AU2018241087A1 - Improvements in or relating to anchors - Google Patents

Abstract

Abstract There is disclosed an anchor for use in a subsea environment. In at least one embodiment, the anchor comprises a body having a portion configured capable of supporting, at least in part, a device. The anchor further comprises a guard means associated with the body and configured so that a portion of the guard means is provided more distal of the body than a portion of the device. In this manner, the arrangement seeks to reduce a risk of the portion of the device becoming subject to interference during handling of the anchor. In another embodiment, a method of use of the described anchor is also disclosed.

Description

[0001] In at least one embodiment, an anchor for use in a subsea environment is disclosed.

BACKGROUND [0002] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application, or patent cited in this text is not repeated herein is merely for reasons of conciseness.

[0003] In this specification, where a literary work, act or item of knowledge (or combinations thereof), is discussed, such reference is not an acknowledgment or admission that any of the information referred to formed part of the common general knowledge as at the priority date of the application. Such information is included only for the purposes of providing context for facilitating an understanding of the inventive concept/principles and the various forms or embodiments in which those inventive concept/principles may be exemplified.

[0004] Tethering arrangements/systems are often used for the tethering of subsea structures for the purpose of enhancing or augmenting the strength and/or fatigue performance of, for example, blowout preventers, wellheads, during subsea drilling, completion, and related operations. Tethering systems often require the provision of a suitable anchoring solution.

[0005] An existing anchoring solution is described in US 9,359,852 (US’852)

The anchoring solution described in US’852 requires the driving of large piles into the seabed so as to allow a portion of the pile to be provided slightly proud (and therefore exposed) of the seafloor. A ‘pile top’ assembly is then secured or affixed to this exposed portion of the pile and then used as a fastening point for an existing tethering system described in US’852.

-2PCT/AU2018/050223 [0006] Accordingly, it will be appreciated, at least by review of the system described in US’852 (where, for example, significant time and resource is required for installing the piles into the seabed), that deployment and operation of existing tethering systems can be time consuming, costly, and present significant safety issues for those involved in at least the deployment and/or installation of the anchors/tethering system.

[0007] Accordingly, solutions which endeavour to address and/or improve on any of the identified deficiencies in existing systems are always sought.

SUMMARY OF THE INVENTION [0008] According to a first principal aspect, there is provided an anchor for use in a subsea environment, the anchor comprising:

a body having a portion or region configured capable of supporting, at least in part, a device; and a guard means associated with the body and configured so that a portion of the guard means is provided more distal of the body than a portion of the device so as to reduce a risk of the portion of the device becoming subject to interference during handling of the anchor.

[0009] The above described principal aspect, and those described below, may comprise any of the following features.

[0010] For the purposes of the description and the following claims, the term “device” is intended to refer to any appropriate resource or equipment required for the application to hand. For example, for applications of a subsea nature, the device could comprise a tensioning system or tensioning assembly that is configured operable with one or more tethers, or tether arrangements. Non-exhaustive examples may include any of the following: hydraulic cylinders, airbags, pneumatic cylinders, chain gypsies, or other like/related equipment/machinery. For the purposes of exemplifying an embodiment of the subject anchor in the description herein, the device is a tensioning system configured operable with an end of a respective tether.

[0011] The tensioning system or assembly may comprise any device, apparatus, assembly, or system (mechanical (or otherwise)) that is configured so as to

-3PCT/AU2018/050223 be operably associable with an end or portion of a tether (or like component) for the purposes of being able to adjust any tension therein, and/or provide for the storage of a portion or length portion of the tether (or like component). In this manner, the tensioning system or assembly may comprise a winch drum about which the portion or length portion of the tether may be spooled.

[0012] Handling activities involving the anchor may include deployment and retrieval operations to/from subsea environments where the anchor unit has been in operational use. The skilled reader will appreciate that any relevant handling operation where the device could be compromised due to adverse contact may be comprise a relevant handling activity for present purposes.

[0013] For the purposes of the description and the following claims, the term “guard means” is intended to refer to any appropriate means, for example, structure or functional structure, dynamic or static in nature, that serves to operate, broadly, as a guard or fender arrangement to protect against interference of the device regardless of the orientation of the anchor (for example, during handling operations). The guard means is configured so as to provide a protective or fending structure that, at least in part, defines a protective zone (eg. protective envelope or profile) within which the device is provided and is generally safe from adverse interference/contact from external objects/structures. When a portion of the guard means makes contact with, or is contacted by a foreign object/surface/structure, the contacting surfaces of the guard means then operates as an interface (ie. interfacing with the counterpart contacting surface) which, at least in part, defines the protective zone within which the device is provided. In this instance, the device is recessed from the interface when defined and/or is recessed from the periphery of the protective zone or envelope provided prior to contact.

[0014] The guard means may be exemplified in some embodiments as a pair of skids like that used, for example, as landing gear for helicopters, whereby the skids are provided more distal of the body of the anchor than one or more portions of the underside of the body (for example, cabin assembly) of the helicopter. In the context of the embodiments described herein, the skids define, at least in part, a protective zone or envelope within which the device is provided.

-4PCT/AU2018/050223 [0015] In some embodiments, configuration of the guard means may come into advantageous practical effect during a number of required handling events, regardless of the orientation of the anchor when being handled. In this manner, for example, during the deployment (and the retrieval) process it is often not possible to control with sufficient precision the orientation of the anchor when seeking to load the anchor back aboard the relevant transportation vessel (for example, a marine vessel). Accordingly, the configuration of the guard means or guard elements serve to, at least in part, protect or fend for the device (for example, tensioning system) from making contact with a deck of the relevant transportation vessel during such an operation and risking damage occurring to the device. Thus, the potential for risk adverse contact occurring is reduced regardless of the orientation of the anchor when being deployed over side (or when being loaded back aboard). In this manner, no undue delay needs to be incurred during the loading process thereby allowing the recovery to be as efficient as possible (ie. reducing safety risks) in view of the prevailing circumstances.

[0016] Optionally, the guard means is configured so that a portion of the guard means is provided more distal of the body than a corresponding portion of the device so as to reduce a risk of the corresponding portion of the device becoming subject to interference during handling of the anchor.

[0017] Optionally, the guard means comprises a pair of guard elements arranged with the body and between which the device is supported or carried by the body.

[0018] Optionally, the guard elements are aligned so as to be substantially parallel to each other.

[0019] Optionally, the guard elements are arranged so as to be substantially symmetrical about a central axis of the body, the central axis of the body being aligned with a forward-aft (hereinafter, lengthwise) direction of the body or anchor.

[0020] Optionally, one or both guard elements define a periphery or peripheral edge provided more distal of the body then one or more portions of the device.

[0021] Optionally, the body comprises a number of generally rectangular plate elements configured in a stacked relationship.

-5PCT/AU2018/050223 [0022] Optionally, one or both guard elements comprise one or more flange portions having a width dimension aligned in a lateral direction of the body, the lateral direction of the body being orthogonal to the lengthwise direction of the body. In this manner, the lengthwise dimension of the or each flange portions is larger in magnitude than the width dimension of the or each flange portions.

[0023] Optionally, one or both guard elements may comprises upper and lower flange portions.

[0024] Optionally, a portion of one or both guard elements comprises a portion of one or more of the generally rectangular stacked plates.

[0025] Optionally, the body comprises a central plane which extends in the lengthwise direction of the body. In one arrangement, both guard elements are symmetrical about the central plane.

[0026] Optionally, a portion or region of the periphery or peripheral edge of one or both guard elements serves to function as a guard element (or, for example, a skid) during a handling operation. In such arrangements, and as noted above, relevant handling operations may include deployment/retrieval operations (of the anchor).

[0027] Optionally, both guard elements are arranged relative to the body in a substantially symmetrical manner about a central region of the body. In this manner, the symmetrical like arrangement facilitates, at least in part, reduced complexity during deployment/retrieval operations of the anchor.

[0028] Optionally, a first side of the body is configured so as to carry a portion of the device.

[0029] Optionally, a second side of the body is provided opposite the first side of the body.

[0030] Optionally, in a first orientation of the body, the first side of the body is or faces uppermost. In this manner, the device is provided in an operable orientation when the anchor is positioned on the seafloor such that the second side is adjacent or proximal the seafloor.

-6PCT/AU2018/050223 [0031] Optionally, a region of the body is configured for carrying a portion of the device, said region of the body being arranged to be substantially planar.

[0032] Optionally, the body of the anchor comprises first and second ends. In one arrangement, the first end corresponds with the forward most end of the body/anchor, and the second end corresponds with the aft most end of the body/anchor.

[0033] Optionally, a portion of the device is configured so as to be operable at or near one of the first or second ends of the body.

[0034] Optionally, the anchor comprises means for facilitating deployment and/or retrieval (hereinafter, deployment/retrieval means) of the anchor to/from a subsea environment. In one arrangement, the deployment/retrieval means is configured so as to be operable about a central region of the body of the anchor. In this manner, the symmetrical arrangement facilitates, at least in part, reduced complexity during deployment/retrieval operations of the anchor.

[0035] Optionally, the deployment/retrieval means comprises one or more annuli (such as, for example, one or more eyelets or padeye(s)), the or each annulus configured for operable association with one or more respective ropes or cables. Optionally, the annulus may be arranged or provided in pairs.

[0036] Optionally, the pairs of annuli or eyelets may be provided symmetric about the central axis of the body.

[0037] Optionally, the tether(s), rope(s) or cable(s) may be fibre rope.

[0038] Optionally, the deployment/retrieval means comprises one or more pairs of eyelets, the or each pair of eyelets being configured for operable association with one or more respective ropes or cables.

[0039] Optionally, a first pair of eyelets is provided at or near the first end of the body. Optionally, a second pair of eyelets is provided at or near the second end of the body.

-7PCT/AU2018/050223 [0040] Optionally, the deployment/retrieval means comprises two pairs of eyelets or padeyes for deployment purposes.

[0041] Optionally, the deployment/retrieval means comprises one pair of eyelets or padeyes for deployment purposes for retrieval purposes.

[0042] Optionally, the deployment/retrieval means and/or eyelets or padeyes may be used for moving (eg. lifting, lowering etc) the anchor to/from a transport vessel.

[0043] Optionally, the device is a tensioning system configured for operable association with a tether. Optionally, the tensioning system is configured so as to provide capacity for storing a length portion of the tether.

[0044] Optionally, the tensioning system comprises a first operative assembly, and a second operative assembly.

[0045] Optionally, the first operative assembly is provided at or near one of the first or second ends of the body.

[0046] Optionally, the first operative assembly comprises a winch drum provided at or near one of the first or second ends of the body.

[0047] Optionally, the first operative assembly comprises one or more winch mounting brackets configured so as to support, at least in part, the winch drum at or near one of the first or second ends of the body.

[0048] Optionally, the or each winch mounting brackets are connected to the body by way of an appropriate fastening system (such as, for example, a nut and bolt fastening system).

[0049] Optionally, a portion of the winch drum is configured so as to be engageable with a portion or region of one of the guard members. In one arrangement, a portion of the winch drum at or near an end of the winch drum is engaged with a portion or region of one of the guard members at or near an end thereof.

-8PCT/AU2018/050223 [0050] Optionally, a portion or region of one or both guard members is configured so as to be engageable with an end of the winch drum.

[0051] Optionally, an end of the winch drum is supported at a portion of one of the guard elements, at or near one of the ends of the body.

[0052] Optionally, the end of the winch drum is supported by way of a sleeve. In such an embodiment, the sleeve is attached to a face of a web which extends between the flanges of the relevant guard element.

[0053] Optionally, engagement between the end of the winch drum and the sleeve is at least supportive in nature, such that the end of the winch drum is, at least in part, supported or carried by the portion of the one of the guard member as appropriate.

[0054] Optionally, an axis of the winch drum is orthogonal to the lengthwise direction of the body. Optionally, the winch drum is arranged so as to rotate about its axis.

[0055] Optionally, the first operative assembly of the tensioning system comprises a ratchet drive and an associated drive pawl arrangement.

[0056] Optionally, the tensioning system comprises a locking mechanism operable for ceasing movement of the winch drum. In such an arrangement, the locking mechanism may be part of the first operative assembly of the tensioning system.

[0057] Optionally, the ratchet drive is provided concentric with the axis of the winch drum.

[0058] Optionally, the drive pawl is provided in operable association with the ratchet drive.

[0059] Optionally, the drive pawl is provided eccentric of the axis of the winch drum.

-9PCT/AU2018/050223 [0060] Optionally, the second operative assembly comprises an annulus or part thereof provided distal (hereinafter, distal annulus) of the winch drum. Optionally, the distal annulus is provided in the form of an eyelet.

[0061] Optionally, the distal annulus is provided at an end of a housing or cover portion which is arranged to provide, at least in part, a cover for a portion of a tether extending between the winch drum and the distal annulus of the second operative assembly.

[0062] Optionally, the first operative assembly comprises a winch pawl rod and associated handle configured so that the drive pawl can be operated.

[0063] Optionally, a region (hereinafter, spool region) of the winch drum is configured so as to allow a spool of material (such as, for example, a spool of a substantially flexible material such as a length portion of a tether) to be carried/stored by the winch drum.

[0064] Optionally, a dimension of the spool region is determined such that an internal angle of an apex created by converging lines extending from opposite ends of the spool region to the distal annulus is not greater than about 10 degrees.

[0065] Optionally, the dimension of the spool region (relative to the axis of the winch drum is, at least in part, determined such that a first angle (for example, a fleet angle) of an apex created by converging first and second lines which extend from respective ends of the spool region to the distal annulus is not greater than about 10 degrees. In this embodiment, the first angle is the addition of a second angle, and a third angle, the second and third angles being formed at the intersection of respective first and second lines with a line which is aligned substantially with the central axis of the body. Optionally, the latter described arrangement is configured so that the second and third angles are each not greater than about 5 degrees.

[0066] Optionally, a central region of the spool region corresponds with a central region of the body. In one arrangement, the spool arrangement is configured so as to allow sufficient capacity of length of the tether so as to allow for acceptable operation of the tensioning system. Optionally, the arrangement of spool region and the distal annulus is configured or arrangement so as to limit the fleet angle to ensure proper

- 10PCT/AU2018/050223 spooling of a portion or portion of the length of the tether material (such as for example, fibre rope, cable, wire or the like) on the winch drum.

[0067] Optionally, the housing or cover portion of the second operative assembly comprises a shape which tapers substantially toward the distal annulus (or eyelet) of the second operative assembly.

[0068] Optionally, the housing or cover portion is connected to the body by way of any appropriate connecting or fastening assembly.

[0069] Optionally, the tensioning system could comprise any tensioning system configured for operation with the anchor.

[0070] Optionally, the body is configured such that the anchor is portable. In this manner, the body is configured such that the anchor can be easily transportable by road, marine vessel, or train.

[0071] Optionally, the anchor comprises a corrosion protection system to protect against corrosion. Optionally, the corrosion protection system comprises a cathodic protection arrangement.

[0072] According to another principal aspect, there is provided a method of deploying, retrieving, or operating an embodiment of an anchor arranged in accordance with the anchor of the first principal aspect, or as described herein.

[0073] According to a third principal aspect, there is provided a method of deploying an embodiment of an anchor arranged in accordance with the anchor of the first principal aspect, or as described herein, into a subsea environment.

[0074] Optionally, the method comprises providing an embodiment of an anchor arranged or configured in accordance with the anchor of the first principal aspect, or as described herein.

[0075] Optionally, the method comprises preparing the anchor for deployment from a surface of a transportation vessel, such as for example, a marine vessel, or the like.

-11 PCT/AU2018/050223 [0076] Optionally, the method comprises attaching a first end of a first support line at or near an end of the anchor, and a second end is attached to an operable unit (such as for example a winch). In one arrangement, the winch may be operable with a length of Dyneema® rope (a length of, for example, about 45m).

[0077] Optionally, the first end of the first support line has a portion providing more than one free end, each free end being attachable to a respective portion of the anchor. In one embodiment, the first end of the first support line has a portion providing two free ends, each free end being attachable to respective portions of the anchor, whereby, optionally, each of said portions of the anchor are symmetrical about the central axis of the body of the anchor.

[0078] Optionally, the method comprises providing a second support line having first and second free ends. The first end of the second support line is attached to the anchor, and the second end is attached to the operable unit.

[0079] Optionally, the first free end of the second support line comprises a portion providing four free ends, each end being attachable to a respective portion of the anchor, whereby, optionally, each of said portions of the anchor are symmetrical about a central axis of the anchor, or are provided at or near a respective corner of the anchor, or the body of the anchor.

[0080] Optionally, the method comprises causing the anchor to be moved overboard whereby the anchor is supported primarily by the first support line.

[0081] Optionally, the method comprises transitioning the support of the anchor from the first support line to the second support line. In this arrangement, the anchor becomes primarily supported by way of the second support line.

[0082] Optionally, the method comprises lowering of the anchor toward the seabed by way of the second support line.

[0083] Optionally, the method comprises lowering of the anchor toward the seabed by way of the first support line.

-12PCT/AU2018/050223 [0084] According to a fourth principal aspect, there is provided a method of retrieving an embodiment of an anchor arranged in accordance with the anchor of the first principal aspect, or as described herein, from a subsea environment.

[0085] Optionally, the method comprises confirming that the anchor is attached to an operative means by way of a first support line. In this manner, the first end of the first support line is attached at or near an end of the anchor, and the second end is attached to the operable unit.

[0086] Optionally, the first end of the first support line has a portion providing more than one free end, each free end being attachable to a respective portion of the anchor. In one embodiment, the first end of the first support line has a portion providing two free ends, each free end being attachable to respective portions of the anchor.

[0087] Optionally, each of said portions of the anchor are symmetrical about a longitudinal axis of the body of the anchor.

[0088] Optionally, the first support line is tensioned so as to raise or lift the end of the anchor at or near where the two free ends of the first support line are attached. In this manner, the initial tensioning of the first support line serves to assist in reducing a suction force which can sometimes be present between the underside of the anchor and the seafloor. Optionally, this initial tensioning action could be undertaken in an iterative manner until the suction force is reduced sufficiently so as to begin raising or lifting the anchor in earnest.

[0089] Optionally, the method comprises raising the anchor to the surface of the water by way of the first support line.

[0090] Optionally, the raising the anchor to the surface of the water could be by way of the second line.

[0091] Optionally, the method comprises causing the anchor to be moved onboard the transportation vessel by way of the first support line, regardless of the orientation of the anchor as it nears the surface of the water, or as it nears any edge of the transportation vessel.

- 13PCT/AU2018/050223 [0092] According to a further principal aspect, there is provided a method of operating an embodiment of an anchor operably configured in accordance with any of the principal aspects and/or as described herein, the method comprising:

causing the device provided with or carried by the anchor to operate or become operable.

[0093] Optionally, the method may comprise causing any action or activity relevant for the proper operation of the device provided with or carried by the anchor.

[0094] Optionally, causing the device provided with or carried by the anchor to operate is achieved by way of a remotely operated means, such as for example a remotely operated vehicle (ROV).

[0095] Optionally, the device provided with or carried by the anchor is a tensioning system operable for use in adjusting a tether operably associated therewith.

[0096] Optionally, the method comprises causing the tensioning system to be operable for the purpose of tensioning the associated tether. For example, the method may comprise adjusting the tether so as to remove or reduce any slack or catenary in the tether.

[0097] Optionally, the method comprises causing a locking mechanism of the tensioning system to be released so as to allow a length portion of the tether stowed by the tensioning assembly to become releasable. In this manner, the ROV can be operated so as to pull out a length of the tether, for example, so a free end thereof may be connected to an adjacent lying structure (such as for example a blowout preventer).

[0098] Optionally, operation of the tensioning system is by causing the ROV to manipulate a winch pawl rod handle associated with the tensioning assembly.

[0099] Optionally, the method comprises causing the tensioning system to be operated so as to remove or reduce any slack or catenary in tether. In one embodiment, this action is undertaken by the ROV at the anchor.

- 14PCT/AU2018/050223 [00100] Optionally, the method comprises causing to be tensioned, or to be further tensioned, the relevant tether by working the end of the tether not associated with the tensioning assembly.

[00101] Optionally, in one embodiment, the end of the tether not associated with the tensioning assembly is associated instead with an operable means provided, for example, with the well head or with the blow out preventer. In one arrangement, the operative means is a hydraulic cylinder that is operable by way of an interface unit. The interface is provided in operable association with the hydraulic cylinder by way of a fluid circuit, whereby interaction with the interface serves to cause the hydraulic cylinder to become operable. Optionally, interaction with the interface in a predetermined manner, serves to cause the hydraulic cylinder to become operable so as to operate in a known or designated way, such as for example, to operate so as to tension the associated tether, and/or operate so as to reduce or remove any tension existing in the relevant tether.

[00102] In one embodiment, operation of the device of the anchor unit is part of an overarching method for installing a tethering system for use with a blowout preventer used with a wellhead, whereby the tension in a tether is adjusted by way of a multi stage tether adjustment method in which a further or subsequent adjustments of the tether is comparatively less than that of an initial adjustment of the tether. In this manner, the initial adjustment serves as a ‘course’ adjustment of the tether, and at least one further adjustment of the tether serves as a ‘fine’ adjustment.

[00103] According to a further principal aspect, there is provided a tethering system comprising at least one embodiment of an anchor arranged in accordance with the anchor of the first principal aspect, or as described herein.

[00104] According to a further principal aspect, there is provided a tethering system comprising at least one embodiment of an anchor arranged in accordance with any of the principal aspects and/or embodiments described herein.

[00105] According to a further principal aspect, there is provided a method comprising operably configuring an embodiment of an anchor (existing or otherwise) so as to accord with the any of the principal aspects, or embodiments described herein.

- 15PCT/AU2018/050223 [00106] Optionally, the anchor so configured in accordance with the present method is an existing gravity anchor.

[00107] Optionally, configuring an embodiment of an anchor according to any of the principal aspects and/or embodiments described herein comprises modifying the embodiment of an anchor according to any of the principal aspects and/or embodiments described herein.

[00108] Various principal aspects described herein can be practiced alone or combination with one or more of the other principal aspects, as will be readily appreciated by those skilled in the relevant art. The various principal aspects can optionally be provided in combination with one or more of the optional features described in relation to the other principal aspects. Furthermore, optional features described in relation to one example (or embodiment) can optionally be combined alone or together with other features in different examples or embodiments.

[00109] For the purposes of summarising the principal aspects of the present invention, certain aspects, advantages and novel features have been described herein above. It is to be understood, however, that not necessarily all such advantages may be achieved in accordance with any particular embodiment or carried out in a manner that achieves or optimises one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS [00110] Further features of the present invention are more fully described in the following description of at least one non-limiting embodiment thereof. This description is included solely for the purposes of exemplifying the principles described herein. The description herein should not be understood as being a restriction on the broad summary, disclosure, or description set out herein. The description will be made with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of one arrangement of a tethering system operationally associated with a subsea blowout preventer;

Figure 2 shows a perspective view of one embodiment of an anchor configured in accordance with the principles described herein;

- 16PCT/AU2018/050223

Figure 3 shows an end view of the embodiment of the anchor shown in Figure 2;

Figure 4 shows an elevation view of the embodiment of the anchor shown in Figures 2 to 3;

Figure 5 shows a plan view of the embodiment of the anchor shown in Figures 2 to 4;

Figure 6 shows a section view of region A shown in Figure 5;

Figure 7 shows a perspective view of the embodiment of the anchor shown in Figures 2 to 7 showing deployment lines (also used for retrieval);

Figure 8 shows a perspective view of the embodiment of the anchor shown in Figures 2 to 7, illustrating the fleet angle;

Figure 9A shows a first stage in a deployment process whereby the embodiment of the anchor shown in Figures 2 to 6 is deployed for operational use in a subsea environment;

Figure 9B shows a second stage in deployment process initiated by the stage shown in Figure 9A;

Figure 9C shows a third stage in deployment process initiated by the stage shown in Figure 9A;

Figure 9D shows a fourth stage in deployment process initiated by the stage shown in Figure 9A;

Figure 10A shows a first stage of one example installation process whereby the embodiment of the anchor shown in Figures 2 to 7 is installed for operational use with a blow-out preventer (BOP) in a subsea environment;

Figure 10B shows a second stage in the example installation process initiated by the stage shown in Figure 10A;

-17PCT/AU2018/050223

Figure 10C shows a third stage in the example installation process initiated by the stage shown in Figure 10A;

Figure 10D shows a fourth stage in the example installation process initiated by the stage shown in Figure 10A;

Figure 11 shows a perspective view of a further arrangement of a tethering system operationally associated with a subsea blowout preventer; and

Figure 12 shows a perspective view of another arrangement of a tethering system operationally associated with a subsea blowout preventer.

[00111] In the figures, like elements are referred to by like numerals throughout the views provided. The skilled reader will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to facilitate an understanding of the various embodiments exemplifying the principles described herein. Also, common but well understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to provide a less obstructed view of these various embodiments. It will also be understood that the terms and expressions used herein adopt the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.

[00112] It should be noted that the figures are schematic only and the location and disposition of the components can vary according to the particular arrangements of the embodiment(s) as well as of the particular applications of such embodiment(s).

[00113] Specifically, reference to positional descriptions, such as ‘lower’ and ‘upper’, and associated forms such as ‘uppermost’ and ‘lowermost’, are to be taken in context of the embodiments shown in the figures, and are not to be taken as limiting the scope of the principles described herein to the literal interpretation of the term, but rather as would be understood by the skilled reader.

[00114] Embodiments described herein may include one or more range of values (eg. size, displacement and field strength etc). A range of values will be understood to

- 18PCT/AU2018/050223 include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which defines the boundary to the range.

[00115] Other definitions for selected terms used herein may be found within the detailed description and apply throughout. Unless otherwise defined, all other scientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the embodiment(s) relate.

DETAILED DESCRIPTION [00116] The words used in the specification are words of description rather than limitation, and it is to be understood that various changes may be made without departing from the spirit and scope of any aspect of the invention. Those skilled in the art will readily appreciate that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the spirit and scope of any aspect of the invention, and that such modifications, alterations, and combinations are to be viewed as falling within the ambit of the inventive concept.

[00117] Throughout the specification and the claims that follow, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00118] Furthermore, throughout the specification and the claims that follow, unless the context requires otherwise, the word “include” or variations such as “includes” or “including”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00119] Figure 1 shows a tethering arrangement 5 provided operable with a subsea blowout preventer (hereinafter, BOP 10). Broadly, the tethering arrangement 5 shown in Figure 1 comprises a number of anchors 15 (four shown) arranged in operable association with the BOP 10 by way of respective tethers 20 (such as for example, fibre ropes). As the skilled reader will readily understand, the tethering arrangement 5 serves the general purpose of enhancing or augmenting the strength and/or fatigue performance of the BOP 10 during, for example, a completion operation.

- 19PCT/AU2018/050223 [00120] The embodiment of each of the anchors 15 shown in Figure 1 is of the gravity type, or often referred to in the technical field as a ‘clump weight’. Rather than using a conventional pile type anchor, which requires a lengthy portion of the pile anchor to be driven into the seabed, the tethering arrangement 5 exploits the convenience (in cost and/or installation time, depending on the prevailing circumstances) in using the self-weight of each anchor 15 to secure the anchor to the seafloor.

[00121] Figure 2 shows a close up perspective view of the embodiment of the anchor 15 shown in Figure 1. Broadly, the embodiment of the anchor 15 in Figure 2 comprises a body 25 having a portion or region 28 thereof configured capable of supporting or carrying a device (such as, for example, a tensioning system 30 which is operably associated with a tether 20 connected to the BOP 10); and a guard means having a pair of guard elements 35A, 35B. In the embodiment shown, the guard means is provided in the form of a pair of skids 36A, 36B (collectively, 36). In the embodiment shown, the skids 36 is associated with the body 25 and configured so that a portion of each skid 36 are provided more distal of the body 25 than one or more portions of the device (in the instance shown, the tensioning system 30). In this manner, any risk of the tensioning system 30 becoming subject to interference during handling (which may, for example, include deployment/retrieval of the anchor 15 into/from a subsea environment from the deck of a (floating) marine vessel) of the anchor is sought to be reduced.

[00122] As noted above, the term “device” is intended to refer to any appropriate resource or equipment required for the application at hand. For the purposes of the description herein, the device comprises the tensioning system 30 which is configured operable with a tether 20. It will be appreciated by the skilled reader that the device could be exemplified by any other like/related equipment/machinery, such as for example, hydraulic cylinders, airbags, pneumatic cylinders, chain gypsies, and the like.

[00123] In its simplest form the body 25 comprises a number of generally rectangular plates 18A, 18B, 18C, and 18D (collectively, plates 18) configured in a stacked relationship, and which make up the general profile of the body. As is shown in Figures 2, 6, 7, and 8, opposing sides of the body 25 provide support for respective skids 36A. 36B.

-20PCT/AU2018/050223 [00124] In the embodiment shown in Figure 2, each skid 36 comprises a pair of contact faces 40A, 40C (upper/lower contact faces of skid 36A), 40B, 40D (upper/lower contact faces of skid 36B) (collectively, 40) respectively and arranged with the body 25 and between which the tensioning system 30 can be supported or carried by the body. The contact faces 40 are aligned so as to be substantially parallel to each other and, in the embodiment shown, arranged so as to be substantially symmetrical about a central axis X of the body 25. Furthermore, as shown in Figure 4, the contact faces 40 are arranged so as to be substantially symmetric about a plane P (which extends through the body 25 at about mid-height of the skids 36).

[00125] Contact faces 40A, 40B provide the outer facing surfaces of upper flange portions 45A, 45B, one or more portions of which are provided more distal of the body 25 than at least one or more of the operational components (see discussion below) of the tethering system 30 (see Figure 3). Lower contact faces 40C (see Figure 4), 40D (see Figure 2) are provided by way of the lower most facing surface (with respect to the orientation shown) of the lower most plate 18A.

[00126] Curved flanges 44A, 44B, 44C, and 44D (including flanges 47A and 47B) are provided in a web-flange like construction and are connected to respective skids 36A, 36B as shown. Flange portions 45A, 45B each have a width dimension which is aligned in a lateral direction of the body (ie. the lateral direction being substantially transverse to the central axis X of the body 25). In this manner, the lateral direction is orthogonal to a lengthwise dimension (being aligned with the forward-aft direction of the body/anchor) of the body 25. As clearly shown in Figure 2, the lengthwise dimension of each flange portion 45 is larger in magnitude than its respect width dimension.

[00127] In substance, the outer facing surfaces of the skids 36A, 36B serve to function, at least in part, as protective guards or fenders during handling operations of the anchor 15, such as for example, deployment/retrieval of the anchor to/from a subsea environment. In at least one respect, the symmetrical nature/configuration of the skids 36A, 36B relative to the body 25 about the central axis X, and about mid-plane P, facilitates, at least in part, reduced complexity of handling of the anchor 15 during deployment/retrieval operations. In this regard, the risk of adverse interference occurring to the tensioning system 30 such as, for example, damaging the tensioning

-21 PCT/AU2018/050223 system when retrieving the anchor back onto the deck of a marine vessel is sought to be reduced (ie. when the anchor is pulled aboard upside down, for example). In this manner, during the retrieval process it is often not possible to control with sufficient precision the orientation of the anchor 15 when seeking to load the anchor back aboard the relevant marine vessel. Accordingly, the configuration of the skids 36A, 36B serve to, at least in part, protect the tensioning system 30 from making contact with the deck during such an operation (and therefore seeking to reduce the risk of damage occurring to the tensioning system).

[00128] With further reference to Figure 2, a first side 50 of the anchor 15 is configured so that the portion or region 28 thereof is capable of carrying a portion of the tensioning system 30. A second side 55 of the body 25 is provided opposite the first side 50 of the body. In a first orientation of the body 25, the first side 50 of the body is or faces uppermost. In this manner, the tensioning system 30 is provided in an operable state when the anchor 15 is positioned on the seafloor such that its second side 55 is adjacent or proximal the seafloor.

[00129] The body 25 of the anchor 15 comprises first 65 and second 68 ends. As shown in Figure 2, a portion of the tensioning system 30 is configured so as to be operable near the first 65 end of the body 25. The tensioning system 30 comprises a first operative assembly 70, and a second operative assembly 75. The first operative assembly 70 comprises a winch drum 80 provided near the first 65 end of the body 25. The first operative assembly 70 further comprises winch mounting brackets 85A, 85B (see Figure 3) configured so as to support, at least in part, the winch drum 80 near the first 65 end of the body 25. The winch mounting brackets 85A, 85B are attached to the body 25 by way of an appropriate fastening system (such as, for example, a nut and bolt fastening system 90A, 90B as shown in Figure 3).

[00130] An end 95 of the winch drum 80 is supported at a portion of the skid 36A, near first end 65 of the body 25 by way of sleeve 100. As shown, sleeve 100 is attached to face 105 of web 110A which is bounded substantially by curved flange 44A of skid 36A (and flange elements 47A). Engagement between end 95 of the winch drum 80 and sleeve 100 is at least supportive in nature, such that end 95 is supported so that an axis A of the winch drum 80 is substantially orthogonal to axis X of the body

-22PCT/AU2018/050223

25. Similar construction is shown for skid 36B whereby web 110B is bounded substantially by curved flange 44B (and flange elements 47B).

[00131] The first operative assembly 70 of the tensioning system 30 comprises a ratchet drive 115 and an associated drive pawl arrangement 120. The ratchet drive 115 is provided concentric with the axis A of the winch drum 80, and the drive pawl 120 is provided eccentric of the axis A of the winch drum. As the skilled reader will appreciate, the drive pawl arrangement 120 is provided in operable association with the ratchet drive 115. The first operative assembly 70 further comprises a winch pawl rod 72 and associated handle 74 (see Figure 4) configured so that the drive pawl arrangement 120 can be operated as appropriate (eg. by way of a remotely operated vehicle (ROV)). The first operative assembly 70 also comprises a locking mechanism (not shown) which is arranged operable so as to cease movement (ie. rotational movement) of the winch drum 80.

[00132] The second operative assembly 75 comprises an annulus provided in the form of an eyelet 125 (shown in clearer detail in Figure 7) through which a portion of a respective tether 20 may pass, and which is provided generally distal of the winch drum 80. The eyelet 125 is provided at a free end of a cover 130 which is arranged to provide, at least in part, a cover for a portion of tether 20 extending between the winch drum 80 and passing through the eyelet 125. The arrangement of a spool region 135 (see discussion below) on the winch drum 80 with the eyelet 125 is configured so as to limit a fleet angle to ensure proper spooling of the tether/fibre rope on the winch drum 80 (discussed below). The cover portion 130 generally comprises an opening 132 through which a portion of the tether 20 passes (enroute to the eyelet 125), and further comprises a shape which tapers substantially toward the eyelet 125; the shape serving to assist in, if needed, focusing or converging the covered portion of the tether 20 toward the eyelet 125 (eg. if the tether becomes slack). The cover portion 130 is connected to the body 25 by way of any appropriate connecting or fastening assembly (eg. an appropriate nut/bolt fastening assembly), or welding process.

[00133] With regard to Figures 3 and 5, a region (hereinafter, spool region 135) of the winch drum 80 is configured so as to allow a spool of material (such as, for example, a spool of a substantially flexible material such as a portion of tether 20) to be carried/stored appropriately by the winch drum 80. An axial dimension of the spool

-23PCT/AU2018/050223 region 135 (relative to axis A of the winch drum 80) is, at least in part, determined such that an internal angle Θ of an apex A_p created by converging lines U, L₂ which extend from opposite ends of the spool region 135 to the eyelet 125 (which, as noted, is configured to limit the fleet angle to ensure proper spooling of the tether/fibre-rope) is not greater than about 10 degrees; this being the addition of angles <xi (preferably no greater than about 5 degrees in the embodiment shown in Figure 5) and a₂ (similarly, preferably no greater than about 5 degrees in the embodiment shown in Figure 5) formed at the intersection of lines Li, L₂ with centre line L_c (which aligns substantially with the axis X) respectively. The spool region 135 is configured so as to allow sufficient storage capacity of a portion of length of the tether 20 so as to allow for acceptable operation of the tensioning system 30.

[00134] The anchor 15 further comprises a half round section of pipe 53 which is associated with the body 45 for the purpose of preventing the tether from abrading on the edge of the body.

[00135] The body 25 is configured such that the anchor 15 is portable. In this manner, the body 25 is configured such that the anchor 15 can be easily transportable by ship, road, or train.

[00136] The anchor 15 comprises means for facilitating deployment and/or retrieval (hereinafter, deployment/retrieval means 140) of the anchor to/from a subsea environment. As shown in Figure 7, the deployment/retrieval means 140 is configured so as to be operable about a generally central region 145 of the body 25 of the anchor [00137] The deployment/retrieval means 140 comprises one or more annuli provided in the form of eyelets or pad-eyes and each configured for operable association with respective ropes or lines 158. As shown, a first pair of pad-eyes 155A, 155B are provided at or near the first 65 end of the body 25, and a second pair of padeyes 155C, 155D are provided at or near the second 68 end of the body. Figure 7 shows the general arrangement of the cables 158 when the anchor 15 is being deployed (as will be discussed below). In the arrangement shown, lines 158 serve to provide a four leg sling 162 (for deployment purposes).

-24PCT/AU2018/050223 [00138] The deployment/retrieval means 140 also provides a further pair of padeyes 163A, 163B which allows a two leg sling arrangement (reference 195 as shown in Figures 9A to 9D) to attach to the anchor for (a) initial deployment purposes (overboard from the deck of a marine vessel before transitioning to use of the four leg sling 162), and (b) retrieval purposes.

[00139] For example, Figures 9A-9D show various stages of the anchor 15 when being deployed from the aft deck 170 of a marine vessel 175 to the seafloor 180 of the seabed 185 (see Figures 10A-10D).

[00140] Figure 9A shows the anchor 15 sitting on the aft deck 170 of a marine vessel 175 ready for deployment. As shown, the anchor 15 is connected to a launch winch 190 mounted on the aft deck 170 by way of a primary line 192. Primary line 192 provides a two leg sling 195 arrangement at its end which connects with the anchor. The winch may be operable with a length of Dyneema® rope (a length of, for example, about 45m). Further, the four leg sling arrangement 162 formed by way of lines 158 is attached to a line 210 (not shown in Figures 9A or 9B, see Figures 9C and 9D).

[00141] At Figure 9B, the launch winch 190 is operated so as to feed out primary line 192 in the aft direction so that anchor 15 is moveable toward the aft most edge 200 of the aft deck 170. As will be clear from Figure 9B, further extension of the primary line 192 will allow the anchor 15 to be moveable overboard toward the water surface 205.

[00142] It is during this step (as well as the corresponding step when retrieving the anchor 15 from operation) that the configuration of the skids 36A, 36B comes into advantageous practical effect. In this manner, during the deployment (and retrieval) process it is often not possible to control with sufficient precision the orientation of the anchor 15 when held by the relevant support lines. Accordingly, the configuration of the skids 36A, 36B serve to, at least in part, protect the tensioning system 30 from making contact with the deck (or any of the sides of the marine vessel) during such an operation and risking damage occurring to the tensioning system. In the embodiment of the anchor 15 shown, the risk of adverse contact occurring is reduced regardless of the orientation of the anchor when being deployed over side, or when being loaded back aboard the marine vessel 175.

-25PCT/AU2018/050223 [00143] Figure 9C shows an advancement of the position of the anchor 15 from that shown in Figure 9B. As can be seen, the anchor 15 is now beyond the aft most edge 200 and is now provided in a substantially vertical orientation being supported by the two leg sling line 195 and line 192.

[00144] Figure 9D shows advancement of the orientation of the anchor 15 whereby cables 158 now deploy in the four leg sling 162 arrangement (consistent with that shown in Figure 7), and are supported by line 210. Line 210 is also operable by way of winch 190. At this point, the two leg sling line 195 is released thereby allowing the anchor 15 to be completely supported by way of the four leg sling 162 arrangement (by way of line 210). Thus, the support for the anchor 15 is therefore transitioned from the two leg sling line 195 (and line 192) to the four leg sling 162 arrangement. Continued ease of line 210 (by the winch 190) will cause the anchor 15 to be lowered toward the seafloor 180 in substantially the orientation shown in Figure 9D (and Figure 7). Buoyancy device 204 is also deployed.

[00145] The skilled person will appreciate that a number of techniques and associated rope/cable configurations could be developed for deployment/retrieval purposes. In effect, the scope of different configurations is vast given the advantage of the anchor 15 configuration not requiring a specific orientation (of the anchor) to be observed given the configuration of the skids 36 serving to protect the tensioning system 30.

[00146] In one embodiment, operation of the tensioning system 30 of the anchor 15 is part of an overarching method for installing a tethering system for use with, for example, a blowout preventer (used with a wellhead during completion operations). In this manner, tension in a tether is adjusted by way of a multi stage tether adjustment method in which an initial adjustment is made which serves as a ‘course’ adjustment of the tether, and at least one further adjustment of the tether serves as a ‘fine’ adjustment. Further or subsequent adjustments of the tether tend to be comparatively less than that of the initial or ‘fine’ adjustment of the tether.

[00147] Figures 10A-10D show various stages of one embodiment of an installation process where the anchor 15 is to be placed in operable association with a blowout preventer (BOP) 215. In practice, installation of the anchor 15 for operational use with the BOP 215 is assisted by a remote operated vehicle (ROV) 220 (which is

-26PCT/AU2018/050223 itself operated by personnel stationed remotely on the marine vessel 175). Operation of the tensioning system 30 of the anchor 15 by the ROV 220 is by way of manipulating the winch pawl rod handle 74. In this manner, the tensioning system 30 can be operated so as to assist in the adjustment of the tether 20 as appropriate.

[00148] Figure 10A shows the anchor 15 at a position prior to contact with the seafloor 180, and within the vicinity of the BOP 215. The BOP 215 is arranged so as to be provided with a number of hydraulic tensioning cylinders 230 (four in the arrangement shown) that can be controlled by a control panel 232 that is also provided with the BOP 215. The tether 20 associated with each anchor 15 will be placed in operable association with a respective tension cylinder 230 provided at the BOP 215.

[00149] Prior to contact with the seafloor 180 the ROV 220 is operated so as to align the orientation of the anchor 15 as appropriate. Generally, the anchor 15 is aligned so that its second 68 end faces the tensioning cylinder 230 that it is to be arranged in operation with. Once done, the anchor 15 is lowered to the seafloor 180 and secured in position by way of its self-weight.

[00150] With reference to Figure 10B, once the anchor 15 is resting on the seafloor 180 (following deployment from the vessel 175), the ROV 220 is operated so as to release the locking mechanism of the tensioning system 30 so as to allow the pulling out of a free end 222 of the tether 20 (by the ROV) for attachment to an end of a cylinder rod 234 of a respective pre-installed tensioning cylinder 230.

[00151] With regard now to Figure 10C, once all the tethers 20 (of all respective anchors 15) have been connected to respective tension cylinders 230, the ROV 220 is operated so as to remove or reduce any slack or catenary in the respective tethers 20 by powering the tensioning system 30 on the respective anchors 15. Winch motivation is applied by the ROV 220 with the interface being by way of a standard ROV torque bucket. In practice, this adjustment represents, in effect, a ‘course’ adjustment of the tether where it is reasonably expected that large amounts of slack or catenary in the tether will be reduced or removed.

[00152] Turning now to Figure 10D, with each of the tensioning systems 30 of the anchors 15 having been operated to remove or reduce any slack or catenary in the respective tethers 20, the ROV 220 is then moved to the tensioning cylinder control

-27PCT/AU2018/050223 panel 232 from which (via the hot-stab port in the control panel 232) the ROV 220 can be operated so as to retract the tension cylinders 230 so as to apply the required pretension. In the embodiment described herein, the required pre-tension is about 5,000 kgf. This subsequent adjustment represents, in effect, a ‘fine’ adjustment of the tether 20 where it is reasonably expected that comparatively small amounts, in comparison with the ‘course’ adjustment, of length of the tether will be reduced or removed.

[00153] The method of retrieval of the anchor 15 from the subsea environment involves, broadly, using the two leg sling line 195 by way of line 192. In this manner, the two leg sling line 195 (by way of line 192) is tensioned so as to raise or lift the end of the anchor 15 where the two free ends of the two leg sling line 195 are attached. Initial tensioning of the two leg sling line 195 serves to assist in reducing a suction force which can sometimes be present between the underside of the anchor 15 and the seafloor. This initial tensioning action could be undertaken in an iterative manner until the suction force is reduced sufficiently so as to begin raising or lifting the anchor 15 in earnest.

[00154] The anchor 15 is then raised toward the water’s surface and above as appropriate by way of the two leg sling line 195 using primary line 192. As discussed herein, during this time, no substantive consideration needs to be had to the specific orientation of the anchor 15 as it is hoisted about edge 200 (which is the point at which contact/interference with the tensioning system 25 is most likely to occur if the anchor is hoisted in an upside down orientation) given the configuration of the skids 36. In effect, the anchor 15 can be retrieved or recovered even if upside down without incurring damage.

[00155] Thus, an advantage of the configuration of the anchor 15 is seen in that the skids 36 serve to assist in reducing the risk that any adverse interference or contact will impact on the tensioning system 30 when the anchor is retrieved back onto the deck 170 of the marine vessel 175, regardless of the orientation of the anchor 15 during the raising/hoisting process. In this manner, little, if any, undue delay needs to be incurred during the loading process thereby allowing the recovery to be as efficient as possible (ie. reducing safety risks) in view of the prevailing circumstances.

[00156] A number of methods could be realised which comprise operably configuring (modifying or otherwise) an embodiment of an anchor (existing or otherwise) so as to embody the principles described herein. The skilled reader will appreciate that

-28PCT/AU2018/050223 any such anchor so configured could include an existing gravity anchor which is arranged so as to exemplify the principles described herein.

[00157] The skilled reader will appreciate that the embodiment of the anchor 15 described herein may be configured (which could comprise an appropriate modification) for operational use with an existing tethering system. Furthermore, a tethering system (existing or otherwise) may be comprised of one or more of the embodiments of the anchor 15 described herein.

[00158] A number of methods could be realised which comprise operably configuring (modifying or otherwise) an embodiment of a tethering system (existing or otherwise) so as to embody the principles described herein.

[00159] Figures 11 and 12 both show different embodiments of tethering systems 400 and 500 where, primarily, further embodiments of anchor units are shown but which exemplify the principles described herein. Figure 11 shows tethering system 400 employing 4 x anchor units 410 tethered to a BOP 420 by way of respective tethers 430. Figure 12 shows tethering system 500 employing 4 x anchor units 510 tethered to a BOP 520 by way of respective tethers 530. The skilled reader would readily appreciate different ways in which the principles of the anchor 15 could be exemplified in other embodiments or forms.

[00160] The skilled reader would readily appreciate the nature of the materials appropriate for making the embodiment described herein. Materials such as stainless steel, having an appropriate self-weight and/or corrosive avoiding components would find ready application. Other materials, or methods for modifying such materials, could be employed for application.

[00161] Future patent applications maybe filed in Australia or overseas on the basis of, or claiming priority from, the present application. It is to be understood that the following claims are provided by way of example only, and are not intended to limit the scope of what may be claimed in any such future application. Features may be added to or omitted from the provisional claims at a later date so as to further define or redefine the invention or inventions.

PCT/AU2018/050223

Claims (19)

1. The claims defining the invention are as follows:

   1. An anchor for use in a subsea environment, the anchor comprising:

   a body having a portion or region configured capable of supporting, at least in part, a device; and a guard means associated with the body and configured so that a portion of the guard means is provided more distal of the body than a portion of the device so as io reduce a risk of the portion of the device becoming subject to Interference during handling of the anchor.
2. 2. An anchor according to claim 1, wherein the guard means comprises a pair of guard elements arranged with the body and between which the device can be provided or carried by the body.
3. 3. An anchor according to claim 1 or claim 2, wherein the anchor comprises a means for facilitating deployment and/or retrievai of the anchor to/from a subsea environment, said means configured so as to be operable about a central region of the body of the anchor.
4. 4. An anchor according to any one of the preceding claims, wherein the device is a tensioning system configured for operable association with a tether.
5. 5. An anchor according to claim 4, wherein the tensioning system comprises a first operative assembly, and a second operative assembly, the first operative assembly being provided at or near one of the first or second ends of the body.
6. 6. An anchor according to claim 5, wherein the first operative assembly comprises a winch drum provided at or near one of the first or second ends of the body.
7. 7. An anchor according to claim 5 or claim 6, wherein the first operative assembly comprises one or more winch mounting brackets configured so as to support, at least in part, the winch drum at or near one of the first or second ends of the body.

   -30PCT/AU2018/050223
8. 8. An anchor according to any one of the preceding claims 'when dependent on claim 6, wherein a portion of the winch drum is configured so as to be engageable with a portion or region of one of the guard members.
9. 9. An anchor according to any one of the preceding claims when dependent on claim 5, wherein the first operative assembly of the tensioning system comprises a ratchet drive and an associated drive pawi arrangement.
10. 10. An anchor according to any one of the preceding claims when dependent on claim

    4, wherein the tensioning system comprises a locking mechanism operable for ceasing movement of the winch drum.
11. 11. An anchor according to any one of the preceding claims when dependent on claim

    5, wherein the second operative assembly comprises an annulus or part thereof provided distal of the winch drum.
12. 12. An anchor according to any one of the preceding claims when dependent on claim

    6, wherein a region of the winch drum is configured so as to allow a spool of a portion (or portion of length) of the tether material to be carried/stored by the winch drum.
13. 13. An anchor according to claim 12. wherein the arrangement of the region and the distal annulus is configured or arranged so as to limit a fleet angle to ensure proper spooling of the portion (or portion of length) of the tether material on the winch drum.
14. 14. A method of deploying, retrieving, or operating an anchor of any one of the preceding claims.
15. 15. A method of deploying an anchor arranged in accordance with the anchor of any one of claims 1 to 13, into a subsea environment.
16. 16. A method of retrieving an anchor arranged in accordance with the anchor of any one of claims 1 to 13, from a subsea environment.

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17. 17. A method of operating an anchor operably configured in accordance with the anchor of any one of claims 1 to 13, the method comprising:

    causing the device provided with or carried by the anchor to operate or become operable.
18. 18. A tethering system comprising at least an anchor arranged in accordance with the anchor of any one of claims 1 to 13.
19. 19. A method comprising operably configuring an embodiment of an anchor (existing or otherwise) so as to accord with the anchor of any one of claims 1 to 13.