When surveying an area for potential oil wells, geologists use various methods to identify deposits of oil beneath the ground. Seismic exploration allows geologists to examine how energy interacts with formations throughout the earth’s surface. By examining the readings on a seismograph, they can come to understand the geologic features in a particular underground area, including rock formations that indicate the presence of oil. On land, onshore seismology requires special equipment to create a powerful series of vibrations beneath the earth. In offshore seismology, air guns are used to generate large bursts of air underwater, creating vibrations that travel into the earth’s crust.
Geologists may also use magnetometers to detect minor changes in the earth’s magnetic field resulting from different rock formations. Magsat, a satellite developed by NASA in 1981, facilitates magnetic exploration of entire continents. With Magsat, geologists can not only locate oil deposits, but also research the movement of tectonic plates.
Additionally, gravimeters allow geologists to take note of minute variations in the earth’s magnetic field. Using these devices, they can more easily identify different types of underground formations, as well as whether they may contain oil or natural gas.