It's important in how it competes with other "profitably produced" bits. The market fungibility of crude oil tends to hide the relevance of comparison between supplies. In other words the supplies that can be compared to WTI vary greatly in production cost, but the market treats them as equivalents, which is why the more expensive supplies appear and disappear from the market based on current price. --snip--
Our true difficulty lies in that the top 20% is depleting very rapidly. We can certainly replace all of that, and more, by tapping more expensive reserves, but it will be very difficult as the required economic shifts will be quite severe and disruptive.
Sure, I get that, but TO this statement, I would say two things:
1) Speaking in general terms, it is false to say that we don't differentiate between relative ease (expense) of extraction between various types of oil. Are we not saying that very thing when we specifically mention that "the tar sands are not commercially viable at $20/barrel, but they are at $80?"
That seems to me to be a specific reference to, and acknowledgement of the fact that getting oil from the tar sands is more expensive/difficult. I'm not sure how else you could interpret such a statement.
2) Speaking in terms specific to this thread...the title specifically is NOT, "How much crude have we found," but rather, an accounting of the various OIL found so far this year, so to differentiate might be a somewhat interesting sidebar, it is by no means relevant to the task at hand...at least, I would not think so.
Anyway, I'm sure my comments will spark a firestorm of disagreement. I'm a corny after all.

-=Vel=-
@ Sense - Yes...I have observed that those who like to say we're going to suffer collapse "any day now," DO tend to discount lots of oil...and it's not all turkey guts and fry vats recycling either (which are silly, of course). But to discount oil found under certain types of rock, or in water, etc, seems...I dunno...the supposed cornys have been accused of "fuzzy logic," but the more I think about it, the "fuzzier" the other side sounds too....