Decoding the mystery behind Shell's shale write down

The Market Currents staff at Seeking Alpha is shedding some light on the huge write down by Shell this week. Is the U.S. oil boom over hyped?

Shell's (RDS.A) $2.1B write down on its North American shale oil exploration acknowledges some of its spending there will not prove economically viable, and that hitting its cash flow targets could get tougher. Adding to the mystery is Shell's refusal to identify which shale formation has taken the write down or to explain the charge.

Shale skeptics might take the write down as first evidence the U.S. oil boom is overhyped, but WSJ's James Herron thinks it more likely that Shell has "just failed to get lucky" - Eagle Ford, where Shell has significant operations, is well known for its “sweet spots,” which yield greater volumes of the prized liquids compared with gas.

Start trading crude oil today, here's where you start.