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drilling for oil 8 September 27, 2010 Science World 9 Fire: ©AP Photo imAges/gerAld herbert; diAgrAm: steVe stANKieWiCZ bird: ©AP Photo imAges/gerAld herbert; rigs: ©ChArles e. rotKiN/Corbis Underwater oil and natural-gas reservoirs provide 30 percent of the U.s.’s oil and 25 percent of its natural gas. here are the parts of a typical offshore installation: bolts & nuts bolts nuts & deep sea drilling Earth Natural rEsourcEs L ast April 20, an explosion rocked the Deepwater Horizon oil-drilling rig—a floating platform the size of two football fields moored in the Gulf of Mexico. The rig, operated by energy giant BP, had just placed a temporary seal on the oil well it was drilling. A more permanent production platform was planned to extract the 50 million barrels of oil in the reservoir that workers had tapped 5,486 meters (18,000 feet) below the seafloor. One barrel equals 159 liters (42 gallons). But two days after the explosion, the fiery rig sank a mile to the bottom of the Gulf. Near the wreckage, broken pipes steadily leaked an estimated 35,000 to 60,000 barrels of oil per day from the underwater well. As of press time, oil pouring out of the damaged well had created a slick covering an area larger than South Carolina. Within the first week, the spill’s magnitude had officially surpassed 1989’s Exxon Valdez spill (see Case Study: Exxon Valdez, p. 12). That had been considered the worst oil spill to occur in United States waters—until now. The Deep- water Horizon spill has earned that title. With the well at an ocean depth of more than 1,524 m (5,000 ft), the recent Gulf spill is also the world’s deepest underwater oil spill that has ever occurred. The huge distance between the seafloor and the sea surface only added to the difficulty of stopping the gushing flow of oil. Although the U.S. has been drilling in the Gulf of Mexico for more than 40 years, some of the shallower wells are running dry. To keep the domes- tic production of oil and natural gas up, energy companies have been searching in even deeper U.S. waters for potential offshore wells. “We’ve been producing oil and gas for many decades, and we’re exhausting the supplies of the easy-to-get oil and nat- ural gas,” says Lincoln Pratson, a pro- fessor of energy and the environment at Duke University in North Carolina. semi-sUbmersible PlAtForm: ocean currents are stronger at greater depths, so deepwater fuel production typically occurs on giant semi-submerged floating platforms anchored to the seafloor. the platforms are mini- cities containing everything from production equipment to workers’ lodgings and cafeterias. oil reserVoir: some production platforms connect to more than one undersea well. With shallow reservoirs running dry, oil and natural-gas companies are drilling into deeper and deeper reservoirs. riser PiPe: this long pipe runs into the well at the seafloor to bring oil and natural gas to the platform. When the deepwater horizon sank, the oil gushed from this pipe. resCUe me: A worker lifts an oily pelican from a marsh. Volunteers will try to remove the oil using dish detergent. Fire brigAde: ships doused the burning wreckage of the deepwater horizon platform for two days before it sank. deePer drilliNg: these two connected oil platforms can drill a series of wells in the same area. How does the U.S. extract natural resources from the ocean floor—and is it worth the risks? 3 2 1 25,000 feet 165 Statues of Liberty 6,000 feet 40 Statues of Liberty 13,000 feet underground 151 feet 17,000 feet 25,000 feet underground underground 3 2 1

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drilling for

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Underwater oil and natural-gas reservoirs provide 30 percent of the U.s.’s oil and 25 percent of its natural gas. here are the parts of a typical offshore installation:

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deep seadrilling

Earth Natural rEsourcEs

Last April 20, an explosion rocked the Deepwater Horizon oil-drilling rig—a floating platform the size of two football fields moored in the Gulf of Mexico. The rig, operated by energy giant BP, had just placed a temporary seal on the oil well it was

drilling. A more permanent production

platform was planned to extract the 50 million barrels of oil in the reservoir that workers had tapped 5,486 meters (18,000 feet) below the seafloor. One barrel equals 159 liters (42 gallons). But two days after the explosion, the fiery rig sank a mile to the bottom of the Gulf. Near the wreckage, broken pipes steadily leaked an estimated 35,000 to 60,000 barrels of oil per day from the underwater well.

As of press time, oil pouring out of the damaged well had created a slick covering an area larger than South Carolina. Within the first week, the spill’s magnitude had officially surpassed 1989’s Exxon Valdez spill (see Case Study: Exxon Valdez, p. 12). That had been considered the worst oil spill to occur in United States waters—until now. The Deep-water Horizon spill has earned that

title. With the well at an ocean depth of more than 1,524 m (5,000 ft), the recent Gulf spill is also the world’s deepest underwater oil spill that has ever occurred. The huge distance between the seafloor and the sea surface only added to the difficulty of stopping the gushing flow of oil.

Although the U.S. has been drilling in the Gulf of Mexico for more than 40 years, some of the shallower wells

are running dry. To keep the domes-tic production of oil and natural gas up, energy companies have been searching in even deeper U.S. waters for potential offshore wells. “We’ve been producing oil and gas for many decades, and we’re exhausting the supplies of the easy-to-get oil and nat-ural gas,” says Lincoln Pratson, a pro-fessor of energy and the environment at Duke University in North Carolina.

semi-sUbmersible PlAtForm: ocean currents are stronger at greater depths, so deepwater fuel production typically occurs on giant semi-submerged floating platforms anchored to the seafloor. the platforms are mini-cities containing everything from production equipment to workers’ lodgings and cafeterias.

oil reserVoir: some production platforms connect to more than one undersea well. With shallow reservoirs running dry, oil and natural-gas companies are drilling into deeper and deeper reservoirs.

riser PiPe: this long pipe runs into the well at the seafloor to bring oil and natural gas to the platform. When the deepwater horizon sank, the oil gushed from this pipe.

resCUe me: A worker lifts an oily pelican from a marsh. Volunteers will try to remove the oil using dish detergent.

Fire brigAde: ships doused the burning wreckage of the deepwater horizon platform for two days before it sank.

deePer drilliNg: these two connected oil platforms can drill a series of wells in the same area.

How does the U.S. extract natural resources from the ocean floor—and is it worth the risks?

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“As a result, we’re having to move into more extreme environments to find very large oil and gas reservoirs,” he says. But is it worth the risks?

naTional resoUrCeThe Deepwater Horizon accident

occurred a mere three weeks after President Obama announced that he wanted to open up protected areas to offshore oil and natural-gas drilling in hopes of expanding the country’s domestic energy production (see map, left). The U.S. relies on nonre-newable resources like oil, uranium (for nuclear energy), coal, and natural gas for 93 percent of its energy needs. Oil, coal, and natural gas are fossil fuels, or energy sources created from once-living plants and animals. These organisms died, collected on the seafloor, and their decaying bodies were covered with layers of mud and silt. Over time, high temperatures and high pressures converted the organic matter into fossil fuels trapped in the surrounding rock. For more than 150 years, the U.S. has been drilling deep holes in the ground to reach these fossil fuels.

Mining and drilling areas that lie under U.S. land and coastal areas supply enough fuel to meet about half of the domestic demand for oil,

at even greater depths is a newer frontier. Currently, a natural-gas plat-form in the Gulf called the Indepen-dence Hub is the deepest, producing gas from a well 2,414 m (7,920 ft) below the sea surface.

spill HaZardsThe biggest hazard from drilling

oil—both on land and in the sea—is an oil spill. As the Deepwater Horizon disaster shows, it’s hard to contain and remove oil that is spilling into the ocean. “We have a variety of tools to clean up the oil,” says Nancy Kinner, an envi-ronmental engineer and co-director of the Coastal Response Research Center, a group run by the National Oceanic and Atmospheric Administration and the University of New Hampshire that studies oil spills.

Booms were one of the first tools deployed for the Gulf oil spill. These tube-shaped floating buoys corral the oil. Once the oil is gathered into a more compact area—and if the waters are calm—a controlled burn may remove the oil from the water’s surface. Skimmers, which are like vacuums that suck up the oil-and-water mix on the surface after it’s

gathered by booms, are another option. To battle the uncontained areas, planes spray dispersants on the water’s surface to break up the oil slick. Dispersants are chemicals that act a lot like shampoos and laundry detergents to separate the oil slick into droplets. When oil is in this smaller size, it breaks down faster and gets mixed into the water, where it will hopefully cause less harm to wildlife. Dispersants have also been sprayed underwater at the source of the leak to try to break apart the oil

before it even reaches the surface.

The primary goal for the spill response in the Gulf of Mexico was to keep the oil from reach-ing marshes that line the

Gulf coast. Marshes are very delicate ecological areas. Different types of animals breed in marshes, and oil can easily kill the lush plant life and diverse animals living there. “Marshes are hard to clean up, and the shal-lows there have a lot of organisms with high economic values, such as crabs, shrimp, oysters, and fish,” says Kinner. “You have to remember that when a big spill occurs, something bad is going to happen. You can’t pro-tect everything.”

and about 90 percent of the demand for coal and natural gas. Obama’s proposal to expand offshore oil and natural-gas drilling would reduce the U.S.’s dependence on foreign oil as well as create jobs and generate rev-enue from the sales of drilling leases. “We’d like to see our dollars stay in the country rather than go overseas for energy,” says Pratson.

sUBMerged fUelsDrilling into the seafloor first

occurred in 1887, when a forward-thinking oilman named H.L. Williams built a wharf in the Pacific Ocean and erected a drilling rig on its end. This was the birth of offshore drill-ing. Since then, the U.S. industry has grown to include roughly 3,500 active oil production platforms in the Gulf of Mexico and several smaller-scale fields in California and Alaska.

Since engineers built the first oil rigs, technology has propelled the industry forward (see Nuts & Bolts, p. 9). The first platforms were like typical oil derricks, large metal towers partially submerged in the continental shelf’s relatively shallow waters of less than 300 m (1,000 ft). More-sophisticated rigs can now be found drilling in deep water up to 1,520 m (5,000 ft). Ultradeep drilling

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in THe U.s.three weeks before the deepwater horizon disaster, President obama

had announced plans to open additional areas to offshore drilling.

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10 September 27, 2010 Science World 11

bAth time: rescue workers clean up an oily pelican. the average wash and rinse time is 45 minutes.

rig or reeF? oil rigs can become havens for wildlife.

CorrAlled sliCK: miles of boom are laid out to try to prevent oil from reaching the land.

learn more about the science of oil spills

at:www.incidentnews.gov

/science

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12 September 27, 2010

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1. What was the name of the offshore oil platform responsible for the oil spill in the gulf?A independence hubB thunderhorseC deepwater horizonD Petronious

2. For about years, people have been drilling for oil and natural gas in the gulf of mexico.A 25B 40C 80D 120

3. What do dispersants do?A corral oil into a smaller areaB evaporate the oilC cause oil particles to clump to-

gether so it’s easier to clean upD break the oil up into

smaller droplets

4. how can oil platforms help wildlife?

A they become habitats like artificial coral reefs.

B laws exist to protect animals near oil platforms.

C Fishers are banned from fishing near oil platforms.

D seismic surveys alert the animals to dangerous areas.

on march 23, 1989, the Exxon Valdez oil tanker left Valdez, Alaska, where it filled its cargo tanks with more than 200 million liters (53 mil-lion gallons) of oil. it soon ran aground on a reef, ripping open 11 of

its tanks. About 41 million l (10.8 million gal) of oil spilled into Alaska’s Prince William sound—enough to fill 17 olympic-size swimming pools. the spill spread along 2,000 kilometers (1,300 miles) of Alaska’s southern coastline. the slick killed sea otters, harbor seals, killer whales, bald eagles, sea birds, fish, and thousands of other animals. today—more than 20 years after the spill—most of the oil has been cleaned up, but oil sheens can still be seen in the sound, and areas of porous rocks still have oil trapped inside them.

soiled site: the Valdez oil spill was the largest in U.s. history prior to the deepwater horizon.

Case sTUdY:eXXon ValdeZ

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effeCTs on aniMalsJust as oil spills can be devastat-

ing to wildlife, searching for oil can also be disruptive. Dolphins, whales, and other ocean creatures that use sound waves to communicate are affected. To find underground oil reserves, oil companies perform seismic surveys. They bounce sound waves from a ship down to the ocean floor. These waves reflect dif-ferently off of different rock layers. Engineers listen for a signal that tells them there are oil reservoirs lurk-ing deep underground. These same signals can confuse animals, caus-ing some to strand themselves on beaches or make it harder for them to communicate with each other.

Once engineers locate the oil reserves and start drilling, though, oil rigs can actually be beneficial to wild-life. “When a rig’s been sitting there for a long time, the legs are almost like a coral reef—just absolutely cov-ered in wildlife,” says Victoria Todd, a marine biologist who has studied por-poises that gather around oil rigs.

fUTUre of fUels?Offshore drilling is one way to

reach oil and natural-gas reserves that were previously untapped. But

new technologies are also allowing companies to extract oil from tar sands (type of sandstone soaked with a sticky oil mixture) in Canada and natural gas from layers of rock that have gas trapped between its particles. These methods are lead-ing scientists at the U.S. Geological Survey to constantly readjust their estimates of the world’s energy resources.

Although technology is allowing us to drill deeper and reach oil and natural gas that was previously untouchable, there is still a limit to how much of these fossil fuels we can extract.

The Gulf oil spill is proving that oil recovery can be a risky business. If disaster strikes, it can be a huge chal-lenge to clean up a spill in extreme or pristine environments. 9

—Karina Hamalainen