Oil makes the world function. Without it, our economies would grind to a halt. It used to be that oil extraction was easy and the discovery of new reserves occurred quite regularly. Today, it’s not only getting harder to extract oil from our known reserves, it’s also getting more challenging to find new petroleum sources.
The truth is, there is still plenty of oil, but most of it is difficult to extract. It is so thick it doesn’t flow easily. It can’t be pumped out of the ground using regular methods. This heavy oil represents 40% of known reserves.
The enhanced oil recovery techniques now in use make it possible to extract this heavy oil, usually by heating and pressurising it so that it thins and flows more easily. For these enhanced oil recovery methods to work effectively, many more wells need to be drilled than are required for conventional techniques: wells to inject heat and pressure, wells to balance pressure across an oil reservoir, and wells to pump out the newly thinned oil.
Read more here: http://www.forbes.com/sites/ciocentral/2012/06/29/the-key-to-the-worlds-energy-future-ip-networks/