Israel 's Delek Drilling and Avner Oil have raised $2 billion in an international bond offering to help fund the development of the huge Leviathan natural gas field off the coast of Israel. An announcement by the firms said demand of $13.5 billion was the largest ever for an Israeli enterprise and it was over-subscribed by 650 percent. "This shows unprecedented confidence by European, U.S. and Israeli financial markets in the vision of Delek Drilling, Avner and Delek Group," Avner Chairman Gideon Tadmor said. "The development of the Leviathan reserve will allow the continuation of the Israeli natural gas revolution and regional and international export that will significantly strengthen Israel 's geo-political standing," he added. Avner and Delek Drilling are major shareholders in the group developing Leviathan, which holds an estimated 19 trillion cubic feet of gas and is expected to go online around 2017. Much of the reserves are earmarked for export.