July 27, 2009 -- Oil, one of the most important, valuable substances on the planet may form in an unexpected place, according to a new study -- the crushing hot furnace of Earth's mantle. The petroleum we rely on to fuel our cars and heat our homes were formed over millions of years as ancient, dead algae and plankton were compressed in layers of sediment and heated. Because of this, oil companies know to look for new reserves in places that are, or once were shallow marine environments. For decades, though, scientists have toyed with a tantalizing alternative theory of petroleum formation: What if chemical reactions between water and minerals deep in Earth's mantle could send black gold bubbling up into the crust? Alexander Goncharov of the Carnegie Institution of Washington in Washington, D.C and a team of researchers have shown that just such a thing is possible. They heated methane (CH4) up to 1,500 degrees Kelvin (2,240 degrees Fahrenheit) and mimicked the squeezing effect of being buried under over 100 kilometers (62 miles) of solid rock. The results were astonishing -- methane readily transformed into butane (C4H10) and propane (C3H8), two common components of crude oil. Related Content:
"We were surprised at how easily we got this result," said Goncharov, whose research was published Sunday in the journal Nature Geoscience. "It shows that hydrocarbons can be formed at a depth of between 70 and 150 kilometers (43 and 93 miles). If there are large enough cracks in the crust, pressure will push this material close enough to Earth's surface for it to be extracted." It's a big "if." Analyses of the world's oil has confirmed that nearly every drop of fuel recovered from Earth's crust was once a living thing. At best, propane and butane from the mantle could be contributing tiny, insignificant amounts to the world's known petroleum reserves. "These latest experiments show without doubt that methane will form heavier hydrocarbons like what you'd find in oil," Henry Scott of Indiana University South Bend said. "It could renew interest in deep hydrocarbons, but it's not going to overturn our ideas on how oil forms." Still, Goncharov said oil companies' exploration programs simply take too narrow a view, focusing their efforts on areas where conventional wisdom tells them to look. Without surveying all of Earth's crust -- an impractically large task -- scientists cannot rule out the possibility that large, commercially valuable ponds of mantle-formed petroleum are just waiting to be discovered. "It's hard to say how much material would be produced in the mantle," Gancharov allowed. "But generally, there are possibilities for oil discovery that haven't been exploited yet. Maybe there should be different criteria for searching for new oil fields." Related Links: Discovery Earth for interviews, images and more. TreeHugger.com: After Sabotaging Own Oil Wells, Exxon Faces $1 Billion in Fines |
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