LOS ANGELES — Federal energy authorities have slashed by 96 percent the estimated amount of recoverable oil buried in California's vast Monterey Shale deposits, deflating its potential as a national "black gold mine" of petroleum.
Just 600 million barrels of oil can be extracted with existing technology, far below the 13.7 billion barrels once thought recoverable from subterranean rock spread across much of central California, the U.S. Energy Information Administration said. The new estimate, expected to be released publicly next month, is a blow to the nation's oil future and to hopes that an oil boom would bring as many as 2.8 million new jobs to California and boost tax revenue by $24.6 billion annually.
The problem lies with the geology of the Monterey Shale, a 1,750-mile formation running down the center of California roughly from Sacramento to the Los Angeles basin and including some coastal regions.
Unlike heavily fracked shale deposits in North Dakota and Texas, which are relatively even and layered like a cake, Monterey Shale has been folded and shattered by seismic activity, with the oil found at deeper strata.
Compared with oil production from the Bakken Shale in North Dakota and the Eagle Ford Shale in Texas, "the Monterey formation is stagnant," said John Staub, a petroleum exploration and production analyst who led the energy agency's research.