Drilling companies beginning to explore the Utica Shale got a piece of good news Friday when the U.S. Geological Survey estimated the rock formation in Ohio, Pennsylvania and other states holds enormous reserves of natural gas and oil.Releasing its first estimate of the Utica, the USGS calculated the shale formation holds about 38 trillion cubic feet of undiscovered, recoverable natural gas, 940 million barrels of oil and 9 million barrels of natural gas liquids like ethane and propane.The Utica lies beneath the Marcellus Shale, where energy firms have drilled thousands of unconventional gas wells in Pennsylvania in recent years. The Marcellus is considered to be one of the richest natural gas reserves in the world.Drillers are just beginning to tap into the deeper Utica. A report this week by the IHS consulting firm said more than 135 drilling permits have been issued for horizontal wells in the Utica, and 11 wells completed, with the most productive located in Harrison and Carroll counties in eastern Ohio.The geological survey’s Utica estimate covered parts of Maryland, New York, Ohio, Pennsylvania, Virginia and West Virginia.Such estimates are highly variable and subject to revision. The USGS estimated last year the eight-state Marcellus region contains some 84 trillion cubic feet of undiscovered, recoverable natural gas, far more than its 2002 assessment of just 2 trillion.“As more (Utica) wells are drilled and more production data is assessed, reserves figures will likely increase,” said Steve Forde, vice president of the Marcellus Shale Coalition, a drilling industry trade group. He hailed the Utica as “another game-changing opportunity.”Domestic production of shale gas has soared in recent years as drillers perfected a technique called hydraulic fracturing, or fracking, and combined it with horizontal drilling to reach previously inaccessible reserves deep underground. The production boom has resulted in lower prices for consumers while stoking concerns about water and air pollution. The drilling industry says its practices are safe.