Hypothetical This is just a guess so bare with me.
Say Shell, BP, Chevron or CNOOC take 80% of the Guyana block for a carry til production then a 60/40 repayment like the SA block. Whoever takes over will almost certainly get a right to first refusal.
Then let's say they still two successful Cretaceous wells. The two most likely well prospects are 700 million barrels each.
Here is the tricky part, you'd have to see what happens with CGX to see what the market is willing to pay. Obviously CGX is a goofy company and currently doesn't have a partner with sufficient capital. I've heard estimates of around $3 a barrel in ground.
So with that let's pretend Eco plays the long game, the production would likely be around 200,000 a barrel per day several years out. So 40,000 net to Eco at a $35 per barrel break even. So assuming a $35 net back split between the 60/40 loan for carry.
40,000 X 35 = 1.4 million X 40% = 560,000 X 365 = 204,000,00 per year.
Assign a 8 PE multiple and 400 mil shares outstanding
You'd end up with a share price of $4 a share.