Method of and apparatus for installation of plate anchors

Methods and apparatus are disclosed for deploying one or more plate anchors on the seafloor prior to later installation (embedment) of the plate anchors using an installation tool such as a suction follower. The methods and apparatus may be used for batch-setting multiple plate anchors on the seafloor for a drilling vessel mooring in which the plate anchors and an installation tool are subsequently engaged for subsequent suction embedment of the plate anchors to design penetration depth.

FIELD OF THE INVENTION

This invention relates generally to mooring systems and methods for drilling vessels.

BACKGROUND

The method of installation for the direct-embedment plate anchor know in the industry as the SEPLA™ anchor (Suction Embedded Plate Anchor) uses a modified suction pile (i.e. suction follower) as the installation tool in order to insert (install) the anchor to its design penetration depth in the seafloor (ref. U.S. Pat. Nos. 5,992,060 and 6,122,847). Using conventional SEPLA anchor installation methodology, the suction follower is lowered from the sea surface with a single plate anchor loaded on the suction follower for installation. The suction follower is then recovered to the sea surface after seafloor installation of the anchor, and the next plate anchor to be installed is then loaded on the suction follower which is then lowered again from the sea surface. This process is repeated for installation of each separate plate anchor. Thus, total installation time for a set of multiple plate anchors includes the time required for recovering the suction follower and again lowering it for installation of each separate anchor.

It is known in a first operation to vertically lower multiple piles or conductor pipes into the water and down to self-weight penetration depth at designated locations in the seafloor, and then in a following second operation to lower a hammer apparatus into the water and to use the hammer apparatus to drive each of the multiple piles or conductor pipes to grade without recovering the hammer apparatus above the water surface until all of the multiple piles or conductor pipes have been driven to grade by the hammer apparatus.

SUMMARY OF THE INVENTION

Disclosed herein are methods of and apparatus for installation of plate anchors for drilling vessels such as drillships and mobile offshore drilling units (MODUs). The disclosed methods and apparatus may be implemented in one exemplary embodiment to provide for multiple plate anchors to be set out on the seafloor prior to the single deployment of the suction follower, e.g., all of the drilling vessels plate anchors for a drilling vessel may be set out on the seafloor prior to the single deployment of the suction follower. Once the suction follower is deployed to depth from an installation vessel, it may be employed to sequentially dock to the separate batch-set plate anchors and embed each to its design penetration depth. In one exemplary embodiment, the follower is only raised above the seafloor (aka seabed) a nominal distance (and not to the sea surface) before moving to the next plate anchor location while the follower is suspended from the installation vessel on its lowering line. Once the multiple anchor embedment process is completed, the suction follower may then be recovered to the installation vessel.

The disclosed methods and apparatus may be implemented in one exemplary embodiment to achieve a reduction in installation time, and enhanced competitiveness, over conventional plate anchor installation methods and apparatus. In this regard, such advantages over conventional methods and apparatus result in one embodiment from the relatively easy process of setting out the plate anchors without the use of the suction follower and from the ability to only deploy and recover the suction follower once to install a full complement of multiple anchors for a drilling vessel. Although advantageously employed for installing multiple plate anchors in a batch set manner, it will be understood that the disclosed methods and apparatus may also be employed to install a single plate anchor in a similar fashion.

In one exemplary embodiment multiple plate anchors may be first set out using a relatively smaller anchor handling vessel that is conventionally employed to carry both plate anchors and suction followers together for the conventional installation of the multiple plate anchors with the suction follower. This may be useful, for example, in a situation where a larger anchor handling vessel is not available. In this embodiment, a smaller vessel may be used that is not capable of carrying the multiple plate anchors together with the suction follower, but is less costly to operate than a relatively larger vessel that is capable of carrying both the multiple plate anchors and the suction followers together. In such an embodiment, once the multiple anchors have been set out by the vessel, it may return to port and load out a suction follower and return to the installation site to deploy the suction follower for installation (embedment) of the multiple plate anchors that have previously been set out on the seafloor by the same vessel.

In another exemplary embodiment, multiple plate anchors may be coupled together to form a linked anchor assembly that allows all of the multiple anchors to lowered together into the water for deployment in one operation. In one embodiment, adjacent pairs of multiple plate anchors of such a linked anchor assembly may be coupled together using anchor connection links that are configured to be uncoupled underwater (e.g., by a remote operated vehicle “ROV”) so as to allow individual anchors to be detached one at a time from the anchor link assembly so that the individual anchors may be placed in separate different locations on the seafloor from each other. Advantageously, such a linked anchor assembly may be assembled from two or more separate anchors on the deck of an anchor installation or handling vessel, and then all of the assembled anchors lowered together over the side (as one linked anchor assembly) in one operation. Individual anchors may then be sequentially decoupled from the other assembled anchors underwater and deployed in separate different locations on the seafloor. Such decoupling of all the separate anchors of the linked anchor assembly may be accomplished in one embodiment without again raising the anchor link assembly to the sea surface, e.g., the linked anchor assembly may only be raised above the seafloor a nominal distance (and not to the sea surface) before moving to the next location for plate anchor deployment while the linked anchor assembly is suspended from the installation vessel on its lowering line. Thus, in one exemplary embodiment, multiple plate anchors may be batch-set on the seafloor in a first operation without again raising the linked anchor assembly to the surface of the water, followed by deployment of a suction follower (as described elsewhere herein) in a second operation to sequentially dock to the separate batch-set plate anchors and embed each to its design penetration depth before again raising the suction follower to the sea surface.

In another exemplary embodiment, multiple plate anchors may be first set out using a relatively smaller anchor handling vessel such as described above that is not capable of carrying a suction follower but which is less costly to operate than a relatively larger vessel that is capable of carrying both the multiple plate anchors and the suction followers together. In such an embodiment, once the multiple anchors have been set out by the smaller vessel, a relatively larger anchor handling vessel capable of carrying a suction follower may then be used to deploy a suction follower for installation (embedment) of the multiple plate anchors that have previously been set out on the seafloor by the smaller vessel.

In one respect, disclosed herein is a method for installing one or more plate anchors in a seafloor underlying a body of water, including: first deploying at least one plate anchor on the seafloor, the plate anchor including an anchor section; then deploying a suction follower into the body of water into a position suspended above the seafloor; then docking the deployed plate anchor to the suction follower, and lowering the suction follower with the docked plate anchor to embed the docked plate anchor into the seafloor; and then raising the suction follower above the seafloor to undock the embedded first anchor assembly from the suction follower.

In another respect, disclosed herein is a suction follower including an elongated follower body with a proximal end and a distal end. The suction follower may further include: an anchor docking feature provided at the distal end of the suction follower, the anchor docking feature being configured to at least partially receive a plate anchor in a docked embedding position; and an integral anchor retrieval mechanism configured to retrieve the plate anchor into the docked embedding position with the docking feature of the suction follower.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1shows a typical Anchor Handling Vessel (AHV)100with a full complement of dual shank plate anchors101on deck configured for multiple (i.e., batch-set) installation in lieu of the conventional one-at-a-time method. Also illustrated as being present for this exemplary embodiment are the mooring pendant103and the recovery pendants102. The pendants may be composed of synthetic fibers manufactured such that they are positively buoyant and can resist the abrasion associated with being immersed and pulled through the seafloor soils; they are known in the industry as mud ropes. Also shown are typical deck winches106that may be used in this embodiment to pull a plate anchor aft over the stern roller107. The plate anchor to be deployed may be connected to the AHV's100aft anchor winch108via workwire104and a J-hook105to pendant line103.FIG. 2shows the anchor101being deployed over the stern roller107by deck winches106while being stabilized with backtension from the aft anchor winch108. As shown, anchor101is suspended by its shanks152by mooring pendant103with fluke150oriented facing downwards. Mooring pendant103is coupled to an eyelet (padeye) provided at the top of shank152, and recovery pendants102may be coupled to the keying flap153prior to deployment of each anchor101as shown. Although a plate anchor having dual solid steel shanks152is illustrated, it will be understood that the disclosed methods and apparatus may be employed to install other types of plate anchors including, but not limited to, plate anchors having a single (mono) steel shank152, plate anchors having bridle-type shank/s, etc.

FIGS. 3A and 3Bshow the plate anchor101being placed on the seafloor109by the AHV100, e.g., after confirming the location is correct. InFIG. 3A, plate anchor101has been further lowered into the water by the AHV to a distance of about 100 feet above seafloor109. As shown inFIG. 3B, plate anchor101has been further lowered into the water by the AHV so that the flat surface of fluke150of plate anchor101is placed on seafloor109with shank152oriented upwards and keying flap153extending horizontally outward in substantially parallel relationship with seafloor109. In this embodiment, the ROV110disconnects the pendant103from the J-hook105on the workwire104as shown inFIG. 3B. Also shown inFIG. 3Aare other plate anchors101that have been previously lowered from AHV100and placed on the seafloor109in a similar manner as the current plate anchor101. As shown, recovery pendants102are floating, as are mooring pendants103of each plate anchor101.

InFIG. 4A, the workwire104is recovered back to the AHV100and the ROV110deploys the recovery pendants102from their previously coiled configuration as shown inFIG. 4B. In one embodiment, a Yale grip125may be provided on the recovery pendant102for the purpose of pulling the plate anchor101into the suction follower111's slot194while allowing the floating free ends of the recovery pendants to remain clear of the seafloor109. Note that the Yale grip125on the recovery pendants is not visible in the coiled condition.

FIG. 5shows another exemplary embodiment of an AHV100with a full complement of eight dual shank plate anchors101on deck ready for batch-set installation using a method that includes linking the multiple anchors together and lowering them all together into the water as a linked anchor assembly. In the alternative embodiment ofFIG. 5, similarly numbered components of AHV100may be of the configuration and type as described in relation toFIG. 1. Moreover, the same type and configuration of recovery pendants102and mooring pendant103may be attached to each anchor101as were employed in the embodiment ofFIGS. 1-4. However, recovery pendants102and mooring pendant103may be utilized in a different manner in the embodiment ofFIGS. 5-10to provide a linked anchor assembly to allow the multiple anchors101to be lowered into the water together in one lowering operation. In this regard, mooring pendant103may be again coupled to an eyelet (padeye) provided at the top of shank152of each anchor101, and recovery pendants102may be coupled to the keying flap153of each anchor101prior to deployment as shown. However, in this embodiment, the two recovery pendants102are attached to a first anchor101aand extended in an outstretched side-by-side manner on the deck as shown, while mooring pendant103that is attached to the first anchor101aremains coiled up or otherwise stowed during anchor deployment. As with other embodiments, although plate anchors101having dual solid steel shanks152are illustrated, it will be understood that the disclosed methods and apparatus may be employed to install other types of plate anchors including, but not limited to, plate anchors having a single (mono) steel shank152, plate anchors having bridle-type shank/s, etc. Moreover, although eight anchors101are illustrated inFIGS. 5-10, it will be understood that the number of linked anchors that may be deployed together in the manner ofFIGS. 5-10may be greater or lesser than eight.

FIG. 6illustrates how first plate anchor101amay be moved aft (in this case onto stern roller107) using deck winches106in order to make room to move a second plate anchor101bfrom its stowed position into an assembly position between first plate anchor101aand winch108. As shown, the outstretched recovery pendants102of first plate anchor101amay be coupled between the keying flap153of first plate anchor101aand the fluke150of second plate anchor101bto form a linked anchor assembly of at least two plate anchors101that may be deployed together in one operation from AHV100. As further shown, second plate anchor101bmay in turn be connected to the aft anchor winch108of AHV100by J-hook105(not shown) on the workwire104to provide backtension for stabilizing the linked anchors during their assembly. Additional anchors (e.g., in this case the remaining six plate anchors101on deck of AHV100) may be added to the linked anchor assembly in a similar manner using additional pairs of recovery pendants102.

It will be understood, however, that it is possible that other types of anchor connection links other than recovery pendants102may be employed to coupled together adjacent pairs of plate anchors101for use in the practice of the disclosed systems and methods. Examples of other types of anchor interconnection links include, but are not limited to, mooring pendants103coupled between the shank and fluke underside of adjacent pairs of anchors101(e.g., in which case recovery pendants102may be coiled up during lowering of the linked anchor assembly toward the seafloor), dedicated anchor linkage cables or lines that extend between any suitable portion of adjacent pairs of anchors101that allow each anchor101to be separately attached and deployed on the seafloor in a manner described elsewhere herein (e.g., in which case recovery pendants102and mooring pendants103may each be coiled up during lowering of the linked anchor assembly toward the seafloor), any other suitable mechanical connection link (e.g., non-flexible, hinged, swiveling, etc.), etc. In any case, as described elsewhere herein, anchor interconnection links may be configured to be detachable as appropriate (e.g., on one end or both end as needed) from anchors101of a linked anchor assembly, e.g., using a remote operated vehicle (ROV) in order to deploy anchors101on the seafloor.

As shown inFIG. 7, the partially assembled linked anchor assembly may be lowered (e.g., one anchor at a time) over stern roller107into the water to create additional deck space for adding each additional anchor101in similar manner to the linked assembly. In this regard,FIG. 7shows first anchor101abeing deployed over the stern roller107while the remainder of the linked anchor assembly (including second anchor101band its recovery pendants102) is stabilized by raising the vessel's tow pins200such that the fluke of the anchor101bears on tow pins200. As shown, first anchor101ais suspended by its keying flap153by recovery pendants102. When connecting additional anchors101to the linked anchor assembly, the tow pins200may be used to hold the partially-deployed linked anchor assembly in place when it is disconnected from aft winch108to allow an additional anchor101to be added to the linked anchor assembly on deck. Alternatively, temporary pendants may be attached between the keying flap153connection points and secure points on the work deck in order to support the linked anchors101during deployment.

FIG. 8Ashows a completely assembled linked anchor assembly800of eight anchors that has been deployed into the water from AHV100. As shown, all eight stowed anchors101ofFIG. 5have now been added to the linked anchor assembly in a manner as described above. In the illustrated configuration ofFIG. 8A, linked anchor assembly800includes plate anchors101ato101hthat are linked together by respective recovery pendants102and suspended from AHV100by J-hook105and work wire104. InFIG. 8A, linked anchor assembly800has been lowered into the water from AHV100using aft winch108to a distance of about 500 feet above seafloor109or other suitable distance. As further shown, anchor101ais the terminal (end) anchor of the linked anchor assembly800, and is therefore in queue to be the first anchor to be deployed on the seafloor.FIG. 8Billustrates a detailed view of anchor101bof linked anchor assembly800.

FIGS. 9A and 9Bshow first plate anchor101abeing placed on the seafloor109by the AHV100, e.g., after confirming the location is correct. InFIG. 9A, linked anchor assembly800has been further lowered into the water by the AHV to a distance of about 100 feet above seafloor109. As shown inFIG. 9B, linked anchor assembly800has been further lowered into the water by the AHV100so that the flat surface of fluke150of plate anchor101ais placed on seafloor109with shank152oriented upwards and keying flap153extending horizontally outward in substantially parallel relationship with seafloor109. In this embodiment, the ROV110approaches and disconnects the recovery pendants102from fluke150of second anchor101b.

InFIG. 10A, the workwire104is raised from the seafloor with the remainder of linked-together anchors101b-101htoward AHV100and moved to the next desired location for placement on the seafloor109of the next (second) anchor101b, which may in one embodiment be done without again raising the linked anchor assembly800to the surface of the water, e.g., the linked anchor assembly800may only be raised above the seafloor109by a nominal distance (and not to the sea surface) before moving to the next location for plate anchor deployment while the linked anchor assembly800is suspended from the AHV100on work wire104. In this way individual anchors101may be sequentially decoupled from each other underwater and deployed in separate different locations on the seafloor, and in one embodiment without again raising the anchor link assembly800to the sea surface.

Referring to bothFIGS. 10A and 10B, ROV110approaches and deploys the mooring pendant103of first anchor101afrom its previously coiled configuration. As shown, recovery pendants102are floating, as are mooring pendants103of each plate anchor101. As before, a Yale grip125may be provided on the recovery pendants102for the purpose of pulling the plate anchor101into the suction follower111's slot194while allowing the floating free ends of the recovery pendants to remain clear of the seafloor109. InFIG. 10A, the next anchor (second plate anchor101b) is now the terminal or end anchor of the linked anchor assembly, and is thus the next anchor101in queued position for detachment and deployment. Thus, it will be understood that the process ofFIGS. 9-10may be repeated for each successive terminal linked anchor101b-101hof linked anchor assembly800until all anchors101of assembly800have been deployed by AHV100in the desired spaced relationship from each other on seafloor109. It will be understood, however, that not all anchors101of assembly800need ultimately be deployed, e.g., in a case where anchor deployment plans change during the anchor deployment operation, where mechanical problems or weather require termination of the anchor deployment operation, etc.

FIGS. 11-24illustrate an exemplary embodiment for rigging, deployment and use of a suction follower111to embed one or more anchors101that have been previously placed on the seafloor109, e.g., in one of the manners described above, or using any other technique suitable for placing one or more anchors101on the seafloor109. Thus, the methodology described and illustrated in relation toFIGS. 11-24may be employed to use a suction follower111to sequentially install each of multiple anchors101that have been placed on the seafloor109using any suitable methodology, e.g., such as either the methodology ofFIGS. 1-4or the methodology ofFIGS. 5-10.

FIG. 11illustrates the rigging configuration of the suction follower111according to one exemplary embodiment. In this embodiment, the follower111will be deployed over the stern roller107in a controlled manner. The follower111is pulled aft by lines113and126connected to the forward tow drum112B and forward deck winch118, respectively in this embodiment. The aft deck winches106are connected to pullback hooks120on lines113and126near the follower111top end. Other rigging illustrated are the so-called hip slings114connected to the forward tow drum112A via line116and the spreader bar arrangement115. In this embodiment, the recovery line117is connected to a proximal end (top)190of the follower111via a bridle arrangement; the bitter end on the line is wound on the aft anchor winch108.FIG. 12shows an elevation view of the rigging arrangement. Once the rigging is ready and the AHV100is over the target location, the seafastenings to the follower111are removed.

FIGS. 13A and 13Bshow the initial steps to deploy the follower wherein lines113and126are tensioned to pull the follower111aft while recovery line117provides backtension to ensure controlled movement of the follower111. The hip slings114are kept taut in anticipation of resisting the vertical load component of the follow as it tips over the stern roller107. Once the center of gravity of the follower111is aft of the stern roller107and the follower111rotates, the pullback hooks120are tripped by deck winches106, releasing the pullback lines113and126.FIG. 14shows an elevation view of the follower111being deployed over the stern roller107in an early stage of the process.FIG. 15shows the deployment as the follower angle reaches approximately 35 deg and the hip slings start to resist the dead load of the follower111.FIG. 16shows the follower111between 45 deg and 90 deg when the hip slings become fully taut at about 60 deg. In the final stage shown inFIG. 17, the AHV's100dynamic positioning system (DP) is shut down aft to reduce propeller wash effects on the follower111and the lowering line117slackened to rotate the follower111to approximately 98 deg while maintaining follower111stickup above the stern roller107at approximately 30% of the follower's111length. Next, lines117and114are paid out simultaneously lowering the follower111past the stern roller107; as the follower top passes the stern roller107, all the load is transferred to the hip slings114. After the lowering line bridle on line117is completely submerged, the load is slowly transferred to the lowering line117in full. Lowering continues until the follower top is approximately 50 ft below the stern roller107or other suitable clearance distance below the stern roller107.

With all of the follower111load on the lowering line117as shown inFIGS. 18A and 18B, the hip slings114are slacked off and disconnected from the spreader bar115and connected to the quad plate119. As shown inFIGS. 19A and 19B, the AHV100lowers the follower111until it is approximately 100 ft or other suitable distance above the seafloor109and near the plate anchor101to be embedded. While AHV100maintains position, the ROV110confirms the orientation of the follower111is correct, e.g., by observing orientation lines on top of follower111. Once the final location of follower111is determined and the orientation of follower111is confirmed, the follower111is lowered until it embeds in the seafloor109a sufficient distance to stop rotating about its longitudinal axis (e.g., about 2 ft or other suitable distance) as shown inFIGS. 20A and 20B. At this time the follower111is approximately 50 ft or other suitable distance from the plate anchor101. The two circle hooks121are deployed from their storage positions on the follower top190and are positioned in the lower guides123by the ROV110.

FIG. 21shows the ROV110connecting the Yale grips125on the floating recovery pendants102(two each in this exemplary embodiment) to the circle hooks121. The circle hooks121are connected to the ends of the integral follower top winches191via the winch lines122(e.g., wires or other suitable type of retrieval line). In one embodiment, two top winches191may be provided at the proximal (top) end of follower111to actuate the two winch lines122that are present on opposing sides of follower111, although a single dual-line winch may be alternatively employed to support two such winch lines122.FIG. 21illustrates a side view of a suction follower111having two such top winches191aand191bdisposed on its proximal end.

As described further herein, two such winch lines122may be coupled (e.g., by ROV110) to two respective recovery pendants102that are in turn attached to spaced-apart coupling points155located near the respective opposing ends of keying flap153of a given plate anchor101. The spacing between the keying flap coupling points155may be at least as wide as the outer diameter of the suction follower111in the plane formed between docking slots194where the docking slots194intersect suction follower111, and the overall width (side to side) of the keying flap may be wider then the outside diameter of the suction follower111in the plane formed between docking slots194where the docking slots194intersect suction follower111. In such a configuration, the winch lines122may be used to simultaneously retrieve the two recovery pendants102coupled near opposing sides of the keying flap153of a given plate anchor101(e.g., such as the plate anchor101illustrated inFIG. 1) so that the plate anchor101may be accordingly retrieved simultaneously by its two recovery pendants102in proper docking orientation (fluke side down) into the anchor docking slots194on the distal end of follower111, e.g., with keying flap153oriented upward toward the sea (water's) surface and with keying flap153oriented in a position within the docking slots194such that the suction follower111is disposed between (e.g., substantially centered between) the coupling points155and corresponding recovery pendants102.

In another possible alternative embodiment, at least one top winch191may be provided on proximal end190of a suction follower111, and configured to lower and retrieve at least one interior winch line through a closed top of the suction follower111, e.g., down through and along the central axis of the interior of the suction follower111. A stuffing box seal or other seal mechanism may be provided to maintain pressure integrity and hydraulic seal at the point where the interior winch line penetrates the top of the suction follower while the interior winch line moves up and down within the suction follower111. In this embodiment, the interior winch line may be lowered through the interior of the suction follower111and attached to a recovery pendant102that itself is coupled at a point at substantially the center of the width of the keying flap153of a plate anchor101such that the plate anchor101may be retrieved by the interior winch line upwards into substantially centered docking engagement with the distal end of the suction follower111.

In one embodiment, one or more top winches191may be hydraulically powered with hot-stab capability, although any other suitable type of winches (e.g., electric winches) may be employed. As shown, optional winch line guides123may be present to keep the winch lines122in the correct orientation for easy passage of the circle hooks121. In this exemplary embodiment, the circle hooks121, winch lines122, winch line guides123and top winches191together form an integral anchor retrieval mechanism, it being understood that an anchor retrieval mechanism may include any other configuration of one or more components (integral or non-integral to a follower111) that are suitable for retrieving and/or reorienting a submerged anchor from a position resting on the seafloor into docked arrangement with a follower111such as further illustrated an described herein. As shown inFIG. 22, the integral follower top winches191tension the winch wires122, thereby pulling the plate anchor101towards the distal end (bottom)192of the follower111. As the plate anchor101approaches the follower111, the follower is raised off the seafloor109by the by the aft anchor winch108using the recovery line117as shown inFIG. 23.

In this embodiment, the ROV110uses a combination hotstab and flying lead124to provide hydraulic power to the follower top winches191although any other technique and/or mechanism for providing suitable anchor retrieval power may be employed including, for example, self-powered integral electric winches, non-integral (e.g., ROV-mounted or sea-surface vessel-mounted) winches, etc. When integral to follower111, it will be understood that actuators need not be positioned on or near the proximal (top) end of the follower, but may be location otherwise, e.g., such as adjacent the top of anchor docking slots194(in which case winch line guides123may not be required). Moreover, other types of integral or non-integral actuators may be employed for tensioning or retrieving wires122including, for example, hydraulic cylinders integral with follower111, etc.

In the illustrated exemplary embodiment ofFIG. 23, a docking feature is provided in the form of two anchor docking slots194that are defined in opposing sides of hollow distal end192of follower111. In this embodiment, the anchor docking slots194are configured with dimensions and size that are complementary to the outer dimensions and size of keying flap153and fluke150of plate anchor101so as to allow the opposing anchor docking slots to cooperate to receive the keying flap153in an aligned position as shown. In this regard, orientation of anchor101rotates by about 90 degrees as it is retrieved due to the location of recovery pendants102at the outboard edge of keying flap153and the positioning of the bottom set of winch line guides123adjacent and aligned with the docking slots194of follower111. This rotation of anchor101places the primary plane of fluke150and keying flap153in a substantially vertically oriented position that aligns with docking slots194to allow keying flap153to be received in docking slots194such that anchor101is at least partially received in the hollow distal end of follower111in a docked embedding position, i.e., a position that is suitable for operably embedding plate anchor111into seafloor109with suction follower111. As the winch wires122pull the anchor101into a docking feature of the suction follower111, the ROV110may assist in assuring the rigging isn't fouled and the anchor101fully slots into the opposing docking slots194of the follower111to dock the anchor101at or near the distal end (penetrating end) of the follower111in a docked position suitable for embedding plate anchor111into seafloor109in a manner as will be further described herein. The ROV110may make a full inspection of the anchor101and rigging at this time after stowing the flying lead124to the follower top winches.

It will be understood that the illustrated opposing docking slots194are just one exemplary embodiment of an anchor docking feature that may be provided on the distal end192of a follower111for retaining a plate anchor101in relation to distal end192of follower111in a position suitable for facilitating embedment of the plate anchor101into a seafloor109by the follower111. An example of another possible type or configuration of anchor docking feature includes, but is not limited to, an anchor support structure (e.g., manufactured of tubular plate or other suitable material/s) that is attached to the distal end192of the follower111in lieu of the docking slots193. Such a structure may be so provided in any form suitable for supporting a plate anchor in a docked engagement with the distal end of a suction follower while the distal end of the suction follower is suspended in a position above the seafloor, lowered to the seafloor, and during anchor embedment operations.

InFIGS. 24A and 24Bthe AHV100is shown moved to the anchor's target location. While AHV100maintains position, and after confirmation by the ROV110that the follower111is in the correct orientation, the follower111is lowered distal end first until it reaches self-weight penetration depth in the seafloor109with the docked anchor101embedded into the seafloor109as shown. From this stage onward, conventional methods of suction embedment, anchor release and extraction and raising of the suction follower from the seafloor and anchor keying may be implemented so as to undock the embedded anchor assembly from the suction follower to leave the undocked first anchor assembly embedded in the sea floor. This may be accomplished, for example, by first using internal water overpressure in the suction follower followed by tension on the recovery line. Further information on suction follower and anchor configuration, anchor embedment, anchor release, and suction follower extraction may be found described in U.S. Pat. Nos. 5,992,060 and 6,122,847, each of which is incorporated herein by reference in its entirety. This procedure is sequentially repeated for each of the remaining multiple anchors to be installed followed by recovery of the suction follower111onto the AHV100. It will be understood that all of the multiple anchors101may be so sequentially installed in a batch manner by the suction follower111without retrieving the follower into the AHV100or above the sea surface. AlthoughFIG. 24illustrates a total of three plate anchors101, i.e., one embedded plate anchor101docked with a suction follower111and two nearby plate anchors101set out on the seafloor109waiting to dock to and be embedded by the suction follower111, it will be understood that any number of plate anchors (e.g., eight plate anchors101, twelve plate anchors101, more than ten plate anchors, etc.) may be set out on the sea floor and then sequentially embedded by a common suspended suction follower111before again retrieving the suction follower111above the sea surface until all plate anchors101have been installed (embedded).