PREVENTing AND
RESPONding to OIL SPILLS
Shell has several decades of operational experience in
a number of Arctic and subarctic regions. We take the
consequences of any potential incident very seriously.
Continuing to build our capability in oil spill prevention and
response is a top priority for Shell.
We have taken significant steps to make sure we can operate
safely and responsibly in the Arctic. Some of our planning
and safety measures for preventing and responding to oil spills
go beyond regulatory requirements. We recognise oil spill
prevention and response capability as a critical element of all
plans to develop oil and gas resources in the Arctic.
Shell applies a multi-layered well control system designed to
minimise risks, so if any one system or device fails it should
not lead to a blowout (an uncontrolled upsurge in oil and gas
at high pressure). At Shell, these barriers are regularly audited
and tested.
We have developed highly advanced technology to locate,
contain and remove oil in various ice conditions.
We know that being able to prevent and respond to oil spills in
ice is the right approach if we are to develop energy resources
while at the same time protecting the environment and local
communities. Having this capability is instrumental to our licence

to operate in the Arctic
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PREVENTing AND RESPONding to OIL SPILLS
SPILLS FROM OIL AND GAS
ACTIVITIES
The oil and gas industry has a strong safety record in
Arctic waters. In over 40 years, a total of more than
500 exploratory and production wells have been drilled
in the seas off Alaska, Canada, Norway and Russia.
This includes more than 150 wells off the coasts of the
USA and Canada, with more than 50 in the Beaufort and
Chukchi Seas. Shell has drilled 33 wells in Alaska, all
but one offshore. During these four decades of offshore
operations, there has never been an oil spill caused by a
well blowout in state or federal waters in the Alaskan and
Canadian Arctic.
Test of mechanical skimmer for cleaning up oil spills in the Arctic (SINTEF photo).
Deepwater Horizon and our response:
PREVENTING SPILLS DURING DRILLING
Modern drilling and blowout prevention techniques have
significantly reduced the likelihood of a blowout. But as
the Deepwater Horizon incident in the Gulf of Mexico
(GoM) in 2010 showed, if it does occur the impacts from
such an incident can be significant.
Shell applies a multi-layered well control system designed to minimise
risks. If any system or device fails, others are in place to prevent a
blowout.
After the spill, Shell took immediate steps to confirm the
safety of our operations globally, including a review
of operating practices, testing frequencies and training
protocols. The Gulf of Mexico tragedy clearly had
important consequences for the energy industry. It is
essential that we understand the events that led to this
unprecedented incident and take steps to further reduce
the likelihood of a similar event happening in the future.
As recognised by the Presidential Commission report on
Deepwater Horizon, some operators such as Shell do
operate to a high standard. Based on Shell’s experience,
we know that when you design wells properly, tragic
incidents such as the Deepwater Horizon one in the GoM
should not occur. Wells must be designed for the range of
risks anticipated. Operators must also follow established
procedures, build in layers of redundancy and proper
barriers, properly inspect and maintain equipment, train
staff, conduct tests and drills, and focus on safe operations
and risk management.
Wherever we operate, our safety performance is critically
important – for the safety of our staff as well as for the
protection of the environment and our neighbours.
Our approach to operating in the Arctic is no different.
We have had plans in place for many years to deal with
an accident of potentially similar impact to that in the
GoM in 2010.
Before exploration drilling begins, seismic and other surveys provide
essential information about the geology of the seabed. They also
give us vital information on pressure and temperature fluctuations
that could be encountered during drilling. The well itself is carefully
designed to cope with these. Our global standards require at least
two independent barriers. Barriers can include cement, casing, and
additional plugs. Sensors down the well convey real-time information
about pressure and temperature back to an operations centre so that
any potentially dangerous fluctuations can be picked up immediately,
and the pressure adjusted or the pumps shut off. At this point the well
can be shut down, with a heavy column of mud pumped down the
well to overcome the pressure, “killing’’ the well. Strongly cemented
casing in the well provides enough support to resist the sudden
pressures.
Shell has developed comprehensive plans to deal with storm or
hazardous ice conditions that might force a shut-down of operations.
These plans are supported by continuous weather and ice
surveillance and forecasting using sophisticated computer modelling,
radar and satellite imagery. Shell employs observers on board
our vessels who monitor ice conditions that could affect drilling
operations.
If for any reason these measures of early detection should fail,
mechanical barriers such as a blowout preventer is designed to seal
off the well. This is a series of valves that can be closed in sequence,
providing back-up in case one device should fail.
Blowout preventers are designed and tested to withstand the
maximum expected pressure. They activate automatically in the event
of a power failure on a drilling platform.
If, despite all precautions, a blowout does occur, a relief well can
be drilled to intersect with the original well and pump in cement
or drilling fluid, cutting off the oil flow. Before any exploration or
production operations the drilling plan has to be approved by
regulators. Before giving approval, they conduct stringent reviews of
the relief well plan.
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Responding to spills
Shell has built an industry-leading capability in preventing
spills and in our readiness to respond to any that occur.
We regularly test our plans and preparedness, and take
part in large-scale joint exercises with other industry partners,
government agencies, scientists and oil spill experts. We
are constantly prepared to mobilise people and equipment
around the world and we continuously fund and conduct
research and development in the areas of oil spill response.
The effectiveness of options to response to spills under Arctic
conditions has been widely tested. These tests include trials
held over three years by the Joint Industry Program (JIP) on
Oil Spill Contingency for Arctic and Ice Covered Waters.
Oil in the sea
Natural seeps occur when crude oil leaks from beneath the
sea floor into the water. They form the largest single source of
petroleum in the marine environment, accounting for 45% of
all oil in the world’s oceans. Seeps have existed for millions of
years and are part of the ecosystem in many areas. There are
natural seeps off the coast of West Greenland, off California,
in the northern Mediterranean Sea, in the Caspian Sea and
in the Gulf of Mexico. These areas normally have a thriving
marine ecosystem, despite the natural seep of a significant
amount of oil into the water. Bacteria naturally present in the
seawater feed off this oil and effectively biodegrade it.
Mechanical containment and recovery
If a spill does occur, the rapid containment and recovery of oil
at or near the source is the first goal. Mechanical skimmers can
be used to remove oil from the water surface and transfer it to
a storage vessel. Skimmers work most efficiently on thick oil
slicks: floating barriers, known as oil booms, are used to collect
and contain spilled oil into a thicker layer. A variety of designs
for skimmer and booms have been adapted for Arctic sea
conditions and several have been proven to work well.
Controlled in situ burning
Oil on water or between layers of ice can also be tackled
quickly, efficiently and safely by controlled burning. This
technique works most efficiently on thick oil layers, so the oil
needs to be contained by fire-resistant booms, ice or by a
shoreline. On average, about 80-95% of the oil is eliminated
as gas, 1-10% as soot and 1-10% remains as a residue.
Following the burning, this residue can be recovered from
the water surface. Controlled burning is a proven response
developed over several decades by the oil industry, emergency
response authorities and scientists. This involved extensive
laboratory and tank testing, large-scale field experiments
and lessons from real incidents. Burns can eliminate 1,000
barrels of oil per hour. Through tests over several decades,
in situ burning has been proven to work well in the Arctic.
Dispersants
Chemical dispersants are another method of cleaning up
spills. They have proven highly effective in the Arctic through
extensive testing. Dispersants are like detergents designed
Testing how to apply chemical dispersants directly from vessel.
for use in marine environments. They accelerate the breakup
of oil slicks into fine droplets that can then disperse and
biodegrade more easily in the sea. The use of dispersants
offshore is generally recognised as an efficient way of rapidly
treating large areas of spilled oil to reduce the impact on
marine life and the environment. They can be applied from
fixed-wing aircraft, helicopters, and vessels.
Capping and Containment dome
Shell is commissioning the building of a subsea containment
system that involves capturing and recovering hydrocarbons
at source in the unlikely event of a well control incident in
the shallow waters off Alaska. This recovery method has
proved effective in shallow water, and is expected to be
ready for the 2012 Alaska drilling season. The containment
system is designed to capture and recover oil and gas
from an undersea well in the event of failure by the blowout
preventer. The recovered oil would be transferred to a surface
processing facility for separation of oil, gas, and water.
Recovery in Arctic conditions
Shell has always recognised that a spill in the Arctic would
pose special challenges. But the low temperatures would
also present opportunities to help contain spilled oil, slow its
spread and provide vital time to respond with a variety of
methods. When exposed to low air and water temperatures,
oil tends to thicken, resulting in slower spreading and a
reduced spill area. Cold water and ice can aid oil spill
response operations by slowing oil weathering (the time it
takes oil to emulsify) and reducing the action of waves to
limit the spread of oil. Evaporation also slows down in cold
temperatures and ice, allowing oil to retain its lighter and
more volatile components longer and making it easier to burn
off. When ice is too concentrated in an area for the use of a
boom to contain the spill, it can act as a natural barrier that
helps collect oil for recovery with skimmers. In the coldest
temperatures, oil released under ice may become trapped
within newly-forming ice. This oil is then effectively isolated
from any direct contact with marine life or birds, and from
natural processes such as evaporation and dispersion. The
fresh condition of the oil, when later exposed, increases the
chances of successful burning.
*
The pictures with oil in ice are from the SINTEF joint industry project.
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The oil spill response vessel, Nanuq (pictured left).
Above: crew members onboard Nanuq, Alaska.
In short
Our track record:
Oil and gas operations are designed to contain oil and gas
in wells and production facilities and prevent oil spills to
the environment. In our efforts to help meet growing global
energy demand, Arctic resources are expected to play an
important role. We recognise that one of the most serious
concerns among communities affected by potential Arctic
development is whether the industry has the capability to
manage a potential oil spill.
Shell has a good record of spill prevention in the Arctic
and subarctic. Our experience from operations in these
regions helps us to work in extreme and unpredictable
weather and ice conditions far from populated centres
and support facilities.
Should a spill occur, Shell has a comprehensive range of
techniques and expertise in place to respond and mitigate
its effect in a variety of operating conditions. Independent
international research by SINTEF has shown that there are
efficient methods in place to manage Arctic spills and spills
in ice-covered waters. But we know we can always learn
more. Shell and the industry continue to invest in research
to improve equipment and operational readiness and are
applying the lessons learned elsewhere to further improve
oil spill response and prevention capabilities in the Arctic.
The Sakhalin 2 project, where Shell is a partner in the
operating company Sakhalin Energy Investment Company
Ltd, provides more evidence of our responsible approach.
This is one of the world’s largest integrated oil and gas
projects and is situated in Russia’s far east, where Arctic-like
conditions exist and the sea is covered by ice much of the
year. Sakhalin 2 is a project with an excellent record of
preventing spills. Since oil production started there in 1999,
the total volume of oil spilled at Sakhalin Energy-operated
assets is around 670 litres over a period that saw total
production of around 100 million barrels (12.77 million
tonnes) of oil. This represents around one litre of oil spilled
for every 22 million litres produced.
An example of this collaborative approach is the Joint
Industry Project (JIP) through The Oil and Gas Producers
(OGP) to advance year-round Arctic spill response
capability. Shell is leading this project, a collaboration of oil
spill response experts from nine major oil companies. The
project will look at the evaluation of environmental impacts
of oil spills, the fate of dispersed oil under broken ice field
and improved oil detection in Arctic waters, especially
in broken ice and at low visibility. The project will also
study the mechanical response to large spills in broken ice
and under ice, ignition techniques for in situ burning, and
advanced modelling that predicts the flow of oil in different
ice concentrations.
Our work in Alaska spans nearly 50 years and includes
safely drilling in the Beaufort and Chukchi seas.
This publication is one of a series of briefing notes on challenges related to oil and gas development in the
Arctic. The series includes Shell in the Arctic, Arctic Biodiversity, Working with Indigenous People, Technology
in the Arctic, Preventing and Responding to Oil Spills, Climate Change and Developing Arctic Oil and Gas.
Disclaimer
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and distinct entities. The collective expression ‘Shell’ and ‘Shell Group’ may be used for convenience where
reference is made in general to those companies. Likewise, the words ‘we’, ‘us’, ‘our’ and ‘ourselves’ may
be used to refer to the companies of the Shell Group in general. These expressions may also be used where
no useful purpose is served by identifying any particular company or companies.
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