An oil and gas group exploring offshore Israel said on Sunday it may have discovered a field that contains an estimated 2.5 trillion cubic feet (tcf) of gas and 255 million barrels of oil. About 30 tcf of gas have been discovered off Israel's Mediterranean coast in recent years, turning the country once dependent on energy imports into a potential exporter. The latest announcement, which was based on 3D seismic data from 2012, covers the Oz license some 50 km (30 miles) from the coastal city of Herzliya in water 1,150 meters (yards) deep.