Not sure abou $150 here is my take on this:
If they discover ONLY 500,000,000 Barrels X $40(their profit per barrel after expenses)=$20,000,000,000 (those zeros drive me nuts) :150,000,000 shares=$133X0.77(their part of concession) =$104.41
Out of that $102.41 I am not sure about taxes,Gov of Guinea cut ...let's say we keep $40...