Sentia, royalties for oil and gas are levied differently from...

Sentia, royalties for oil and gas are levied differently from accounting taxes. This below may help your calcs.

NZOG's share of the devpt costs is US$34M. Add to this perhaps some drilling costs for Hector etc, so perhaps US$37-8M. These are 100% deductible at the beginning of the project.

Therefore for the first US$37-8M of revenue from the project, just assume a NIL royalty rate, then go at 20% after that, with an ongoing deduction of US$10 a barrel for your operating costs.

Profit versus cashflow for NZOG will look very different at the beginning. There will be a lot of deductions for company tax that may not have a cash effect (as the cash was spent long ago). I would focus more on the cashflow that will sit on their balance sheet as that is where the real value is.