Nano-Prospecting

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What is needed is a means of mapping the pore structure and the voids between formations, he says, and to do this, researchers need sensors that are smaller than the pores. So the aim is to create micro- or nanosensors that can not only pass through the pores, but also form mesh networks to create detailed, 3-D maps of the structure of rock formations.

Another possibility with smaller-sized pores is to use magnetic nanoparticles to enhance aboveground sensing techniques, says Adams. By pumping the sensors into a rock formation, it could be possible to map the formation by detecting slight changes that the nanoparticles create in the earth's magnetic field.

The researchers believe that, in addition to locating and mapping oil and gas, nanoparticles might also be able to help recover the fuels. "The trouble is that the oil in the pores sticks to the walls," says Adams, even when high-pressure steam is blasted into the rock. The hope is that with the right nanoparticles, the researchers might be able to free the hydrocarbons from the rock.

Despite this potential, the energy industry hasn't shown much interest in nanoparticles until now. It was the high price of oil that caused its change of heart, Adams says. "All the big formations have been tapped, and most fields are in depletion. So cheap and easy oil is getting scarcer," he says.

Pister agrees. "A huge amount of money has been put into traditional extraction techniques," he says. But these have reached their limits in existing reservoirs. "They are about as tapped out as they can get."

However, there are lots of challenges ahead. Little is known about how nanoparticles will flow through porous rock. "And we have not generally designed nanoparticles for use at high temperatures and high pressures, nor for extreme chemical environments," says Adams. If these problems can be overcome, the payoff is likely to be great.