Hard-to-get natural gas supplies huge Hundreds of trillions of cubic feet of natural gas in the U.S. lie trap-. trap-. ped in "unconventional" reservoirs reser-voirs and recovering these supplies might cost $200 billion. That estimate was made in a report by the National Petroleum Council after an 18-month-long study of natural gas trapped in coal seams, shale, and "tight" sand formations. These resources have not been developed because the estimated cost of production is higher than the current selling price of natural gas. Also, the report said, the technology needed for production has not been tested and industry U hesitant about making major financial commitments until it ap- . pears the natural gas can be sold for a reasonable profit. The NPC estimated ultimate recovery re-covery of 192 to 574 trillion cubic feet of natural gas from tight sands by the year 2000. This compares with lu4.9 trillion cubic feet of , domestic natural gas reserves at the end of 1979. The U.S. uses ' about 2X) trillion cubic feet of natural gas a year. The NPC is a federally chartered. privately funded industry group. It studied 12 areas known to contain con-tain natural gas in tight formations and on which extensive data were available. The appraisals of these basins were extrapolated to cover other basins about which not as much is known.