Oil and gas exploration, or commonly called as hydrocarbon explorations is the term used by geologists to look for oil and natural gas. The exploration allows oil and mining companies to harvest natural gas and hydrocarbons from different parts of the earth. Drilling is expensive and as such hydrocarbon explorations are done to identify possible areas which contain these deposits while limiting cost and reducing its impact on the environment.
Before a drill location is identified, geologists must evaluate the area and ensure that five factors are present – source rock, reservoir, migration, trap and seal or cap rock. As explorations are expensive and costly, these factors must be present before any drilling is done. Once the factors are considered, geologists employ several techniques to ensure the success of the drilling. The first methodology involves geophysical survey or seismic survey. This process includes the measurement of electrical currents, heat flow, density variation, gravitational and magnetic irregularities and geochemical reactions.
Seismic survey is one of the popular methods that geologists use in determining if hydrocarbons exist especially in deep water surveillance. The method makes use of sound to determine the level of the rock formations in the deep water. Many companies make use of vibrator trucks or small explosive charges on land and record the sound using a geophone.
Aside from seismic surveys, geologists may also make use of offshore surveys which involves the use of compressed air to create large bubbles which burst upon reaching the surface area. The sound waves from the burst will then travel below and reach the rocks where the vibrations are then recorded by hydrophones. As each rock produces different sound waves, geologists are also able to identify the rock type that exists in the deep.
Some explorations may also make use of magnetometers and gravimeters to measure the earth’s gravity pull at the surface whereas geochemical prospecting involves the measuring of natural gases using high-tech instruments.
Remote Sensing is also one of the techniques that geologists used to determine the structure of the exploration site. An aerial photograph is done to map the surface area of the proposed site, revealing important details such as the soil type, vegetation, minerals and other features.
In certain instances where data is limited, some oil and gas companies also perform a wildcat well especially in areas that are not explored before. The wells provide mining companies information on the site and whether oil or natural gas are available.