The Douglas Complex is a 54-metre (177 ft) high system
of three linked platforms in the Irish Sea, 24 kilometres (15 mi) off
the North Wales coast. The Douglas oil field was discovered in 1990, and
production commenced in 1996. Now operated by Eni, the complex consists
of the wellhead platform, which drills into the seabed, a processing
platform, which separates oil, gas and water, and thirdly an
accommodation platform, which is composed of living quarters for the
crew. This accommodation module was formerly the Morecambe Flame jack-up
drilling rig.
The Liverpool Bay Development - BHP Petroleum's
largest single project worldwide - comprises four oil and gas fields,
together with significant offshore and onshore facilities used for
extracting, transporting and processing these reserves.
Offshore
operations are centred on the Douglas complex - a three-platform
facility that monitors and controls the development's three unmanned
satellite platforms at Lennox, Hamilton and Hamilton North. Oil and gas
from all four fields are received at Douglas.
The oil - produced
from the Lennox and Douglas fields - is then processed, blended and sent
through a 20km pipeline, to the offshore storage installation, before
being loaded into tankers, for export worldwide.
Gas - extracted
from Hamilton and Hamilton North as well as from Lennox - is
part-processed on Douglas before it travels via a 34km pipeline to BHP's
state-of-the-art gas terminal, at Point of Ayr, on the North Wales
coast.
The total recoverable reserves in Liverpool Bay are
currently estimated to be in excess of 150 million barrels of oil and
1.2 trillion ft³ of gas. With peak oil production expected to average
some 70,000 barrels per day, and a peak gas capacity of 300 million ft³
per day, the life of the development is projected to be at least 20
years.
THE DOUGLAS COMPLEX
The three-platform Douglas Complex,
sited 24km from the North Wales coast, is the nerve centre of the
offshore development. It is manned around the clock, controlling and
monitoring activities in all four Liverpool Bay fields from a central
control room located on the accommodation platform.
Alongside the
accommodation platform, linked by a 46m-long bridge, is the central
processing platform, which has eight legs and weighs 10,715t. This
processes all of the oil and gas produced in the fields. The processing
platform also houses two massive 42MW gas turbine generators, which
provide the power for all of the offshore units.
The third platform
in the Douglas complex is the wellhead tower, where the fluids are
received before they are piped across a 50m bridge, to the central
processing platform.
Like the satellite platforms in Liverpool Bay,
Douglas is protected by a 500m shipping exclusion zone, which is
constantly monitored by radar and patrolled 24 hours a day, by one of
the development's three support vessels.
THE SATELLITE PLATFORMS
Lennox, Hamilton and Hamilton North are satellite production platforms,
linked by pipeline and communications systems to the Douglas Complex.
In order to reduce their size and visual impact, the three platforms
are unmanned. Despite this, the regular servicing of these facilities
still takes place thanks to the Irish Sea Pioneer - a mobile,
self-elevating operations support vessel (OSV), which moves around the
development to carry out testing, inspection and maintenance. Once in
position alongside a platform, the OSV lowers its four giant legs onto
the sea bed and then lifts itself out of the water to the level of the
platform deck.
A bridge link is then created between the
satellite and the OSV to allow engineers and technicians to carry out
their work.
THE OFFSHORE STORAGE INSTALLATION
All of the oil
produced in Liverpool Bay is sent from Douglas to the development's
offshore storage installation - an 870,000bbl-capacity tanker, which is
permanently moored outside shipping lanes in the Irish Sea. Designed
with safety as a key priority, the OSI is a double-sided vessel - with
its ten cargo tanks flanked by segregated 4.8m-wide seawater ballast
tanks. As well as being manned around the clock, it is protected by an
800m exclusion zone, which is continuously monitored by radar and
patrolled 24 hours a day by a high-powered support boat.
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