Either bad science (estimates are worthless) or politics (screw the estimates) at work here. Wish I knew which.
The initial reserves estimate was criticized by many as unsupported by data from the drilling that was going on.
Unlike other shale deposits around the country, the Monterey Shale is more uneven and the oil is buried deeper. Some companies have used hydraulic fracturing, which pumps massive amounts of water, sand and chemicals to break up rock formations, with mixed success.
“From the information we’ve been able to gather, we’ve not seen evidence that oil extraction in this area is very productive using techniques like fracking,” John Staub, an analyst who led the energy agency’s research, told the Times.
The original estimate in 2011 was done by Intek, a Virginia-based engineering company.
The company’s work “was very broad, giving the federal government its first shot at an estimate of recoverable oil in the Monterey Shale. They got more data over time and refined the estimate,” Intek senior associate Christopher Dean told the newspaper.
http://fuelfix.com/blog/2014/05/21/estimate-of-recoverable-monterey-shale-oil-slashed/