kinds of naturally occurring oil-consuming bacteria:
sulfate-reducing bacteria and acid-producing bacteria are
anaerobic, while general bacteria are aerobic. These bacteria act to remove oil from an ecosystem, and their biomass
tends to replace other populations in the food chain.
Most marine oil spills are the result of accidents during
transportation; however, deep-sea accidents during production or exploration activities also occur. Although they
are rare, they may have a significant impact on the environment, such as the accident with the Deepwater Horizon
platform in 2010. Spilt oil penetrates the plumage of birds
and the fur of mammals, reducing its insulating ability and
making them more vulnerable to temperature fluctuations
and much less buoyant in the water. Cleanup and recovery
from an oil spill is difficult and depends upon many factors including the type of oil spilled, the temperature of
the water, weather condition, and the types of shorelines
and beaches involved.
The worst oil spills recorded in history include the
crude oil carrier Amoco Cadiz accident in 1978, about
5 km off the coast of Brittany, France. The vessel
contained 1857 barrels of crude oil when it ran aground.
Severe weather resulted in the complete breakup of the
vessel and the entire cargo was spilled into the sea. The
fuel oil was swept onto the French shoreline, and the total
extent of the spill includes more than 300 km of coastline,
where the oil penetrated the sand on several beaches to
a depth of half a meter. The resultant environmental
impact was massive due to delayed cleanup operations
owing to rough seas. In 1979, the Ixtoc I exploration well
in the Gulf of Mexico suffered a blowout in waters 50 m
deep. Due to a loss of hydrostatic pressure, the drilling
rig lost mud circulation. Without the counterpressure from
the circulating mud, the pressure in the oil reservoir forced
oil up the well resulting in a disastrous blowout. Large
quantities of oil and gas reached the surface and caught
fire. The fire and the eventual collapse of the drilling rig
caused damage to the underlying foundations of the well
structures, which led to significant amounts of oil leaking
into the Gulf. The incident led to the loss of 84,500 barrels
of oil that spread to beaches. The water contamination
directly affected food fish and octopus species. In early
1991, a disastrous environmental impact resulted from
the war in Kuwait. The retreating Iraqi military forces set
700 oil wells on fire in Kuwait. This severely affected
the Gulf economy and environment and destroyed several
tankers and terminals that resulted in the loss of close to
8.5 million barrels of oil each day. One of the most devastating manmade environmental disasters occurred in 1989.
The Exxon Valdez, an oil tanker that was carrying about
200,000 m
3 of oil, hit Prince William Sound’s Bligh Reef
on the south coast of Alaska and released
42,000–120,000 m
3 of crude oil into the sea. An inaccessible location made it difficult to deploy rescue and clean
up operations quickly. The oil spilled retains its toxicity
to this day putting a large amount of marine life and vegetation at risk. In 2009 an oil and gas leak occurred in
the Montara well in the Timor Sea, off the northern coast
of Western Australia in shallow waters. The oil spill was
released following a blowout and continued leaking for
74 days. The oil leak could have been as high as 2,000 barrels. BP’s Deepwater Horizon explosion in 2010 killed
11 people and injured several others, as well as resulted
in a severe oil spill. The oil spill flowed for 3 months
and spewed out 5.8 million barrels of crude oil. The spill
is considered one of the worst accidents in US history
and caused grave damage to the surrounding wildlife and
biosphere, putting at risk many endangered species. The
Gulf’s fishing and tourism industry were also seriously
affected. A 6-month offshore drilling moratorium below
150 m of water was enforced.
The Arctic area with its cold climate and waters represents a particularly vulnerable environment with respect
to wildlife, biodiversity, fisheries, and nature. Environmental regulations in the Arctic realm are typically stricter
than further south. Accidents analogous to BP’s Deepwater Horizon disaster in the Gulf of Mexico are expected to
have a much stronger impact on the highly sensitive Arctic
environment. The risk resulting from transportation at sea
has been shown quite plainly from the accident of the
Exxon Valdez tanker in 1989 in offshore southern Alaska.
There is already a risk of oil spills from the increased oil
tanker traffic, and there are additional concerns raised by
the increased petroleum exploration and production activities. The conditions in Arctic environments are less favorable for removing oil spills than in moderate or warm
climate conditions. The water temperature is close to zero
degrees Celsius, slowing down microbial processes and
reducing the dissolution and evaporation of oil compounds. Because oil-degrading microbes are usually
found in environmental samples, including relatively pristine Arctic environments, it is likely that the potential for
oil degradation is already present in the ocean around
Northern Greenland, but it is not known how fast and to
what extent the degraders will respond to increased oil
concentrations in waters and sediments. A better understanding of the potential of the indigenous microbial communities to react to naturally or accidentally spilled
hydrocarbons is necessary to delineate risks and develop
possible measures for remediation in the future.
Future targets for the petroleum exploration
One of the open questions is how much oil and gas will be
discovered in previously unexplored offshore areas.
Potential targets include shallow shelf areas that in the past
were not accessible, because of, e.g., the harsh environmental conditions in the Arctic, unconventional resources,
and deepwater areas (see Regional Marine Geology). In
well-explored basins (see Marine Sedimentary Basins),
further deepwater exploration will probably include more
giant gas discoveries in relation to oil giants and a move to
deposits in deeper water along passive continental margins (Chakhmakhchev and Rushworth, 2010).
The deep water is where many of the largest finds of
recent times have been made – but also poses challenges,
222
ENERGY RESOURCES
sulfate-reducing bacteria and acid-producing bacteria are
anaerobic, while general bacteria are aerobic. These bacteria act to remove oil from an ecosystem, and their biomass
tends to replace other populations in the food chain.
Most marine oil spills are the result of accidents during
transportation; however, deep-sea accidents during production or exploration activities also occur. Although they
are rare, they may have a significant impact on the environment, such as the accident with the Deepwater Horizon
platform in 2010. Spilt oil penetrates the plumage of birds
and the fur of mammals, reducing its insulating ability and
making them more vulnerable to temperature fluctuations
and much less buoyant in the water. Cleanup and recovery
from an oil spill is difficult and depends upon many factors including the type of oil spilled, the temperature of
the water, weather condition, and the types of shorelines
and beaches involved.
The worst oil spills recorded in history include the
crude oil carrier Amoco Cadiz accident in 1978, about
5 km off the coast of Brittany, France. The vessel
contained 1857 barrels of crude oil when it ran aground.
Severe weather resulted in the complete breakup of the
vessel and the entire cargo was spilled into the sea. The
fuel oil was swept onto the French shoreline, and the total
extent of the spill includes more than 300 km of coastline,
where the oil penetrated the sand on several beaches to
a depth of half a meter. The resultant environmental
impact was massive due to delayed cleanup operations
owing to rough seas. In 1979, the Ixtoc I exploration well
in the Gulf of Mexico suffered a blowout in waters 50 m
deep. Due to a loss of hydrostatic pressure, the drilling
rig lost mud circulation. Without the counterpressure from
the circulating mud, the pressure in the oil reservoir forced
oil up the well resulting in a disastrous blowout. Large
quantities of oil and gas reached the surface and caught
fire. The fire and the eventual collapse of the drilling rig
caused damage to the underlying foundations of the well
structures, which led to significant amounts of oil leaking
into the Gulf. The incident led to the loss of 84,500 barrels
of oil that spread to beaches. The water contamination
directly affected food fish and octopus species. In early
1991, a disastrous environmental impact resulted from
the war in Kuwait. The retreating Iraqi military forces set
700 oil wells on fire in Kuwait. This severely affected
the Gulf economy and environment and destroyed several
tankers and terminals that resulted in the loss of close to
8.5 million barrels of oil each day. One of the most devastating manmade environmental disasters occurred in 1989.
The Exxon Valdez, an oil tanker that was carrying about
200,000 m
3 of oil, hit Prince William Sound’s Bligh Reef
on the south coast of Alaska and released
42,000–120,000 m
3 of crude oil into the sea. An inaccessible location made it difficult to deploy rescue and clean
up operations quickly. The oil spilled retains its toxicity
to this day putting a large amount of marine life and vegetation at risk. In 2009 an oil and gas leak occurred in
the Montara well in the Timor Sea, off the northern coast
of Western Australia in shallow waters. The oil spill was
released following a blowout and continued leaking for
74 days. The oil leak could have been as high as 2,000 barrels. BP’s Deepwater Horizon explosion in 2010 killed
11 people and injured several others, as well as resulted
in a severe oil spill. The oil spill flowed for 3 months
and spewed out 5.8 million barrels of crude oil. The spill
is considered one of the worst accidents in US history
and caused grave damage to the surrounding wildlife and
biosphere, putting at risk many endangered species. The
Gulf’s fishing and tourism industry were also seriously
affected. A 6-month offshore drilling moratorium below
150 m of water was enforced.
The Arctic area with its cold climate and waters represents a particularly vulnerable environment with respect
to wildlife, biodiversity, fisheries, and nature. Environmental regulations in the Arctic realm are typically stricter
than further south. Accidents analogous to BP’s Deepwater Horizon disaster in the Gulf of Mexico are expected to
have a much stronger impact on the highly sensitive Arctic
environment. The risk resulting from transportation at sea
has been shown quite plainly from the accident of the
Exxon Valdez tanker in 1989 in offshore southern Alaska.
There is already a risk of oil spills from the increased oil
tanker traffic, and there are additional concerns raised by
the increased petroleum exploration and production activities. The conditions in Arctic environments are less favorable for removing oil spills than in moderate or warm
climate conditions. The water temperature is close to zero
degrees Celsius, slowing down microbial processes and
reducing the dissolution and evaporation of oil compounds. Because oil-degrading microbes are usually
found in environmental samples, including relatively pristine Arctic environments, it is likely that the potential for
oil degradation is already present in the ocean around
Northern Greenland, but it is not known how fast and to
what extent the degraders will respond to increased oil
concentrations in waters and sediments. A better understanding of the potential of the indigenous microbial communities to react to naturally or accidentally spilled
hydrocarbons is necessary to delineate risks and develop
possible measures for remediation in the future.
Future targets for the petroleum exploration
One of the open questions is how much oil and gas will be
discovered in previously unexplored offshore areas.
Potential targets include shallow shelf areas that in the past
were not accessible, because of, e.g., the harsh environmental conditions in the Arctic, unconventional resources,
and deepwater areas (see Regional Marine Geology). In
well-explored basins (see Marine Sedimentary Basins),
further deepwater exploration will probably include more
giant gas discoveries in relation to oil giants and a move to
deposits in deeper water along passive continental margins (Chakhmakhchev and Rushworth, 2010).
The deep water is where many of the largest finds of
recent times have been made – but also poses challenges,
222
ENERGY RESOURCES