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Abstract: Soil Fluorescence - The Key to Pay Zone Recognition

Gerry G. Calhoun, John Fontana

Aromatic hydrocarbons are among the most mobile compounds in oil due to their superior solubility in water. They are present in nearly every petroleum of every gravity. This study illustrates that these compounds migrate to the surface and maintain their identity with a correlation coefficient of up to 90%.

UV fluorescence from 250 mm. to 500 mm. captures a signature of the relative amounts of four groups of aromatics present in oils and also in the soils overlying oil traps. These groups are: Benzene (one ring); Naphthalene (two rings); Anthracene-Phenanthrene (three and four rings); and the more complex aromatics larger than five rings.

Oils from various formations contain varying amounts of these four groups and so provide a distinct signature for each oil. This study documents the genetic relationship between trapped oil in the subsurface and its expression at the surface micro seep with a series of comparisons of oil-to-soil synchronous scans in the UV range. Examples are taken from East Texas, West Texas and Colorado and from Cretaceous to Ordovician in the geologic column.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada