Right, the unconventional sources are harder to produce. And in particular, there is really no chance of getting the kind of rates
we need. A lot of people think about volume in the ground, but don't really think about volume to the market. In other words, how much volume can one get out of the ground and to the market with any given oil field per year. The volume to the market determines how much oil we have to use for any given year. Tar sands for example have plenty of volume in the ground, but the rates are limited in ways that conventional oil is not due to processing the sand. On top of that, the EROI is much lower. So the rates we get out of the tar sands are much lower. At the end of the day, the peak of conventional oil wells signal a peak of oil production. Now put that on top of increasing demand, and it doesn't take much to see one has a really big problem.
The 2020 price will depend a lot on the state of conventional oil wells, politics, and demand. There is quite a bit of uncertainty on the conventional well reserves because there is no accountability on the figures provided by oil producing nations. In a basic nutshell, we don't have access to trustworthy data. So projections vary from now to 2040 on world production decline. But by looking at current world production for crude, it seems to have leveled off for the last 9 years. What production gains we have had comes from other liquids. And that is one of the reasons we've seen so much speculation on oil in the market.
Here is a link with a break up on liquids: