The problem with finding
oil, or course, is the stubborn opacity of dirt. Geophysicists do
their best to overcome this through the use of seismic imaging techniques.
They work like ultrasound, sending out sound waves from the surface
of the earth down toward potential oil reservoirs; the waves that
bounce back are interpreted at the receiving end to reveal (or not)
any signs of oil. However, most undiscovered oil is very deep, so
by the time these echoes come back to the surface, the data they
yield can sometimes seem almost as baffling as chicken scratch.
Pennington shows an image
of a reservoir near Traverse City. "It's about 4,500 feet deep,"
he says. "It's hard to image something carefully that's that
In fact, oil companies
poked several deep holes in the ground before finally hitting this
70-acre reservoir, which was once a coral reef. It has since yielded
about 1 million barrels of oil worth $20 million to $30 million.
Funded by the DOE, the
researchers are using those dry holes to get a lot closer to the
reef with their seismic imaging equipment. They hope that this new
proximity will yield much better pictures of what's down there.
Using a technique known
as crosswell seismic imaging, they will lower equipment deep into
two wells, one on either side of the ancient reef. One side will
send out seismic waves, and the other will receive them.
This way, the scientists
expect to get a much clearer view of the reef's composition. "We'll
use the amplitudes of the reflected seismic waves to tell us about
the characteristics of the rock and the fluids that saturate the
rock," Pennington said. "Some places have gas, some have
water, and some have oil, and the amplitudes of the reflected waves
will vary depending on the fluid."
They don't expect to
end America's oil shortage in the near future. Underground, the
earth is such a complicated place that seismic imaging is always
tricky. "It's a big mess down there," Turpening admits.
Pennington agrees. "There's
a lot of stuff going on, and on the first try, we'll probably do
However, once they learn
from those inevitable mistakes, they will bring their improved technology
to a commercial drilling site and use it to help narrow down where
the oil is and where it isn't.
"This will help
find better ways to characterize the interior of these reefs,"
Turpening said. "We'll get a lot clearer image."