Sidebar: The nature of oil

By Paul Salopek | Tribune correspondent

July 29, 2006

Petroleum is civilization's lifeblood. So goes the cliche. But although it is one of the most studied substances on Earth, it remains essentially mysterious, elusive.

In some respects, crude really does resemble blood. It scabs on exposure to air. It is organic and viscous. Some companies warm oil to about 90 degrees to make it slip more easily, with less friction, through pipelines. This temperature approximates that of the human body. Cold oil will coagulate. It coats the inner surfaces of the pipes with waxy buildups, much like arterial plaque. Pipelines must be cleaned regularly with the industrial equivalent of a cardiac balloon: a plastic plug that oil workers call a "pig."

Oil is not sterile. It supports bacteria and fungi. Terminal managers tell of draining old storage tanks and finding "vines" of oil-eating algae growing inside--some of them many feet long.

Petroleum responds moodily to temperature. The same volume of crude at a typical tank farm can rise and fall by thousands of barrels over a 24-hour cycle: It swells in midday heat and contracts in the cool of the evening--a giant, black, slow-beating heart. Companies are forced to measure their production in "standard barrels"--the exact amount of space that oil occupies at 60 degrees, when, as petroleum engineers say, "a barrel is really a barrel."

Oil's fluid dynamics can be elegant.

Every day in the U.S., scores of different gasolines or crudes gurgle simultaneously through a vast system of pipelines. No physical barriers separate these disparate shipments of fuel. Instead, engineers have designed the pipes to "roll" their contents forward rather than squirt them in laminar flows, like water gushing from a garden hose. In this way, a carefully calibrated degree of turbulence keeps the fuels from blending. What little does get mixed is called "slop" and must be refined all over again. The complexity, cost and frailty of this circulatory system are beyond the comprehension of all but a few Americans.

Perhaps the most remarkable thing about oil is this: After 150 years of unleashing its explosive power to shrink the world and expand our dominion of nature, and after reshaping it into innumerable useful byproducts--from plastic cradles to vinyl body bags--we still do not understand fully where oil comes from or how it was made.

The notion that it is the cooked and condensed remains of dinosaurs is at best marginally correct. Most geologists agree that terrestrial life never existed in sufficient abundance to explain the vast amount of crude now lurking in the ground. Instead, many scientists believe petroleum was born in water--as algae and minute life forms called plankton that once drifted in ancient seas. Fed by ancient sunbeams, the plants bloomed in oceanic quantities, died and were buried in sea-bottom silts.

Because of this, some experts call the energy locked inside oil "fossilized sunlight." But this remains a theory. No one has yet synthesized crude from dead plant matter.

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