29 May 2009 Rice University
Hellooo down there!
Rice labs hope tiny clusters will find new oil in old wells
Laboratories at Rice University are collaborating on a new way to detect oil deposits in wells once thought to be tapped out.
Groups led by Rice professors James Tour, Michael Wong and Mason Tomson and Rice researcher Amy Kan are collaborating on a system by which hydrophilic carbon clusters (HCC) -- microscopic entities designed to sense the presence of oil -- can be sent into a well by the billions and come back to the surface full of valuable information.
"Generally, 30 to 50 percent of the oil in a well is left downhole, because they don't know it's there or don't know exactly where it is," said Tour, the Chao Professor of Chemistry and professor of mechanical engineering and materials science and of computer science. "That's why, when oil prices spiked last year, people were going out and buying old oil fields that had been abandoned or closed. A lot of guys have made a lot of money that way."
Tour, who spoke about research into what some have called "nanobots" -- a term he fears may be misleading -- at the recent Nanotech 2009 Conference in Houston, said that because oil deposits can hide in bands as small as 300 nanometers wide, electronic sensors can't help find them. The team's solution is to send tagged macromolecular clusters that can pass through the deposits, mixed with saltwater or other fluids, into a well. The researchers can collect and analyze them after they return to the surface.
"Inside our clusters are small molecules that will report to us whether they've seen oil or water and how much of each along their paths," Tour said. "We put a trillion of these downhole, and we'll analyze 100,000 at the other end to get an average of what they've seen."
Hydrophilic (water soluble) carbon clusters are being designed by Rice researchers to sense the presence of oil that remains in old wells. The HCCs are sheets of carbon one atom thick and 60 nanometers long, with embedded molecules that will detect oil, sulfur and water and store information about how much of each they encounter along their path.
Wong said, “We are chemically constructing these nano-sized clusters to be able to handle being exposed to high temperatures, pressures and salty conditions found in a reservoir.”
Though the clusters may take time to work themselves through the subsurface rock, they come back to the surface full of good information that may take no more than a day to analyze.
Custom versions of these "smart" clusters will be able to give the specifics of what's in a well, he said. "We can tag them differently, much like having an internal bar code," said Tour, who suggested regularly pumping HCCs into a well could provide constant monitoring of its status.
"We've got a long way to go before we know for sure if it works," said Tomson, whose lab is working to prove the concept this summer. "Within six to nine months after that, we'll have a pretty good idea of whether we're on to something."
The HCCs could be ready for oil field testing in a year or two, but commercialization is going to depend on the industry's willingness to invest. "It's potentially a very high-visibility project," said Tomson, who also directs the Brine Chemical Consortium of oil and productions and service companies. "It's just the kind of thing they would be excited about."
"We're always going to need oil," Tour said. "The worst thing we could do is spend all that money drilling and then just abandon the wells, leaving a lot of oil underground and looking somewhere else when there's a lot left there."
Tomson is a professor of civil and environmental engineering, and Wong is an associate professor in chemical and biomolecular engineering and in chemistry.
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