Oil is a fossil fuel formed from the remains of plants and animals over thousands and thousands of years. The intense heat and pressure under the surface of earth causes the formation of oil from the organic materials. Oil fields are areas that are rich in petroleum (oil) below the ground. This oil is extracted from oil wells. The work of the geologists is to find out the most probable location of oil below the earth surface before they start to extract.
The first important step is to locate oil. Many methods are being used to find oil. One way is with the help of satellite images that examine surface rocks. It can also be found with the use of sensitive gravity meters. These measure any tiny changes in the earth’s gravitational field which might have probably been due to oil flowing. There are sensitive magnetometers as well which can detect the smell of hydrocarbons using sensitive electronic noses called sniffers. Of all, the most common way is seismology in which shock waves are sent into the hidden rock layers and waves reflected back are interpreted. These shock waves could be created by explosives or slamming heavy plates into the ground for exploration over land and compressed air gun for exploration over water.