(FORTUNE Magazine) – In the quiet waters off the coast of Vietnam lies an area known as Bach Ho, or White Tiger Field. There, and in the nearby Black Bear and Black Lion fields, exploration companies are drilling more than a mile into solid granite--so-called basement rock--for oil. That's a puzzle: Oil isn't supposed to be found in basement rock, which never rose near the surface of the earth where ancient plants grew and dinosaurs walked. Yet oil is there. Last year the White Tiger Field and nearby areas produced 338,000 barrels per day, and they are estimated to hold about 600 million barrels more.

Oil and natural gas are being found in places no one expected and in greater quantities than anticipated just a decade ago. In the mid-1990s the world's reserves of oil were thought to total about 890 billion barrels. Today reserves stand at 1.1 trillion barrels; the U.S. Geological Survey estimates that continued reserve growth, along with undiscovered resources, could bring world oil estimates to as much as three trillion barrels. "We're finding there are pretty substantial oil reserves in the world," says Tom Ahlbrandt, world energy project chief at the USGS. "New exploration and drilling technologies are making major new discoveries possible."

The increase in reserve estimates is fueling the offbeat theories of maverick scientists who believe that the expression "fossil fuels" is a misnomer and that the earth contains a virtually endless supply of oil. Their ideas fly in the face of the conventional wisdom that oil and natural gas come from the remains of animals and plants buried millions of years ago. Subterranean heat and pressure, mainstream science says, transformed this organic dreck into coal and oil. Though their theories vary, the upstarts believe instead that wellsprings of oil and gas lie deep within the earth, deeper than most oil companies drill, and that supplies are constantly replenished. "With the White Tiger Field in Vietnam, 90% of the production is coming from basement rock, where there were never any fossils," argues C. Warren Hunt, a geologist in Calgary. "What they've been teaching us in school about oil coming from fossils is wrong."

If true, the theories may mean we can stress less about running out of oil: There's more where that came from! We can also worry less about tensions in the Middle East or other hot spots cutting off our long-term supply. Problem is, most scientists scoff at such theories. Oil companies maintain that even if the rebels are right, the cost of searching for and extracting deep oil is prohibitive. ConocoPhillips, the $38-billion-a-year giant, is drilling for oil in the basement rock of the Black Lion Field off the coast of Vietnam. The company says the field is "unique," and the project is economically feasible because the oil is found at relatively shallow levels in the basement rock. "If you drill deeper into basement rock, you're probably going to find some hydrocarbons, but the chance of finding giant fields is pretty small," says Roger Pinkerton, ConocoPhillips's recently retired head of global exploration. He argues that there are much more accessible--albeit environmentally controversial--sources that will yield plenty of oil for the foreseeable future: to name two, the East Coast of the U.S. and Alaska's National Wildlife Refuge.

Drilling deep into granite probably will never make economic sense unless the industrialized world runs dangerously low on oil or is cut off from its supply. But in the meantime scientists like Thomas Gold, a retired Cornell astronomy professor, are content with poking holes in traditional theories surrounding fossil fuels. It isn't just that hydrocarbons are being discovered in anomalous places like basement rock; Gold notes that primitive hydrocarbons like methane are also found in the atmospheres of Jupiter, Saturn, and other planets.

He laid out his theories, which he believes better address those inconsistencies, in his 1998 book, The Deep Hot Biosphere: The Myth of Fossil Fuels. He argues that natural gas and oil were created with the earth's formation and reside deep inside the planet. Intense heat and pressure push them from there toward the surface. As to why biological matter (what some deem fossils) is found in oil, Gold says hydrocarbons attract a primitive type of microbe called archaea that lives deep underground; it feeds on and contaminates the oil.

Controversial yet renowned, Gold is credited with figuring out in the 1960s that pulsars were actually radio emissions from rapidly spinning collapsed stars, or neutron stars. To test his non-fossil-fuel theory, Gold in the 1980s persuaded the Swedish government to drill deep in a region near Siljan Lake, about 150 miles north of Stockholm. The Swedes drilled about four miles into basement rock and produced some 80 barrels of oil before the equipment became hopelessly gummed up with putty-like iron oxide. To Gold and his supporters, those 80 barrels were wet, black evidence that oil is no fossil fuel. Critics countered that the oil was merely regurgitated fluid and contaminants from the drilling operation. Because of equipment failures and ballooning costs, the project was abandoned.

Gold insists that the Siljan Lake results have led Soviet scientists and explorers to drill more than 300 deep wells into basement rock since then, producing some oil--but not vast amounts. (In fact, Russian scientists have entertained theories similar to Gold's for as long as 100 years.) "The U.S. petroleum geological community has a viewpoint firmly opposed to the notion of oil being of nonbiological origin--but not the Russian, Chinese, or Vietnamese," says Gold. "The U.S. has ignored completely the obviously very important Swedish results."

Gold isn't the only Western researcher to offer an alternative theory of where oil comes from. Other scientists argue that seismic activity on the ocean floor triggers a geochemical reaction between carbon and hydrogen that produces oil and natural gas. Still others say that bacteria deep within the earth--not dead dinosaurs--are making more oil every day. Scientists from around the world will gather in London this June to debate the origins of oil at a conference sponsored by the American Association of Petroleum Geologists and Britain's Institute of Petroleum.

At this point most scientists believe there's a perfectly logical explanation for why fossil fuels can be found in basement rock. "These are fractured rocks where the basement rock has been uplifted and the adjacent sedimentary rocks [that hold decaying plants and animals] pushed into that space," says USGS research geologist Gregory Ulmishek. He adds, "Geology is an empirical science, and we are sure that all the oil and gas that has been found in 150 years of exploration is of a biological nature." Of course, even long-standing scientific doctrines have been proved wrong. There was that little dogma about the earth's being flat.

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