Saturday, November 26, 2005

Tech solving costly oilfield problem

Argen Duncan El Defensor Chieftain Reporter

ADUNCAN Oilfield workers extract an expensive problem with petroleum, but members of New Mexico Tech's hydrology department are helping find a solution.

Professor of Hydrology Robert Bowman has spent about five years developing a process to remove organic contaminants from the water found in reservoirs with petroleum. Besides having applications beyond the oil field, the procedure could allow for productive use of the water that is now simply disposed of in expensive ways.

Hydrology master's student Craig Altare, who has worked on the project for two years, recently presented the research findings at the Geological Society of America's annual convention. Researchers have also conducted successful field tests.

Besides a lot of salt, the "produced water" contains organic substances such as benzene because of contact with the petroleum, Altare said.

"They are carcinogenic to varying degrees," he said.

Bowman said 10 gallons of produced water typically accompany one gallon of oil.

"So it's a really, really large volume," he said.

Currently, Altare said, treatment usually involves pumping the produced water back into the ground or, in a minority of situations, other processes.

Bowman said this might account for 10 percent of petroleum production costs.

The new procedure could save companies money. Desalination facilities could also use the technology, as they need to remove organic compounds from the water before extracting the salt, he said.

Bowman also said the Public Service Company of New Mexico, a collaborator in the project, is interested in running a power plant with the treated water instead of the fresh water from the San Juan River that it uses now.

Lynn Katz, associate professor in the University of Texas-Austin Department of Civil, Architectural and Environmental Engineering, has collaborated on the project on a way to destroy the contaminants once they're out of the water.

Katz said she thinks the biggest value in the work is the ability to re-use the produced water by combining the procedure with another process appropriate for the desired application.

"So there could be some beneficial application for reusing this water, especially in arid regions, where re-use would be helpful," she said.

The procedure, developed with funds from the U.S. Department of Energy, uses a column containing zeolites, a naturally occurring mineral crushed to a sand-like consistency, modified with the organic molecule surfactant. The raw materials aren't very expensive, Altare said.

Operators pump produced water through the column, where the surface of the surfactant-modified zeolites absorbs the contaminants. The water retains the salt and may not be usable, depending on its concentration.

"Our process doesn't make it better or worse," he said. "It just removes contaminants other than the salt, basically."

Altare says at some point, the surface can absorb no more contaminants, so operators blow compressed air through the column to strip away the organic compounds. Although they can then re-use the column, the substances still require treatment.

A bioreactor that faculty at the University of Texas-Austin are developing could provide it.

Katz said regenerating the columns for re-use is an element in the procedure's cost-effectiveness.

With the bioreactor, operators put compost in the column and inject bacteria into it.

"So we do inoculate them with bacteria, but they're common bacteria," she said.

The bacteria get used to the material they feed on and eat the organic compounds to turn them into carbon dioxide and water.

"And that way, the process leads to complete destruction of organic contaminants," Katz said.

She and Kerry Kinney, an associate professor in the same department, have worked with Tech faculty and students since the project's beginning.

Katz said she thinks the process starting in the laboratory and progressing to field trials is "neat." She added it presents a good opportunity to train graduate students and let them see laboratory projects become field trials.

The developers tested the entire procedure with a pilot-scale column, one smaller than full size, for three weeks in Farmington with natural gas producer Burlington Resources. Los Alamos National Laboratory has acted as a liaison between the producer and Tech.

"And overall, we had a very successful field test," Altare said. "Everything formed pretty much as we thought it would or better."

He said researchers would next analyze the data from the test. Bowman said they would probably try a full-scale system next summer.

After that, he said, he hopes people will begin adapting and using the technology.

aduncan@dchieftain.com

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