Transcript for Wrestling with Uncertainty, segment 07 of 16


Several million years from now this black muck may well become a source for oil and gas. As the basin continues to subside in the sands of the barrier bar that protect this lagoon, just slowly across it a new layer will be formed, and over millions of years other layers will be added, burying this muck deeper in the crust.

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As mud like this is buried, natural gas begins to form near the surface from the action of bacteria. As the sediment is buried farther, temperature rises, and the organic material begins to cook. In geological terms, it matures. Oil begins to form at about seventy-five degrees Centigrade and thermally-derived natural gas at about one hundred fifty. Pushed by pressure and buoyancy, the oil and gas migrate slowly through the earth. Most is lost to the surface, but the remainder - only one or two percent of all the petroleum that's generated - gets trapped in porous reservoirs by layers of impermeable rock. In some petroleum provinces converging crustal plates have folded and broken the rocks. In places such as the Rocky Mountains, California, and Alaska, this deformation tests our ability to locate oil and gas.