A new study plays down the fracking potential of California's vast Monterey Shale oil deposits.
Federal energy experts in 2011 estimated the Monterey Shale formation overall to hold a staggering 14 billion barrels of recoverable oil.
A study out Tuesday by the U.S. Geological Survey is the latest to deflate those boom estimates. The new study says that the most productive part of the giant Monterey formation has just 21 million barrels of oil recoverable by fracking. That's in addition to 393 million barrels recoverable by conventional drilling.
The Monterey Shale not long ago was regarded as a game-changer in California, where Gov. Jerry Brown has resisted calls from environmentalists to ban fracking.