my rough valuationOil in place (177mb +458mb) = 635 million...

my rough valuation
Oil in place (177mb +458mb) = 635 million barrels.
Exoma share = about 300mb (50%)
Say 33% is ultimately recovered = 100mb
Present value of in ground resource is say 20% of a barrel =US$20, so 100mb x $20 = US$2 billion.
Total Exoma shares and options on issue = 570 million.
So estimated value about $3.50 per share ($2b/570)
discuss?