[Editors] MIT uses math to find oil

[Elizabeth Thomson]

MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA  02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

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MIT uses math to find oil
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For Immediate Release
TUESDAY, AUG. 15, 2006
Contact: Elizabeth A. Thomson, MIT News Office
Phone: 617-258-5402
Email: thomson at mit.edu

Mathematical procedures developed at MIT may soon help energy 
companies locate new sources of oil many kilometers underground.

Working closely with teams at Shell International Exploration and 
Production, the MIT researchers have demonstrated the power of one of 
their procedures by mapping out an underground oil-trapping 
geological formation based on limited seismic data.

To keep up with the world's growing demand for oil, energy companies 
must drill deeper and look harder in increasingly complex geological 
structures. But locating such structures many kilometers beneath the 
Earth's surface is difficult, and getting it right is important. 
Companies can spend as much as $100 million drilling a single well -- 
a costly mistake if it comes up dry.

To find promising underground sites, companies collect seismic data 
by using air guns or explosives to send shock waves deep into the 
ground. How the waves are reflected by underground layers provides 
information that sophisticated signal-processing techniques can turn 
into 3-D images of the subsurface. But identifying promising 
geological structures within those images is difficult.

The Stochastic Systems Group (SSG) at MIT's Laboratory for 
Information and Decision Systems specializes in designing 
mathematical procedures, or algorithms, that can quickly analyze 
complex images. Could some of their algorithms be useful in the oil 
exploration business? Professor Alan S. Willsky, director of the SSG, 
and Shell researchers started a project to find out.

Obvious candidates were procedures for defining a continuous surface 
from a limited set of data points. As a first target, the researchers 
selected the task of mapping out "top salt," that is, the surface 
along the tops of contiguous salt domes. Salt domes form deep 
underground when heavy layers of sediment deposit on salt beds from 
ancient oceans. The salt extrudes upward like globules in a lava 
lamp, in the process tilting and blocking off sedimentary layers and 
creating traps where oil can accumulate.

To generate a map, industrial experts pick points in the onscreen 
images that they think may be the top salt, and the computer fills in 
the gaps. By changing their "picks," the experts produce multiple 
maps for consideration, each one covering several kilometers in 
length, width and relief. Generating those maps quickly is critical.

The MIT algorithms are well suited to the task. The key is how the 
different picks relate to one another. "There are statistical 
relationships between things that happen at different points in 
space," said Willsky, the Edwin Sibley Webster Professor of 
Electrical Engineering. "You don't expect properties of the rock at 
one point to be completely independent of the properties a meter 
away."

Given a set of picks, the MIT algorithms automatically define 
statistical relationships from one pick to the next and fill in the 
missing points based on those relationships. Moreover, they calculate 
the uncertainty associated with each generated point.
But identifying the top salt is only the beginning. The company also 
needs to see the shapes of geologic formations to guide their 
drilling. With a salt dome, for example, the company needs to drill 
into the adjacent sedimentary layers but not into the salt itself 
because it will contain no oil.

Again, the MIT researchers have algorithms that can help -- 
algorithms that they have been using to help medical researchers 
interpret data from MRIs and CT scans.

Key to the success of this research is constant interaction between 
the MIT and Shell researchers. "We don't just develop tools and throw 
them over the transom to Shell," said Willsky. "We're constantly 
looking over each other's shoulders" to find areas of mutual interest 
and potential benefit. Teaching each other about their separate areas 
of expertise is also critical. For Shell, the challenge is to 
understand MIT's "modern mathematical tools" well enough to build 
them into the company's existing analytical methods.

This research was funded by Shell International Exploration and 
Production through MIT's Computer Science and Artificial Intelligence 
Laboratory.

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Elizabeth A. Thomson
Assistant Director, Science & Engineering News
Massachusetts Institute of Technology
News Office, Room 11-400
77 Massachusetts Ave.
Cambridge, MA  02139-4307
617-258-5402 (ph); 617-258-8762 (fax)
<thomson at mit.edu>

<http://web.mit.edu/newsoffice/www>
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