Gulf Oil Spill

As a graduate student at BYU, I remember being in the Physics Department
office one day when a man entered and announced to the secretary, “Hi, there.
I’m a high pressure salesman.”
He was right of course. This salesman sold high pressure equipment.
My graduate research project involved subjecting small samples to
pressures as high as fifty thousand times atomospheric pressure. Since I didn’t
want to crush my samples, I enclosed them in a liquid, much like a baby before
birth is protected by amniotic fluid. However, the fluid for my research could not
be water, since ordinary water at high pressures, even at room temperature, turns
into a form of ice. Physicists are not particularly creative so they call these forms
of ice: Ice I, Ice II, Ice III, and so on.
Because of my previous work in high pressure, I was interested to read
about the first dome placed over the oil leak in the Gulf of Mexico. On the topic of
“Methane Clathrate” from Wikipedia, we read: “At sufficient depths, methane
complexes directly with water to form methane hydrates, as was observed during
the Deepwater Horizon oil spill in 2010. BP engineers developed and deployed a
sub-sea oil recovery system over oil spilling from a deepwater oil well 5,000 feet
below sea level to capture escaping oil. This involved placing a 280,000 pound
dome over the largest of the oil leaks to collect as much as 85% of the leaking oil.
BP deployed the system on May 7-8, when it failed due to the buildup of methane
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clathrate inside the dome.”
The plan failed because of the buildup of a type of ice formed from both
water and methane. This ice obstructed the flow of the oil, and also because ice
doesn’t weigh as much as oil, it made the dome more buoyant.
The ice we’re talking about here has several names including methane
clathrate, and methane hydrate. However, my favorite name for it is fire ice.
Shown below is a photo of burning fire ice, doing what few other ices can do,
which is to burn.
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(The picture comes from the article “Methane Clathrate,” previously cited.
Of course, ordinary ice doesn’t burn, and water doesn’t burn either, but the
methane locked up in methane clathrate will burn.
From the article entitled, “Volatile Methane Ice Could Spark More Drilling
Disasters”, located at Discovery.com, we read, “Methane hydrates only exist in
cold water–just above or below freezing–and at the undersea pressures found in
deep water off the continental shelf. ‘It’s a lot like ice,’ said William Dillon, a retired
marine geologist with the U. S. Geological Survey.’ The conditions that form them
exist at the sea floor and in the sediments below…And if hydrates are warmed by
oil moving through pipes, they can turn into methane gas (known as ‘kicks’ to
drillers) that can shoot back up the drilling pipe and ignite the rig. Investigators
are already focused on that scenario as a possible cause of the blast aboard the
Deepwater Horizon rig on April 20.
“Methane hydrates only exist 3,000 to 5,000 feet below the sea floor. The BP
drill went down to 18,000 feet.
“Robert Bea, a civil engineering professor at the University of California,
…has been interviewing workers who were aboard the rig before it blew. He said
the BP platform shut down several weeks before the accident because of hydrate
problems. ‘Whether it was either methane hydrate or gas, it really doesn’t make a
difference,’ he said. ‘It has unanticipated, undesirable effects. Based on my
interview and investigation, methane seeped into the core.’”
This volume change when methane ice turns to methane gas is not hard to
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understand if you think about what happens when you pop corn. Moisture is
locked into each kernel of corn. When that water turns into steam, there’s a 1600
fold increase in the volume. That sudden increase causes a small explosion in the
kernel of corn.
The same thing happens when the methane trapped in methane clathrate
turns into a gas. In this case, there’s a 168 fold increase in volume. When this gas
is released in a drilling core, since its density is much less than water or oil, it will
quickly escape upward to the drilling platform. Furthermore, as methane gas rises
up the drill core to lower and lower pressures, by the time it reaches the surface,
the methane gas has undergone another 140 fold increase in volume. (“Methane
Clathrate,” Wikipedia, previously cited.)
From the Wikipedia article entitled, “Deepwater Horizon Explosion,”
“According to interviews with platform workers conducted during BP’s internal
investigation, a bubble of methane gas escaped from the well and shot up the BP
column, expanding quickly as it burst through several seals and barriers before
exploding. Survivors describe the incident as a sudden explosion which gave
them less than five minutes to escape as the alarm went off.”
Of course the difficulties with methane clathrate found in deep sea oil
production would not be a problem if we drilled at shallower depths off our coast,
or on land, such as in Alaska, or if we made better use of coal and natural gas that
we have in such abundance in the United States.
One thing the BP disaster may point out to us is that we need a more
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rational energy policy.
By the way, does this discussion make me a high pressure newspaper
columnist? One can always hope.
Your comments are invited. Weyland can be reached at
jack.weyland@gmail.com