The Deepwater
Horizon oil spill is an oil spill in the Gulf of Mexico which flowed
for three months in 2010. The impact of the spill continues since the well
was capped. It is the largest accidental marine oil spill in the history
of the petroleum industry. The spill stemmed from a sea-floor oil gusher
that resulted from the April 20, 2010 Deepwater Horizon drilling rig
explosion. The explosion killed 11 platform workers and injured 17
others.
At
approximately 9:45 p.m. CDT on April 20, 2010, methane gas from the well,
under high pressure, shot all the way up and out of the drill column,
expanded onto the platform, and then ignited and exploded. Fire then
engulfed the platform. Most of the workers escaped the disaster by
lifeboats or were airlifted out by helicopter, but eleven workers were
never found despite a three-day Coast Guard search operation, and are
presumed to have died in the explosion. Efforts by multiple ships to douse
the flames were unsuccessful. After burning for approximately 36 hours,
the Deepwater Horizon sank on the morning of April 22, 2010.
Federal
authorities banned commercial and recreational fishing in a large stretch
of water off four states, from the mouth of the Mississippi River off
Louisiana to western parts of the Florida Panhandle.
On July 15, the leak was stopped by capping the gushing wellhead.
Long-term
impact of Gulf of Mexico oil spill remains unclear. The oil spill will
have long-term effects on businesses the environment, wildlife and jobs in
the Gulf Coast region.
The Effects
of Oil on Wildlife
Oil affects wildlife by
coating their bodies with a thick layer. Many oils also become stickier
over time (this is called weathering) and so adheres to wildlife even
more. Since most oil floats o nthe surface of the water it can effect many
marine animals and sea birds. Unfortunately, birds and marine mammals will
not necessarily avoid an oil spill. Some marine mammals, such as seals and
dolphins, have been seen swimming and feeding in or near an oil spill.
Some fish are attracted to oil because it looks like floating food. This
endangers sea birds, which are attracted to schools of fish and may dive
through oil slicks to get to the fish.
Oil that sticks to fur or feathers, usually crude and bunker fuels, can
cause many problems. Some of these problems are:
•hypothermia in birds by
reducing or destroying the insulation and waterproofing properties of
their feathers;
•hypothermia in fur seal pups by reducing or destroying the insulation
of their woolly fur (called lanugo). Adult fur seals have blubber and
would not suffer from hypothermia if oiled. Dolphins and whales do not
have fur, so oil will not easily stick to them;
•birds become easy prey, as their feathers being matted by oil make them
less able to fly away;
•marine mammals such as fur seals become easy prey if oil sticks their
flippers to their bodies, making it hard for them to escape predators;
•birds sink or drown because oiled feathers weigh more and their sticky
feathers cannot trap enough air between them to keep them buoyant;
•fur seal pups drown if oil sticks their flippers to their bodies
•birds lose body weight as their metabolism tries to combat low body
temperature;
•marine mammals lose body weight when they can not feed due to
contamination of their environment by oil;
•birds become dehydrated and can starve as they give up or reduce
drinking, diving and swimming to look for food;
•inflammation or infection in dugongs and difficulty eating due to oil
sticking to the sensory hairs around their mouths;
•disguise of scent that seal pups and mothers rely on to identify each
other, leading to rejection, abandonment and starvation of seal pups;
and
•damage to the insides of animals and birds bodies, for example by
causing ulcers or bleeding in their stomachs if they ingest the oil by
accident.
Oil does not have to be sticky to endanger wildlife. Both sticky oils such
as crude oil and bunker fuels, and non-sticky oils such as refined
petroleum products can affect different wildlife. Oils such as refined
petroleum products do not last as long in the marine environment as crude
or bunker fuel. They are not likely to stick to a bird or animal, but they
are much more poisonous than crude oil or bunker fuel. While some of the
following effects on sea birds, marine mammals and turtles can be caused
by crude oil or bunker fuel, they are more commonly caused by refined oil
products.
Oil in the environment or
oil that is ingested can cause:
•poisoning of wildlife
higher up the food chain if they eat large amounts of other organisms
that have taken oil into their tissues;
•interference with breeding by making the animal too ill to breed,
interfering with breeding behaviour such as a bird sitting on their
eggs, or by reducing the number of eggs a bird will lay;
•damage to the airways and lungs of marine mammals and turtles,
congestion, pneumonia, emphysema and even death by breathing in droplets
of oil, or oil fumes or gas;
•damage to a marine mammal's or turtle's eyes, which can cause ulcers,
conjunctivitis and blindness, making it difficult for them to find food,
and sometimes causing starvation;
•irritation or ulceration of skin, mouth or nasal cavities;
•damage to and suppression of a marine mammal's immune system, sometimes
causing secondary bacterial or fungal infections;
•damage to red blood cells;
•organ damage and failure such as a bird or marine mammal's liver;
•damage to a bird's adrenal tissue which interferes with a bird's
ability to maintain blood pressure, and concentration of fluid in its
body;
•decrease in the thickness of egg shells;
•stress;
•damage to fish eggs, larvae and young fish;
•contamination of beaches where turtles breed causing contamination of
eggs, adult turtles or newly hatched turtles;
•damage to estuaries, coral reefs, seagrass and mangrove habitats which
are the breeding areas of many fish and crustaceans, interfering with
their breeding;
•tainting of fish, crustaceans, molluscs and algae;
•interference with a baleen whale's feeding system by tar-like oil, as
this type of whale feeds by skimming the surface and filtering out the
water; and
•poisoning of young through the mother, as a dolphin calf can absorb oil
through it's mothers milk.
Animals covered in oil at
the beginning of a spill may be affected differently from animals
encountering the oil later. For example, early on, the oil maybe more
poisonous, so the wildlife affected early will take in more of the poison.
The weather conditions can reduce or increase the potential for oil to
cause damage to the environment and wildlife. For example, warm seas and
high winds will encourage lighter oils to form gases, and will reduce the
amount of oil that stays in the water to affect marine life.
The impact of an oil spill
on wildlife is also affected by where spilled oil reaches.
Credit: The Times Picayune
Offshore
Drilling
Drilling
offshore dates back as early as 1869, when one of the first patents was
granted to T.F. Rowland for his offshore drilling rig design. This rig was
designed to operate in very shallow water, but the anchored four legged
tower bears much resemblance to modern offshore rigs. It wasn't until
after World War II that the first offshore well, completely out of sight
from land, was drilled in the Gulf of Mexico in 1947. Since then, offshore
production, particularly in the Gulf of Mexico, has resulted in the
discovery and delivery of a great number of large natural gas and oil
deposits. There are 3859 active platforms in The Gulf of Mexico .
There are two
basic types of offshore drilling rigs: those that can be moved from place
to place, allowing for drilling in multiple locations, and those rigs that
are permanently placed. Moveable rigs are often used for exploratory
purposes because they are much cheaper to use than permanent platforms.
Once large deposits of hydrocarbons have been found, a permanent platform
is built to allow their extraction.
Types of offshore oil
and gas structures include:
1, 2) conventional
fixed platforms (deepest: Shell’s Bullwinkle in 1991 at 412 m/1,353 ft
GOM);
3) compliant tower
(deepest: ChevronTexaco’s Petronius in 1998 at 534 m /1,754 ft GOM); \
4, 5) vertically moored
tension leg and mini-tension leg platform (deepest: ConocoPhillips’
Magnolia in 2004 1,425 m/4,674 ft GOM);
6) Spar (deepest:
Dominion’s Devils Tower in 2004, 1,710 m/5,610 ft GOM);
7,8) Semi-submersibles
(deepest: Shell’s NaKika in 2003, 1920 m/6,300 ft GOM);
9) Floating production, storage, and offloading facility (deepest: 2005,
1,345 m/4,429 ft Brazil);
10) sub-sea completion
and tie-back to host facility (deepest: Shell’s Coulomb tie to NaKika
2004, 2,307 m/ 7,570 ft).
Deepwater Horizon
The DEEPWATER HORIZON was a Reading & Bates Falcon RBS8D design
semi-submersible drilling unit capable of operating in harsh
environments and water depths up to 8,000 ft (upgradeable to
10,000 ft) using 18¾in 15,000 psi BOP and 21in OD marine riser.
Rig Type
5th Generation Deepwater
Design
Reading & Bates Falcon RBS-8D
Builder
Hyundai Heavy Industries Shipyard, Ulsan, South Korea
