The runner-ups were - from second to fifth position - Malaysia's Petronas, UAE's ENOC, Kuwait's KPC and Saudi Arabia's Saudi Petroleum.
The survey was conducted by Applied Trading Systems (ATS) of Singapore and covers the 80 major petroleum trading companies in the region.
In another survey, also conducted by ATS, to find out the regions "Most Improved Companies", IOC came in third behind Phibro and Marubeni.