Classification: Internal 2010-09-20

Gjøa Power cable

A green solution

Svein-Egil Dretvik

Project Manager

Gjøa Risers and Cables

Content

• Gjøa project overview

• Power from shore.

A green solution

• Cable design

• Technology qualification

• Cable fabrication

• Installation

• Conclusions

Gjøa

Licencepartners:

• GDF SUEZ E&P Norway (30%)

Production Operator

• Petoro (30%)

• Statoil (20%)

Development Operator

• Shell (12%)

• RWE Dea (8%)

Gjøa - Based on history…

• The oil and gas field

discovered in 1989

• Named after Amundsen’s

1903 polar exploration vessel

• Statoil named operator for

the development phase in 2004

• Investment decision in

december 2006

• PDO approved in 2007

• Commercial production in October 2010

- GDF SUEZ E&P Norway takes over the operatorship

• 4 gas / 8 oil producers

• 4 templates and one satellite

• Tie-in of Vega and Vega South

• Power from Shore - Mongstad

• Rich gas export through FLAGS

to St. Fergus

• Stabilized oil export through

TOR2 to Mongstad

• Topside dry weight 22 000 t

• Topside size 110 x 85 m

• Hull dry weight 14 300 t

• LQ capacity 100 cabins

• Production Capacity:

Gas: 17,3 mill Sm3/d

Oil: 13800 Sm3/d

• Gjøa processing platform

– Flexible topside facilities and spare capacities

– Semi as field centre and hub for future satellite

tie-ins

– Integrated operations to the next level

– Vega/Vega south gasfield satellite tie-ins

– Area prospectivity and exploration

• Largest ongoing project on NCS

– Total investment NOK 40 billion

– Creating new opportunities in the region

– Total man-years 35.000

– 1 million manhours per month

Gjøa field development overall schedule

• Production templates installed summer 2008

• Drilling started December 2008

• Pipelines, umbilicals and risers installed and connected during 2009

• Production floater mating performed in December 2009 at Stord. Hull

fabricated in Korea, topside at Stord, living quarter Arendal

• Tow out of floater to field started 13. June 2010

• Subsea Powercable installed from late April to 17. May 2010

• First electricity delivered from shore to floater 11.July 2010

• First production planned Q4 2010

• Hand over of operator responsibility to Gas de France Suez after

production startup

Gjøa - Power generation evaluation

With Power Generation Offshore

compressor

WHRU

26MW

LP

Compressor

LM2500+

27 MW

WHRU

27MW

El power

generator

27 MW

El. power

Gas export

WHRU

27MW

El power

generator

27 MW

El. power

compressor

LM2500

26 MW

WHRU

26 MW

Gas export LP

Compressor

El. motor

17MWPower from shore

40 MW

With Power Generation Onshore

Fired Heater

Fuel Gas

Fuel GasFuel Gas Fuel Gas

Fuel Gas

Fuel Gas

Transformer

Equipment Bulk Struct Total delta

weight

8a1 -322 -50 18 -354

El. motor

13MW

LM2500+

27 MW

LM2500+

24 MW

LM2500+

26 MW

Reduction of

210 000 tonnes

CO2

each year

which represent

the disposal of

100 000 cars/

12 000 km

Gjøa Power from shore

– CO2

Emissions Gjøa+Vega

Scenario 8a1 - CO2

emissions

-

50 000

100 000

150 000

200 000

250 000

300 000

350 000

400 000

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

Ton C

O2

/ year

Platform Generation

Cable from Shore

Gjøa power cable design (115 kV XLPE)

Project:

115 kV AC cable system for Gjøa floating oil

platform in the North Sea, Norway for Statoil

Cable type:

XLPE 3 x 240 mm2

Cu, static cable with lead

sheath

XLPE 3 x 300 mm2

Cu, dynamic cable with

corrugated copper sheath

Length:

99 km static submarine cable

1,5 km dynamic submarine cable

Scope of supply:

Cable system including accessories

and installation – turnkey by ABB High

Voltage Power cable systems

Year:

Installation April-May 2010

Pic

ture

: A

ke

r K

va

ern

er

Fatigue capacity Lead and Copper sheath

• Lead as water shield used commonly for

static cables above 36 kV.

– Studies performed in the Feed phase

of the project showed lead to have far

to little fatigue resistance for the

dynamic part.

–Copper was therefore selected as

material for water shield and studies

and testing were started.

• In the tender phase ABB chose to

corrugate the copper, thus giving it a

better estimated fatigue life.

Overview dynamic and static sections

Static cable 99 km

For the dynamic

cable, lead sheath

have been replaced

by copper sheath

Cable length 1.5

km dynamic section

Flexible transition joint

Mongstad

Technology Qualification

• Test program established in ABB Research Centre in Vesterås in order to

obtain and construct SN curve for actual copper material for dynamic cable

–Horizontal bending rig testing 7 specimens at the time (Corrugated

copper and complete internals with conductor and insulation)

–Vertical testing of corrugated copper shield (Without internals)

–Material testing (Conventional method), Optional

• Full scale flex test performed at Marintek off hang off and bending

stiffener and touch down point performed at Marintek proved fatigue life

time above 30 years

• Full scale test of flexible fabric splice between static and dynamic cable

performed in Karlskrona. Splice bending tested and followed by high

voltage test

Bending Axial

Corrugated copper sheath, bending and axial

fatigue testing for dynamic cable (Vesterås)

Flex testing of bottom and top section of

dynamic cable at Marintek in Trondheim

Flexible splicing dynamic/static cable new

development for Gjøa by ABB

Dynamic section is spliced to

static section at fabrication yard.

Traditionally stiff transition joint

have been used. For Gjøa a

flexible transition joint system

have been qualified by ABB

High volt tests, bending and

tensile tests have been preformed

proving the feasibility

Length: 6,7m Weight: 2500 kg

Traditional stiff transition joint:

New qualified Flexible transition joint:

Mechanical and electrical testing

in Karlskrona

After bending trails the cable is inspected visually and electrically tested to

prove fit for purpose

Bending test High volt test

Cable fabrication

• Copper conductor welding, 57 km length

• PEX extrusion in vertical tower, 57 km

length

• Metallic sheath (Lead or Copper) and Core

jacket (2mm PE) extrusion, 57 km length

• Cable assembly also vertical. Three

conductors, PVC profiles and fibre optic

cable, 18 km length

• Factory joint of 18 km long batches

• Armouring

• Outer cover polymeric sheath

Power cable load out in Karlskrona by new

built installation vessel North Ocean 102

• Installation is initiated with cable

pull in at landfall Mongstad. Cable

pull in onshore through pre

trenched area assisted by onshore

winch

• Installation commence with cable

lay down steep slope at landfall and

laying in narrow corridor in

Fensfjorden

• Offshore installation from kP 35

toward Gjøa in wither corridor

• Dynamic section laid down at

seabed with buoyancy on waiting

for the floater to arrive in field for

hook-up

Power cable load out in Karlskrona

Dynamic cable

Bending stiffener

Static cable

Steep slope VIV supressors,

200 kg pull test

Landfall at

Mongstad

Installation vessel North Ocean 102

7000

tonnes

capasity

Dynamic chute, upper and lower position

• Dynamic shut improves the weather criteria to Hs 4.0 m.

• Sea trail performed in Fensfjorden in March 2010 with positive results in

HS=3.0 m

Installation vessel North Ocean 102

Midwater Survival System

• Contingency procedures developed

for Gjøa by ABB/KS to avoid cutting

the cable

- In bad weather (Hs above 4.0 m)

• Tested by sea trails in Fensfjorden

together with Dynamic shut with

positive result

- In Hs=3.0 m in March 2010

• Allow for weather of maximum

Hs=8.0 m before cable cutting is

required

Power cable Installation and Operation

•Cable installed from Late April to 17. May 2010

•Weather conditions during installation was favourable and operation

performed as expected

•Some damage to outer yarn due to high forces from dynamic chute

(rollers)

•Survey system did not perform and separate survey vessel used

•The cable have been in operation since 11. July at 25% of design capacity.

Full capacity required from production start up

Conclusions

• Power from shore – an environmentally friendly solution

• Reduced noise onboard the Gjøa platform – improved working

environment

• Extensive technology qualification program

• Purpose built installation vessel with innovative lay spread

• Extensive Statoil involvement and constructive teamwork with ABB

• Installation performed as expected

Gjøa Power cable. A green solution

Svein-E Dretvik

Project Manager Gjøa Risers and Cables

svd@statoil.com

www.statoil.com

Thank you