According to a person with knowledge of the country's tanker loading schedule, India is set to overtake South Korea as the No.2 buyer, taking 377,000 bpd, Reuters reported.
South Korean loadings are set to drop by 48 percent from a month earlier to 238,000 bpd, which, sources say, is partly due to refinery maintenance season.
Belarus is taking its first barrels since February. Iran has been producing around 3.8 mbd over the past few months, according to a Reuters survey.
Iran's total crude and condensate exports for October are expected to fall by nearly a fifth from the previous month.
The drop in output from the Organization of the Petroleum Exporting Countries' number three producer should help the group tighten global supply, supporting oil prices which hit a 27-month high this week.
Shipments of Iranian condensate have dropped due to a technical problem at the South Pars field, with maintenance work expected to take up to two months to complete, National Iranian Oil Company's Director of International Affairs Saeed Khoshrou told Reuters in late September.
The preliminary schedule for October shows a decline of some 800,000 bpd from a six-year high of nearly 2.9 mbd in February.
Tehran had been regaining market share at a faster pace than analysts had projected since sanctions were lifted.
The Islamic Republic was exempt from an OPEC deal to reduce output, allowing the country to regain market share after Western sanctions over its nuclear program were lifted in January 2016.
Exports to Europe are set to drop 39 percent to 510,000 bpd in October from a month earlier. Exports to the Middle East will hold at 111,000 bpd.