SECRETS OF BLACK GOLD
SCIENTISTS DEBATING WHERE PETROLEUM COMES FROM
By John Tiffany
As debate heats up over whether the world’s petroleum supply is finite,
fueling higher domestic prices for gasoline and heating fuel, there has been for quite some time now disagreement among scientists over the origins of oil. Are we nearing the dreaded Peak Oil that everyone is talking about these days? Or could there conceivably be a virtually endless supply of “black gold”? All of this has been going on under the radar of the mainstream media, which has failed to inform the American people about this critical new energy research.
There are basically two theories on the origin of oil, the biogenic theory and the abiogenic theory. The prevailing theory claims that oil is an organic “fossil fuel” deposited in finite quantities near the planet’s surface. But is it possible that some so-called fossil fuels are actually made without fossils? According to some scientists, natural processes in the Earth’s magma are continuously generating petroleum.
The idea that heated organic material results in petroleum has been around for hundreds of years. In 1757, Russian scientist M.V. Lomonosov wrote:
“Rock oil originates as tiny bodies of animals buried in the sediments which, under the influence of increased temperature and pressure acting during an unimaginably long period of time, transform into rock oil.” But others disagree.
Says researcher Russell Hemley of the Carnegie Institution of Washington’s Geophysical Laboratory in D.C.:
“Experiments point to the possibility of an inorganic source of hydrocarbons at great depth in the Earth—that is, hydrocarbons that come from simple reactions between water and rock and not just from the decomposition of living organisms.”
Regardless of where petroleum comes from, there is little doubt that coal is a true fossil fuel. There have been observations that the bottoms of bogs in the British Isles are well on their way to becoming lignite, the lowest grade of coal, and they are all younger than the Younger Dryas (YD) glaciation—about 10,000 years old.
The YD was the most significant rapid climate change event that occurred during the last deglaciation of the North Atlantic region. Previous ice core studies have focused on the abrupt termination of this event because this transition marks the end of the last major climate reorganization during the deglaciation.
Many of the gas-bearing formations in the Gulf of Mexico are built from Mississippi River sediments that are geologically very young. Still this does not tell us definitively whether they are of biological origin or not.
The so-called inorganic or abiogenic oil idea has been getting more attention lately, at a time when it seems energy and petroleum are on everyone’s mind, with oil more expensive than ever and many people fearing future shortages.
However, scientists from the minority inorganic oil camp, promoting diverse ideas, have a way to go if they want to overturn the dominant theory of organic petroleum genesis. Actually most scientists agree that inorganic petroleum exists. They just differ widely in their ideas on how it forms and how widespread it is versus organic petroleum.
By the mid-20th century, the organic model was pervasive, given a big boost by modern chemistry, paleontology and geology. Barry Katz, who is a petroleum geologist at Chevron, points to a 1936 paper
by Alfred Treibs, in which Treibs showed that chemical compounds in oil called porphyrins have the same chemical structure as chlorophyll, thus seeming to link at least some petroleum to plant materials.
Oleanane, a “biomarker” compound involved in the evolution of flowering plants, is present in Tertiary and Upper Cretaceous rocks and oil, suggesting that higher plants were somehow converted into this oil.
Other biomarkers appear to point to an algal origin for many deposits of oil, according to Marcio R. Mello of High Resolution Technology and Petroleum in Rio de Janeiro, Brazil. Mello says geologists have linked biomarkers to the specific environments in which petroleum formed.
The organic camp leans toward the belief that oil comes from source rocks resembling oil shale. Oil shale contains a waxy substance called kerogen, consisting of long-chain polymers. It is believed organic material deposited in shale from plant life as it forms becomes this kerogen material on reaching about 100 degrees centigrade, a process referred to by oil geologists as diagenesis. When further heated, according to the theory, the kerogen is converted into crude oil or gas, depending on how much hydrogen it happens to contain.
This process is called catagenesis. This involves breaking the kerogen down into shorter-chain molecules. The inorganic camp follows a different model:
They think hydrocarbons start off as simple compounds such as methane, a common natural gas, and then “chain up” the ladder through a cooling process.
Thomas Gold, the late Cornell University astronomer, suggested that methane migrates upward from the mantle, where it transforms into more complex hydrocarbons and then accumulates in igneous rocks. The evidence of biomarkers, he argued, is mainly from microorganisms interacting with the petroleum along its migration route.
With the support of the Swedish government in the 1980s, Gold drilled a deep well into the 32-mile-diamerter Siljan Ring, the site of an ancient meteorite impact, believed to be 368 million years old. The granite here has been shattered, perhaps to a depth of 20 miles. If Gold’s hypothesis about the origin of methane is correct, methane might be found seeping up through this wound in the Earth’s outer layer. Further, the shattered granite might prove to be a gigantic reservoir of methane.
After three years and the expenditure of $40 million, however, drilling at the Siljan Ring was terminated. The drill penetrated to 3 miles before it got stuck. No significant methane had been found.
Gold maintained that the drilling stopped just short of an apparent reservoir at 4.5 miles, probably located by seismic methods. Another, deeper hole would vindicate him, he believed. The drillers did find an assortment of hydrocarbons that could have been deposited by upward-seeping methane.
Also, tons of micrometer-sized grains of magnetite were taken out of the hole. Gold opined that these grains were synthesized by bacteria subsisting upon upwardly seeping methane at a depth of over 3 miles.
In addition, Russian drillers on the Kola Peninsula report the existence of mysterious circulating fluids as far down as 7.5 miles.
Despite the problems and disappointments at the first hole, some Swedish investors seem ready to finance a second hole at the Siljan Ring.
Alexander Kitchka, a geologist at the National Academy of Sciences in the Ukraine, says that outside North America, scientists are working on hybrid ideas that combine mantlederived hydrogen with biologically derived carbon to explain the origins of oil.
Alexei Milkov, a Russian petroleum geologist with BP in Houston, Texas, who was educated in Russia, notes that the success of Russian petroleum exploration did not come from the inorganic model. He adds that the subject of petroleum’s origins is more widely discussed in the former Soviet Union than elsewhere.
“When I talk with practicing Russian geologists, they often ask my views on the abiogenic origin of petroleum,” Milkov says. “This never happens in the United States, where organic is accepted fully and without scientific questioning.”
(Issue #8, February 20, 2006)