TOP 5 PROJECTS
Valhall overhaul could extend
operations by up to 40 years
BP started oil production from new fa- cilities on the Valhall feld off south- ern Norway on Jan. 26, 2013. Group CEO Bob Dudley said the redevelop- ment, estimated to have cost close to
$3 billion, was one of the company’s most
complex feld expansion developments to
date. It is designed to prolong production
from Valhall until 2050, with capacity to handle 120,000 b/d of oil, 200,000 b/d of NGLs,
and 143 MMcf/d ( 4 MMcm/d) of gas.
The centerpiece of the project is a new
production, utilities, and accommodation
platform (PH) bridge-linked to the main Valhall complex’s existing six steel platforms.
These and the new installation are now powered 100% from shore via a newly-laid 294-km
(182-mi) DC cable from Lista, the frst such
arrangement on any feld offshore Norway.
BP discovered Valhall in 1975, and the original three production facilities began operating in 1982. At the time of sanction, estimated
recoverable reserves were 435 MMboe. In
the event, nearly 1 Bbbl of oil were produced
prior to the start-up of the PH platform, and
the company and its partner aim to deliver a
similar volume over the remaining feld life.
Capacity has been boosted in recent years by
the addition of two unmanned wellhead platforms north and south of the feld center, and
a dedicated water injection (IP) platform. Produced oil continues to be exported through
a pipeline that runs via the Ekofsk offshore
center to Teesside in northeast England. Gas
is sent to Emden on the German north coast
via the Norpipe trunkline system.
BP’s redevelopment plan for Valhall was
approved by Norway’s parliament in June
2007. Aside from extending feld life, the partners’ goals in opting for a brand new platform
included improved effciency of production
operations and, according to analysts ScanBoss, avoided the need to jack up the existing
platforms as the feld is subject to subsidence.
Prior to project sanction, BP awarded
Wood Group and its US subsidiary Mustang
Engineering a front-end engineering design
(FEED) contract for the PH platform. Design was performed in accordance with Gulf
of Mexico practice, ScanBoss said.
Post-sanction, Heerema Fabrication Group
secured the 11,000-ton topsides, the 2,000-ton
weather deck module, and the 350-ton fare
tower at the group’s covered assembly hall
in Zwijndrecht, the Netherlands. Aker Verdal
in Norway built the 7,500-ton jacket and 12
piles, weighing 4,100 tons. UK fabricator SLP
built and then delivered the 3,200-ton, 180-
man living quarters, and the 900-ton power-
from-shore module in 2010, despite entering
receivership the previous year. Saipem’s
crane barge S7000 installed the jacket in June
2009 and the deck and topsides modules the
following summer, along with the bridge link
to Valhall’s IP platform.
Fabricom performed FEED for associated
modifcations to the existing platforms and
these were later implemented by maintenance
contractor Aker Offshore Partner, which was
also responsible for hook-up of the PH. JP
Kenny handled FEED for the reconfguration
of pipeline tie-ins between PH and the existing
PCP process platform, with Subsea 7 managing the offshore installations.
ABB provided the power-from-shore system for the new converter stations, based
on its HVDC Light technology. Nexans engineered the high-voltage power cable, which
it also installed during 2009-2010 using the
cable-lay vessel Skagerrak. The system was
frst tested in June 2011, and later used briefy
to supply power to the entire Valhall complex
following a fre on the PCP platform prior to
the start-up of the new platform.
Switching to onshore-generated power should
cut Valhall’s carbon dioxide (CO2) emissions by
300,000 tons annually during the next fve years,
Various design and construction issues
combined to delay start-up of the redevelop-
ment by more than two years. As a result,
BP had to seek permission to keep the PCP
and QP quarters platforms in service, but
these will eventually be decommissioned,
ScanBoss reported, along with the original
DP drilling platform.
One associated scheme was the addition
of gas-lift at the north and south fank wellhead platforms. Subsea 7’s Seven Navica installed two 8-in. diameter gas-lift lines to the
two installations in 2010, along with a 30-in.
caisson at the WP platform in the feld center. Next year BP hopes to submit a plan for
development of reserves on Valhall’s west
fank, which could involve drilling 14 new
wells, including six water injectors.
The company has further plans to redevelop the nearby Hod feld, possibly via a
new unmanned wellhead platform with 25
well slots. Production would be sent for processing to the Valhall center via a new 12-
km ( 7.4-mi), 12-in. multi-phase pipeline, with
power and control supplied from Valhall
through fber-optic subsea cables. •
BP Norge’s new Valhall PH platform.