"Our overall goal is to make images of the permeability
of the earth," he says. "In our business, that's a big deal.
It's the Holy Grail . . . a grand challenge, it's so hard to do.
“At the moment the best we can do is to make
a point measurement, not an image, by taking a piece of rock out
of a hole that one is drilling. “We have no idea what the
permeability is between holes,” he says.
Fragments of theory seem to indicate that the more
permeable the earth is, the more seismic energy it will soak up.
Proving this experimentally has not been simple; in fact, all investigative
aspects (theory, lab experiments and field data) of the problem
need a lot of work.
"But you can see if you were an oil company
and you could make such images, it would be incredibly valuable,”
Turpening said. "In an oil field, you could drill a crooked
borehole and hit just the sweet spots.”
The field data portion of the problem could be improved
significantly by using a site where Turpening and his longtime research
colleague Wayne Pennington, chair of the geological and mining engineering
and sciences department, have been conducting studies for years.
The old oil field near Traverse City has two wells
bored thousands of feet deep, and the scientists have been using the
site to improve seismic imaging techniques used for finding oil. It
will take two more holes to conduct further experiments on the relationship
between seismic energy and permeability.
This grant will be used to determine where the new
holes should be drilled and how deep they have to be. "We'll
need additional funding to drill the holes and acquire the seismic
data,” he added.
In August Turpening will join other experts in the
field, Steve Pride of Lawrence Berkeley National Lab and Professor
Jerry Harris of Stanford University, to present their research program
to ExxonMobil in Houston.
If you could image the earth's permeable places,
Turpening said, "you'd be king."
Related projects -- Field data acquisition has just
been completed on the first phase of a project to image facies and
fluid distribution within carbonate reefs, using crosswell seismic
amplitude-versus-offset studies. The pictures to the left are from
the field, near Traverse City, in late June. That project is supported
by the Tulsa office of the National Energy Technology Laboratory
of the Department of Energy.