Is there more oil deep within the earth?

July 27th, 2009 - 3:34 pm ICT by IANS  

Washington, July 27 (IANS) Scientists have found that petroleum can be formed under the very high pressure and temperature conditions found deep within the earth. The finding potentially multiplies underground oil deposits manifold.
The oil and gas that fuel our homes and cars started out as living organisms that died, were compressed, and heated under heavy layers of sediments in the earth’s crust. Scientists have debated for years whether some of these hydrocarbons could also have been created deeper in the earth and formed without organic matter.

Now scientists from Carnegie Institution’s Geophysical Lab have found that ethane and heavier hydrocarbons can be synthesised under the pressure-temperature conditions of the upper mantle — the layer of earth under the crust and on top of the core.

Methane is the main constituent of natural gas while ethane is used as a petrochemical feedstock.

The scientists first subjected methane to pressures exceeding 20,000 times the atmospheric pressure at sea level and temperatures ranging from 700 to over 1,200 degrees Celsius.

These conditions mimic those found 64 to 153 km deep inside the earth. The methane reacted and formed ethane, propane, butane, molecular hydrogen, and graphite.

“The notion that hydrocarbons generated in the mantle migrate into the earth’s crust and contribute to oil-and-gas reservoirs was promoted in Russia and Ukraine many years ago,” wrote the authors of the study, which was carried out in association with scientists from Russia and Sweden.

“The synthesis and stability of the compounds studied here as well as heavier hydrocarbons over the full range of conditions within the Earth’s mantle now need to be explored.

“These and related questions demonstrate the need for a new experimental and theoretical programme to study the fate of carbon in the deep earth,” the study authors added.

These results were published in the July online issue of Nature Geoscience.

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