Subsea module

Details Subsea module Subsea module

1999-02-26

2001-02-06

Lillis, Eileen D. (Department: 3673)

Wells

Submerged well

Multiple wells

C166S352000, C166S355000, C166S345000

Reexamination Certificate

active

06182763

ABSTRACT:

FIELD OF INVENTION
The invention relates to a subsea module or station for offshore production of oil or gas, comprising at least two wellheads with associated christmas trees, and a manifold, whereby the christmas trees and the manifold are provided on or at a bottom frame (template). Such a module is intended for connection to a production vessel at the sea surface, by means of one or more risers, preferably flexible and hose-like risers.
BACKGROUND OF THE INVENTION
When developing marginal offshore production fields it is important to keep the costs low. A substantial cost factor with known forms of development, is due to subsea pipelines and cables between christmas trees at the wells and product receiver sites, for example a platform or a floating production vessel. Typically the distances involved may be about 2 km. In this connection it is to be noted that modern drilling technology makes it possible to produce by means of a reduced number of christmas trees, because the boreholes or wells can have several branches. This will make it possible to develop subsea fields in some instances by employing a small number of wellheads and christmas trees assembled on a common subsea module or station at the seabed.
International patent application PC/NO96/00201 dated Jul. 8, 1996 relates to a system for offshore production of hydrocarbons by employing a moored production vessel or ship. The present invention can be regarded as a further development thereof and is based on the idea that the production vessel can by lying directly above or in the immediate vicinity of the subsea module in production at the seabed and that the well fluid flows are transferred directly between the module and the vessel without relying on pipelines or cables on the seabed. In this connection the invention is not exclusively based upon location of the production vessel by means of mooring, as according to the international patent application mentioned above, but can also employ mean as known per se for dynamic positioning of the vessel.
BRIEF SUMMARY OF THE INVENTION
Thus, in a module as stated in the introduction above, the novel and specific features according to the invention in the first place comprise that on or at the template there is provided a swivel device having fluid connection to the manifold and being provided with connection members being preferably directed laterally, for risers and an umbilical from a production vessels at the sea surface.
On the basis of this fundamental solution, which in actual practice can be embodied in various forms, it is possible to obtain a number of advantages, of which in particular the following are mentioned:
Reduced costs in that pipelines and cables on the seabed are avoided,
the production vessel employed does not need any modifications worth mentioning, in relation to common ship designs, and therefore will be relatively inexpensive,
the same production vessel can be used for installing and possibly retrieve the swivel device, or also for well maintenance, which contributes to reduced operational costs,
very small marginal subsea fields can be profitable by using this novel arrangement, so that the degree of extraction can be increased for the fields,
the equipment employed can be re-used by moving it from field to field.
A preferred embodiment of the present invention comprises a subsea module for offshore production of oil or gas, comprising a well template having a number of locations for christmas trees, at least one wellhead, at least one christmas tree mounted on the at least one wellhead, a swivel device provided in one christmas tree location, the swivel device having fluid connection to the at least one christmas tree and the swivel device being rotatable about a first, central vertical axis, at least one connecting member provided on the swivel device for connection with the at least one riser and with an umbilical or control cable from a production vessel at sea surface, a housing rotatable about the first central, vertical axis, at least one attachment member provided on the housing, a yoke connected to the at least one attachment member and pivotable about a horizontal axis at one end, the yoke adapted to be connected at its outer end to at least one mooring line of the production vessel.
In one aspect of the preferred embodiment, the housing is rotatably arranged on a base structure being carried by a supporting frame adapted for taking up mooring forces directly from the attachment elements without imposing any noticeable stresses on the swivel device.
In another aspect of the preferred embodiment, the yoke contains yoke limbs connected to attachment members and a lower end of the at least one riser is connected centrally to the swivel device and extends outwards from the swivel device centrally between the yoke limbs.


REFERENCES:
patent: 3701261 (1972-10-01), Nolan, Jr.
patent: 4023619 (1977-05-01), Marquaire et al.
patent: 4211281 (1980-07-01), Lawson
patent: 4398846 (1983-08-01), Agdern
patent: 4625806 (1986-12-01), Silcox
patent: 5040607 (1991-08-01), Cordeiro et al.
patent: 5255744 (1993-10-01), Silva
patent: 2 656 274 (1989-12-01), None
patent: 2 168 939 (1986-07-01), None
patent: 8701005 (1988-10-01), None
patent: 177780 (1995-08-01), None
patent: 90/03492 (1990-04-01), None

Affiliated with

Also associated with

Rating

Subsea module does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Subsea module, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Subsea module will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2573147