Fewer natural gas reserves are being added for every dollar spent on exploration and production, and higher costs are undermining the economics of drilling more gas wells, Cambridge Energy Research Associates said in a recent report.“Conventional wisdom is that all producers are enjoying a windfall from higher prices; however, the less-visible cost of gas production has moved up as dramatically as market prices,” said J. Michael Bodell, CERA director, upstream gas strategies.The report, “Diminishing Returns,” analyzed full-cycle costs for wells drilled in 2005. The study also identified a shift toward unconventional gas production, now accounting for 25% of total U...