Despite the potential to dilute the stock and its price, its share value has risen almost 9% from $1.71 to $1.86 since the options were exercised, ABN Amro Craigs broker Peter McIntyre said.
"It's turned into a win-win situation. This will provide enough working capital for the next three to four years and will deal with [oil production and exploration] debt during 2009-10," Mr McIntyre said.
For the first half of the year, the separate stocks of NZOG and Pike River Coal, which NZOG spun off its books in May 2007 while retaining a 30.63% stake, were the top two performers on the sharemarket for share value appreciation.
Aside from its stake in Pike River, NZOG has a 12.5% stake in the offshore Taranaki field, Tui, alongside Australasion Worldwide Exploration's 42.5% stake, and a further 15% in the development Kupe field in Taranaki.
The estimates of the Tui field, which has been producing oil since last July, have been recently upgraded to an estimated 50.1 million barrels.
This comes at a time when global oil prices are at record levels, holding at just above $US140 ($NZ185) a barrel for the past fortnight.
Mr McIntyre said the extra working capital would allow NZOG to look at its next exploration options.
In late April, NZOG rewarded its long-suffering shareholders with their first dividend in a decade, 5c per share, only the second time in the company's 27-year history it had paid a dividend.
Pike River, which like NZOG is about to experience record prices, in this case for specialist hard coking coal, is almost at the production stage at its Brunner seam in the Paparoa Ranges near Reefton, nearing the completion of a 2.3km tunnel it has been working on for the past 21 months in exceptionally rugged terrain.
