Oil and gas resources are organic, formed by the effects of heat and pressure on sediments trapped beneath the earth's surface over millions of years.  While ancient societies made some use of these resources, the modern petroleum age began less than a century and a half ago.  Advances in technology have steadily improved the ability to find and extract oil and gas, and to convert them to efficient fuels and useful consumer products. More resources of this type and oil shale have been quantified elsewhere, but they have not yet been proven exploitable and ex tractable economically. 

Thermally enhanced oil recovery technique enables oil field services in oman producers to extract more of the difficult ‘heavy oil’ and thus extend the life of existing oil fields and open possibilities for new wells that had previously been deemed too difficult or costly to extract from.

The world's oil production has not, in fact, peaked. There's still a vast amount of oil out there and that production will continue to increase year after year for a long time. However, the problem is that an increasing proportion of this supply is in places that are more difficult and more expensive to get to.

In 1950, the US Geological Survey estimated that the world’s conventional recoverable resource base was about 1 trillion bbl [bbl = Oil barrel: 42 US gallons, 158.9873 liters, or 34.9723 Imperial (UK) gallons]. Fifty years later, that estimate had tripled to 3 trillion bbl. Only one-third of the world’s recoverable known oil resources havebeen produced so far, the enormous amounts of hard to remove resources, such as heavy oil and shale oil make it clear that there is sufficient oil for decades to come. 
In addition to light oil resources of about 3 trillion bbl, heavy oil resources are estimated at 4.3 trillion bbl; slightly less than 1 trillion bbl of oil has been produced.