How to Find Oil and Gas 

For oil and gas reserves to occur – either in solid, liquid or gaseous form – a specific number of criteria must be satisfied. First and foremost, there must be a source rock, rich in organisms, which is responsible for producing the petroleum itself. Then, a reservoir rock containing many pores and holes must be present to store the produced petrol. Finally, above that there must be a layer of impregnable rock, known as a trap, which prevents the oil and gas from escaping to the surface.

In order to detect the presence of these three criteria and therefore pinpoint the likely location of an oil reservoir, geologists employ a number of techniques. The most effective and widespread of these is seismic testing. This involves send sonic waves into the ground and waiting for the reverberations to bounce off the rocks below and return to the surface. The density, porousness and depth off the rock will result in differing times for the signals to return to the surface. From this data, geologists are able to estimate whether or not an oil or gas reserve is possibly located in the vicinity.

The technique of seismic testing occurs normally in three different forms:

• By dropping explosives down drilled shafts (or tossing overboard, if at sea) to create a loud enough blast to measure the sonic reverberations. However, this technique, for obvious reasons, is inefficient and potentially dangerous, and as such has become increasingly outdated.
• More commonly, seismic testing on land occurs by pounding the Earth’s surface with a thumper truck, which sends massive vibrations underground by slamming heavy plates on the ground.
• At sea, giant air-guns, capable of blasting out sonic vibrations of up to 250 decibels, are used to map underwater locations.

As well as offering information about the possible presence of oil in rock formations, seismic testing has also suggested that there may be much more life present underground than previously imagined. Scientists have also been entertaining the idea that such discoveries could yield further information about life on other plants as well. This article, Oil Industry Research Sheds Light on Where Life Exists on Earth and Beyond, talks about such exciting revelations in more detail.

Other techniques used to verify the presence of oil in subsurface rock formations is by analysing those above ground. This can be achieved by the collection of rock and soil samples, or, in less accessible places, by satellite imagery and photography obtained from the use of drone technology. This latter development is discussed further in this article: Unmanned Drones used to Identify North Sea Oil Reserves.

Once a trap and possible reservoir has been located, the only really sure-fire way of ascertaining whether it contains oil is by drilling. Unfortunately, more often than not, such drilling does not yield positive results. In fact, only one in ten of modern wildcat wells yield results which are economically viable for prolonged oil accumulation. However, they do have a better chance of becoming an extension or development well to supplement another one.