UNDERWATER FOUNDATION AND INSTALLATION METHOD

MX433784BActive Publication Date: 2026-05-19EQUINOR ENERGY AS

Patent Information

Authority / Receiving Office: MX · MX
Patent Type: Patents
Current Assignee / Owner: EQUINOR ENERGY AS
Filing Date: 2022-02-25
Publication Date: 2026-05-19

AI Technical Summary

Technical Problem

Existing methods for connecting a lower pipe portion to a subsea foundation, such as a suction anchor, are inconvenient and unreliable, particularly during underwater deployment, as they require complex operations and may be hindered by water conditions.

Method used

A method and system for connecting a lower pipe portion to a subsea foundation involves deploying the foundation below sea level with the lower pipe portion in an engaged position, allowing it to be released and connected to an upper pipe portion using an extraction arrangement, with optional use of a pipe overlap section for alignment and stability, facilitating connection without protruding beyond the foundation's bottom.

Benefits of technology

This approach simplifies and stabilizes the connection process, reducing operational complexity and costs by allowing manual or mechanical connection methods, ensuring reliable alignment, and minimizing underwater operations, thus enhancing the installation efficiency of subsea foundations.

✦ Generated by Eureka AI based on patent content.

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Figure MX433784B0

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Abstract

A method for connecting a lower pipe portion to a subsea foundation is provided. The method comprises: providing the subsea foundation, wherein the subsea foundation includes an upper pipe portion connected to the subsea foundation; deploying the subsea foundation below sea level; and connecting the lower pipe portion to the upper pipe portion. A subsea foundation system is also provided. The subsea foundation system comprises: a subsea foundation; an upper pipe portion connected to the subsea foundation; and a lower pipe portion, wherein the subsea foundation system is positioned so that, below sea level, the lower pipe portion can be connected to the upper pipe portion. The lower pipe portion could be connected to the subsea foundation in a recessed position prior to deployment below sea level.The lower pipe portion could be connected to a withdrawal arrangement prior to deployment below sea level. The subsea foundation could comprise a pipe overlap section that is positioned to overlap a portion of the upper pipe portion and / or the lower pipe portion when the lower pipe portion is connected to the upper pipe portion.

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Description

UNDERWATER FOUNDATION AND INSTALLATION METHOD Field of Invention The invention relates to a submarine foundation system and a method of connecting a lower pipe portion to a submarine foundation. Background of the Invention Many subsea devices, such as well equipment and wellhead, require a foundation in which they can be placed during use. For example, a subsea well assembly will generally comprise a foundation. The foundation is used to support the subsea well extending into the seabed and wellhead equipment such as a preventer. One well-known type of subsea foundation is the suction anchor. A suction anchor used as a subsea foundation comprises a skirt. The suction anchor is lowered onto the seabed and then sucked down to the seabed by reducing the pressure within the skirt. Once the suction anchor has been sucked down to the seabed, the suction anchor could provide a foundation for a well or other subsea device. It has been found that in certain circumstances, it could be beneficial if the underwater foundation also included an interior member in the form of a pipe. It has been pQcznn / zznz / E / YiAi Ref. 332017 found that it is beneficial for the subsea foundation to have a shorter pipeline during transportation and before deployment below sea level, but a longer pipeline before the subsea foundation is landed on the seabed. It is known from WO2017 / 179992 to provide a subsea foundation comprising a suction anchor with a two-part inner member. In this case, the lower part of the member protrudes from the suction skirt of the suction anchor and is coupled to the suction anchor at the installation site. This is achieved by first placing the lower part on the seabed, then deploying the suction anchor below sea level, then connecting a pull-out line between the lower part and the machine anchor, and then connecting the lower part to the upper part below sea level using a pull-out line through the center of the inner member. However, there is a desire for an alternative, more convenient and / or more reliable method and apparatus for connecting a lower portion of a two-part pipeline or interior member to the subsea foundation at the installation site. Summary of the Invention In a broad aspect, the present invention rorznn / zznz / E / YiAi provides a method of connecting a lower pipe portion to a subsea foundation, the method comprising: providing the subsea foundation, wherein the subsea foundation comprises an upper pipe portion connected to the subsea foundation, deploying the subsea foundation below sea level; and connecting the lower pipe portion to the upper pipe portion. The upper pipe portion may not protrude beyond the bottom of the suction anchor. The underwater foundation could comprise a suction anchor and the upper pipe portion could be connected to the suction anchor. In another broad aspect, the present invention provides a subsea foundation system, for example, for deployment below sea level, wherein the subsea foundation system comprises: a subsea foundation; an upper pipe portion connected to the subsea foundation and a lower pipe portion, wherein the subsea foundation is positioned such that below sea level, the lower pipe portion can be connected to the upper pipe portion. The upper pipe portion may not protrude beyond the bottom of the suction anchor. The underwater foundation could comprise a suction anchor and the upper pipe portion could be connected pQcznn / zznz / E / YiAi with the suction anchor. The lower pipe could be connected to the subsea foundation, for example, a suction anchor of the foundation in a wedged position. The subsea foundation could be deployed below sea level with the lower pipe portion in the wedged position. The lower pipe portion could be released from the wedged position below sea level. In this way, the subsea foundation could be positioned such that, below sea level, the lower pipe portion could be released from the wedged position and connected to the upper pipe portion below sea level. In a first aspect, the present invention may provide a method of connecting a lower pipe portion to a subsea foundation, the method comprising: providing the subsea foundation, wherein the subsea foundation comprises an upper pipe portion connected to the subsea foundation, e.g., a suction anchor of the subsea foundation, connecting the lower pipe portion to the subsea foundation, e.g., the suction anchor, in an engaged position; deploying the subsea foundation below sea level with the lower pipe portion in the engaged position; releasing the lower pipe portion from the engaged position below sea level; and connecting the lower pipe portion to the upper pipe portion. In a second aspect, the present invention may provide a subsea foundation system for deployment below sea level, the subsea foundation system comprising: a subsea foundation, e.g., a subsea foundation comprising a suction anchor; an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; and a lower pipe portion connected to the subsea foundation, e.g., the suction anchor, in a nested position, the subsea foundation system being positioned such that below sea level, the lower pipe portion can be released from the nested position and connected to the upper pipe portion. By connecting the lower pipe portion to the subsea foundation, for example, a foundation suction anchor, in a nested position and then deploying the subsea foundation below sea level with the lower pipe portion in the nested position, both the subsea foundation and the lower pipe portion could be conveniently deployed to the desired position where the lower pipe portion can / may connect to the upper pipe portion, this could facilitate the connection of the lower pipe portion to the subsea foundation. This is because the location of the lower pipe portion will be known and only one deployment operation needs to be performed for the two components. The desired position could be any position in the water column where water conditions are sufficiently stable so as not to interfere with the connection of the lower pipe portion to the upper pipe portion. Generally, water conditions are sufficiently stable so that the lower pipe portion can be connected to the upper pipe portion at a depth or position where the water is not influenced by waves at the water surface. In some climatic conditions, there is little disturbance of the water by waves, and in these circumstances, the depth or position where the water is not influenced by waves is closer to the water surface than is generally the case. Additionally or alternatively, the lower pipe portion could be connected to a withdrawal arrangement and then deployed below sea level with the lower pipe portion connected to the withdrawal arrangement. The withdrawal arrangement could be used to connect the lower pipe portion to the upper pipe portion. The lower pipe portion could be connected to a withdrawal arrangement, and the subsea foundation could be positioned such that, below sea level, the lower pipe portion can be connected to the upper pipe portion using the withdrawal arrangement. In a third aspect, the present invention may provide a method of connecting a lower pipe portion to a subsea foundation, the method comprising: providing a subsea foundation (optionally comprising a suction anchor) comprising an upper pipe portion connected to the foundation, e.g., the suction anchor, which connects the lower pipe portion to a stripping arrangement; deploying the subsea foundation below sea level with the lower pipe portion connected to the stripping arrangement; and connecting the lower pipe portion to the upper pipe portion below sea level using the stripping arrangement. The method may further comprise connecting the lower pipe portion to the subsea foundation in a nested position before or after connecting the lower pipe portion to the stripping arrangement. In a fourth aspect, the present invention may provide a subsea foundation system for deployment below sea level, wherein the subsea foundation comprises: a subsea foundation (e.g., comprising a suction anchor); an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; and a lower pipe portion connected to a pull-out arrangement, wherein the subsea foundation system is positioned such that below sea level, the lower pipe portion can be connected to the upper pipe portion using the pull-out arrangement. By connecting the lower pipe portion to a withdrawal arrangement before the subsea foundation is deployed below sea level, the lower pipe portion could be conveniently coupled to the upper pipe portion without having to connect the withdrawal arrangement to the lower pipe portion below sea level when connection might be more difficult. In particular, connecting the lower pipe portion to a withdrawal arrangement before the subsea anchor is deployed below sea level has the benefit that the connection of the withdrawal arrangement to one or both of the lower pipe portion and the subsea foundation can be performed manually (optionally, using suitable mechanical devices, such as a crane) instead of using one or more remotely operated vehicles. This results in cost and monetary savings. Additionally or alternatively, a pipe overlap section is provided. The pipe overlap section may be positioned to overlap a portion of the upper pipe section and / or the lower pipe section when the lower pipe portion is connected (directly or indirectly) to the upper pipe section. The method may comprise providing the upper and lower pipe portions and the pipe overlap section. The method may comprise connecting the lower pipe section to the upper pipe section such that the pipe overlap section overlaps a portion of the upper and / or lower pipe portions. In a fifth aspect, the present invention provides a subsea foundation system, the subsea foundation system comprising: a subsea foundation (optionally comprising a suction anchor); an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; a lower pipe portion; and a pipe overlap section, the pipe overlap section being positioned to overlap a portion of the upper pipe portion and / or the lower pipe portion when the lower pipe portion is connected to the upper pipe portion. In a sixth aspect, the present invention provides a method of connecting a lower pipe portion to a subsea foundation, the method comprising: providing the subsea foundation (optionally comprising a suction anchor) comprising an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; providing a lower pipe portion and a pipe overlap section; and connecting the lower pipe portion to the upper pipe portion such that the pipe overlap section overlaps a portion of the upper pipe portion and / or the lower pipe portion. By providing a pipe overlap portion, the lower pipe portion could be reliably connected with the upper pipe portion. The characteristics of each of the first through sixth aspects could be applied to any of the other aspects from the first through sixth. In other words, while the characteristics of each of these aspects could be independent, they could also be used in combination. Thus, when used in combination, for example, the present invention could provide a method of connecting a lower pipe portion to a subsea foundation, the method comprising: providing the subsea foundation, wherein the subsea foundation pQcznn / zznz / E / YiAi comprises (optionally, a suction anchor and) an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; providing the lower pipe portion and a pipe overlap section; connecting the lower pipe portion to a pull-out arrangement; connecting the lower pipe portion to the subsea foundation, e.g., the suction anchor in an engaged position; deploying the subsea foundation below sea level with the lower pipe portion in the engaged position and connecting to the pull-out arrangement;releasing the lower pipe portion from its wedged position below sea level; and connecting the lower pipe portion to the upper pipe portion using the pull-out arrangement such that the overlapping pipe section overlaps a portion of the upper pipe portion and / or the lower pipe portion. The present invention may provide a subsea foundation system for deployment below sea level, the subsea foundation system comprising: a subsea foundation, e.g., comprising a suction anchor; an upper pipe portion connected to the subsea foundation, e.g., the suction anchor; a lower pipe portion connected to the subsea foundation, e.g., the suction anchor, in a nested position and connected to a pull-out arrangement;and a pipe overlapping section, wherein the subsea foundation system is positioned such that below sea level, the lower pipe portion can be released from the wedged position and connected to the upper pipe portion using the pull-out arrangement, wherein the pipe overlapping section is positioned to overlap a portion of the upper pipe portion and / or the lower pipe portion when the lower pipe portion is connected to the upper pipe portion.; The following optional features are applicable to any of the above aspects. The upper pipe section could not protrude beyond the bottom of the subsea foundation, for example, beyond the bottom of the suction anchor. This could make transporting the subsea foundation, for example, the suction anchor, easier. When the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion could protrude beyond (i.e., extend beyond) the bottom of the underwater foundation, e.g., the suction anchor. This means that when the underwater foundation is lowered or lowered to the seabed, the lower pipe portion could connect to and penetrate the seabed before the underwater foundation, e.g., before the suction skirt of a suction anchor, if present. This could facilitate the installation of the underwater foundation on the seabed. For example, if the foundation comprises a suction anchor, this could help ensure that the suction anchor is in the correct orientation before the suction skirt of the suction anchor makes contact with the seabed. The lower pipe section could be connected to the upper pipe section when the subsea foundation, for example, the suction anchor, is below sea level, but before it reaches the seabed. For example, the subsea foundation could be suspended above the seabed while the lower pipe section is connected to the upper pipe section. The lower pipe portion may be directly connected to the upper pipe portion. For example, an upper end of the lower pipe portion may directly abut the lower end of the upper pipe portion. Alternatively, the lower pipe portion may be indirectly connected to the upper pipe portion, such as by means of the pipe overlap portion. When the lower pipe portion is connected to the upper pipe portion, the internal holes of the pipe portions may be connected in fluid communication. The upper pipe portion and the lower pipe portion may have, at least substantially, the same bottom and / or outside diameter. The lower pipe portion could be in the embedded position during transportation of the subsea foundation, e.g., the suction anchor, to the installation site. Thus, the method could comprise transporting the subsea foundation to the deployment site below sea level with the lower pipe portion in the embedded position. For example, the lower pipe portion could be placed in the embedded position on shore or when the subsea foundation is on a vessel for transportation, i.e., before the subsea foundation is deployed below sea level. When the lower pipe section is in the engaged position, it cannot protrude beyond the bottom of the subsea foundation, for example, beyond the bottom of the suction anchor. This could prevent the lower pipe from getting in the way during transportation of the subsea foundation. The wedged position could be a position in which the lower pipe portion is coupled with the exterior of the underwater foundation, for example, with the exterior of the suction skirt of the suction anchor. The lower pipe portion could be shorter than the underwater foundation, for example, it could be shorter than the suction skirt of the suction anchor. As a result, when connected to the underwater foundation, for example, the suction skirt, the lower pipe portion could not protrude beyond the top or the bottom of the underwater foundation, for example, the suction anchor. Alternatively, the lower pipe portion could be longer than the subsea foundation, for example, it could be longer than the suction skirt of the suction anchor. In this case, the lower pipe could be connected to the subsea foundation, for example, the suction skirt, such that the lower pipe portion does not protrude beyond the bottom of the subsea foundation, although it does not protrude beyond the top of the subsea foundation, for example, beyond the top of the suction anchor. The subsea foundation, for example, the suction anchor, could comprise one or more lugs (i.e., projections) for supporting the lower pipe portion when it is in the engaged position. The lugs could be provided on the outside of the subsea foundation, for example, on the outside of the suction skirt of the suction anchor. One or more of the lugs could support the lower pipe portion in a vertical direction when the bottom of the subsea foundation is horizontal. The lower pipe portion could be held in the wedged position by one or more straps. The straps could extend around the subsea foundation, for example, around the suction anchor and the lower pipe portion. The straps could be liner straps. The step of releasing the lower pipe portion from the wedged position could involve releasing one or more of the straps. For example, the straps could be released using an ROV. The straps could be released by cutting the straps. The straps could be cut below sea level. Once the straps have been released, the lower pipe portion could be allowed to drop or descend in a controlled manner from the wedged position to a position below the subsea foundation, for example, below the suction anchor. If the lower pipe portion is connected to the subsea foundation, for example, to the suction anchor, such as by means of a pull-out arrangement, the connection, for example, the pull-out arrangement, could retain the lower pipe portion in a suspended position below the subsea foundation and / or below the upper pipe portion. The pull-out arrangement could be used to connect the lower pipe portion to the upper pipe portion. The lower pipe portion may be able to move (e.g., it may fall under the action of gravity or be lowered in a controlled manner through any known lifting method such as with the aid of a crane, a pulley system or hydraulic cylinders) from the embedded position to a position below the underwater foundation when it is below sea level. The lower pipe portion may be able to fall from the embedded position in a relatively slow manner compared to if the lower pipe portion were released when the foundation is not in water. This is due to the resistance of seawater. In this way, the lower pipe portion may be able to fall in a relatively slow and / or controlled manner from the embedded position to a position below the suction anchor. The lower pipe portion, when in the wedged position, could be reversed compared to its position when connected to the upper pipe portion. In this way, the lower pipe portion could rotate 180° as it drops from the wedged position to a position below the suction anchor and the upper pipe portion. Once the lower pipe portion has been connected to the upper pipe portion, the foundation could further be lowered into and / or installed in and / or on the seabed. When connected to an extraction arrangement, the lower pipe may be connected, directly or indirectly, to the extraction arrangement. The lower pipe may be connected to the extraction arrangement such that the extraction arrangement can be operated to extract the lower pipe portion in connection with the upper pipe portion. When the foundation comprises a pipe overlap section, the lower pipe portion could be indirectly connected to the extraction arrangement by means of the pipe overlap section, for example, if the pipe overlap section is connected to the lower pipe portion. When the lower pipe section is connected to the extraction arrangement and the subsea foundation, e.g., the suction anchor, is prepared for deployment, the lower pipe section could not (yet) be connected to the upper pipe portion. The extraction arrangement could be connected to the lower pipe section when the subsea foundation is located above the water surface. For example, the extraction arrangement could be connected to the lower pipe section when the subsea foundation is located on the shore or on a vessel. This could reduce the number of operations that need to be performed below sea level. The step of connecting the lower pipe portion to the upper pipe portion may comprise extracting the lower pipe portion toward the upper pipe portion using the extraction arrangement. The extraction arrangement could comprise one or more extraction lines. For example, the extraction arrangement could comprise two extraction lines. This could allow for reliable and / or regular extraction while minimizing the number of components. Each of the lines could be a rope, wire, chain, etc. One or more of each of the extraction lines could extend parallel, adjacent, and / or close (along at least part of their length) to the upper pipe portion. One or more of each of the extraction lines could extend through the subsea foundation, for example, through the suction anchor. One or more of the extraction lines could extend through one or more of the respective extraction line conduits. The, or each, extraction line conduit could extend through the subsea foundation, for example, through the internal volume of the suction anchor and through a top surface of the internal volume. For example, the extraction line conduit could pQcznn / zznz / E / YiAi extend through the internal volume of the suction anchor and through a top surface of the internal volume. This could allow the extraction line to extend, in a movable manner, through the internal volume and the top surface without affecting the required seal of the internal volume.This is because the extraction line conduit could be connected, in an airtight manner, to the upper surface of the internal volume and in use, could seal with the seabed before the pressure is reduced in the internal volume to suck the suction anchor towards the seabed. The extraction lines could extend through the upper pipe portion. The extraction lines could extend through the wall of the upper pipe portion. The extraction lines could extend through the wall of the upper pipe portion at an elevation that is above the foundation, for example, above the suction anchor, yet below other components, such as a conductor housing (if present). This could mean that the extraction lines do not have to pass through the suction volume if the foundation is a suction anchor. Extraction line ducts, if present, may extend internally or externally from the upper pipe portion. pQcznn / zznz / E / YiAi In use, the line may be the only component inserted into or passed through the line conduit (perhaps different from the seabed as the foundation is sucked to the seabed). The line conduits may be separate conduits from the upper and lower pipe sections. The line conduit may not be a conduit through which the subsea well extends. The or each extraction line duct may have a diameter that is the same as or slightly larger than the maximum outside diameter of the extraction line passing through the extraction line duct. The extraction line conduit could help protect the extraction line as the foundation is grounded into the seabed, for example, as the suction anchor is being sucked into the seabed. The or each extraction line conduit may have connectors that connect it to internal reinforcements in the foundation and / or the upper pipe section. The extraction line conduit connectors may have a relatively small width dimension (compared to their height and length), this is to minimize the resistance that the extraction line conduit connectors might cause when fixing the foundation to the seabed, for example, by sucking the suction anchor into the seabed. pQcznn / zznz / E / YiAi The underwater foundation could comprise a pull-line fastener for each pull-line. The pull-line fastener could be located at the top of the underwater foundation. For example, on top of / above the suction anchor. The pull-line fastener could be located above the internal suction volume of the suction anchor (if a suction anchor is present). The pull-line fasteners could be located at the same height as the top of a conductor housing (if present). If the foundation includes I-beams supporting the wellhead, for example, at the top plate of the suction anchor, the drawlines could be passed through the foundation, for example, outside the internal volume, between two I-beams. The drawline fasteners could be located at the same height as, or above, the top of the I-beams (if present). This is so that the fastener and the top of the drawline could be easily accessible and not obstructed by the presence of the I-beams. The extraction arrangement, for example, the extraction lines, could be positioned so that they can be operated while the subsea foundation is suspended by a lifting arrangement or arrangement, for example, lifting wires or cables. For example, the extraction lines could be positioned so that they can be pulled through the subsea foundation while the foundation is suspended below sea level. The extraction wires could be facing outwards in a radial direction, although relatively close to the upper pipe portion. The pull-line fasteners may comprise a one-way mechanism, for example, a ratchet, that allows the pull-line to be pulled through the foundation towards the top of the foundation, for example, towards the top of the suction anchor, although this, in at least one mode of operation, prevents movement of the pull-line in the opposite direction, i.e., back to the foundation / suction anchor. The or each pull-line may be pulled through the respective pull-line fastener in a first direction and the pull-line fastener may act to prevent respective movement of the pull-line in a second, opposite direction.The first direction could be an upward direction, for example, through and out of the internal volume of the suction anchor and could cause the lower pipe portion to move towards the upper pipe portion, the second direction could be a downward direction, for example, towards the internal volume of the suction anchor and could cause the lower pipe portion to move out of the upper pipe portion. A pulling mechanism, such as a crane, winch, ROV or buoyancy aid etc., could be used to pull the pulling line through the subsea foundation (e.g., in a direction towards the top of the suction anchor) to pull the lower pipe portion towards and then perhaps into connection with the upper pipe portion. The extraction line attachments may include a lock or lock. This could be used to lock or immobilize the extraction line in a certain position. To connect the lower pipe portion to the upper pipe portion, the extraction lines could be pulled through the subsea foundation, for example, using a pulling mechanism to pull the lower pipe portion toward the upper pipe portion. The extraction line could be pulled through the extraction line conduit and / or the extraction line clamp. When the force on the extraction line is released, the extraction line clamp could act to prevent the extraction line from moving backward in the opposite direction. The extraction line tether could have a release mechanism. This could allow the extraction line to be released when desired, for example, during recovery of the underwater foundation. The lower pipe portion could comprise and / or be connected to the extraction line connection points. There could be one extraction line connection point for each extraction line. These could be, for example, extraction line connection wings. The extraction line connection wings could extend radially outward from the lower pipe portion. This allows the extraction lines to be radially separated from the lower pipe portion. This radial separation could assist in aligning the lower pipe portion with the upper pipe portion for connection. When the lower pipe portion is connected to the upper pipe portion, the extraction line connection points could be aligned, for example, below the respective extraction line support. This allows the extraction line to extend directly above the extraction line connection point, through the extraction line conduit to the extraction line support. Connecting the lower pipe portion to the extraction arrangement could involve coupling one or more extraction lines to the lower pipe portion and to the underwater foundation, for example, to the suction anchor. The extraction lines could be sufficiently long so that the lower pipe portion can be placed in the engaged position when the extraction lines are connected between the lower pipe portion and the underwater foundation. The pull lines may be slack or loose when the lower pipe portion is in the wedged position and / or before the pull lines are pulled up through the subsea foundation. When the lower pipe portion is released from the wedged position, the pull lines may act to retain or hold the lower pipe portion in a suspended position below the upper pipe portion. The pull lines may then be pulled to cause the lower pipe portion to be connected to the upper pipe portion. By connecting the lower pipe section to the extraction lines before deployment below sea level, operations could be minimized. This way, once below sea level, there would be no need to connect the extraction arrangement to the subsea foundation and / or the lower pipe section. The connection of the lower pipe section to the upper pipe section could be achieved by pulling the extraction lines through the subsea foundation. pQcznn / zznz / E / YiAi The pipe overlap section (if present) could overlap the upper pipe portion and the lower pipe portion. The overlap section could be long enough to provide sufficient alignment between the upper and lower pipe portions without the need for a narrow gap or clearance over a long distance that might prevent subsea coupling of the two parts. For example, the pipe overlap section could overlap the upper pipe portion and / or the lower pipe portion by about Im. When the lower pipe portion is connected to the upper pipe portion, the upper pipe portion and / or the lower pipe portion may be received within at least a portion of the pipe overlap portion. The pipe overlap section could have an inside diameter that is equal to the outside diameter of the upper pipe portion and / or the lower pipe portion. The inner diameter of the lower pipe portion could be the same as the inner diameter of the upper pipe portion. The outer diameter of the lower pipe portion could be the same as the outer diameter of the upper pipe portion. pQcznn / zznz / E / YiAi When the lower pipe portion and / or the upper pipe portion is received within the pipe overlap section, the pipe overlap section may be coaxial with the lower pipe portion and / or the upper pipe portion. The overlapping section of the pipe could ensure that a connection exists between the upper and lower pipe portions in a lateral direction. For example, the overlapping section of the pipe could allow the connection to withstand lateral forces. A simple end-to-end connection of the upper and lower pipe portions without an overlapping section could be feasible for disengaging while the lower pipe portion is being submerged within the seabed, for example, if the lower pipe portion hits an obstruction, such as a rock on one side. The pipe overlap section could be connected to and / or integral with either the upper or lower pipe portion. The pipe overlap section could be connected to either the upper or lower pipe portion prior to deployment of the subsea foundation. The pipe overlap section could be welded to either the upper or lower pipe portion. This weld could be performed before the foundation is deployed below sea level. The pipe overlap section could also overlap the pipe portion to which it is welded. When the overlapping pipe section is connected to the lower pipe portion, the overlapping pipe section and the lower pipe portion could together form a pipe extension. When connecting the upper pipe portion to the lower pipe portion, the method may comprise receiving the upper pipe portion and / or the lower pipe portion within the pipe overlap section. The upper pipe portion and / or the lower pipe portion may be received within the pipe overlap section until it abuts the other of the lower pipe portion and / or the upper pipe portion. In this manner, the abutment of the lower pipe portion and the upper pipe portion may act as a stop to prevent the upper pipe portion or the lower pipe portion from being received further within the pipe overlap section. The overlapping section of pipe could be placed in the nested position with the lower pipe portion. When the pipe overlap section is connected to the lower pipe portion, the extraction arrangement could be connected to the lower pipe portion by means of the pipe overlap section. In this way, the extraction arrangement, for example, the extraction lines and / or the extraction line connection wings, could be connected to the pipe overlap section. The pipe overlap section could be configured, for example, short enough so that when the upper pipe portion and the lower pipe portion are connected, the pipe overlap section is not obstructed by other foundation components, such as stiffener plates (if present). The stiffener plates could be plates which, if the foundation comprises a suction anchor, extend radially between the outer suction skirt and the inner pipe of the suction anchor. The foundation may comprise a pipe connection guide for guiding the connection between the upper pipe portion and the lower pipe portion. The pipe connection guide may be attached (directly or indirectly, such as via the pipe overlay section) to (e.g., one end of) the upper pipe portion and / or the lower pipe portion. For example, when the pipe overlay section is attached to the lower pipe portion, the pipe connection guide may be located at an upper end of the pipe overlay section that receives the upper pipe portion. The pipe connection guide may comprise a guide funnel. The guide funnel may be circumferentially discontinuous. This is so that the guide funnel does not interfere with other foundation components, such as the reinforcing plates (if present). When the guide funnel is circumferentially discontinuous, for example, made from obliquely angled guide pieces, the foundation parts, for example, the reinforcing plates, may be located between the discontinuous pieces when the lower pipe portion is connected to the upper pipe portion. In this way, the connecting guide could comprise one or more obliquely angled guide pieces. The connection guide could have a wider diameter at its inlet, which could facilitate the connection of the lower pipe portion to the upper pipe portion. For example, when the connection guide is provided in the pipe overlap section, the connection guide could help guide either the upper or lower pipe portion into the pipe overlap section. When the lower pipe portion is connected to the upper pipe portion, they could be held together by using a pull-out arrangement and / or a friction fit between the overlapping portion and the lower pipe portion and / or the upper pipe portion. There could be no other fixing device holding the upper and lower pipe portion together. This is because this connection might not be necessary. This is because the movement of the foundation placement on the seabed could act to keep the upper and lower pipe portions connected together. However, the compressive forces between the upper pipe portion, the lower pipe portion, and the overlapping pipe section might mean that they are required to form an effective stop between the upper and lower pipe portions.This could be provided by the upper and lower pipe portions being of the same diameter. Not having a fixing device / means between the upper pipe portion and the lower pipe portion could make retrieval of the suction anchor easier. Alternatively, there could be a locking device that secures the lower pipe portion to the upper pipe portion when they are connected. For example, the upper and lower pipe portions could be locked together with a snap-fit ring (e.g., in an overlapping section). The upper and lower pipe portions could be locked together using any type of connection, such as a threaded connection or a quick-release connection. The system could comprise an internal locking and releasable, reusable tool. The tool could be positioned so that, in use, it can be retained on the lower section as it is pulled upward and then snapped into place. The snap-on ring could be designed to retain or support a specific weight. The snap-on ring could be released as the foundation recovers. The foundation could be positioned so that, if the suction anchor is recovered from the seabed, the lower pipe section is not recovered. This could be facilitated if there were no fixing device / means between the upper and lower pipe sections, or if a fixing device were present, it had a release mechanism. If retrieval of the suction anchor is desired, the retrieval method may comprise disconnecting the stripping arrangement from the subsea foundation. This may be achieved by releasing the stripping line fasteners and / or severing the stripping lines (e.g., using cutters). The method may comprise forcing the foundation out of the seabed, e.g., by pumping fluid into the internal volume of the suction anchor to force the suction anchor out of the seabed, while leaving the lower pipe portion and, optionally, the pipe overlay section, if present, underneath. The suction anchor, the upper pipe portion, the lower pipe portion and the pipe overlap section (if present) could together form at least part of a subsea foundation system. The subsea foundation could be a foundation for a subsea well. Thus, the subsea foundation could be a subsea well foundation. The well could be an oil and / or gas well. The upper pipe portion and the lower pipe portion when connected together could provide a pipe for a well, for example, a conductor. When the foundation includes a suction anchor, the upper pipe could extend through the suction anchor into the suction skirt. The upper pipe (and the lower pipe when connected to the upper pipe) could provide, for example, at least part of a suction anchor's core pipe. The present invention may provide a subsea well foundation, the foundation comprising: a suction anchor, the suction anchor comprising an inner pipe for a well and an outer suction skirt pQcznn / zznz / E / YiAi located around / near the inner pipe, wherein the inner pipe comprises the upper pipe portion and the lower pipe portion. Alternatively, the upper pipe could be connected to and / or extend outside the foundation, for example, outside the suction skirt of the suction anchor. Even in this case, the upper pipe could not protrude beyond the bottom of the foundation. Deployment of the subsea foundation below sea level could mean moving the subsea foundation from a location above water to a location within a body of water. The underwater foundation, which is intended for deployment below sea level, could mean that it is suitable for deployment below sea level and therefore has not yet been deployed below sea level. Thus, it is in a state where it has not yet been deployed below sea level. The term 'submarine foundation' does not mean that the foundation is necessarily below sea level, but rather that in use it will be below sea level, that is, it will be used below sea level. While the terms submarine and seabed, etc., are used herein, it should be appreciated that this means according to any large body of water such as the ocean, lake, etc. and in any corresponding bed of water / bed below this body of water. Brief Description of the Figures In the following, certain preferred embodiments of the present invention will be described by way of example only with reference to the accompanying figures, in which: Figure 1 shows an underwater foundation comprising a suction anchor; Figure 2 shows an enlargement of detail 1 of Figure 1; A cross-section of a pipe extension is shown in Figure 3; An underwater foundation for deployment is shown in Figure 4; Figure 5 shows an underwater foundation during deployment; and Figure 6 shows an underwater foundation for installation on the seabed. Figure 1 shows a subsea foundation 1 comprising a suction anchor 2. The suction anchor 2 comprises an outer suction skirt 4, a top plate 6, and a core pipe 8 that connect or join together an internal suction volume. The core pipe 8 is indirectly connected in an airtight manner to the top plate 6. pQcznn / zznz / E / YiAi Detailed Description of the Invention While the present invention is described herein in relation to a subsea foundation comprising a suction anchor, it should be appreciated that the invention could be applied to other types of subsea foundations which may not comprise a suction anchor. The central pipe 8 comprises an upper pipe portion 10 and a lower pipe portion 12. The lower pipe portion 12 can be connected to and disconnected from the upper pipe portion 10. The upper pipe portion 10 does not protrude beyond the bottom of the suction skirt 4 of the suction anchor 2. The lower pipe portion 12 however, does not protrude beyond the bottom of the suction anchor 2. In this way, when the underwater foundation 1 is submerged into the seabed, the lower pipe portion 12 will reach and penetrate the seabed first. This could facilitate installation as a part (the lower pipe portion 12) can be penetrated into the seabed to retain the foundation 1 in an approximate location relative to the seabed while the orientation of the suction anchor 2 can be assessed and adjusted, if required. The central pipe 8 is fixed to the suction anchor 2 at an upper end on the upper plate 6 and is supported and centralized at the lower end by means of the reinforcing plates 14. The suction anchor 2 comprises the I-beams 16 (four of which can be seen in Figure 1) on the top plate 6. These I-beams 16 act to reinforce the top plate 6 and to support the wellhead (shown in dashed lines). The connection between the upper pipe portion 10 and the lower pipe portion 12 is overlapped by a pipe overlap section 18. The pipe overlap section 18 could be fixed, such as welded, to the lower pipe portion 12 which together could form a pipe extension 20 as shown in Figure 3. The pipe overlap section 18 partially overlaps the lower pipe portion 12 so that a reliable connection can be made between the lower pipe portion 12 and the pipe overlap section 18. The pipe overlap section 18 and therefore the lower pipe portion 12 are connected with an extraction arrangement 22. The extraction arrangement 22 is used to connect the lower pipe portion 12 with the upper pipe portion 10 below sea level. The extraction arrangement 22 comprises two extraction lines 24 extending through the suction anchor 2 via extraction conduits 26. The extraction conduits 26 at their upper ends are connected to (and pass through) the suction anchor top plate 6 in a sealed manner. These conduits 26 allow the extraction lines 24 to pass through the internal volume of the suction anchor without compromising the sealed nature of the internal volume. The extraction lines 24 and the extraction line conduits 26 pass through the top plate 6 between two of the I-beams 16. The pipe overlap section 18 is connected to the drawline connection wings 28. Each of the drawlines 24 extends between a drawline connection wing 28 at one end to a drawline fastener 30 at the other end. The drawline fasteners 30 are shown more clearly in Figure 2. Each of these drawline fasteners 30 grips a drawline 24 and allows it to be pulled through and out of the suction anchor. To accomplish this, each of the fasteners 30 comprises a one-way mechanism such as a ratchet and lock for retaining the drawline 24 once it has been pulled through the fastener 30. The extraction line connection wings 28 allow the extraction lines 24 to be radially separated from the central pipe 8. The extraction line ducts 26 are held in a fixed position relative to the central pipe 8 by pQcznn / zznz / E / YiAi the extraction line duct connectors 32. These connectors 32 connect the extraction line ducts 26 with the central pipe 8 and the internal reinforcements 14. At the upper end of the pipe overlap section 18 is a pipe connection guide 34. This guide 34 is constituted of a number of obliquely angled guide pieces that form a circumferentially discontinuous guiding funnel. When the lower pipe portion 12 is connected with the upper pipe portion 10 and the pipe overlap section 18 is superimposed on the upper pipe portion 10, the pipe connection guide 34 is used to guide the upper pipe portion 10 towards the pipe overlap section 18. The pipe connection guide 34 is circumferentially discontinuous so that it can be located between the internal reinforcements 14 as shown in Figure 1. The method of connecting the lower pipe portion 12 to the upper pipe portion 10 is illustrated in Figures 4, 5 and 6. Initially, prior to deployment below sea level, the pipeline extension (comprising the pipe overlay section 18 and the lower pipe portion 12) is connected to the extraction arrangement 22. This is achieved (in either order) by connecting each of the extraction lines 24 at one end to a fastener 30, which passes each of the lines 24 through a respective extraction line conduit 26, and coupling the other end to the lower pipe portion 12 by means of connecting wings 28 connected to the pipe overlay section 18 which is connected to the top of the lower pipe portion 12. Also, prior to deployment below sea level, (before, during or after connection of the extraction arrangement) the lower pipe portion 12 and the overlapping pipe section 18 are connected to the outside of the suction anchor 2 in a wedged position as shown in Figure 4. The lower pipe portion 12 and the overlapping pipe section 18 when in the wedged position are supported by lugs 36 which are connected to the outside of the skirt 4 of the suction anchor 2. The lower pipe portion 12 and the overlapping pipe section 18 may be secured to the suction anchor 2 in the wedged position by means of straps (not shown). Once the lower pipe portion 12 has been connected to the extraction arrangement 22 (in this case by means of the pipe overlap section 18) and connected to the outside of the suction anchor 2 in the engaged position, the underwater foundation 1 could be deployed below sea level. For example, the underwater foundation could be retained by means of lifting wires (not shown) pQcznn / zznz / E / YiAi connected to the pad eyes 38. Once below sea level, the subsea lower pipe portion 12 and the overlay pipe section 18 may be released from the wedged position, such as by cutting the straps (if present). The lower pipe portion 12 and the overlay pipe section 18 are allowed to drop into a suspended position below the suction anchor 2 as shown in Figure 5. The connection between the extraction arrangement and the lower pipe portion 12 and the overlay pipe section 18 retains the lower pipe portion 12 and the overlay pipe section 18 in the suspended position. The lower pipe portion 12 could then be connected to the upper pipe portion 12 by pulling the extraction lines through the conduits 26 and the fasteners 30. This pulling could be accomplished, for example, by a winch. Once pulled through the suction anchor 2 by the desired amount, the excess extraction line could be cut off above the fasteners 30. As the lower pipe portion 12 is pulled towards the upper pipe portion 10, the pipe connection guide 34 may guide the lower part of the upper pipe portion 10 towards the pipe overlay section 18. The upper pipe portion 10 is received in the pipe overlay section 18 until the end of the upper pipe section 10 abuts the end of the lower pipe section 12. In this position, the lower pipe portion 12 and the pipe overlay section 18 protrude from the lower part of the suction skirt 4 as shown in Figure 6. The underwater foundation 1 may then be landed on and submerged in the seabed. If it is desired to retrieve the suction anchor 2 from the seabed, this could be done in a manner that leaves the lower pipe portion 12 and the pipe overlay section 18 below the seabed. Before pumping fluid into the suction anchor 2 to force it out of the seabed, the extraction lines could be freed, either by cutting the lines or by releasing the fasteners 30. As a result (and because there is no longer any other securing device between the upper pipe portion and the lower pipe portion), when the suction anchor 2 is forced out of the seabed, the lower pipe portion 12 and the pipe overlay section 18 are left below on the seabed. It is noted that in relation to this date the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

CLAIMS The invention having been described above, the property claimed is that contained in the following claims:

1. A method of connecting a lower pipe portion to a submarine foundation, characterized in that it comprises: providing the submarine foundation, wherein the submarine foundation comprises an upper pipe portion connected to the submarine foundation, connecting the lower pipe portion to the submarine foundation in an embedded position; deploying the submarine foundation below sea level with the lower pipe portion in the embedded position; releasing the lower pipe portion from the embedded position below sea level; and connecting the lower pipe portion to the upper pipe portion.

2. The method according to claim 1, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the foundation.

3. The method according to claim 1 or 2, characterized in that the fitted position is a position in which the lower pipe portion is coupled with the outside of the foundation and the lower pipe portion does not protrude beyond the bottom of the foundation.

4. The method according to claim 1, 2 or 3, characterized in that it comprises: connecting the lower pipe portion with a extraction arrangement and then, deploying the underwater foundation below the sea level with the lower pipe portion connected with the extraction arrangement, wherein the connection of the lower pipe portion with the upper pipe portion comprises the use of the extraction arrangement to connect the lower pipe portion with the upper pipe portion.

5. The method according to any preceding claim, characterized in that it comprises providing an overlapping section of pipe, wherein the connection of the lower pipe portion with the upper pipe portion comprises overlapping the overlapping section of pipe on a portion of the upper pipe portion and / or the lower pipe portion.

6. A subsea foundation system for deployment below sea level, comprising: a subsea foundation; an upper pipe portion connected to the subsea foundation; and a lower pipe portion connected to the subsea foundation in a nested position, wherein the subsea foundation system is positioned such that, below sea level, the lower pipe portion can be released from the nested position and connected to the upper pipe portion.

7. The underwater foundation system according to claim 6, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the underwater foundation.

8. The underwater foundation system according to claim 6 or 7, characterized in that the fitted position is a position in which the lower pipe portion is coupled with the outside of the underwater foundation and the lower pipe portion does not protrude beyond the bottom of the underwater foundation.

9. The underwater foundation system according to claim 6, 7 or 8, characterized in that the lower pipe portion pQcznn / zznz / E / YiAi is connected to a withdrawal arrangement and wherein the underwater foundation system is positioned such that, below sea level, the lower pipe portion can be connected to the upper pipe portion using the withdrawal arrangement.

10. The underwater foundation system according to any of claims 6-9, characterized in that it comprises a pipe overlapping section, wherein the pipe overlapping section is positioned to overlap a portion of the upper pipe section and / or the lower pipe section when the lower pipe portion is connected to the upper pipe section.

11. The underwater foundation system according to any of claims 6-10, characterized in that it comprises a pipe connection guide for guiding the connection between the upper pipe portion and the lower pipe portion.

12. A method for connecting a lower pipeline portion to a subsea foundation, comprising: providing a subsea foundation and an upper pipeline portion connected to the subsea foundation, connecting the lower pipeline portion to a withdrawal arrangement; deploying the subsea foundation below sea level with the lower pipeline portion connected to the withdrawal arrangement; and connecting the lower pipeline portion to the upper pipeline portion below sea level using the withdrawal arrangement.

13. The method according to claim 12, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the underwater foundation.

14. The method according to claim 12 or 13, characterized in that it comprises: connecting the lower pipe portion to the subsea foundation in a nested position; deploying the subsea foundation below sea level with the lower pipe portion in the nested position; and releasing the lower pipe portion from the nested position below sea level.

15. The method according to claim 12, 13 or 14, characterized in that the extraction arrangement comprises two extraction lines that are connected at one end to the underwater foundation and at the other end to the lower pipe portion.

16. The method according to any of claims 12-15, characterized in that it comprises providing a pipe overlap section, wherein the connection of the lower pipe portion with the upper pipe portion comprises overlapping the pipe overlap section on a portion of the upper pipe portion and / or the lower pipe portion.

17. A subsea foundation system for deployment below sea level, characterized in that the subsea foundation comprises: a subsea foundation; an upper pipe portion connected to the subsea foundation; and a lower pipe portion connected to a withdrawal arrangement, wherein the subsea foundation system is positioned such that, below sea level, the lower pipe portion can be connected to the upper pipe portion using the withdrawal arrangement.

18. The underwater foundation system according to claim 17, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the underwater foundation.

19. The underwater foundation system according to claim 17 or 18, characterized in that the extraction arrangement comprises two extraction lines that are connected at one end to the underwater foundation and at the other end to the lower pipe portion.

20. The underwater foundation system according to claim 17, 18 or 19, characterized in that the lower pipe portion is connected to the underwater foundation in a wedged position and wherein the underwater foundation system is positioned such that, below sea level, the lower pipe portion can be released from the wedged position.

21. The underwater foundation system according to any of claims 17-20, characterized in that it comprises a pipe overlapping section, wherein the pipe overlapping section is positioned to overlap a portion of the upper pipe section and / or the lower pipe section when the lower pipe portion is connected to the upper pQcznn / zznz / E / YiAi pipe section.

22. The underwater foundation system according to any of claims 17-21, characterized in that it comprises a pipe connection guide for guiding the connection between the upper pipe portion and the lower pipe portion.

23. A method of connecting a lower pipe portion to a subsea foundation, comprising: providing the subsea foundation comprising an upper pipe portion connected to the subsea foundation; providing a lower pipe portion and a pipe overlap section; and connecting the lower pipe portion to the upper pipe portion such that the pipe overlap section overlaps a portion of the upper pipe portion and / or the lower pipe portion.

24. The method according to claim 23, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the underwater foundation.

25. The method according to claim 23 or 24, characterized in that it comprises: connecting the lower pipe portion to the underwater foundation in a wedged position; deploying the underwater foundation below sea level with the lower pipe portion in the wedged position; and releasing the lower pipe portion from the wedged position below sea level.

26. The method according to claim 23, 24 or 25, characterized in that it comprises: connecting the lower pipe portion with a extraction arrangement and then, the underwater foundation is deployed below the sea level with the lower pipe portion connected with the extraction arrangement, wherein the connection of the lower pipe portion with the upper pipe portion comprises the use of the extraction arrangement to connect the lower pipe portion with the upper pipe portion.

27. The method according to any of claims 23-26, characterized in that the pipe overlapping section is fixed on the lower pipe portion and overlaps a portion of the upper pipe portion when the lower pipe portion is connected with the upper pipe portion.

28. A subsea foundation system, comprising: a subsea foundation; an upper pipe portion connected to the subsea foundation; a lower pipe portion; and a pipe overlap section, wherein the pipe overlap section is positioned to overlap a portion of the upper pipe portion and / or the lower pipe portion when the lower pipe portion is connected to the upper pipe portion.

29. The underwater foundation system according to claim 28, characterized in that the upper pipe portion does not protrude beyond the bottom of the underwater foundation and wherein, when the lower pipe portion is connected to the upper pipe portion, at least part of the lower pipe portion protrudes beyond the bottom of the underwater foundation.

30. The subsea foundation system according to claim 28 or 29, characterized in that the subsea foundation is for deployment below sea level, wherein a lower pipe portion is connected to the subsea foundation in a wedged position and wherein the subsea foundation system is positioned such that, below sea level, the lower pipe portion can be released from the wedged position.

31. The underwater foundation system according to claim 28, 29 or 30, characterized in that the lower pipe portion is connected to a withdrawal arrangement and wherein the underwater foundation system is positioned such that, below sea level, the lower pipe portion can be connected to the upper pipe portion using the withdrawal arrangement.

32. The underwater foundation system according to any of claims 28-31, characterized in that the pipe overlapping section is fixed on the lower pipe portion and overlaps a portion of the upper pipe portion when the lower pipe portion is connected to the upper pipe portion.

33. The method or system of underwater foundation according to any preceding claim, characterized in that the underwater foundation comprises a pQcznn / zznz / E / YiAi suction anchor.