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H-7 Platform Removal Project
Vidar Eiken, Statoil
H-7 Booster Platform
H-7 was one of two Booster
platforms on Norpipe in the
German sector of the North Sea,
installed in 1976, taken out of
service in 1999 and by-passed in
2007
Immediately following bypass, the
platform was made cold. All
redundant systems were shut
down, hydrocarbon systems were
cleaned, hazardous materials
removed, and the platform de-
manned
Dry weight of the H-7 topside/MSF
and jacket was approximately 8900
tons
Water depth 41 m
Project Main Objectives
Completely remove the installations to shore for dismantling,
in accordance with the requirements from authorities and the
OSPAR Decision 98/3
The removal and disposal should be based on the most cost
efficient method and meet Statoil’s and Gassco’s HSE
standards and requirements
Recycling and re-use of materials will be done to the extent
possible
(Target was 98 % for steel jacket and 94% for topside)
Procurement Strategy
One major supplier with a total EPR (Engineering,
Preparations, Removal) responsibility
Disposal (D) was included as an option
The Contractors were allowed to tender with own «preferred
method»
During the pre-qualification process the selected candidates
performed an Extended Method Statement
Final technical qualification was performed as part of the
tender evaluation
Contract for seabed clean-up, rock dumping and survey were
established based on Company Frame Agreements
Schedule and Contractors
Statoil executed the project as a TSP (Technical Service Provider) to
Gassco
Project start-up in 2009
Tender issued in October 2010
EPRD Contract was awarded to AF Decom Offshore in December 2011
Main Contractor
Vessel Owner:
Subsea subcontractor:
Engineering, offshore topside surveys (helicopter) and subsea survey in
2012
Offshore removal and disposal completed in 2013
Vessel Type: WIV
161m long, 49m wide
DP class 2
111 POB
1200Te main crane
4300m2 free deck space
Built by Samsung in Korea
Delivered in December 2012
H-7 was the «first project»
Jack-Up Vessel «Pacific Osprey/Orca»
Vessel Positioning at H-7
Lifting Restrictions
No lift zone, lift
anticlockwise only
Lift route piece small
Lift route modules
Familiarisation Activities
All contractors and main subcontractors participated in Risk Assessments,
Hazid`s, and Hazop`s
HSE awareness seminars were arranged for offshore management
personnel including foremen level
The first HSE awareness seminar was held onboard the crane vessel
Pacific Orca enabling involved personnel to become familiar with the
vessel and crew
All offshore operators attended a 2 day familiarization session
Emergency preparedness table top exercises conducted in two sessions
Offshore Execution General
Offshore operations 19/2 - 2/7 2013
3 vessel trips to field using 165.000 offshore manhours
9 major topsides lifts, M012 the heaviest about 900Te
More than 1000 smaller lifts
Piece small, 1200Te brought to shore by PSV
Topside Removal – Piece Small
Method
Make Safe: Prepare areas for access/work
Frontrunning: Removal of non-metal &
hazardous waste
Removal of structure: Mechanical methods
preffered
Processing: Sorting/cutting to container size
on platform and vessel deck
Transport & disposal: Containers shipped to
AFEBV
2 excavators at offshore location
7 modules removed + crane booms
Topside Removal – Reverse
Installation
11 Topside modules removed:
M01 Living Quarter & Helideck
M03, M05 Crane Cabs
M06 Control Module
M11 Generator Module
M07, M08, M09, M10 Utility Deck
M12 MSF South
M13 MSF North
Overall weight => 4600 mT
Offshore Execution Subsea
Jacket removed in 4 lifts
Use of 2 WROV’s and dredger
Diamond wire cutter for all cuts
Debris and grout delayed dredging
Jacket Removal – Top Sections
Above water preparations:
Installation of rigging
platforms
Securing of center piles
Weight = 800 mT
Jacket Removal – Bottom Sections
Subsea preparations:
Remove 14 concrete covers
Dredging and pile cutting
Removal of 2x 36 inch risers
Weight = 600 mT
Onshore Disposal
Topsides:
Yard: AF Env. Base Vats (AFEBV)
More than 60 waste fractions
Weight: 6376 mT
Recovery rate 97.9%
Jacket:
Yard: AFEBV & Hoondert
Weight: 2600 mT
Recovery rate 99.8%
HSE Statistics Offshore
•All the preparatory works paid off !
•Injuries
–1 substitute work / (stumbled at deck level)
–1 finger injury when using the grinder
–Even wearing safety glasses, dust and high
winds resulted in a number of eyes being
washed by the medic
•165.000 manhours worked
H-7 Lessons Learned
Project Main Objectives have been met
Takes some time to «warm up» new crews
Number of lifts and efficient utilisation of crane
Weather limitations, particularly for the smaller
lifts
Lift plans to include planned use of tugger lines
Uncertainty in module weights
ROV visibility challenges, shallow waters and
high currents
Debris and concrete around legs
Dredging may be time consuming, equipment is
essential
B-11 Preparations for 2015
•Good interaction with the operator prior to platform shut-down
(make cold phase)
Monthly IF meetings with the operator prior to and after
decommissioning
Platform competence of the «old crew» members are very
important
AF DO had continous presence of 4 persons for 5 weeks
(Aug./Sept. 2014)
•Additional helicopter surveys in cold phase to support and
verify AF DO engineering
6 survey trips x 2 days x 5 persons have been planned
These are combined with planned operator maintenance
trips
B-11 Preparations for 2015
•Trial dredging of all platform piles/legs during offshore
survey
Inspect condition of mini-packers seals and identify any
grout spillage at an early stage
Grout has been identified
•Reduced number of lifts and size compared to H-7
Focus on more efficient utilisation of the maine crane
•Lift plans already include detailed planned use of tugger
lines
•Uncertainty in module weights
Rigging arrangement designed for flexibility
Selection of contractor and removal method
has been a great success
We have safely removed the platform
Within schedule cost and time
Our special thanks to: