowline system installed within a bottom founded offshore platform. A plurality of conductor guides are vertically aligned within a wellbay interior and structurally connected to a jacket of the platform. A plurality of flowlines are each connected to a remote well and run, bundled together, within the conductor guides which provide lateral support, directly or indirectly, to the flowlines.

A BRIEF DESCRIPTION OF THE DRAWINGS

The brief description above, as well as further features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of illustrative embodiments which should be read in conjunction with the accompanying drawings in which: [0006]
FIG. 1 is a side elevational view of a platform incorporating the present invention; [0007]
FIGS. [0008] 2A-2C are cross sectional views of flowline bundles in accordance with various embodiments of the present invention;
FIG. 3 is a perspective view of the lower section of a platform illustrating an embodiment of the present invention; [0009]
FIG. 4 is a cross sectional view of a platform incorporating the present invention, taken a line [0010] 4-4 of FIG. 1;
FIG. 5 is a side elevational view of a portion of a platform under construction to incorporate the present invention; [0011]
FIG. 6 is a partially cross sectioned view of a connection between a conductor and a connection at the confluence of individual pulltubes into a bundle; and [0012]
FIG. 7 is a cross section of the connection of FIG. 6, taken at line [0013] 7-7 of FIG. 6.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

FIG. 1 illustrates a bottom founded [0014] platform 12 installed on ocean floor 16. A platform jacket 14 having a plurality of legs 18 and bracing 20 (simplified for the purposes of illustration) supports facilities acting as a central hub 15 for a number of remote satellite wells, not shown, connected through pipelines 22. The conductor supported flowline bundles 10 of the present invention provide the connection between pipelines 22 at ocean floor 16 and processing facilities 15 on decks of the platform. Here the flowline bundles are brought to the platform deck within well bay 30.
[0015] Individual flowlines 32 are run within pulltubes 34, which in turn are provided lateral support, directly or indirectly, by conductor guides 36 similar to those used to support drilling and production risers for local operations from the platform. Conductor guides 36 are presented and tied to bracing 20 at regular intervals along jacket 14.
Conventionally, [0016] conductor guides 36 are supported to only provide lateral support to large diameter, heavy walled “drive pipes,” “conductors,” or “conduits” 38 secured within the guides. Drilling risers, casing, tubing and productions risers are all run through such conductors for development at the site of the platform. The lateral support function may also be advantageously provided in the present invention along the vertical run of the conductor supported pulltube bundles 10. However, additional supports 20′ may be provided to the conductor guides 36 at the base of the jacket where the curved base of the pulltubes 34′ are vertically supported.
In this embodiment, [0017] platform jacket 14 has an upper portion 24 and a lower portion 26, connected through docking pins at connections 28. Lower portion 26 is illustrated in greater detail in FIGS. 3 and 4. Fabricated as a separate piece, jacket base 26 may be most easily handled with an array of preinstalled pulltubes 34′.
The upper portion of [0018] jacket 14 provides lateral support to vertical runs of the flowline bundles with conductor guides 36. A range of bundling options are illustrated in FIGS. 2A, 2B and 2C.
FIG. 2A shows a plurality of [0019] pulltubes 34 bundled together with frequently spaced clamps 40. This lowers the effective slenderness ratio of the individual pulltubes 34 and allows less dependence on vertical support and permits greater spacing between support. This is important as the intervals of conductor guides 36 is determined by the framework design and jackets of conventional design, suitable for other purposes, will tend to provide excessive unsupported spans absent bundling techniques. The shielding effect of adjacent, conventionally applied conductors also facilitates this use of conductorless bundled pulltubes.
FIGS. 2B and 2C illustrate options in which a [0020] conductor 38 provides continuous lateral support and the heavy walled conductor then spans the distances between support from the jacket at conductor guides 36. The embodiment of FIG. 2B runs a plurality of pulltubes 34 within conductor 38. See also FIG. 1. This allows the individual pulltubes to have relatively thin walls since the conductor provides axial load support and corrosion protection. The embodiment of FIG. 2C runs a plurality of flowlines 32 without the benefit of pulltubes. Intermittent support may be provided within conductor 38 with inflatable packers or diaphragms, etc.
Although accommodations would need to be provided for the large diameter flanges common to production risers, it may also be possible to bundle combined groups of local production risers and import flowlines through a single set of [0021] conductor guides 36.
FIGS. 3 and 4 [0022] illustrate jacket base 26 suitable for use in combination with any of the flowline bundling embodiments discussed above. Individual pulltubes 34′ provide large diameter curves tied into the jacket base through legs 18, braces 20, or pile sleeves 42. The large diameter of the curve is necessary to allow pig access to the pipelines. Bringing the lower end of pulltubes 34′ down within the jacket frame and tying off at the legs or pile sleeves provides maximum strength to resist “snag” forces from anchor entanglement with a minimum of additional steel.
The upper ends of the pulltubes of the jacket base may be provided special support for vertical load at [0023] connections 44. Connections 44 bring the individual pulltubes together, substantially aligned with the wellbay, for vertically running, conductor guide supported, flowline bundles 10.
[0024] Connections 44 are illustrated in greater detail in FIG. 5, illustrated here during platform installation where it may be advantageous to field install the pulltubes and conductors of the vertical runs. Field installation provides an opportunity to defer costs until stages of field development when satellite wells are completed, pipelines run, and these resources of the hub are required. But field installation may also provide benefits by maintaining a minimal initial weight for the platform. This can extend the range where lift installation is possible, as opposed to launch installation which requires additional framing to handle transitory, one time loads associated with installation.
Filed installed [0025] conductors 38 can be mated with the connection 44 at the confluence of groups of pre-installed pulltubes 34′ with a cruciform 46 such as illustrated in FIGS. 6 and 7. The cruciform is run on the bottom of the conductor as it is run through conductor guides 36 and, upon engagement of the downwardly facing plates 48 into slots 50, serves to transfer the vertical load of conductor 38 to the platform through connection 44. A guide cone 52 on connector 44 may facilitate engagement. Cruciform 46 also maintains access for connecting messenger wires 54 between upper and lower platform sections 24 and 26, with field installed and preinstalled pulltubes, respectively.
A complete messenger wire can not be preinstalled when the pulltubes are all preinstalled from top to bottom. Thus, [0026] messenger wires 54A installed with the bottom platform section 26 needs to be connected with messenger wires 54B fed from the surface. The services of a remotely operated vehicle, ROV, 56 may be deployed to make these connections after conductor 38 is set. Similarly, the ROV can attach a primary pulling cable to the far end of preintalled messenger wire 54A which is accessible at the lower end of pulltube 34′. Joined, the messenger wires allow the primary pulling cable, itself attached to the flowline, to be brought to the surface and then to pull the flowline itself, through pulltubes 34 and to the surface where they are connected to platform facilities 15. Flanges 60 on the lower end of pulltubes 34 may facilitate passage of the flowlines across the junction.
An appendix is attached to and filed with this provisional application. The disclosure of which is hereby incorporated. [0027]
A number of variations have been disclosed for employing the present invention. However, other modifications, changes, and substitutions are intended in the foregoing disclosure. Further, in some instances, some features of the present invention will be used without a corresponding use of other features described in these illustrative embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein. [0028]

Claims

What is claimed is:

1. A flowline system installed within a bottom founded platform having a plurality of conductor guides vertically aligned within a wellbay interior and structurally connected to a jacket of the platform, said flowline bundle comprising:

a plurality of flowlines, each connected to a remote well and run bundled together to the wellbay within the conductor guides which provides lateral support thereto.

2. A flowline system in accordance with

claim 1

, further comprising:

a conductor supported by the jacket in the wellbay at the conductor guides providing lateral support to the plurality of flowlines run therewithin.

3. A flowline system in accordance with

claim 1

, further comprising a plurality of pulltubes run within the conductor, each pulltube surrounding one of the flowlines.

4. A flowline system in accordance with

claim 1

further comprising:

a plurality of clamps;

a plurality of pulltubes bundled and secured together by said clamps, the bundle of pulltubes extending through the conductor guides.

5. A flowline system in accordance with

claim 1

, further comprising

a conductor supported by the jacket in the wellbay at the conductor guides providing lateral support directly to a plurality of flowlines run therewithin.

6. A flowline system in accordance with

claim 3

, further comprising a plurality of internal supports which surrounding the pulltubes within the conductors to provide direct lateral support between the conductor wall and the pulltubes.

7. A flowline system in accordance with

claim 6

, wherein the internal supports are inflated diaphragms.

8. A flowline system in accordance with

claim 1

further comprising preinstalled curved pulltubes connected to the base of the platform jacket and field installed vertical conductors.

9. A flowline system in accordance with

claim 9

further comprising a connection between the field installed vertical conductor and the preinstalled curved pulltubes.

10. A flowline system in accordance with

claim 9

wherein the connection is an interlocking cruciform plate gravity connection.

11. A flowline bundle in accordance with

claim 1

wherein the conductor is an open caisson, further comprising:

an upper caisson section comprising field installed vertical conductor sections;

a lower caisson section preinstalled to the base of the platform jacket;

a connection between the upper and the lower caisson sections;

a plurality of upper straight pulltubes within the upper caisson section; a top plate connected to the top of the upper caisson section and supporting the upper straight pulltubes and the flowlines therewithin;

a flared downwardly facing termination at the lower end of the upper straight pulltubes;

a plurality of curved pulltubes preinstalled within the lower caisson section and vertically separated from the upper straight pulltubes; and

a flared upwardly flared termination at the upper end of the curved lower pulltubes corresponding to the flared downwardly facing termination of the upper straight pulltubes.