Remember when back in April we showed a strange map of the Iranian oil tanker armada, which according to Windward data was storing as much as 50 million barrels offshore, yet which was just sitting on anchor going nowhere?

As a reminder, Iran has lacked sufficient land storage facilities to store its oil and, to enable it to keep pumping crude, has relied on its tanker fleet to park excess stocks until it can find buyers.

Well, we can now close the book on what happened to all those tankers full of oil, because according to Reuters, capitalizing on the run up in oil prices following the OPEC output deal which exempted Iran from a production freeze, Iran has sold more than 13 million barrels of oil that it had long held on tankers at sea as it scrambled to sell at higher price levels in its attempt to regain market share.

Citing industry sources, Reuters notes that in the past three months, in the window provided since the Algiers deal, Tehran sold almost half the oil it had held in floating storage, which had tied up many of its tankers as it struggled to offload stocks in an oversupplied global market.

As a result of the rush to dump its offshore-held oil, unsold oil is now tying up only 12 to 14 Iranian tankers, out of its fleet of about 60 vessels, compared with around 30 in the summer.

Who bought it? Mostly China and Europe:

The oil sold in recent months has gone to buyers in Asia including China, India and South Korea and to European countries including Italy and France, according to the sources and data. It was unclear which companies bought the oil.

Having demonstrated good faith during the recent sales, Iran is now looking to cements its market share gains and is using the deal exemption to push into new markets in Europe, including Baltic and other central and eastern European countries.

As part of the Vienna OPEC deal meant to address excess oil inventory, Iran was exempt from production cuts. The country successfully argued it should not limit its production which was slowly starting to recover after the lifting of international sanctions in January last year. While the deal did not come into effect until the beginning of 2017, industry sources said Tehran had already been offering aggressive discounts, aiming to coax buyers globally into stocking up for winter in anticipation of the OPEC cut.

Reuters further notes that in another sign of the rising activity, Iran's oil ministry news agency SHANA reported in late December that the number of tankers able to berth at major terminal Kharg Island had reached a record in 2016 of 10 vessels at the same time.

"Iran got its way at OPEC and the Saudis agreed not to limit their capabilities. Iran will go ahead and look to export whatever they can for winter demand (globally)," said Mehdi Varzi, a former official at NIOC who is now an independent global industry consultant. "This is a commercial policy of trying to get rid of a lot of their crude oil on tankers as holding oil on tankers is very expensive."

The good news did not stop there: while in the past, numerous foreign ship insurers refused to work with Iran over fears of a backlash by either the Obama administration or Saudi Arabia, in recent months they have resumed providing cover for Iranian vessels, which has also given Iran more scope to use its tankers to make deliveries or carry out ship to ship oil transfers rather deploying them for storage.

Now the next question is as Iran and Saudi Arabia face off in direct competition for the same end clients, especially those in Asia, how much of a discount will Iran offer to remain competitive, and whether the Saudis will match these price cuts, as the temptation to cheat on the Vienna deal suddenly rises.