One of the latest attempts to learn where the oil is hiding would involve injecting hundreds of millions of tiny carbon clusters deep into natural underground reservoirs, where changes to their chemical makeup would signal whether they've come across oil, water or other substances.
The clusters, referred to as "nanoreporters" and roughly 30,000 times smaller than the width of a human hair, also can tell the temperature, pressure and other factors that can help a company zero in on more oil.
Major oil companies, including Royal Dutch Shell, BP, ConocoPhillips and Marathon, are funding the research at Rice University. Scientists at Rice say they hope to begin field tests in the next year.
If oil companies could recover 50 percent of the crude in their fields instead of 35 percent, it would double the world's proven reserves of about 1.2 trillion barrels, the IEA says.
Though it could take a couple of decades to reach 50 percent, even a modest increase in the amount of oil recovered in coming years will alter the debate about peak oil — the point at which half the world's reserves have been depleted.
The debate pits those who say there's enough oil to last a hundred years or more against those who see a looming scramble for a shrinking supply. The latter group foresees supply shortages and price spikes that could cripple the global economy (pfffft... whatever).
Nansen Saleri, the former head of reservoir management for Aramco, Saudi Arabia's national oil company, said improving worldwide recovery rates by 10 to 15 percent could provide an additional 50-year supply of oil at current consumption rates.
"I'd say 15 to 20 percent (recovery) is doable, especially if you assume we're going to be in a robust price environment," said Saleri, whose Houston-based consulting business, Quantum Reservoir Impact, helps producers improve recoveries.
As they're [nanoreporters] pumped with water through a reservoir's nooks
and crannies, the molecular makeup of the Rice University nanoreporters is designed to change depending on what they encounter — petroleum, hydrogen sulfide, other substances.
The nanoreporters have tags similar to bar codes on retail packages that will tell scientists how long they've been underground — three months, six months, nine months, longer. Companies can then pinpoint where oil might be trapped. For example, if a large number of nine-month nanoreporters come across oil while three-month nanoreporters don't, scientists can assume the crude is deeper in the reservoir.
BP says advancements in technology — including gas injection — will likely allow it to recover 60 percent of the oil at its massive Prudhoe Bay field in Alaska. The original estimate three decades ago was 40 percent.