In oil and gas industry, floating liquefied natural gas (FLNG) is not just a term that rolls elegantly off the tongue but one also used to describe an offshore facility floating above a natural gas field.
FLNGs produce, liquefy, store and transfer liquefied natural gas via carrier ship to the mainland where both the market and the money is based.
FLNG technology can unlock gas resources from underwater gas fields that may once have been economically or environmentally challenging to obtain. This can help to meet growing demand for natural gas — the cleanest-burning hydrocarbon — which is set rise by more than half by 2040, according to the International Energy Agency. Many natural gas resources are located in offshore fields, but geographic, technical and economic limitations make a number of these difficult to develop.
FLNG technology is
designed to overcome these challenges. It is complementary to conventional
onshore liquefied natural gas (LNG) as it helps accelerate the development of
gas resources to meet growing demand.
is liquefied natural
Liquefied natural gas
(LNG) is natural gas, a mixture of methane and ethane, that has been cooled
down to liquid form so it can be easily transported. In its liquid state, LNG
takes up around 1/600th the volume of natural gas in its gaseous state. It is
odorless, colorless, non-toxic and non-corrosive. Hazards, however, include
flammability after vaporization into a gaseous state, freezing and asphyxia.
process removes dust, acid gases, helium, water and hydrocarbons that could
cause difficulty downstream. Aboard an FLNG facility, natural gas produced from
underwater fields is processed and chilled to -162° Celsius (-260° Fahrenheit).
This shrinks its volume by 600 times to create LNG. The advanced design of
facility’s on-board LNG plant packs a typical land-based LNG plant into around
one quarter of its normal size.
Natural gas is mainly
converted into LNG to achieve natural gas transport over the seas where laying
pipelines is possible. LNG achieves a higher reduction in volume than
compressed natural gas (CNG) which makes LNG cost efficient in marine transport
over long distances. LNG is principally used for transporting natural gas to
markets, where it is regasified and distributed as pipeline natural gas.
How does FLNG work?
The FLNG facility is moored directly above the
natural gas field. It routes gas from the field to the facility via risers. The
gas is then processed and treated to remove impurities and liquefied through
freezing, before being stored in the hull. Ocean-going carriers will offload
the LNG, as well as the other liquid by-products, for delivery to markets
worldwide. The conventional alternative to this would be to pump gas through
pipelines to a shore-based facility for liquefaction, before transferring the
gas for delivery.
Safety on Floating Liquefied Natural Gas
safety on the facility by locating storage facilities and process equipment as
far from crew accommodation as possible. The accommodation areas of visiting
LNG carriers are also at maximum distance from critical safety equipment.
Safety gaps have been allowed between modules of process equipment so that gas
can disperse quickly in the event of a gas leak.
are the benefits of FLNG?
Natural gas is
relatively clean burning compared to other fossil fuels. It is also more easily
found, cheaper and actually provides a number of environmental and economic
Firstly, there is no
need for pipelines, compression units, dredging, jetty construction or an
onshore LNG processing plant as processing is done at the gas field. This helps
maintain marine and coastal environments. The facility is also able to be
decommissioned and re-deployed elsewhere relatively easily.
Floating liquefied natural gas is more economically viable than pumping gas to the shore, opening new business opportunities for both developing countries and regions where disputes would make pipelines impractical. As well as this, the role of LNG as direct use fuel without regasification is growing slowly but surely.
What are the drawbacks of FLNG?
When it comes to the
design and construction of the FLNG facility, every element of a conventional
LNG facility needs to fit into a space around one quarter the size, whilst
maintaining safety and flexibility of production. Containment systems and
product transfers also need to withstand the effects of the wind and waves.
What is the history of Floating Liquefied Natural Gas?
development of offshore LNG production began in the mid-1990s. Mobil developed
a FLNG production concept based on a square structure with a moon pool in the
center, known as ’The Doughnut‘, in 1997. Following that, major projects
conducted by the EU and major oil and gas companies made great progress in
steel concrete hull design, topside development and LNG transfer systems. The
first completed FLNG production facility was the PFLNG Satu, off the shore of
Sarawak in Malaysia.
Since the mid-1990s,
Shell has been working on its own FLNG technology. This includes engineering
and the optimization of project developments in Namibia, Timor Leste/Australia,
and Nigeria. In July 2009, Royal Dutch Shell signed an agreement with Technip
and Samsung allowing for the design, construction and installation of multiple
Shell FLNG facilities.
facility is set to be the biggest one ever.
Prelude: What is the future of FLNG?
Launched in 2013, Prelude is Shell’s first FLNG facility. She recently reached a significant milestone when gas was introduced onboard for the first time. The Gallina, an LNG Carrier from Singapore, shipped the gas to the facility and utilities can now switch to run on gas rather than diesel.
Prelude is now on
location, 475km (295 miles) north-north east of Broome, Western Australia, in
around 250 metres of water. Once operating, Prelude FLNG will produce and
liquefy natural gas from the Browse Basin. Once fully operational, the project
will deliver LNG to Shell’s customers around the world while creating
significant economic and social benefits for Australia. They include hundreds
of jobs, tax revenues, businesses opportunities for local companies, and
Prelude’s hull is 488 metres long (1,600 feet). Despite its large proportions, the floating liquefied natural gas facility will take up just a quarter of the footprint of an equivalent land-based LNG plant. She is designed to remain at sea for around 25 years in severe weather conditions and even withstand a category five cyclone. FLNG facilities can then be re-deployed to develop new gas fields.
FLNG technology offers
countries a more environmentally-sensitive way to develop natural gas
resources. Prelude will have a much smaller environmental footprint than
land-based LNG plants, which require major infrastructure works. It also
eliminates the need to build long pipelines to the mainland.
In conclusion, and over the lifespan of Prelude, the project is expected to add billions of revenue to Australia’s economy, create hundreds of direct and indirect jobs, spend billions on Australian goods and services and improve the country’s balance of trade through export of LNG, LPG and condensate.