Iran’s oil minister says the country has discovered a huge gas field containing an estimated 50 trillion cubic feet of gas in the Caspian Sea.Rostam Qassemi says the field is located at a depth of 2,300 feet (700 meters) within Iran’s maritime borders. His comments were posted on the ministry’s news website, shana.ir, on Sunday. Iran sits atop the world’s second-largest proven reserves of natural gas and is the second-largest OPEC oil producer. Most of its gas production is used domestically. The country relies on oil exports for about 80 percent of its public revenues.