It's important to understand the difference between price and value.
ERHC'S price is $.0003, or $900,000
Erhc's value even without a deal with Total is higher than Erhc's price of $900k, because we know they have revenues.
Kosmos says ERHC'S block is valued at $500 million but that's not ERHC'S price which is $900k.
Total values ERHC based on what it believes is in the EEZ. But that belief changes as we learn more through drilling. So yes, learning there's oil in Block 6 could raise Total's valuation to billions or leave it near the Kosmos valuation to hundreds of millions.
But valuation is not the same as price especially when you have an illiquid market where trading is only possible in Canada and only at a few brokerages at that.