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A Consol Energy Horizontal Gas Drilling Rig explores the Marcellus Shale outside the town of Waynesburg, PA on April 13, 2012. Shale gas is natural gas stored deep underground in fine-grained sedimentary rocks. It can be extracted using a process known as hydraulic fracturing – or "fracking" – which involves drilling long horizontal wells in shale rocks more than a kilometre below the surface.
Gov. Jerry Brown has signed legislation to establish California's first rules for how oil drillers use a technique known as fracking.
The measure from Democratic Sen. Fran Pavley of Agoura Hills requires drillers to disclose the chemicals they use and acquire permits before they use hydraulic fracturing. That process involves injecting water, sand and chemicals into deep rock formations to release oil or natural gas.
Drilling companies have been exploring whether fracking could help them access oil in California's Monterey Shale.
Pavley's bill was approved last week amid concerns from some conservation groups over last-minute changes affecting environmental reviews.
Brown said in his signing message Friday that SB4 establishes strong environmental protections. He also says he will seek further changes next year to clarify the new requirements.