May 12, 2010 9:38 AM by Sharlee Jacobs
NEW ORLEANS (AP) - The explosion of the Deepwater Horizon oil
rig illustrates the energy industry's push to drill ever deeper in
search of huge oil deposits, despite the mammoth risks and unique
challenges associated with exploration in such a hostile
The lure of the deep is driven by technological advances that
make previously inaccessible oil now reachable, and dwindling
supplies at shallower depths due to years of exploration. High
energy prices and lucrative government incentives have also made it
more financially feasible.
"That's where the oil is," said Eric Smith, associate director
of Tulane University's Energy Institute. "You can't find any oil
any cheaper anywhere else."
But the work is highly technical. In mile-deep seas, where BP
PLC's Deepwater Horizon rig was plumbing for oil in an ocean
canyon, the work is done in total darkness and near-freezing
temperatures. Water pressure is enough to crush a submarine, and
the explosive methane gas that likely ignited on the Deepwater
Horizon can be much more damaging if not properly controlled.
"The deep water is way too risky," said Kieran Suckling,
executive director of the Center for Biological Diversity, a legal
advocacy group that opposes such drilling.
Gulf of Mexico oil is a crucial part of the U.S. energy supply.
While land-based production has steadily declined, output from the
Gulf has doubled over the past two decades, surpassing that of any
state including Texas and Alaska.
More companies are developing projects in mile-deep seas, and
most of the oil produced in the Gulf now comes from sites more than
1,000 feet below the water's surface.
Drilling applications approved by the federal government last
year went to wells at an average depth of 2,114 feet - triple what
was seen just a decade ago, according to an Associated Press
analysis of data from the federal Minerals Management Service.
This expansion of drilling ever deeper was fueled by the 1995
Deep Water Royalty Relief Act, which exempts companies from paying
a percentage of royalties to the government on oil and gas found.
"Prior to that, the Gulf was becoming a dead sea in terms of
exploration activities," said David Dismukes, director of policy
analysis at Louisiana State University's Center for Energy Studies.
"The relief act stimulated a lot of activity ... and concerns
about environmental safety in the Gulf."
Politically, U.S.-produced oil from the Gulf of Mexico is an
easier sell than continued reliance on foreign sources or tapping
pristine Alaskan wilderness.
"In terms of oil that's available to us, it's either imported
from places where it's bountiful," Smith said, "or we find deep
water deposits off the coast of Africa, Brazil and the Gulf of
That is widely expected to continue despite the Deepwater
Horizon disaster, which killed 11 workers and has already fouled
the Gulf with 4 million gallons of crude.
"This country's pretty well committed to oil and gas, and
nobody's really happy when the price goes through the roof," said
Philip Johnson, a petroleum engineering professor at the University
of Alabama. "My suspicion is that we're going to proceed with
production out of the Gulf of Mexico - and that means we're going
to keep trying to get farther and farther offshore."
But the conditions down there have challenged oil companies to
come up with technological solutions.
Beyond about 1,500 feet, sunlight is unable to penetrate. The
temperature at 5,000 feet in the Gulf is about 40 degrees. The
water pressure is about 2,300 pounds per square inch, conditions
that can damage hydraulic systems or cause leaks.
A remotely operated underwater vehicle designed for 5,000 feet
of water is "a whole world of different engineering" than one
used at 500 feet, said Louisiana State University oceanographer
Robert S. Carney. Yet companies must rely on those vehicles to
detect or repair leaks and other problems.
Blowouts like the one that hit the Deepwater Horizon are also
more powerful at extreme depths. They can thrust gas, oil, water
and debris toward the surface with incredible force.
In the intense pressure and cold of the deep, methane hydrates
exist in a slushy, crystalline form. But as methane rockets upward
in a blowout, passing into lower-pressure zones, it converts to a
gaseous state and gains tremendous force.
The use of heat in cementing, or sealing a well, which was under
way prior to the blast, can destabilize methane hydrates at extreme
depths. Halliburton Co., which was doing the cementing of the
Deepwater Horizon well, acknowledged as much in an industry
presentation last year, calling the risks "a challenge to the
safety and economics."
Ultra deepwater rigs like Horizon are also required to have more
robust blowout preventers that can withstand the intense pressure.
The rig's preventer was designed to withstand 15,000 pounds of
pressure per square inch, a standard for drilling at these depths.
At an oil industry conference in Houston last week, there was an
advanced 20,000-pound model on display.
Investigators trying to pinpoint a cause of the explosion are
looking at both the blowout preventer and Halliburton's cementing.
Interviews with rig workers conducted as part of BP's internal
investigation indicate a bubble of methane escaped from the well
and rocketed up the drill column, expanding as it approached the
Transocean Ltd., which owned the rig and leased it to BP, is the
major player in deepwater drilling, which 40 rigs worldwide working
5,000 feet down or greater. It said in a statement that the
company's first commitment is safety.
"The company continues to strive and apply its core safety
tools consistently across all its operations around the world,"
The ongoing struggle to cap the leak also underscores the
challenges when things go wrong far below the surface. BP's initial
attempt to cap the underwater gusher with a 100-ton house-sized box
designed to funnel the oil to a tanker ship was scrapped due to the
formation of an icy slush that clogged it.
Company officials are now focused on positioning a smaller
containment vessel, known as a Top Hat, or plugging a portion of
the leak with junk. Those methods are long shots, however, never
tried at such depths, and it could be up to three months before a
relief well shuts off the leak entirely.
"Think of this same thing happening at less water depth: We
could have easily sealed that well," said Satish Nagarajaiah, a
Rice University engineering professor who focuses on offshore
structures. "Now the challenges are bigger."
As oil companies continue to push the boundaries into new
frontiers, they encounter unknowns: different sands, different
hydrocarbons, different gas pressures. There's less of a history
that can be used to assess problems that drilling may encounter.
"There's a real change when you go from conventional deepwater
to much greater depths," said Tyler Priest, a University of
Houston professor and expert on the history of offshore petroleum.
"There are unknowns."
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