Legendre Field Decommissioning Environment Plan - Department of ...

Seabirds and turtle species are mostly unlikely, while cetacean and shark species have a
higher possibility of being present in the Legendre area.
Table 1: North West Shelf biological resources, breeding cycles and human activity
seasons
SPECIES JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Hawksbill turtle
nesting
Flatback turtle
nesting
Green turtle
nesting
Loggerhead turtle
nesting
Whale migration Nth Sth
Whale shark
aggregation
Seabird nesting
Legendre
Decommissioning
Key
Project description / Overview
Main aggregation period
Peak activity, presence reliable and predictable
Low level of abundance/activity/presence
Activity not occurring within the area
Execution timing for the decommissioning of the Legendre facilities and subsea equipment is
dependent upon field economic limit. Production operations will cease and decommissioning
work will commence from this commercially determined point in time. Apache currently has
approval for Economic End of Field life from January 2011.
The decommissioning work for the removal of the MOPU and the FSO from WA-20-L is
estimated to commence on 1 March 2011, weather permitting and subject to receiving the
necessary approvals. The subsea disconnection and removal activities are planned to start
late March/early April 2011 with completion anticipated to be early May 2011.
The Legendre facilities to be decommissioned include (see Figure 2):
“Ocean Legend” MOPU;
A single flexible 2.5 km oil export pipeline;
83 pipeline stability saddles;
1 Pipeline end manifold (PLEM);
1 Underbuoy hose with floatation modules;
1 Catenary anchor leg mooring buoy (CALM buoy);
6 mooring piles and anchor chains;
1 Floating export / import hose and hawser; and
The “Karratha Spirit” FSO tanker.
Decommissioning of the Legendre facilities will likely proceed in several phases (dependent
upon work vessel availability); with subsea removal being executed after the MOPU “Ocean
Legend” and FSO “Karratha Spirit” have departed the permit area. It is expected that the
plugging and abandoning of the wells will take 47 days to complete, the flushing and
Legendre Decommissioning EP Summary.docx Page 4 of 10