In a simmering US political challenge to the main method for completing gas wells in shale, a secondary issue over proprietary information is starting to dissipate.The larger threat is federal regulation of hydraulic fracturing, refinements of which have combined with horizontal drilling to unlock the enormous potential of shales.The oil and gas industry has used hydraulic fracing for 60 years. Regulation of the practice has occurred effectively at lower levels of government.But activist lawmakers and regulators want to impose federal regulation. The producing industry, wary of new delays and costs, says that level of oversight isn't necessary.In support of a new layer of regulation, envi...