Breagh Development - RWE.com

Breagh Environmental Statement
Section 2 – Proposed Development
The HLV will moor at the installation site using up to 8 anchors which will be managed by up
to two anchor handling vessels. The template will be lifted from the barge and lowered into
position over the pre drilled wells and the two docking piles installed. After the docking piles
have been installed the template will be recovered to the surface.
The jacket will then be lifted from the barge and lowered into position over the pre-drilled
wells guided by the docking piles. Each leg of the jacket will be secured to the seabed. A
platform foundation assessment has been undertaken to identify the most suitable method
(Senergy Ltd, 2008). Four methods were considered; pile driven, drilled and grouted piles,
gravity based structure (GBS) and suction piles. Of these methods suction piles are not
considered feasible due to the presence of chalk as water ingress through fractures in the
chalk make it difficult to generate enough suction in the pile to penetrate it through the hard
chalk. Difficulties associated with drilled and grouted piles and GBS lead to driven piles
being the preferred option with up to 8 piles being required as a worst case option. A site
specific geotechnical survey and test programme has been undertaken by Fugro in April
2010 to establish the seabed strength.
The HLV will commence piling activities which are expected to last up to a maximum of 10
days. Piling activities will be initiated using the soft start method to minimise impact upon
cetaceans in the area. An Marine Mammal Observer (MMO) will be present during piling
activities. Once the piles are driven to a sufficient depth to secure the jacket to the seabed
the piles will be grouted to the jacket sleeves. The size of the piles which will be required to
secure the Breagh A NUI to the seabed have not been defined but are not likely to be
greater than 2.44 m in diameter.
Upon completion of piling the HLV will lift the topsides into position on the jacket and the
topsides welded to the top of the jacket legs. In total, installation activities will be
approximately 44 days. Table 2-5 details installation vessel requirements assuming no
weather delays.
Table 2-5 Summary of vessel requirements for installation of the NUI
Vessel Type Duration (Days)
Working Fuel
Consumption (t/d)
Total Fuel Use (t)
Barge - na -
Tow Tug 44 18 792
Heavy lifting Vessel 23 55 1,265
HLV Tug 23 18 414
Anchor Handling Tug
(x2)
16 18 288
Standby Vessel 23 2 (idle) 46
Guard Vessel (NFFO) 44 3 (idle) 132
TOTAL 209 - 2,937
Process Description
There will be no separation or processing of produced water on Breagh A. The Breagh
hydrocarbons will be metered and sent via export pipeline to TGPP Onshore Terminal for
processing and metering prior to passing to the National Transmission System (NTS).
Individual metering of wells for reservoir monitoring will be installed. The design capacity of
2-10