James Van Blaricum
Magnetometers
In addition to using seismology to gather data concerning the composition of the Earth's crust, the magnetic properties of underground formations can be measured to generate geological and geophysical data. This is accomplished through the use of magnetometers, which are devices that can measure the small differences in the Earth's magnetic field. In the early days of magnetometers, the devices were large and bulky, and only able to survey a small area at a time. However, in 1981, NASA launched a satellite, equipped with magnetometer technology, capable of taking magnetic measurements on a continental scale. This satellite, called Magsat, allows for the study of underground rock formations and the Earth's mantle on a larger scale, and provides clues as to tectonic plate movement and the location of deposits of petroleum, natural gas, and other valuable minerals.
Gravimeters
In addition to using variances in the Earth's magnetic field, geophysicists can also measure and record the difference in the Earth's gravitational field to gain a better understanding of what is underground. Different underground formations and rock types all have a slightly different effect on the gravitational field that surrounds the Earth. By measuring these minute differences with very sensitive equipment, geophysicists are able analyze underground formations and have a clearer insight into exactly what types of formations lie below ground; and, whether or not they have the potential for containing hydrocarbons like natural gas.
Exploratory Wells
The best way to gain a full understanding of subsurface geology and the potential for natural gas deposits to exist in a given area is to drill an exploratory well. This consists of actually digging into the earth's crust to allow geologists to study the composition of the underground rock layers in detail. In addition to looking for natural gas and petroleum deposits by drilling an exploratory well, geologists also examine the drill cuttings and fluids to gain a better understanding of the geologic features of the area. Logging, explained below, is another tool used in developed as well as exploratory wells. Drilling an exploratory well is an expensive, time consuming effort. Therefore, exploratory wells are only drilled in areas where other data has indicated a high probability of petroleum formations. For more information on the process of drilling natural gas wells, click here.