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11/06/2001
Oil, Mud and Old Worms
It may be my imagination but didn''t the Diamondback pitchers
throw back more than the usual number of new baseballs prior to
the seventh game? Were the umpires not properly rubbing them
down with Lena Blackburne''s Baseball Rubbing Mud? We will
never know the answer to that mystery. Last week, we left
another mystery unsolved, namely, why did the whale opt to
leave the land and return to the sea? If the whale had foreseen
that it would be hunted to near extermination, in part for its oil to
light those oil lamps, would it have stayed on land?
Today, of course, another kind of oil takes center stage. Even
acknowledging the law of supply and demand, isn''t it a bit
strange that, with all the uncertainties in the Arab world, the
price of oil has dropped significantly? The search for oil outside
that desert world is and has been intense and controversial, as
shown by the recent arguments over drilling in Alaska. The
November Smithsonian magazine has an article that deals with
one of the alternate approaches, deepwater drilling. The article is
by James R. Chiles and is titled "Getting in Deep".
The extraction of oil from the depths of the sea is not an
undertaking to be entered into lightly. This is especially true
when you''re talking drilling down into an ocean bottom a mile or
more deep. That is what''s going on in the Crazy Horse oil field
in the Gulf of Mexico about 75 miles south of the coast of
Mississippi. The Smithsonian article describes the operations
aboard the new drill ship, the Discover Enterprise. At 835 feet in
length, it''s about twice the distance from home plate to the
centerfield wall in Yankee Stadium. The cost of deepwater
drilling is impressive. When everything is counted in - support
personnel, 150-man crew, ship rental, etc. - it costs about a third
of a million bucks a day. I figure that''s about $10 million a
month and this particular job took about 8 months.
Let''s delve into the technology of drilling for oil in these deep
waters. Just like that special Rubbing Mud used to prepare a
major league baseball for action, the right mud is a key factor in
the drilling process. An MIT Web site outlines the various roles
that mud plays. First, consider that drill bit at the bottom of the
mile-long rotating shaft. For those who, like myself, are
mechanically challenged, the drill bit is that part at the bottom in
which is embedded the abrasive, pieces of diamond or other hard
material. While the rapidly rotating drill bit is cutting into the
sea bottom, it needs lubrication. Bring on the mud, which is
pumped down the "drill" pipe surrounding the rotating shaft. The
mud then exits through either the space surrounding the pipe or
the space between that pipe and another larger "rise" pipe
surrounding it. The special mud is made from different
materials, one of which might be the clay mineral called
bentonite. If I''m not mistaken, I think bentonite was something
investigators were looking for in those letters as a possible
carrier for the anthrax spores.
The mud not only lubricates the drill bit but also serves as the
garbage disposal by carrying away with it the debris from the
drilling. But that''s not all. The pressure of that mile-high
column of mud prevents any water or oil from gushing up
through the drill hole. Ok, you say, so much for the mud. Let''s
get on with it. But wait, it''s not that simple. That mud packed
into a mile high pipe weighs a good bit and if it weighs too much
the pressure can get so high that it causes cracking of the
sediment and rock around the drill bit. That can result in what
are known as "blowouts" of oil or gas.
Remember the good old days? (I forgot. Most of you probably
are too young!) We oldsters remember when we saw movies of
oil gushing high into the air out of newly drilled wells. The
scene would typically show those witnessing the gusher cheering
while being splattered by falling oil. Environmentalists hadn''t
appeared on the scene and all that spilled oil wasn''t a concern.
Now, a gusher is called a blowout, the change in terminology
perhaps an indication of today''s environmental concerns. Well,
in order to keep the weight of the mud low enough to prevent
blowouts in deepwater drilling, the composition of the pumped
mud has to be changed to make it lighter as the hole gets deeper.
So much for the mud. If you''re the guy or gal in charge of the
drilling operation on our ship, you''re sitting at your computer
control console. At your disposal is your ROV (remotely
operated vehicle). Anything that goes wrong a mile down has to
be tended to by the ROV - too deep for divers. This underwater
vehicle has a robotic arm and claw that allows it to carry out your
wishes. One of the ROV''s duties is to use a hose to spray
antifreeze around another important component of the drilling
operation, the BOP or blowout preventer. The BOP is a big deal.
It''s roughly four stories high (47 feet) and, with its innards of
valves, electronics and hydraulic gear, weighs in at a mere 360
tons! The BOP surrounds the drill pipe and in emergencies it
swings into action to clamp down the well and prevent a
blowout.
Maybe you''re wondering about that ROV spraying antifreeze on
the floor of the sea. Even though we''re in the warm waters of the
Gulf of Mexico, the temperatures are near freezing at the bottom
and the pressures are tremendous. You may remember that
we''ve talked about ice at the bottom of the oceans. Not ordinary
ice, but methane hydrate, a compound of water and methane that
forms at these pressures and temperatures. The methane hydrate
ice can clog up the pipes lead to trouble - hence the antifreeze.
The article describes how, when they were ready to pull up stake
and leave that particular Crazy Horse well, a latch on the BOP
got stuck. This essentially pinned the ship to the bottom of the
sea. The feeling was that methane hydrate ice had formed and
was jamming the latch. It took a day of applying antifreeze and
trying to jockey the ship enough to spring the latch loose.
Finally, the latch opened but they never knew whether methane
hydrate was really the culprit.
This has only touched on a couple of the many problems of
deepwater drilling. While researching the subject, I came across
a Penn State Web site citing some work published last year in
Nature by Professors Frederick Williams and Charles Fisher and
graduate assistant Derk Bergquist. They were also carrying out
deep-water studies but weren''t interested in oil. Instead, their
concern was the marine life surrounding so-called hydrocarbon-
seep sites in the Gulf of Mexico. These seep sites are places in
cold, calm water where fluids from the earth''s interior seep up
from the sea bottom. Seep sites are quite different from those
hot, sometimes violent thermal vents on the seafloor. In both
cases, the fluids emitted end up spawning a weird world of life
around the vents.
We''ve all seen pictures of the tubeworms that grow around those
hot thermal vents. They also thrive around the cold seep vents.
This isn''t particularly exciting except for one thing. These seep
site tubeworms turn out to be the true old-timers of the animal
kingdom, some estimated to be at least 175 to 250 years old!
How did the Penn State crew determine this? It''s a pretty neat
experiment. They took this special submarine down to the seep
sites. The submarine was equipped to allow them to stain the
white tubeworms'' casings a blue color. A year later, they
returned and collected the animals. By measuring the new white,
unstained growth they could determine how much the tubeworms
grew during the year. Here I''m guessing, but the Web site report
implies that they obtained measurements on tubeworms of
different lengths. Such data would also give them a handle on
how the growth rate varies with age. Just like us, the tubeworms
grow in spurts, more rapidly when they are young than when
they''re older.
With the data they gathered, the researchers calculated that it
takes 175 to 250 years for a tubeworm to grow in length to two
meters (about the height of Michael Jordan). While they don''t
give the measurements, they do say that they''ve collected
specimens "much, much longer" than 2 meters. This, of course,
implies that these tubeworms are much, much older. Who
knows, Methuselah may finally have met his match!
Back to baseball, my hat''s off to those D-backs, who certainly
earned a well-deserved victory. As a confirmed Yankee-hater in
my youth, when my Philadelphia Athletics suffered horrendous
defeats at the hands of the Bronx Bombers, I never thought I
would be rooting for them in my dotage. But in the last few
years these guys in pinstripes have shown us the meaning of
teamwork and they have embodied the spirit of that great Yankee
philosopher who said, "It''s never over ''til it''s over." Now it''s
over, but thanks for a great ride!
Allen F. Bortrum
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