A newly found oil deposit
Oil (aptly called “black gold”) is the major driving force of today’s world economy. Crude oil, after extraction, is distilled into various components such as gasoline, diesel, tar and petrochemicals. Because it is a product of fossilization, crude oil is buried deep beneath the earth’s surface in the form of deposits. However, digging up every patch of available land or boring random holes in the ocean bed is not a realistic option for discovering oil deposits. Hence, geologists have developed indirect methods that indicate the possible location of oil reserves.
Signs of Reservoir Rocks
In the quest for oil deposits, geology of the surface and surrounding areas has been the major marker for a long time now. Oil starts with a quantity of organic matter and sediments that transform into oil when subjected to intense pressure over a long time; such deposits are usually located in a rich “source rock.” The oil then gradually moves out of the source rock into another more porous location known as a “reservoir rock.” The oil is trapped in this reservoir by a rigid exterior that forms over the top. The presence of such a rock structure is a prominent sign of oil deposits.
Signs of Various Geophysical and Chemical Changes
Geologists can detect reservoir rocks by focusing on the various geophysical and chemical changes brought about by an oil deposit on its immediate surrounding. These changes can also be considered indirect markers of oil deposits.
Gravitational changes: The earth’s gravitational force field does not have the same effect on all substances. Oil pockets may exhibit a slight change in gravitational response to a sensitized gravity meter.
Magnetic changes: Presence of viscous fluid (such as oil) can contribute to changes in magnetic flux. Magnetometers may be able to detect oil reserves under a rock bed based on this concept.
Presence of hydrocarbon: By using hydrocarbon sniffers, traces of hydrocarbons can be found in an area that would indicate a greater probability of finding an oil deposit in the vicinity.
In spite of the various methods devised to pick up signs of potential oil deposits, the probability of actually finding an oil trap at the location is very low. The only way to be certain of the presence of oil in the area is to perform a test drilling procedure.