The operating costs to process 2mmcf/day of raw gas at 8% helium...

The operating costs to process 2mmcf/day of raw gas at 8% helium is US$120/mcf approx with 37700mcf/year of helium produced it appears..

So total extraction costs of about AUD7m/year might remain constant.

The main difference however is the helium produced if avg 3% versus 8%. At 8% it's average US120/mcf operating cost approx when producing 37700mcf/yr of helium. If avg 3% and producing 14138mcf/yr approx (37700 x (3/8)) of helium the same extraction costs of AUD7m apply to 14138mcf/yr so the operating costs per mcf produced would be a fair bit higher by the look of it.

Obviously for BNL if they can get higher than 3% over time from the vacuum process if there were impurities in the original data that will help improve potential margins.