EP3368723B1

EP3368723B1 - Offshore apparatus and method

Info

Publication number: EP3368723B1
Application number: EP16815708.9A
Authority: EP
Inventors: Michael Kannegaard; John Anthony GILL; Jeanne Mia LØNSTRUP; Meinte VAN DER BRUG
Original assignee: Maersk Drilling AS
Current assignee: Noble Drilling AS
Priority date: 2015-10-29
Filing date: 2016-10-31
Publication date: 2022-05-18
Anticipated expiration: 2036-10-31
Also published as: EP3368723A2; WO2017071711A2; DK3368723T3; WO2017071711A3

Description

FIELD

The present invention relates to offshore apparatus and methods, for example for use in the exploration and extraction of mineral resources from subterranean reservoirs.

BACKGROUND

In the offshore oil and gas industry wellbores are drilled below the seabed using specialised drilling platforms or vessels, known colloquially as drilling "rigs". Multiple types of drilling rig exist, such as fixed platforms, jack-up rigs, mobile offshore drilling units (MODUs), semi-submersibles, drilling ships and the like. The particular type of rig used can depend on a number of factors, such as water depth, rig availability, expected longevity of the associated reservoir, and the like.
Once a well has been drilled and appraised, it will be completed with the appropriate downhole infrastructure to permit production (and/or injection), and then capped at the wellhead with a production tree, known as a X-mas tree. Such completion operations may be achieved from the same drilling rig, or may be achieved using a different service rig. Further, during the life of the well it may be necessary to perform workover or intervention operations, which again could be supported by the drilling rig, or alternatively with a different service or workover rig.
The production tree may be located on a subsea wellhead, with a tie back to a surface production facility. In alternative arrangements the tree may be located at surface, on a surface or wellhead platform. Multiple wellbores will typically be present, such that a cluster of trees are provided on the wellhead platform.
Surface tree systems will typically require rigs, such as drilling rigs, service rigs, workover rigs and the like to operate alongside the wellhead platform. For example, portions, such as cantilever portions, of a rig may extend over the wellhead platform. Like in all offshore operations, safety is paramount, and risk to personnel, the environment and equipment must be minimised. In many circumstances there is a risk of objects being dropped from height, for example between separate decks of a wellhead platform, or indeed from a rig operating alongside a wellhead platform. For safety reasons some operators may establish no-entry zones for personnel, for example in defined drop zones, such as below a rig cantilever portion. This may restrict or delay certain operations which cannot otherwise be performed while the rig cantilever portion is in position, or while inter-deck operations are being performed. Also, irrespective of personnel access, there will always be a risk of damage to equipment, such as production trees, from dropped objects and the like. This may be compounded by the close proximity of equipment in tree clusters on the production platform.
US 4 703 813 A (SIELER ) discloses an apparatus and method useful in offshore well drilling operations for cleaning the annular space between mudline suspension risers during and after cementing operations.
WO 2014/108542 (KANNEGAARD ) discloses an offshore drilling rig comprising a drill floor deck having a hole defining a first well centre. The drilling rig further comprises a first hoisting system configured for hoisting and lowering tubular equipment through the first well centre. The drilling rig comprises a support structure and a mounting structure, separate from the first hoisting system, for suspending suspendable equipment from an elevated position above the drill floor deck.

SUMMARY

An aspect or embodiment relates to an offshore platform for use in combination with an offshore rig, according to the appended claims.
In use, any objects passing, for example intentionally passing and/or accidentally passing (i.e., dropped), from the offshore rig may be confined within the confinement zone defined by the sheath arrangement. Such confinement provided by the sheath arrangement may thus minimise or eliminate the extent of a drop zone on the upper deck. This may provide a number of advantages. For example, the risk to personnel may be reduced, and may permit personnel to perform operations on the upper deck while the offshore rig is extended over the upper deck. Further, the risk of damage to equipment may be reduced, such as the risk of damage to wellheads and associated equipment (such as production trees) accommodated on the offshore platform.
In normal operations objects may extend form the offshore rig, through the upper deck of the offshore platform, to perform operations associated with the installation, intervention and/or decommissioning of an offshore well. Objects passing from the offshore rig may include tubing, conductor pipe, casing strings, liners, risers, drill strings, bottom hole assemblies, completion equipment, intervention equipment, tools and the like. While many objects may be intentionally passed, in some instances objects may be dropped from the offshore rig, such as tools, equipment and the like, and as noted above, the sheath arrangement assists to minimise risk from such dropped objects.
The offshore rig may define a drilling rig. The offshore rig may be operable adjacent, for example alongside, the offshore platform. The offshore rig may comprise a cantilever portion which is extendable over the offshore platform. The cantilever portion may comprise the rig aperture. The cantilever portion may comprise a BOP (Blow Out Preventor) enclosure.
The offshore rig may define a service rig, workover rig or the like.
The offshore rig may define a drill centre, wherein operations supported by the offshore rig, such as drilling, running equipment and the like, are provided along the drill centre. Accordingly, the rig aperture is provided on the drill centre. The offshore rig may be positioned over the offshore platform such that the drill centre is aligned with the upper deck aperture.
Although the term "drill centre" is used, this is not intended to be limited only to drilling operations, or indeed to limit the rig to a drilling rig.
The offshore platform may define a wellhead platform. In such an arrangement the offshore platform may accommodate a terminating end of one or more surface wells, along with associated equipment, such as wellheads, production trees and the like.
Generally, a wellhead platform is a structure or structures, which support the upper end (opposite of the reservoir) of the well including any superstructures, one or more well processing stations or similar. Such a wellhead platform is typically a structure (such as a jacket based or gravity based platform) resting on the seabed ranging from very basic configurations to complex facilities. The offshore wellhead platform may comprise one or more well-processing stations. Alternatively, the offshore wellhead platform does not comprise any well-processing stations. In such cases, well-processing tasks such as drilling may be performed by a drilling rig placed next to the wellhead platform.
The wellhead platform typically fulfils one or more of the following functions in supporting a well:

(i) shield the well from accidental impacts from ships and vessels;
(ii) keeping a completed surface well from otherwise tipping over;
(iii) provide structure where pipes can be mounted for connecting to a valve assembly or production tree mounted on each well and interfacing these pipes with various equipment or manifolds on and/or off the platform, such as pumps and storage tanks;
(iv) supporting production trees so that they are substantially static relative to the platform (at least during production) as the platform and/or well is exposed to forces from current, wind and wave.

The sheath arrangement may define a circumferential confinement zone. The sheath arrangement may comprise one or more tubulars.
The sheath arrangement may circumscribe the upper deck aperture. The sheath arrangement may extend upwardly from the level of the upper deck. That is, no gap between the upper deck and the sheath arrangement may be present. Such an arrangement may assist to minimise risk of objects being dropped from the upper deck and through the upper deck aperture downwardly to a lower deck.
The sheath arrangement may be securable around a peripheral region of the upper deck aperture. The sheath arrangement may be securable around a peripheral region of the rig aperture.
The sheath arrangement may extend through the upper deck aperture. This may assist to minimise the risk of objects being dropped from the upper deck and through the upper deck aperture downwardly to a lower deck.
The sheath arrangement may extend through the rig aperture.
At least a portion of the sheath arrangement may be rigid.
At least a portion of the sheath arrangement may be flexible. At least a portion of the sheath arrangement may comprise a flexible material, such as a chain-link material. The sheath arrangement may define a sheath curtain. Such an arrangement may provide advantages in terms of installation, storage, and the like.
At least a portion of the sheath arrangement may be formed or comprise a metal or metal alloy material, composite material, plastic material or the like.
At least a portion of the sheath arrangement may be supported by the upper deck. At least a portion of the sheath arrangement may be secured to the upper deck. At least a portion of the sheath arrangement may be supported by the offshore rig. At least a portion of the sheath arrangement may be secured to, for example suspended from, the offshore rig.
At least a portion of the sheath arrangement may be provided on the offshore rig. For example, a portion of the sheath arrangement may be provided on the offshore rig, and a remaining portion of the sheath arrangement may be mated or otherwise arranged relative to the portion provided on the rig.
At least a portion of the sheath arrangement may be extended, for example lowered, from the offshore rig, for example through the rig aperture, during deployment of the sheath arrangement. The sheath arrangement may be deployed entirely from the offshore rig, for example by extending downwardly towards the platform.
At least a portion of the sheath arrangement may be extended, for example raised, from the offshore platform an upwardly towards the offshore rig during deployment of the sheath arrangement. The sheath arrangement may be deployed entirely from the platform, for example by extending upwardly towards the rig.
The sheath arrangement may comprise a load point or support on an outer surface thereof. The load point or support may permit connection of a load to the sheath arrangement. This may permit the sheath arrangement to at least partially support a connected load.
The sheath arrangement may comprise a support arrangement on an outer surface thereof. This may permit the sheath arrangement to be used as a structural support to facilitate offline (i.e., offset from the drill centre) operations such as slickline and wireline operations, hoisting operations such as during installation of production trees and the like. The support arrangement may comprise one or more arms, for example cantilever arms. The support arrangement may comprise one or more pulleys, sheaves or the like. The support arrangement may comprise a winch assembly.
The sheath arrangement may comprise a unitary component. Alternatively, the sheath arrangement may comprise multiple components. In one embodiment the sheath arrangement may comprise a first component connected or mounted to the offshore platform, and a second component connected or mounted to the offshore rig.
The sheath arrangement may be telescopic. For example, the sheath arrangement may comprise telescoping tubular structures. This may facilitate storage of the sheath arrangement when not in use. This may facilitate improved deployment of the sheath arrangement. Such a telescoping arrangement may provide a degree of movement compensation, for example to accommodate relative movement between the offshore platform and offshore rig.
The sheath arrangement may extend downwardly relative to the upper deck towards a first lower deck. The sheath arrangement may therefore define a confinement zone for confining objects passing between the upper and first lower decks. This may minimise or eliminate the extent of a drop zone on the first lower deck.
The offshore platform may accommodate equipment or apparatus associated with surface wells within the space defined between the first lower deck and upper deck. Such equipment or apparatus may comprise wellheads, production trees, pipework and the like. The provision of a confinement zone between the first lower and upper decks, in addition to reducing risk to personnel, may also reduce risk of damage to such sensitive equipment.
The sheath arrangement may define a continuous confinement zone both above and below the upper deck.
The first lower deck may define a first lower deck aperture aligned with the upper deck aperture.
The sheath arrangement may define an upper sheath portion extending upwardly relative to the upper deck and a lower sheath portion extending downwardly relative to the upper deck. At least part of the upper and lower sheath portions may be integrally formed.
The sheath arrangement may terminate at the first lower deck. The sheath arrangement may terminate above the first lower deck. The sheath arrangement may extend through a lower deck aperture. The sheath arrangement may extend below the first lower deck, for example towards a second lower deck.
The sheath arrangement, or portions thereof may define a permanent installation.
The sheath arrangement, or portions thereof, may be removable.
The offshore rig may be used to support a number of procedures or operations. For example, rig operations may include deploying and installing a conductor, drilling through a conductor, re-entering an existing well, deploying completion equipment and the like.
The offshore platform may accommodate multiple wells arranged in a cluster around the drill centre. The upper ends of the wells may be moveable to be aligned with the drill centre of the offshore rig. This may permit multiple wells to be established and accessed from a common drill centre. Such movement/alignment of the wells may be performed in accordance with desired operator procedures, such as those described in the applicant's copending patent applications DK PA2015 00668 and GB 1522856.2 .
In one example, the offshore platform may be configured to selectively allow access to the wells. For example, the sheath arrangement itself, or indeed the platform, may comprise a plate arrangement. Such a plate arrangement may be configured to form a flange, when associated with the sheath arrangement, to selectively prevent objects or equipment from accessing the wells, (e.g. those wells not at the drill centre).
In some examples, the plate arrangement may comprise an operable hatch or otherwise opening. Such a hatch may permit, when opened, access to the wells (e.g. to permit intervention operations to be carried out on the other wells when the sheath arrangement is at the drill centre.) The plate arrangement may be configured to allow access to other wells when drilling operations are occurring through the sheath arrangement (e.g. even at times when the plate arrangement is associated with the sheath arrangement).
In some examples, the plate arrangement may comprise at least one separation plate. Such a separation plate may be configured to extend downwardly from the plate arrangement. Such a separation plate may be configured to inhibit objects passing through the hatches to adjacent regions at the platform (e.g. adjacent wells). Further, such a separation plate may be configured to come into contact with a deck as the sheath arrangement is lowered, which may reduce or avoid impact of the sheath arrangement on wellheads.
The sheath arrangement may comprise an access hatch. The access hatch may be arranged such that, when in situ, the access hatch is user accessible from a deck (e.g. the upper deck). Such an access hatch, when opened, may permit access to the equipment passing within the sheath arrangement.
The sheath arrangement may be configured to flex compliantly in order to accommodate relative movement between the offshore rig and upper deck, when in use. For example, the sheath arrangement, or at least a portion thereof, may be axially and/or longitudinally compliant in order to accommodate relative movement between the offshore rig and upper deck, when in use. In some examples, the sheath arrangement may comprise specific compliant portions, for example one or more flexible joints.
An aspect or embodiment relates to a method for confining objects extending between an offshore rig and an offshore platform, according to the appended claims.
Also disclosed herein is a sheath arrangement for use between an upper deck of an offshore platform and an offshore rig positioned over the offshore platform, wherein the sheath arrangement is alignable with a rig aperture provided on the rig and defines a confinement zone for confining objects which pass downwardly from the offshore rig through the rig aperture.

Claims

An offshore platform (10) for use in combination with an offshore rig (42), comprising:
an upper deck (22) defining an upper deck aperture (28) which is alignable with a rig aperture (48) of the offshore rig (42), when said offshore rig (42) extends over the upper deck (22), to permit objects to extend between the offshore rig (42) and through the upper deck (22); and

a sheath arrangement (34) aligned with the upper deck aperture (28) and extending upwardly relative to the upper deck (22) to be alignable with the rig aperture (48), wherein the sheath arrangement (34) defines a confinement zone (40) for confining objects which pass downwardly from the offshore rig (42) through the rig aperture (48).
The offshore platform (10) according to claim 1, wherein the offshore platform (10) is an offshore wellhead platform configured to accommodate an upper terminating end of at least one well (14a).
The offshore platform (10) according to any preceding claim, wherein at least one of:
the sheath arrangement (34) circumscribes the upper deck aperture (28);

the sheath arrangement (34) extends upwardly from the level of the upper deck (22);

the sheath arrangement (34) is securable around a peripheral region of the upper deck aperture (28);

the sheath arrangement (34) is securable around a peripheral region of the rig aperture (48);

the sheath arrangement (34) extends through the upper deck aperture (28); and

the sheath arrangement (34) extends through the rig aperture (48).
The offshore platform (10) according to any preceding claim, wherein at least a portion of the sheath arrangement (34) is rigid, and/or at least a portion of the sheath arrangement (34) is flexible to define a sheath curtain (236).
The offshore platform (10) according to any preceding claim, wherein at least a portion of the sheath arrangement (34) is supported by at least one of the upper deck (22) and the offshore rig (42).
The offshore platform (10) according to any preceding claim, wherein at least a portion of the sheath arrangement (34) is at least one of:
extended from the offshore rig (42) during deployment of the sheath arrangement (34); and

extended from the offshore platform (10) and upwardly towards the offshore rig (42) during deployment of the sheath arrangement (34).
The offshore platform according to any preceding claim, wherein the sheath arrangement (34) comprises a support arrangement on an outer surface thereof, wherein the support arrangement comprises a hoisting support arrangement (60).
The offshore platform according to any preceding claim, wherein the sheath arrangement (134) at least one of:
comprises a first component (138) connected or mounted to the offshore platform (10), and a second component (136) connected or mounted to the offshore rig (142);

comprises a compliant portion; and

is telescopic.
The offshore platform (10) according to any preceding claim, wherein the sheath arrangement (34) extends downwardly relative to the upper deck (22) towards a first lower deck (24) to define a lower confinement zone for confining objects passing between the upper (22) and first lower (24) decks.
The offshore platform (10) according to any preceding claim wherein the offshore rig (42) comprises a cantilever portion (42) which is extendable over the upper deck (22) of the offshore platform (10), the cantilever portion (42) defining the rig aperture (48).
The offshore platform (10) according to any preceding claim, wherein the offshore rig (42) defines a drill centre (50) and the rig aperture (48) is provided on the drill centre (50) such that the drill centre (50) is positionable within the confinement zone (40) defined by the sheath (34).
The offshore platform (10) according to claim 11, wherein the offshore platform accommodates multiple wells (14,14a) arranged in a cluster around the drill centre (50).
The offshore platform (10) according to claim 12, wherein the upper ends (16) of the wells (14,14a) are moveable to be aligned with the drill centre (50) of the offshore rig (42).
A method for confining objects extending between an offshore platform (10) and an offshore rig (42) which extends over an upper deck (22) of the offshore platform (10) such that an upper deck aperture (28) of the offshore platform (10) is aligned with a rig aperture (48) of the offshore rig (42), the method comprising:
extending a sheath arrangement (34) between the upper deck (22) of the offshore platform (10) and the offshore rig (42) such that the sheath arrangement (34) is aligned with the upper deck aperture (28) and the rig aperture (48) and defines a confinement zone (40) for confining objects which pass downwardly from the offshore rig (42) through the rig aperture (48).
An offshore system, comprising:
an offshore platform (10) according to claim 1; and

an offshore rig (42) having a rig aperture (48), wherein the offshore rig (42) is extendable over the upper deck (22) of the offshore platform (10) to align the rig aperture (48) with the upper deck aperture (28) and permit objects to extend between the offshore rig (42) and through the upper deck (22); and

wherein the sheath arrangement (34) is extendable between the upper deck (22) of the offshore platform (10) and the offshore rig (42).