Mine life of the project has been extended out to 2033, with average output overall put at 180,00-200,000oz per annum and "approximate" all-in sustaining costs of $800 per ounce.
Based on current reserves and a gold price of US$1500 per ounce, the project has an after tax net present value of $892 million.
Using "market consensus gold pricing" increases the NPV estimate to $1 billion.
OceanaGold's other major operating theatre is New Zealand, while the Didipio operation in Philippines is closed due to socio-political issues.
Shares in OceanaGold were down 6% to A$2.41 in morning on trade on a down-day for the ASX gold patch.
At that price OceanaGold is capitalised at $1.5 billion - or about US$1 billion!