H-7 Platform Removal Project - Oil & Gas...

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: