The present invention relates to a subsea wellhead foundation and to methods for installing a subsea wellhead foundation, for example, for use with a petroleum well.
Wellhead systems for subsea wells are traditionally known to comprise a wellhead having a wellhead housing secured to a well casing. Wellhead systems for subsea wells also generally have a valve stack, such as a blow out preventer (hereinafter referred to as BOP) or valve tree, located permanently or temporarily on the wellhead, for example, during drilling, work-over operations and various phases of the operation. Such subsea wells can be used, for example, for petroleum exploration and/or for the injection of fluids (such as water or CO2) into a subterranean reservoir, as well as for extraction/production of hydrocarbons.
Installation of such subsea wellhead systems is typically carried out by an installation vessel, such as a ship or a drilling rig. The process is demanding, with high requirements for installation accuracy while maintaining strict safety standards to avoid risk to personnel or equipment. It is commonly a requirement, for example, that a foundation for supporting the subsea wellhead be installed substantially vertically within strict limits for permitted deviation from the vertical (typically a few degrees). Vessels used for such offshore installation processes are typically highly specialized units which are costly to operate, with efficiency also being a key concern for operators.
Publications which may be useful to understand the field of technology include WO 2017/179992 A2, WO 2017/091084 A1 and WO 2021/091397 A1.
There is a continuous need for improved technology for such wellhead foundations.
An aspect of the present invention is to provide improvements in technology for such wellhead foundations, or at least alternatives to known solutions and techniques. An aspect of the present invention is in particular to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art.
In an embodiment, the present invention provides a subsea foundation for installation on a sea floor. The subsea foundation includes a receptacle which is configured to receive a wellhead housing, and a conductor pipe which is arranged to extend from the receptacle and which is configured to receive a well pipe therethrough. The conductor pipe comprises a first section and a second section. The first section comprises a first end and a second end. The first section is connected to the receptacle at the first end and is pivotably connected to the second section at the second end so that the conductor pipe is configurable between a compact configuration, in which the conductor pipe comprises a bend therein, and an extended configuration, in which the conductor pipe is substantially straight.
The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:
A first embodiment of the present invention provides a subsea foundation for installation on a sea floor, the subsea foundation comprising: a receptacle configured for receiving a wellhead housing, a conductor pipe extending from the receptacle and configured for receiving a well pipe therethrough, the conductor pipe comprising a first section being connected to the receptacle at one end thereof and being pivotably connected to a second section at a second end thereof, so that the connector pipe is configurable between a compact configuration in which the conductor pipe comprises a bend therein, and an extended configuration, in which the conductor pipe is substantially straight.
A second embodiment of the present invention provides that the subsea foundation may comprise a suction anchor base.
A third embodiment of the present invention provides that the suction anchor base may be substantially cylindrical, and the first section of the conductor pipe may be arranged concentrically inside the suction anchor base.
A fourth embodiment of the present invention provides that the first section of the conductor pipe may be fully located within the suction anchor base.
A fifth embodiment of the present invention provides that the suction anchor base may be cylindrical, and the second section of the conductor pipe may be shorter than the radius of the suction anchor base so that in the compact configuration, the second section of the conductor pipe may be located inside the suction anchor base.
A sixth embodiment of the present invention provides that the second section of the conductor pipe may be longer than the radius of the suction anchor base, and that the suction anchor base may comprise a recess therein for locating the second section with the conductor pipe in the compact configuration.
A seventh embodiment of the present invention provides that, in the extended configuration, the conductor pipe protrudes outside the suction anchor base.
An eighth embodiment of the present invention provides that the subsea foundation may comprise a hinge joint between the first and second sections of the conductor pipe, thereby enabling the pivotal connection therebetween.
A ninth embodiment of the present invention provides that the hinge joint may comprise a disengaged configuration in which an end of the second section may be held distal to the second end of the first section where pivotal movement therebetween may be enabled, and an engaged configuration in which the second end of the first section may be engaged with an end of the second section and the conductor pipe may be in the extended configuration.
These and other embodiments will become clear from the following description of illustrative embodiments, which are provided as non-restrictive examples, under reference to the attached drawings.
The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, “upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the present invention. The terms are used for the reader's convenience only and shall not be limiting.
The subsea foundation 1 comprises a receptacle 2 which may be used to receive a wellhead housing 3. The receptacle 2 is located on an upper component 10 of the subsea foundation 1, which in this case is in the form of a circular plate or platform. The receptacle 2 defines an aperture therethrough for the receipt of a wellhead housing 3. A lower component 12 extends from the upper component 10, the lower component 12 in this example being in the form of a hollow cylinder, and the upper and lower components 10, 12 together defining an anchor recess. The lower component 12 may be considered to be a suction anchor base. The upper component 10 may also comprise a valve that may be used to operate the suction anchor by permitting water to be removed from the anchor recess, and thereby anchoring the subsea foundation 1 on the seabed via suction. The upper component 10 may additionally comprise stiffening and/or reinforcement members, as is the case in
The subsea foundation 1 is illustrated in cross-section in
As previously indicated, the receptacle 2 defines an aperture in the upper component 10, and may be located concentrically with the upper component 10 and/or the lower component 12. From the upper component 10, in a downwards direction, extends a conductor pipe 5, comprising a first section 5a and a second section 5b. The conductor pipe 5 may act as a guide for, for example, any pipes, casings, tubings or the like that extend from the wellhead, e.g., into a well. The conductor pipe 5 extends within the lower component 12 (e.g., extends within the skirt) and may be either partially or fully located within anchor recess defined by the upper and lower components 10, 12 depending on the geometry of the conductor pipe 5 and the upper and lower components 10, 12.
As illustrated in
In
In this example, the second section 5b of the conductor pipe 5 is longer than the radius of the cylindrical lower component or skirt 12. The movement of the second section 5b may therefore be limited by the presence of the second section 5b, and in both compact and extended configurations, the conductor pipe 5 partially protrudes from the lower part 12. Although not illustrated in this example, the lower part 12 may comprise a recess for receiving the second section 5b of the conductor pipe 5, thereby enabling the conductor pipe 5, in the compact configuration, to be held at a level above the lower rim 18 of the second component 12. The conductor pipe 5 may additionally or alternatively comprise a third section which is pivotably connected to the second section 5b (e.g., via a further hinge joint similar or identical to the one described herein), and which may enable the conductor pipe 5 to be folded in a U-shape or in a J-shape inside the lower component 12, also enabling the conductor pipe 5 to be held at a level above the lower rim 18 of the lower component 12.
In some other examples, the length of the second section 5b may be shorter than the radius of the second part 12 (or the width, in the case where the second part may be in the form of an extruded polygon, rather than a cylinder). In such cases, it may be possible to contain both the first and second sections 5a, 5b of the conductor pipe 5 completely inside the lower component 12. It should also be noted that the length of the first section 5a of the conductor pipe 5 is shorter than the length of the lower component 12, and as such, in the compact configuration, the conductor pipe 5 is able to be completely contained within the lower component 12. In some other examples, the length of the first section 5a of the conductor pipe 5 may be longer than the length of the lower component 12, in which case, in the compact configuration, there will remain a section of the conductor pipe 5 that protrudes from the lower component 12.
With the conductor pipe 5 in the compact configuration, the subsea foundation 1 may be more easily transported that would otherwise be possible. For example, in cases where the conductor pipe 5 is able to be completely contained within the anchor recess, and/or is able to be held completely above the lower rim 18 of the second component 12, the subsea foundation 1 may be able to be transported in the upright orientation (e.g., the orientation as shown in
In cases where the first section 5a is longer than the length of the lower component 12, or in cases where movement of the second section 5b is limited by the lower component 12, thereby requiring at least a part of the conductor pipe 5 to protrude from the anchor recess, the subsea foundation 1 may still be transported in the upright position, but, for example, on a raised platform. Such transport means may be preferable to, for example, having to transport the subsea foundation 1 on its side, which would then require adequate anchoring of the subsea foundation 1 to a vessel during transport, and subsequent reorientation of the subsea foundation 1 from a horizontal to a vertical position before installation.
In
Once the conductor pipe 5 is in the expanded configuration and the hinge joint 5 is in the engaged configuration, the subsea foundation 1 may be ready to be installed in a subsea location. Having the conductor pipe 5 protruding from the lower component 12 may assist to provide an accurate and efficient installation of the subsea formation 1 in a desired position, and may assist to prevent washout during installation and subsequent drilling operations. Having a longer conductor pipe 5 may, for example, permit the conductor pipe 5 to reach a greater depth in a seabed, ocean floor, lakebed, or the like, where the earth may be harder and less prone to erosion, thereby preventing washout.
Further details of the hinge joint 14 and the geometry of the first and second parts 5a, 5b are shown in
The hinge pin mechanism 20 is in an upper position in
Having such a subsea foundation 1 with a conductor pipe 5 comprising a first and second section 5a, 5b, the section 5b being pivotably connected to the first section 5a may allow a conductor pipe 5 that is longer, and with a greater possible diameter than other solutions. The diameter of the conductor pipe 5 may, for example, be able to be wider than in cases where the conductor pipe 5 is telescopic, thereby requiring a smaller diameter with each telescopic section. Having a pivotal connection may also be a simpler solution that is less prone to problems (e.g., sticking or excessive wear) than known solutions which may comprise many and/or complex moving parts.
The present invention is not limited by the embodiments described above; reference should be had to the appended claims.
Number | Date | Country | Kind |
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20210741 | Jun 2021 | NO | national |
This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/NO2022/050128, filed on Jun. 7, 2022 and which claims benefit to Norwegian Patent Application No. 20210741, filed on Jun. 8, 2021. The International Application was published in English on Dec. 15, 2022 as WO 2022/260529 A1 under PCT Article 21(2).
Filing Document | Filing Date | Country | Kind |
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PCT/NO2022/050128 | 6/7/2022 | WO |