The International Energy Agency in Paris issues its look-ahead to oil markets in the next five years on Tuesday. So what’s the key question, and why do so many energy pros follow this agency?

To many analysts, consensus is spelled I-E-A. The International Energy Agency forms consensus, says consultant Bob McNally of the Rapidan Group.

He says consensus used to be that OPEC would intervene whenever prices fell. Until last fall, when it didn’t. The big question now – a central question in the upcoming medium-term report – is how a new world without an OPEC price-stabilizer might look.

Some analysts see a prolonged period of low crude oil prices, perhaps below $75 a barrel. McNally’s take: “We told our clients, welcome back to Space Mountain, the Disneyland roller coaster.”

In other words, volatility.