The easy oil is gone so where do we look now?

In 2008, Canadian economist Jeff Rubin stunned the oil market with a bold prediction: With the world economy growing at 5 percent a year, oil demand would grow with it, outpacing supply, thus lifting the oil price from $147 to over $200 a barrel.

The former chief economist at CIBC World Markets was so convinced of his thesis, he wrote a book about it. "Why the World is About to Get a Whole Lot Smaller" forecast a sea change in the global economy, all driven by unsustainably high oil prices, where domestic manufacturing is reinvigorated at the expense of seaborne trade and people's choices become driven by the ever-increasing prices of fossil fuels.

In the book, Rubin dedicates an entire chapter to the changing oil supply picture, with his main argument being that oil companies "have their hands between the cushions" looking for new oil, since all the easily recoverable oil is either gone or continues to be depleted – at the rate of around 6.7% a year (IEA figures). "Even if the depletion rate stops rising, we must find nearly 20 million barrels a day of new production over the next five years simply to keep global production at its current level," Rubin wrote, adding that the new oil will match the same level of consumption in 2015, as five years earlier in 2010. In other words, new oil supplies can't keep up with demand.

Of course, Rubin at the time was talking about conventional oil – land-based and undersea oil – as well as unconventional oil sands. The shale oil "revolution" in the United States that took off soon after the publication of his book has certainly changed the supply picture, and the recent collapse in oil prices has forced Rubin to eat his words. With U.S. shale oil production soaring from 600,000 barrels a day in 2008 to 3.5 million barrels a day in 2014, the United States over the past few years has flooded the market with new oil from its shale formations, including the Eagle Ford in South Texas and the Bakken in North Dakota. According to the Energy Information Administration (EIA), total U.S. production (conventional and unconventional) will increase to 9.3 million barrels a day this year, the most since 1972.

While some observers, including oil giant BP, are now predicting a slowdown in U.S. shale oil production as wells are depleted at a faster rate, to be replaced by Middle Eastern output that has lost ground to U.S. shale, the thesis posed by Jeff Rubin in 2008, that the world is running out of oil, seems to have changed to: Is the world swimming in oil?

In this continuing climate of abundant oil production, Oilprice.com sought to find out where the new oil will be found. The data could be used in a further analysis to determine whether an oversupplied market will continue to depress oil prices into the future – or whether a price correction is likely given a tightening of the market on the supply side.

According to a 2013 report by Wood Mackenzie, the world holds 1.4 trillion barrels of oil equivalent oil and gas reserves, with the Middle East, Latin America, North America and Africa identified as the key regions for future oil plays.

Of course, many of the new fields are uneconomic at current prices, so it is instructive to look at the largest oil fields to see where oil producers are likely to keep pumping, even though many of these fields are in decline.

They include Ghawar and Safaniya in Saudi Arabia, Burgan in Kuwait, and Rumalia and West Qurna-2 in Iraq. These five fields were named the most important by Oilprice.com in an article last June. Ghawar, the world's largest field, has an estimated 70 billion barrels of remaining reserves, more than all but seven other countries, according to the EIA. In production since the 1950s, it continues to produce at 5 million barrels a day.

If you noticed the dominance of the Middle East in this list, you'd be right. Current estimates have over 80 percent of the world's proven oil reserves located in OPEC member countries, with Middle Eastern reserves comprising 65 percent of the OPEC total.

Adding to the Oilprice.com list, Forbes named Majnoon in Iraq, Khuzestan (also the name of a province) in Iran, Kashagan in the Caspian Sea, Khurais in Saudi Arabia, the Tupi field offshore Brazil, Carabobo in Venezuela's Orinoco heavy oil belt, and the North Slope of Alaska among its top 10 fields of the future.

Fortune places the Orinoco belt in Venezuela among its six largest untapped fields, at an eye-watering 513 billion barrels of recoverable crude. In comparison the Chicontapec Basin in Mexico, also on the list, is a Lilliputian at 10 billion barrels. Others include the Santos and Campos Basins in offshore Brazil, at 123 billion barrels, the Supergiant field in the southwest desert of Iraq, at between 45 and 100 billion barrels, and the Jubilee Field in Ghana, estimated to contain 1.8 billion barrels of recoverable crude.