Iran has pushed back its tender for the development of its Azadegan oilfield until at least 2018, Reuters reports.

“The companies are still assessing the technical surveys. The tender will not take place in 2017,” the Managing Director of the National Iranian Oil Company (NIOC), Ali Kardor told Iranian media, Reuters reports.

Petronas, Total, and Impex submitted surveys of the oilfield. The tender has already been pushed back to permit oil companies more time to appraise the oilfield, Reuters reported in June.

Azadegan is estimated to contain 37 billion barrels of oil, according to Reuters, and is the largest oil field in Iran. It is located on the Iraqi border.