4 way horizontal wellhead feedthrough...

4 Way Horizontal Wellhead Feedthrough System

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01229 580500For Further Information on this and other products, please telephone Sales / Technical Department on:

Tronic Ltd., (Head Office) Sanside Road, Ulverston, Cumbria, LA12 9EF England. International Tel: +44 1229 580500 Fax: +44 1229 586604 Sales Fax:+44 1229 580500

5

Horizontal Tree - components

Subsea wellhead connection systems transmit the power or signal from a subsea connector accessible by driver or ROV, through the annulus.

Systems, for power and instrumentation normally comprise the following components:

■ Wet Mate, Controlled Environment (CE) connectors that complete

the connection betweentree and hanger.

■ Dry Mate connectors, mated at the surface and subsequently deployed subsea or downhole.■ Conductors contained within oil-filled hose transmitting the signal / power through internal

conduits in the tree and hanger.■ Driver / ROV operated connections to the umbilical / subsea modules.

HORIZONTAL CONFIGURATIONS

In horizontal configurations, the CE plug connector is mounted (compliantly) horizontally on a carriage within the bonnet on the tree. A receptacle with a right-angled exit leads to dry mate connectors at the bottom of the hanger.

Once the tubing hanger has been run, the carriage is actuated by ROV, causing the plug connector to mate with the receptacle, completing the connection.

Options for monitoring during run-in are available on request.

The sea water connection to power supply or control system is made by using ROV, stab plate or driver mated CE or mini CE connectors.

As technology allows the production of oil from new subsea field developments where the production and environmental conditions are ever more arduous, the need to monitor downhole conditions becomes an increasingly important factor in well management. The recent development of horizontal tree wellheads has necessitated the development of new electrical connector systems that allow topside connection to downhole pressure and temperature transducers which are synergistic with the tree’s operating philosophy.


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INTRODUCTION

This project was started in March 1996 in response to a request for a competitive bid from FMC acting on behalf of KOS / Statoil following the success of a Tronic produced horizontal tree, single pin downhole connector system. This system was designed for operation on the Statoil Norne development at a temperature of 121oC and a pressure 10 kpsi.

This was to be a frame agreement for the Asgard and Gullfaks development in the North Sea. The requirement being for a minimum of 88 horizontal tree connector systems supplied over a three year period. The scope of supply was for a full electrical system connecting up to three downhole gauges to the control system interface on the subsea tree.

Design life of the system was to be 20 years. Principle differences from the previously supplied Norne system were the requirement for three signal lines plus earth and an increase in design temperature to 145oC (@ 10 kpsi design pressure).

TRONIC DESIGN PHILOSOPHY

It is Tronic’s design philosophy to provide at least two or more sealing barriers between produced fluids and any electrical conductor.

Pressure balancing is also used wherever possible using dielectric gels / oils in conjunction with elastomeric bladders / diaphragms to reduce leak inducing pressure differentials and stresses within the system.

Primary pressure barriers in contact with produced fluids use either metallic / metallic or metallic / polymeric testable seal interfaces rather than elastomeric seals which may degrade over the service life when in constant contact with produced fluids at high temperatures. All primary barriers are backed up by at least two elastomeric seal barriers. DESIGN SPECIFICATIONThe system was split into two discrete sub-assemblies to aid delivery logistics. The two sub-assemblies defined were:

The Tubing Hanger System and the Tree Bonnet Assembly.

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PERFORMANCE SPECIFICATION

Design life 20 yearsDesign temp Tubing Hanger 18˚C to 145˚C

Wellbore flow.Design temp Bonnet -18˚C to 121˚C

ELECTRICALNumber of WMEC contacts 4 (3 + earth)Nominal working voltage 250 VdcTest voltage (60 seconds) 1500 VdcNominal working current 5AInsulation resistance at 20˚C >1GWInsulation resistance at 145˚C for 48 hours >500MWContact resistance <2.5 milli ohms

MECHANICALNominal working pressure (wellhead cavity) 10 kpsiMaximum test pressure 15 kpsiAnnulus nominal pressure 10 kpsiMaximum continuous working temperature 145˚CNumber of subsea matings 100Tubing Hanger internal test pressure 725 PSITubing Hanger system internal design pressure 10 kPSIInstallation depth (max) 305 Metres

MISALIGNMENT CAPABILITYAxial position ± 0.118" (3mm)Maximum TH rotation ± 1˚ (3mm at T.H.

periphery)Linear contact engagement length 0.100"

DMEC CONNECTOR TERMINATIONCable crimp termination strength 5 kgf1/4" Cable pull out force 220 kgf

Tubing Hanger Assembly & Bonnet AssemblyWet Mate Receptacle, Harness / Boot / Cable Assembly, 3 Way Dry Mate Receptacle (Splitter assembly), Down Hole Plug, Wet Mate Plug Carraige Assembly & Internal Penetrator.

Tubing Hanger Assembly Wet Mate Receptacle, Harness / Boot /Cable Assembly, 3 Way Dry Mate Receptacle (Splitter assembly) & Down Hole Plug.

Tubing Hanger Assembly Wet Mate Receptacle, Harness / Boot / Cable Assembly & 3 Way Dry Mate Receptacle (Splitter assembly).

TUBING HANGER SYSTEM DESCRIPTION1. Up to three downhole gauge cables are terminated to the T.H. base by means of a dry-mate electrical connector (DMEC) comprising of a cable terminating dry-mate plug (DMPC) and dry-mate receptacle (DMRC). A crimp termination (rather than soldered) method will be employed as the means of terminating the inner gauge signal wire to the DMPC.

2. When less than three cables are terminated, dummy plugs are used in place of DMPC’s. The dummy plugs protect the connector pins in the unused DMRC’s. The system will therefore allows interchangeability of DMPC’s and dummy plugs at any time during the life of the system.

3. All interfaces at the DMEC are testable, either by low pressure gas (helium) or hydrostatically to 10,000 PSI.

4. To provide environmental protection to the T.H. signal wires, the cavity between the DMEC and the WMEC at the TH / tree spool interface is sealed using metal / metal primary seal arrangements with elastomeric back-up seals. These arrangements are testable during installation to allow sealverification. Test ports and fill / vent ports are fitted with plugs incorporating metal / metal seals and elastomeric back up seals.

5. In the unlikely event of the primary and secondary seals failing and the T.H. cavity becoming flooded, two further levels of protection will remain, allowingreliability to be maintained for the design life.

5a. The second level of protection comprises a gel filled harness / boot arrangement which forms a continuous pressure balancing diaphragm enclosing the signal wires and their terminations on the rear of the DMEC and the WMEC.

5b. The third level l comprises termination sleeves sealing the interface between the signal wires and the connector pins.

6. A four pin wet mateable receptacle (WMRC) is mounted horizontally in the T.H. One of the contact pins is be grounded to the connector housing and the housing itself grounded to the T.H. body by the metal / metal seal interface.

7. The receptacle body features a means of ensuring accurate orientation in the tubing hanger.

8. The receptacle housing will resist fouling from debris by providing vent slots for debris ejection.

9. Galling between the connector housings during make-up will be avoided.

10. The sealing boot arrangement at the rear of the connector forms a manifold for three separate elastomer pressure balancing conduits to carry the signal cables to the DMEC arrangement at the bottom of the Tubing Hanger.


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Bonnet AssemblyWet Mate Plug & Plug Carraige Assembly in foreground & Internal Penetrator (without field assemblable cable gland).

TREE BONNET ASSEMBLY DESCRIPTION1. The tree bonnet assembly will comprises a moving carriage assembly carrying the WMPC stroked by the bonnet mechanism to allow its withdrawal, enabling removal of the T.H. under normalconditions. This carriage assembly carrying will also provide a means of allowing the WMPC to align with the WMRC, under the defined maximum T.H. to actuator bonnet misalignment conditions.

2. The WMPC will feature a shear point, which allows T.H. retrieval to be carried out safely and with aminimum of damage to the system in the event that the bonnet actuating mechanism fails and theWMPC cannot be withdrawn.

4. Moving parts have suitable bearing materials or coatings to prevent galling during the 20 yearsystem working life.

5. The carriage assembly is keyed and oriented to the bonnet assembly preventing torsional loadsgenerated from the actuator, being transmitted to the WMPC body.

6. Free movement of the WMPC body and carriage assembly is allowed for in the design.

7. Signal wires from the WMPC are fed to an exiting internally fitted penetrator or connector.

8. The signal wires are run in a pressure compensated 'gel' filled hose loosely coiled around the bonnet actuation rod.

9. The internal penetrator will feature primary metal / metal seals and elastomeric back-up seals.

10. Earth continuity will be maintained from the T.H. through the bonnet to the surface control module.

11. Verification of the WMPC and internal penetrator assembly function is required during F.A.T.

12. The external bonnet connection system features a signal wire carrying conduit hose assembly leading to a wet mate stab plate mounted connector.

13. The hose will interfaces to the bonnet, enveloping the internal penetrator outlet, providing directpressure compensation. The hose length is specified by the wellhead manufacturer.

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Plug Carriage AssemblyWet Mate Receptacle & Plug / Carriage Assembly Alignment details etc.,

DEAD

STOP

STROKE =

AngularMisalignment

(plan view)= +/- 1 degree

Misalignment Zone = 6mm dia max

(To Dead Stop)

DEAD

STOP

DEAD

STOP

Contact Engagement Zone = 0.125"

Contact Engagement Zone = 0.125"

AngularMisalignment(front view)= 1 degree max+-

Wet Mate Plug

Receptacle Wet Mate Plug /Carriage Assembly

Wet Mate Plug

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TP644

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TP212

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The Internal Penetrator provides the environmental seal. The internal penetrator is rated at 10,000 psi working (15,000 psi test). Sealing between the penetrator and tree is achieved by two "O" rings and metallic "C" Seal. The internal penetrator is provided for onward connection to a standard Mini CE connector via an oil hose hose conduit or standard subsea cable.

MAIN FEATURES & PERFORMANCE■ Terminates up to 4 signal lines.

■ Dielectric oil / gel pressure balanced signal wire

terminations.

■ Compact design

■ At least 2 levels of seal redundancy.

■ Qualified for operation at 10 kpsi / 500 degrees C for up to 20 years.

■ Proof pressure 15 kpsi.

■ Pressure energised polymer / metal or metal / metal primary barrier seals with elastomeric back-up seals.

■ Final barrier environmental penetrator manufactured to requirements of API 6 A.

TECHNICAL SPECIFICATION

Electrical:Net working Current: 5 AmpNet working voltage: 250 Volt DCMax test voltage: 1500 Volt DCMin insulation resistance: 1 GW @ 500 V / 200 deg CInsulation resistance: > 500 MW @ 1450 deg C for

48 hoursMax contact resistance: < 2.5 mW Qualified at: 5,000 psi @ 500 deg CNo. of contacts: 4

Environmental:Design Pressure: 10,000 psiDesign Temperature: 500 deg C

Mechanical:Termination: Gel / oil protected

Quality / Test:Complient with: A.P.I. - 6A & A.P.I. - 17 DApprovals: Lloyds (7RC) requirements of

API 6 A.

Internal Penetrator

Hose Conduit to Wet Mate CE Plug

Bonnet assembly

Internal Penetrator

Field Installable Cable Gland

Internal Penetrator with Field AssembleableCable Gland & Hose Conduit entering Bonnet Assembly

4 Way Internal Penetrator

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4 way horizontal wellhead feedthrough...

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