Iran Oil Deal Back On Table, What's The Impact To The Oil Market?

Oil prices suddenly plunged earlier today on the news that the US and Iran are discussing sanction relief. In exchange for ceasing Iran's uranium enrichment activities at 60%, the US would allow Iran to export up to 1 million b/d and gain access to frozen funds abroad.

Now there's a particular language here that I am merely interpreting. Will the deal allow Iran to export 1 million b/d or 1 million b/d of additional crude?

I don't know, but I will assume the latter because Iran would never agree to the former considering it already exported ~1.4 million b/d of visible crude in May.

Now looking at Iranian crude exports, we've assumed at least an additional ~450k b/d of crude that has avoided satellite detection. If you combine that with the visible tanker data, Iran exported close to ~1.8 million b/d in May. 

Assuming that the deal between the US and Iran is an additional ~1 million b/d on top of that, then Iran would be back to its theoretical max.