This application is the U.S. national stage application of International Application PCT/NO2016/050118, filed Jun. 8, 2016, which international application was published on Dec. 15, 2016, as International Publication WO 2016/200271 in the English language. The International Application claims priority of Norwegian Patent Application No. 20150766, filed Jun. 12, 20165. The international application and Norwegian application are both incorporated herein by reference, in entirety.
The invention relates to a system and a method for establishing a collection of well foundations, the well foundations being formed of suction-foundation units, which are arranged to be set down into an unconsolidated mass, especially seabed sediments.
When establishing a collection of several wells in a location in a field where hydrocarbons are being extracted, it is often important to space the wellheads evenly in a predetermined pattern with a view to, among other things, being able to prefabricate components that form interconnections between the wellheads. When such collections of wells are to be established in subsea fields, a prefabricated frame structure is often used, which is put down on the sea floor to form a model or template for how the different wells are to be established relative to each other. In addition, the frame structure functions as a foundation for the wellheads and associated elements. Such a frame structure may weigh several hundred tonnes, and it is complicated and expensive both to transport it to the field and to place it on the sea floor. Because of the great weight, there is also a limit to how many wellheads such a frame structure may comprise.
The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.
The object is achieved through the features that are specified in the description below and in the claims that follow.
The invention provides a system and a method for establishing a foundation for a collection of several wells, each well foundation consisting of a suction-foundation unit, and the relative positions of the suction-foundation units, that is to say the horizontal spacing of the suction-foundation units, their difference in height, center-axis direction and so on, are controlled by means of an alignment template which is positioned temporarily or permanently on a sea floor. The alignment template is provided with several cut-outs extending through it, each being arranged to receive and align a suction-foundation unit. The suction-foundation units, which are handled separately, are put into respective cut-outs in the alignment template and pushed down into the sediments below the sea floor in a manner known per se, by the suction-foundation unit being evacuated so that negative pressure develops inside the suction-foundation unit.
The suction-foundation unit and the alignment template may be provided with engagement means for aligning the suction-foundation units around their center axes, for example by the jackets of the suction-foundation units being provided with one or more ribs that engage with corresponding grooves in the cut-outs in the alignment template.
The cut-outs of the alignment template may be encircled by guiding means facilitating the insertion of the suction-foundation unit into the cut-out, for example by each cut-out being encircled by an upstanding funnel or several elements with slanted guide faces.
The alignment template may be provided with laterally stabilizing means, which, by penetration into the sea floor, prevents unintended displacement of the alignment template during the installation of the suction-foundation units. The laterally stabilizing means may be formed as skirts extending downwards from the bottom side of the alignment template.
The alignment template may be provided with system components arranged for use during the installation of the foundations or for use in the subsequent establishing or operation of the well. Typically, such components may consist of pumps, manifolds, pipelines, cables and so on.
The alignment template may be provided with coupling means arranged to fix the alignment template temporarily or permanently to the suction-foundation units.
The alignment template is typically provided with 2×2 or 1×3 cut-outs. When more suction-foundation units than the number contained in the alignment template are being installed, the alignment template may be moved in steps for the installation of further suction-foundation units, the new position of the alignment template being controlled by it being brought into engagement with one or more of the previously installed suction-foundation units. It is an advantage if, in its new position, the alignment template is in engagement with at least two installed suction-foundation units.
The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.
In a first aspect, the invention relates more specifically to a system for establishing a collection of well foundations, the well foundations being formed of suction-foundation units that are arranged to be driven down into a sea floor, characterized by an alignment template including several through cut-outs, each arranged to receive a suction-foundation unit, being positioned over the sea floor and forming a means of positioning the suction-foundation units before the suction-foundation units are forced down into the sea floor, the alignment template and the suction-foundation unit being provided with complementary engagement means for the horizontal directional orientation of the suction-foundation unit relative to the alignment template.
The cut-outs of the alignment template may be encircled by means with sloping surfaces arranged to center the suction-foundation unit in the respective cut-out. The suction-foundation unit is thereby guided into the cut-out even if it is not positioned exactly, in the horizontal plane, when being lowered towards the alignment template.
The alignment template and/or the suction-foundation unit may be provided with coupling means arranged to fix the suction-foundation unit relative to the alignment template. Especially when the alignment template is going to constitute a permanent part of the well assembly, this may be an advantage.
The alignment template may include laterally stabilizing means, which are arranged to penetrate into the sea floor. An advantage of this is that the alignment template cannot unintendedly be pushed out of position, for example by impact from the suction-foundation unit during the placement thereof.
The alignment template may be provided with system components arranged for monitoring and controlling the establishing of the well foundations and/or the operation of the well. It may be an advantage if such equipment can be assembled and tested while still on the surface.
The alignment template may be provided with at least three cut-outs. An advantage of this is that the alignment template may be held fixed by means of two installed suction-foundation units while the third suction-foundation unit is installed, which may improve the precision in the placement of the suction-foundation units.
The alignment template may be provided with one or more protection elements projecting up between the cut-outs to shield a first wellhead against damage during the installation of a second suction-foundation unit and a second wellhead. The advantage of this is that a collection of producing wells may be supplemented with more wells without the risk of the producing wells being damaged.
In a second aspect, the invention relates more specifically to a method of establishing a collection of well foundations by the use of a system according to the first aspect of the invention, characterized by the method comprising the following steps:
The method may include the further steps:
An advantage of this is that the well assembly may include a large amount of well foundations without the size of the single elements used during the establishing having to be increased.
In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings, in which:
In the figures, the reference numeral 1 indicates an alignment template for positioning suction-foundation units 2 by driving them into an unconsolidated mass 31 over a structure not shown, where, through a supporting pipe 22 in the suction-foundation unit 2, a well not shown is to be established for the potential extraction of a fluid, typically hydrocarbons. The unconsolidated mass 31 is especially subsea sediments and is bounded by a sea floor 3.
The alignment template 1 includes several evenly spaced cut-outs 11. The
Each cut-out 11 is provided with an engagement means for the horizontal directional orientation of the respective suction-foundation unit 2, shown in
The cut-outs 11 are encircled by a guiding means formed as a ring 12 projecting up from the alignment template 1 and being provided with a slanted guide face 121 arranged to center the suction-foundation unit 2 when this is lowered towards the cut-out 11.
The alignment template 1 is further provided with several laterally stabilizing means, shown in
The alignment template 1 and the suction-foundation units 2 are provided with coupling means 15 (see
By providing the alignment template 1 with at least three cut-outs 11, the direction of the alignment template 1 can always be controlled during the stepped movement, by the alignment template 1 being in engagement with two completely installed suction-foundation units 2.
A significant advantage of the system and method according to the invention is that the establishing of the well foundation may be carried out by using lifting equipment of moderate capacity as, independently of the total number of wells in the collection, none of the modules in the collection of well foundations will ever include more than one suction-foundation unit 2 or one alignment template 1.
The alignment template 1 may be designed in such a way that it gives little risk of damaging equipment involved if fishing equipment, for example a trawl, comes into contact with the well foundation. The alignment template may in itself be formed with slanted and/or rounded side faces or be provided with attachments for trawl caps of a kind known per se.
Reference is now made to
The use of the verb “to comprise” and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article “a” or “an” before an element does not exclude the presence of several such elements.
The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.
Number | Date | Country | Kind |
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20150766 | Jun 2015 | NO | national |
Filing Document | Filing Date | Country | Kind |
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PCT/NO2016/050118 | 6/8/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2016/200271 | 12/15/2016 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5526882 | Parks | Jun 1996 | A |
8025463 | Foo | Sep 2011 | B2 |
20030155119 | Crain | Aug 2003 | A1 |
20090297276 | Foo et al. | Dec 2009 | A1 |
20120024535 | Lieske, II | Feb 2012 | A1 |
Number | Date | Country |
---|---|---|
202176267 | Mar 2012 | CN |
20130037384 | Apr 2013 | KR |
Entry |
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Norwegian Search Report, Norwegian Patent Application No. 20150766, dated Jan. 8, 2016. |
International Search Report, PCT/NO2016/050118, dated Sep. 1, 2016. |
Written Opinion and Response, PCT/NO2016/050118, dated Sep. 1, 2016. |
Written Opinion and Response, PCT/NO2016/050118, dated Feb. 23, 2017. |
International Preliminary Report on Patentability, PCT/NO2016/050118, date of completion Jun. 9, 2017. |
Number | Date | Country | |
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20180171574 A1 | Jun 2018 | US |