(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`CORRECTED VERSION
`
`(19) World Intellectual Property Organization
`;,,.B,.,a,io..a13.,m...
`(43) International Publication Date
`17 August 3000 (17-08-2000)
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`-
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`_-
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`I
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`I‘
`_
`PCT
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`llfllllllllllllflllillllllllil|||||fll||1l||||||1||1II||11||||1I
`(10) lfltemithflfll Publication Nlmlbel”
`W0 00/47864 A1
`
`(51) International Patent Classification’:
`34104. 33l038
`
`E2113 331035,
`
`(21) International Application Number:
`
`PC'l'a'GBO(1n'00462
`
`_
`..
`.
`(22) lnternat1onal‘.F1ItngDate.10February20D0(10.0Q.2000)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`99031304
`9907844-.6
`19991748
`99152282
`
`11 February 1999 (11.02.1999) GB
`6Apri1 1999 (06.04.1999) GB
`13 April 1999 (13.04.1999) N0
`29.iune1999(29.06.1999) GB
`
`(71) Applicant (for all designated States except US): FMC
`CORPORATION IUSIUS]; 200 East Randolph Drive,
`Chicago, IL 60601 (US).
`
`('12) Inventors: and
`(75) lnventorsmpplicants (for US only): ANDERSEN.
`Ton [Nome]; Sognsvamsveien WA’ N037: 0510
`(N0). BREDA, Jaren ENDING]: Sundveien 14B. N-1397
`Nesoya (N0). GATI-IERAR, Nicholas [GBIGB]; 18
`Juniper Avenue. Juniper Green, Midlothian EH14 SE
`(GB). GRENDSTAI),
`Jens
`[Nome]; Linneaveien
`4, N-3050 Mjondalen (NO). I-IAAVIMB, Stein, Tore
`[NOJNO]; Milnsiers vei 4. N-3610 Kongsberg (N0).
`HATLO, Andreas [NOJNO]; Hasle Gitd, N-3125 Tons-
`berg (N0). I-lAl.1GE.N,Tarjei [NO.lNO]:D1‘. Bryns vei 6B.
`N-3610 Kongsberg (NO). I-IOEL, Karl—Willie [NO!NO]',
`Heggedalsskogen 50, N-1389 Heggedal (NO). KENT,
`{Continued on nextpuge]
`
`(54) Title: SUBSEA COMPLETION APPARATUS
`
`completion
`A snboea
`(57) Abstract:
`comprises a wellhead (10) having a side
`wall
`through which extends a production
`fluid conduit (30). The completion further
`comprises
`a
`flow control package (82)
`rernovably located externally of the wellhead
`and containing at least one production flow
`control valve: an end of the production flow
`conduit
`(30) being releasably coupled to
`the flow control package (82) by a subsea
`rnatable connector (34. 84). A controls cap
`may be secured to the top of the wellhead
`(10). connected to a nearby controls interface
`by jumpers (122).
`Service lines are led
`downhole through the controls cap.
`
`W000/47864A1
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`1
`
`FMC 1005
`
`

`
`WO 00/47864 A1
`
`Richard IGBIGB]; 2 Craigmill Collages, Newburgh, Fife
`KYI4 613}! (GB). RANGNES, Atle [NOJNO]; Rundtorn
`44. N-1370 Asker (NO).
`
`(AM. AZ. BY. KG, KZ, MD. RU. TJ. TM), European patent
`(AT, BE. CH, CY. DE. DK. ES, FI, FR, GB, GR, IE, IT, LU.
`MC, NL. PT. SE), CIAPI patent (BF, BJ, CF, CG, CI, CM,
`GA. GN, GW. ML. MR. NE. SN. TD, TG).
`
`(74)
`
`Agent: PHILLIPS 3: LEIGH; 5 Pemberton Row. London
`EC4A 3BA (GB).
`
`Published:
`with itsrernational Search report
`
`(81}
`
`Designated States (national): AE. AL. AM, AT. AU. AZ,
`BA, BB, BG. BR. BY, CA. CH. CN. CR, CU. CZ, DE, DK,
`DM, EE, ES, FI, GB, GD, GE. GH, GM, HR. HU, ID, IL,
`IN, IS, JP, KE. KG. KP, KR. KZ. LC. LK, LR, LS. LT. LU,
`LV, MA, MD, MG. MK, MN. MW. MX, NO, NZ. PL. PT,
`RO, RU, SD, SE. SG, SI, SK, SI... TJ, TM, TR, TT, TZ. UA,
`UG, US. UZ, VN, YU. ZA, ZW.
`
`(48) Date of publication of this corrected version:
`2 August 200]
`
`(15) Information about Correction:
`see PCT Gazelle No. 31.’200l of 2 August 2001 , Section II
`
`(940
`
`Designated States (regional): ARIPO patent (GH. GM.
`KE, LS, MW, SD. SL. SZ. TZ. UG, ZW}, Eurasian patent
`
`For two-letter codes and other abbreviations. refer to the ”Gm‘d-
`ance Notes on Code: andAbbrev£cm‘ons" appearing at the begin»
`ning afeach regular issue ofrhe PCT Gazette.
`
`2
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`wo []fl,l4'}s54
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`PCTJ‘GB00!00462
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`1
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`SUBSEA COMPLETION APPARATUS
`
`Field of the Invention
`
`This invention relates to apparatus for drilling and completion of subsea wells for
`
`controliing fluid flow from and within such wells and for subsea fluid processing
`
`operations.
`
`Background of the Invention
`
`Oonventionally, subsea completions are carried out from a drilling vessel or platform
`
`primarily designed for well drilling and installation of the subsea wellhead. These vessels
`
`are highly specialised and expensive to operate. They have usually been used to perform
`
`the entire installation sequence of the wellhead and completion.
`
`The key components of known wellhead and completion designs must be installed or
`
`removed in a set sequence, as the installationfremoval of one component is dependent on
`
`the prior installationlremoval of another. For example, in a completion including a
`conventional Christmas tree, removal of the tubing hanger and production tubing requires
`
`20 the prior removal of the tree. With horizontal tree designs, the tubing hanger and its
`
`tubing has to be pulled prior to tree removal. This is a time consuming procedure that
`
`may be necessary for maintenance or repair of the valves and other equipment
`
`incorporated in the subsca completion, including the tree.
`
`25 A subsea completion will almost always contain service lines extending downhole for
`
`controlling, monitoring and powering downhole equipment. The type of equipment and
`
`hence the required service lines may vary considerably between completion projects.
`
`Hitherto it has been usual for these service lines to exit the well through a tree attached to
`
`the wellhead. This has often necessitated detailed wellhead design changes from one well
`
`30 development to another. During installation of a tubing hanger and an associated tubing
`
`string into the wellhead, or during its removal, it may also be desirable to maintain
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`communication with the downhole equipment via the service lines. Completion designs
`
`currently in use allow such communication for up to five service lines.
`
`It is desirable to
`
`increase the number of service lines available for such communication whilst the tubing
`
`string is being rurtfretrieved.
`
`GB 2320937 concerns a horizontal subsea christmas tree in which a separate tree block is
`
`located on and surrounds a substantially cylindrical wellhead housing. Hydraulic control
`
`lines run through a corrosion cap at the housing upper end and an internal cap provided in
`
`the housing. These lines pass through a tubing hanger to a downhole safety valve.
`
`I0
`
`There are several known solutions for the production of oil and gas from the bottom of the
`
`sea. One favoured solution is where several single wells are drilled and completed and
`
`flowlines are extended from each well along the seabed to a centrally located manifold
`
`unit placed on the seabed. The subsea manifold thus collects fluids from several wells,
`
`equalising the pressure differential between he wells and pumps the combined fluids to a
`
`production platform.
`
`It has been suggested that a subsea manifold also may have
`
`processing equipment, e.g. Troll Pilot. Manifolds are very heavy and complex and are
`
`usually installed using special crane barges. In addition, a large number of ilowlines and
`
`connections are needed.
`
`Process, e.g. separation equipment is commonly placed on fixed or floating production
`
`platforms, such that well fluids are brought to the surface to be processed, e.g.
`
`the
`
`separation of water from the hydrocarbons and gas from oil. Processing can also include
`
`equipment for sand removal, chemical additives removal, water or gas injection, "artificial
`
`lift" technology or chem.ica1 injection.
`
`Fixed or floating platforms are of necessity very large in order to carry necessary
`
`processing, storage and utility features. With increasing depths the size of the platform
`
`must be increased correspondingly. For fixed platforms there is a limit to the water depth
`
`30 where they can be used. Floating platforms can be used at any depth, but they need to be
`
`held in position by anchor chains, tension legs or dynamic positioning against the heavy
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`PCTIGBOOIOIMGZ
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`wind and wave forces experienced. All this equipment increases the platform weight and
`
`complexity, which in turns means, increased costs.
`
`Another element which makes it more expensive to explore and develop subsea oil and
`
`5 gas fields at greater depths are the costs connected with the running and retrieval of
`
`equipment between the surface and the seabed.
`
`It takes longer time to make a "trip “ and
`
`the lifiing equipment must be larger.
`
`There is therefore a need to develop more eficient systems for the exploitation of
`
`to hydrocarbons from great depths, e.g. down to 4000 meters. Along with this there is also a
`
`need to be able to place more processing equipment on the seabed, so that the size of the
`
`platform can be reduced.
`
`From GB 2285274 is known a subsea system comprising a template with a square centre
`
`section with a number of outwardly projected arms, which can he folded up during
`
`installation, so that the template can be installed through a rig‘s moonpool. The arms
`
`include means for supporting a well while a manifold placed on the centre section can
`
`process well fluids front all the wells. One problem with this arrangement is that there
`
`will be dimensional mismatches for example because a well is slightly askew. The pipes
`
`between well and manifold must therefore be flexible and have connectors at both ends.
`
`Such an arrangement then means that a number of subsea operations must be performed in
`
`order to complete the system.
`
`Summary of the Invention
`
`We have developed wellhead and completion components providing greater flexibility as
`
`regards installation and retrieval and which reduce the interdependence between key
`
`components during such procedures. We have also developed apparatus for linking
`
`downhole service lines to an external control I monitoring 1 supply point which permits
`
`greater standardisation of the wellhead design and allows operation, whilst the tubing
`
`30 hanger is being installed or removed, of downhole equipment attached to the service lines.
`
`The apparatus also allows one or more wells to be connected to subsea flow control and
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`processing equipment. This may be provided in modular form. permitting greater
`
`standardisation between individual components. A given module may also he readily
`
`supplemented or replaced by another when appropriate, as control and processing needs
`
`change throughout the lifecycle of the associated well.
`
`In a first aspect,
`
`the present
`
`invention provides a subsea completion comprising a
`
`wellhead from which extends a production fluid conduit; the completion comprising a
`
`flow control package removably located externally of the wellhead and containing at least
`
`one production flow control valve; characterised in that a continuation of the production
`
`10 fluid conduit extending away from the wellhead is releasably coupled to the flow control
`
`package by a subsea marable connector whereby the flow control package and
`
`components within the wellhead respectively may be installed and retrieved independently
`
`of each other .
`
`The flow control package perfomis at least some of the functions of the Christmas tree in
`
`prior art completions, in that it provides control of fluid flows from and for to the well,
`
`but it may be assembled from individual components, eliminating the need for large and
`
`complex forgings. At the same time this permits great flexibility in design to suit the
`
`requirements of a particular completion project.
`
`The relocation of flow control
`
`components from a christmas tree forming part of the main wellhead structure to a flow
`
`control package located remote to the wellhead leads to a design which nevertheless is
`
`suitable for use in a wide variety of operating environments. The flow control package
`
`may be installed or retrieved independently of completion components located within the
`
`wellhead. Moreover use of a drilling vessel or platform is unnecessary for such
`
`installation and retrieval. For example a smaller and less costly to operate diving support
`
`vessel can be used, freeing up the drilling vessel for use elsewhere. Casing hangers and
`
`completion tubing and a tubing hanger may be consecutively installed in the wellhead
`
`without having to remove the BOP stack and install other components. The flow control
`
`package may be located at the wellhead, or nearby. Horizontal and conventional
`
`30 christmas trees have to be positioned on the centre line of the wellhead; the flow control
`
`6
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`

`
`5
`
`package does not. One conventional or horizontal tree serves one wellhead; a single flow
`
`control package according to the invention may serve one or more wellheads.
`
`Preferably a further conduit extends from the wellhead, having one end in communication
`
`with a tubing annulus and its other end releasably coupled to the flow control package by
`
`a subsea matable connector external to the wellhead. A yet further conduit may extend
`
`from the wellhead, having one end communicating with a region above or below a tubing
`
`hanger received within the wellhead, and its other end releasably coupled to the flow
`
`control package by a subsea matable connector external to the wellhead. These various
`
`conduits thus permit fluid circulation within the completion via the flow control package,
`
`equivalent to the circulation possible using a conventional or horizontal ehristmas tree.
`
`The various connectors may be separate, but preferably are combined to form a unitary
`hub connector.
`
`When the or each connector is disconnected, a part of the or each connector associated
`
`with the wellhead is preferably sealed by a valve, plug or cap.
`
`The tubing hanger may contain an annulus flow passage connected to the tubing annulus
`
`conduit and containing a flow control valve of equivalent filnction to an armulus master
`
`valve. Alternatively this valve may be positioned in the tubing annulus conduit or in the
`
`wellhead. The tubing hanger may also contain a flow control valve positioned in a
`
`production fluid flow passage connected to a tubing string; this valve having a function
`
`equivalent to the production master valve of a conventional or horizontal completion.
`
`Alternatively this valve may be positioned in the production fluid conduit or in the
`
`wellhead. The wellhead may be of unitary construction or may comprise a flow spool
`
`connected to a separate lower wellhead part and containing the tubing hanger.
`
`The flow control package may contain valves of equivalent function to the production
`
`wing valve, annulus wing valve, armulus valve, crossover valve and other flow control
`
`valves normally found in a conventional or horizontal subsea christmas tree and even
`
`7
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`manifolds. These valves may be separate subasseml:-lies or grouped to form a service
`
`valve block and a production flow valve block. Where required, the flow control package
`
`may also contain a production choke having an inlet connected to the production master
`
`valve or wing valve equivalent, and an outlet coupled to an isolation valve, a manifold
`
`connector or flow line connector.
`
`The flow control package may conveniently be used to house any other equipment needed
`
`to control or monitor the production phase of a given well development, such as flow
`
`meters, detectors, sensors and chemical injection ports.
`
`In accordance with a second independent aspect of the invention, there is provided a
`
`controls cap secured at the top of a wellhead, characterised in that a plurality of service
`
`lines are led downhole through the controls cap from outside the wellhead, a jumper
`
`connecting the service lines in the controls cap to an external controls interface. Where
`
`Is the completion includes an internal tree cap and a tubing hanger below the controls cap,
`
`the necessary electrical and hydraulic connections may be led from the controls cap,
`
`through the tree cap and tubing hanger and into the tubing annulus. Alternatively, the
`
`completion may comprise a tubing hanger located below the controls cap and having a
`
`through bore; a first plug being positionable in the through bore for diversion of
`
`production fluid into a tubing hanger side outlet; a second plug positionable in the through
`
`bore above the first plug; the service line(s) being led from the controls cap, through the
`
`tubing hanger and into the tubing annulus. A test port preferably communicates with the
`
`space defined between the first and second plugs. Primary and secondary a.nnulus seals
`
`may be positioned between the tubing hanger and the wellhead, with a test port
`
`communicating with the void defined between the primary and secondary seals.
`
`During installation and workover/maintenance, when the controls cap is removed,
`
`communication with the service lines may be provided via a running tool engaged with
`
`the tree cap or tubing hanger. The external controls interface, may be situated for
`
`30 example nearby on the seabed, on an adjacent flow manifold, or attached to the wellhead.
`
`The physical link between the downhole service lines and the external controls interface
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`8
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`PCTIGB00l00462
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`7
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`can thus be entirely independent of the christmas tree or flow control package. This
`
`differs from prior conventional or horizontal tree designs, where part or all of the service
`
`lines link has to be incorporated into the body of the tree. Where desired, the controls
`
`interfacemay be provided by a subsea control module located in the flow control package
`
`of a subsea completion according to the first aspect of the invention. This subsea control
`
`module may also control elements of the flow control package, such as valves and/or
`
`chokes. The controls cap of the invention enables a greater number of service lines to be
`
`connected to downhoie equipment than has been possible hitherto, which connection can
`
`be maintained during installation or removal of the completion.
`
`A further independent aspect of the invention provides a subsea drilling and production
`
`system, comprising a framework, a well housing and a flow control module removably
`
`located ‘externally of the well housing and containing at least one production flow control
`
`valve, characterised in that the flow control module is located on the framework and the
`
`well housing is rigidly connected to the framework. The connection can therefore be
`
`established during the construction of the framework.
`
`In that way, the later subsea
`
`installation of a pipe spool and appropriate fluid flow connectors is unnecessary. The
`
`required fluid flow channels,
`
`lines, pipes and the like may be integrated into the
`
`fiamework to form structural components thereof;
`
`so simplifying the framework
`
`construction, and saving weight and materials. Where two or more well housings are
`
`provided, the framework may advantageously be used as a template for multiple well
`
`drilling operations. Fluid flow connections can he established to all the wellheads and
`
`with fluid flow control and processing equipment, via the framework or template, with a
`
`very much reduced need to make up subsea flow connections. The template also performs
`
`25 the usual function of establishing the correct spacing between the wellheads.
`
`A yet further independent aspect of the invention provides a subsea drilling and
`
`production system comprising a many-sided framework comprising structural members
`
`arranged to support well fluid flow control andfor processing modules, characterised in
`
`30 that well housings are located in the corners of the framework and rigidly connected to the
`
`structural members.
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`WO 00147864
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`PCTlGB[|0:‘l!0462
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`In GB 220256] is shown a standard template frame. Several templates can be joined
`
`together into a larger unit. In the template are locations for various modules and
`
`interconnecting pipework.
`
`Since the modules must he installed at predetermined
`
`locations in the template, an exchange of modules will at times make it necessary to
`
`remove other modules, to gain access.
`
`According to a still further independent aspect of the invention, a subsea drilling and
`
`production system comprising a framework, :1 well housing and a plurality of modules for
`
`the control andfor processing of well fluids, is characterised in that the frame includes a
`
`plurality of connecting locations for the modules and all modules and connecting
`
`locations have a common connecting interface such that modules can be exchanged with
`
`each other and secured at any connecting location on the framework. This system
`
`achieves a greater degree of standardisation than in prior systems. Preferably modules can
`
`be connected together in a stacked configuration, in arbitrary order, as well as capable of
`
`being located anywhere on the Emmework, or being easily exchanged with other modules.
`
`For a given well completion, using the present invention, fewer and smaller modules may
`
`be required, so that modules can be handled by smaller vessels.
`
`Further preferred features are described below with reference to the drawings which show
`
`illustrative embodiments of the invention.
`
`Brief Description of the Drawings
`
`Fig. 1 is a schematic sectional view of a wellhead forming a first embodiment of the
`
`present invention, without the flow control package installed;
`
`Figs. 2a and 2b are similar views of respective alternative embodiments, Fig. 2a being a
`
`partial view of the wellhead on a slightly larger scale;
`
`Fig. 3 is a diagrammatic plan view of the flow control package installed on the wellhead
`
`of Fig. 1,
`
`Fig. 4 is a side view of the flow control package and wellhead of Fig. 3, in partial section;
`
`10
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`Figs. 5 - 10 diagrammatically illustrate various stages of a well drilling and completion
`
`operation using the apparatus ofthe invention;
`
`Fig. 1 1 shows apparatus of the invention undergoing a workover via a BOP;
`
`Figs. 12a and 12b illustrate two alternative configurations of the apparatus of the
`
`invention, undergoing tubing entry workover via a dedicated intervention package and
`
`riser;
`
`Fig. 13 shows a modification of the apparatus of Fig. 1, providing disaster recovery in the
`
`event of bore damage to the wellhead;
`
`Fig. 14 shows an alternative connector hub which may be used in the present invention;
`
`Fig. 15 is a top view illustrating a flow control package of the invention for use with
`
`multiple wells;
`
`Figs. 16-21 show various alternative flow package configurations and arrangements for
`
`their connection to the wellhead and a manifold;
`
`Fig. 22 is a schematic side view (not to scale) of a framework or template embodying the
`
`invention,
`
`' Fig. 23 shows an adaptation of the figure 23 embodiment for use with a conventional tree
`
`and also contains a key to symbols used in figs. 22, 23, 24, 29, 30, 31, 32, 33 and 34;
`
`Fig. 24 schematically shows flow connections possible using the arrangement of fig. 22;
`
`Figs. 25 and 26 are side and plan views respectively of a fiirther embodiment;
`
`Figs. 27a-d illustrate various possible template configurations;
`
`Fig. 28 is a schematic plan view of a preferred template;
`
`Fig. 29'is a view similar to fig. 25 showing further details;
`
`Fig. 30 is a side view corresponding to fig. 26;
`
`Figs. 31-33 are schematic side views showing combinations of modules;
`
`Fig. 34 shows an alternative template for use with a pennanent guide base;
`
`Fig. 35 shows various different modules used to form embodiments of the invention, and
`
`combinations of such modules with various templates;
`
`Fig. 36 illustrates comparative installation and workover times for a completion including
`
`a flow package and controls cap according to the present invention, and various known
`
`30 completion types.
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`Description of the Preferred Embodiments
`
`10
`
`Referring to Fig.
`
`1 there is shown a wellhead 10 supported in an outer housing and a
`
`permanent guide base 12, both attached to a conductor casing 14. Casing strings 16 are
`
`5 suspended within the wellhead 10 by hangers 18. A tubing string 20 is suspended from a
`
`tubing hanger 22 landed within the wellhead 10. The tubing hanger 22 has a vertical
`
`through here 24 permitting full bore access to the tubing string during workovers.
`
`In
`
`production mode, production fluid is diverted to a tubing hanger side outlet 26, by a plug
`
`28 in the through bore 24.
`
`10
`
`The side outlet communicates with a production fluid conduit 30 having one end
`
`extending through a side wall 32 of the wellhead 10 and its other end (not shown in Fig.
`
`1) terminating at one part of a subsea matable connector, contained within a connector
`
`hub 34. Chain dotted line 36 indicates the flow path provided by the conduit 30 to the
`
`15 hub 34.
`
`A further conduit 38 extends through the wellhead side wall 32 to a subsea matable
`
`connector part in the hub 34, as indicated by chain dotted line 40. The end of conduit 38
`
`within the wellhead conununicates with the production annulus via a flow passage 42
`
`20 formed in the tubing hanger 22. The junction between the conduit 38 and the flow
`
`passage 42 is sealed by a pair of sealing elements 44, 46 carried by the tubing hanger 22.
`
`The production fluid conduit 30 and the tubing hanger side outlet are similarly sealed
`
`together by the sealing element 46 and a further sealing element 48.
`
`25 A yet further conduit 50 extends through the wellhead side wall 32 from a location above
`
`the tubing hanger 22, to a subsca rnatable connector part in the hub 34, as indicated by the
`
`chain dotted line 52. The end of the conduit 50 within the wellhead 10 communicates
`
`with a flow passage 54 extending above an internal
`
`tree cap 56.
`
`For completion
`
`installation and worl-covers, if desired, fluid can be circulated through the flow passage 54
`
`30 and conduit 50, either with or without the tree cap 56 in place. The tree cap 56 is sealed
`
`to the wellhead by a sealing element 58.
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`Electrical, optical andlor hydraulic service lines 60 for communication with downhole
`
`equipment are routed through the tubing hanger 22 and tree cap 56. Communication fi'om
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`there to a workoverlproduction controls system is achieved by installing suitable linking
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`5 controls connections. As shown in Fig. 1, for production, a controls cap 62 is installed
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`above the tree cap 56, and includes a stab connector 64 which mates with the various lines
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`in the tree cap 56. During workover and installation, a similar stab connector is provided
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`on the various running tools. From the controls cap a suitable jumper extends to a
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`controls/communication interface provided at or near the subsea well, for example a
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`to subsea control module in the flow control package.
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`To provide isolation of the well required as part of the completion operation, the tubing
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`hanger through bore 24 is closable by a remotely operable valve 66. When open, valve 66
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`provides unobstructed access to the tubing 20. Likewise, the annulus flow passage 42 in
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`Is the tubing hanger is closable by a valve 68. The valves 66, 68 may be electrically or
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`hydraulically actuated valves of known kind, e.g. ball valves, and respectively fulfil
`functions equivalent to the production master valve and annulus master valve in prior
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`completion designs.
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`20 When the hub 34 is disconnected from the flow control package as shown in Fig. 1, the
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`flow connection parts in it are sealed by a pressure cap 70.
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`Fig. 2a shows an alternative embodiment in which the tree cap 56 is replaced by a plug 57
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`received in the tubing hanger through bore 24, above the plug 28. A test port 29 may be
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`25 provided, having one end communicating with the space between the plugs 28 and 57, e.g.
`for monitoring possible leakage past plug 28. The other end of test port 29 (not shown)
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`may terminate at the upper surface of the controls cap 62 or at some other convenient
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`location for connection to an umbilical or monitoring equipment. Optionally, a tubing
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`hanger secondary lockdown mechanism 23 may be provided above the tubing hanger 22.
`30 Conduit 50 may be connected to a port or like flow passages schematically illustrated at
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`51, to provide fluid communication with the wellhead interior above the tubing hanger 22.
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`As shown in Fig. 2a, the production fluid conduit 30 may pass through the wellhead side
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`wa.l132a1a.IowerleveItb.anthean.nulus conduit 38,rathert.ha.n vice versaasshown in
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`Fig, 1- A secondary sealing element 45 may he provided above the scaling element 44,
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`with a test port 47 having one end in communication with the void defined between the
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`elements 44, 45, the wellhead 10 and the tubing hanger 22. The other end of the port 47
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`may be connected to an umbilical or monitoring equipment in similar manner to port 29,
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`eg. for detecting annulus fluid leakage.
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`Fig. 21: shows various possible further modifications. Ratherthan the unitary construction
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`ofFig. 1.thebodyformingthcwelH1ndlOcomprisesasepara1eflowspool72sec1uedm
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`a lower part 74 of the wellhead by a connector 76. The flow spool 72 carries the various
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`conduits 30, 38, 50 and the connector hub 34.
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`It may therefore be secured to existing
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`subsea weliheads using a suitable adapter, converting then: for use with the flow control
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`package of the present invention. A separate flow spool is also advantageous in that it
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`-
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`rnaybeneadily replaocdintheeveut ofbore dmage,andcanbeinstalledafterdxi]ling
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`operations are completed, so reducing the risk of damage.
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`An alternative or additional modification shown in Fig. 2b as compared to Figs. 1 and 2a
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`20 isthatthe Valves 66, 68 ilifiactllbinghmigerarercplacedbyvalves 73, 80 inthe
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`production fluid and annulus conduits 30, 38 respectively- These valves may either be
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`locatedinexternalpipeworkattachedtothewelJheedasshown,orinthewel1headside
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`wall. Relocation of the annulus valve 80 as shown in Fig. lb or to the wellhead side wall
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`ullowsthcsea144ofFig, 1 tobeeliminarted.
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`25
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`A yet further possible modification shown in Fig. 2b is that the tree cap 62 is of solid
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`construction. The construction shown in Pig, 1 incorporates a plug 134, permitting tubing
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`entry access without removal ofthe cap, eg for lightweight intervention operations.
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`30 Figs. 3 and 4 show the flow control package 82 installed around the Wellhead 10. As
`shown,_ a hub connector 84 lies above and males with the hub connector 34 of the
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`wellhead after removal of the pressure cap 70. However, many other connector
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`configurations will also be suitable to provide fluid communication between the wellhead
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`and flow control package. Hub connector 84 contains complementary connector parts
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`providing fluid tight couplings with the connector parts of the wellhead hub 34.
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`5 Production conduit 30 is thereby connected via pipe 85 to a production flow block 86
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`containing flow control valves. Some or all of these valves may provide well fluid
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`isolation and pressure containment, serving as a barrier between the producing formation
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`and the environment. These valves may have functions equivalent to the production
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`master and/or wing valves in a christrnas tree. The hub connectors 34 and 84 likewise
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`interconnect the annulus conduit 38 and the BOP circulation conduit 50 with respective
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`conduits 88 and 90 leading to a service block 92 containing valves for example
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`ftmctionally equivalent to an annulus wing valve, annulus access valve and crossover
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`valve, and/or others having any additional service control functions required for a given
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`completion project. The service valve block shown in Fig. 3 contains two such valves. A
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`crossover conduit 94 extends between the service valve block 92 and the production flow
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`block 86. The various valves in the flow control package include associated actuators 96,
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`98, 100 which are hydraulically powered and/or may have operating shafts 102, 104, 106
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`coupled to ROV receptacles 108, 110, 112 in ROV panel 114. Production flow is directed
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`' from block 86 through a production choke 116 and from there to a flow line or manifold
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`connector 118, coupled to a flowline 119 as shown. The production choke is optional,
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`depending on project requirements.
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`The flow control package 82 may also include the controls/communication interface in the
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`form of a subsea control module 120 containing equipment for monitoring and controlling
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`the operation of downhole equipment such as a Di-ISV and pressure and temperature
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`sensors, as well as for controlling the valves 66, 68 or 78, 80 associated with the tubing
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`hanger 22, wellhead 10 or flow spool 72. Module 120 may also control the valves in the
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`flow control package 82 itself, as well as the production choke 116 and any other
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`equipment which may be included in the flow control package for a given completion
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`project. As shown in Fig. 4, ajumper 122 provides the necessary electrical and hydraulic
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`connections between the control module 120 and the controls cap 62.
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`Figs. 5 to 10 illustrate a typical instal