November 22, 1995 Contact: Robert Irion (408/459-2495)

UCSC SCIENTISTS TO HELP IMPROVE SEISMOLOGICAL TOOLS FOR FINDING OIL AND GAS RESERVES

FOR IMMEDIATE RELEASE

SANTA CRUZ, CA--Billions of barrels of oil lurk beneath the floor of the Gulf of Mexico, shrouded by twisted layers of rock and domes of salt. If Ru-Shan Wu's group does its job well, the oil industry soon will have far better tools to find that black gold.

Wu and his colleagues at the UC Santa Cruz Institute of Tectonics are developing a new way to make 3-D images of subterranean structures that hide deposits of oil and natural gas. Their method promises to work hundreds or even thousands of times faster than existing 3-D mapping techniques, which require too much computer memory and expensive processing time to make them feasible for widespread use. The U.S. Department of Energy will fund the UCSC team's work during the next three years with a grant of $697,000.

The grant is part of a federal program known as the Advanced Computational Technology Initiative (ACTI), which invites collaboration among U.S. national labs, industries, and universities. ACTI projects are intended to help gas and oil companies tap into U.S. petroleum fields to the fullest possible extent--thereby lowering the nation's dependence on foreign oil.

"This is a good opportunity for us to apply the theoretical techniques we have developed in recent years to a crucially important technology," says Wu, a research geophysicist. "There are risks involved--it may not work in very complex geologic environments. But if it does, it would represent a breakthrough for 3-D imaging in complex media."

Wu directs the project, which received its first annual allotment of $199,000 in August. Assisting him are Eli Silver, director of the Institute of Tectonics; Thorne Lay, chairman of the Earth Sciences Department; and postgraduate researchers Xiao-Bi Xie, Lian-Jie Huang, and Ling Zhang.

The UCSC effort is part of a three-pronged research program coordinated by the Los Alamos National Laboratory. Other lead institutions are the Massachusetts Institute of Technology and the Colorado School of Mines. Several petroleum and computing companies have participated in the UCSC project and will contribute resources and expertise: ARCO, Conoco, Cray Research, nCUBE, Schlumberger, Shell, Sun Microsystems, and UNOCAL. According to Silver, no previous project at the Institute of Tectonics has featured such extensive ties with industry.

ACTI arose because oil reserves in the U.S. are becoming more difficult to detect, especially in heavily drilled offshore regions like the Gulf of Mexico. Analysts believe that enough oil and gas still exists to keep the nation's refineries chugging through the next century, but only if geologists can devise more cost-effective ways of finding the remaining deposits.

Industry geologists have relied on seismic waves for decades to plumb for offshore oil. They use air guns and other controlled sources to hammer the seafloor, then detect the sounds bouncing off various layers in the earth with an array of sensitive receivers. Pockets of petroleum alter the paths of the sound waves in a characteristic way. Hundreds of sources, many thousands of receivers, and many hours of processing on a supercomputer can help researchers pinpoint those pockets. That saves the costs of drilling a dry exploratory well. However, the task becomes far more challenging when a huge dome of salt--common under the Gulf of Mexico--warps the sound waves and masks the oil beneath.

"For oil companies, 3-D imaging is their bread and butter, but it's a very difficult job," says Silver. "You can imagine thumping on the roof of a tall building, listening to the sound waves that return, and trying to make an image of what's inside. The echoes from the floors, walls, and all of the large objects would create a bloody mess."

Wu and his team think their technique will greatly accelerate the 3-D data analysis that can eat up so much computer time. In essence, the technique compresses subterranean structures into a series of 2-D sheets, rather than analyzing the whole 3-D medium, which is far more complex. The method also neglects the multiple echoes among various layers that can make the imaging process prohibitively time-consuming.

For the first two years of the project, the seismologists will create fast new computer codes and refine their theory of how seismic waves travel through salt domes and other formations. The main focus, says Wu, will be to ensure that the simplifications do not distort the images and make them unreliable. In the project's final phase, they will test the method with real data from the field.

Government funding makes this sort of work possible, Wu observes, because industries hesitate to devote money to long-term research that carries a degree of risk.

The researchers believe the speedy technique will prove handy for any study of the earth's upper layers, from probing fault zones to tracking plumes of pollutants in contaminated soils--or even for seismic monitoring of nuclear test-ban treaties. "What Ru-Shan is working on is more than just a slight quantitative improvement," Silver says. "Everyone in the field recognizes this as an extremely useful thing to do."

Editor's note: You may contact the principal researchers as follows:

Ru-Shan Wu: (408) 459-3653 or wrs@earthsci.ucsc.edu Eli Silver: (408) 459-2266 or silver @earthsci.ucsc.edu Thorne Lay: (408) 459-3164 or tlay@earthsci.ucsc.edu

A color diagram illustrating the geologic setting of a typical undersea oil deposit is available by contacting Robert Irion at the UC Santa Cruz Public Information Office.

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