The fate of the first global oil deal in 15 years could be decided on Wednesday when OPEC members travel to Iran to persuade the country to participate in a deal to freeze output levels, possibly by offering Tehran special terms. Dominant OPEC power Saudi Arabia and non-OPEC Russia, the world's top two producers and exporters, agreed on Tuesday to freeze production levels but said the deal was contingent on others joining in - a major sticking point with Iran absent from the talks and determined to raise production. OPEC members Qatar, Venezuela and Kuwait said they were ...