Ann: Gemini 4 Well Campaign IP30 Production on Target, page-3

So, the four wells cost CAD$4.8 million = AUD $5.18 million (inclusive of tie-in costs).

Currently producing at 650 boe/day, of which 89% is oil.

So just focusing on the oil (with 20% transportation/marketing costs, not sure what these would be to be honest).

= 650 * .89 * 365 (days) * US$70 (per WTI barrel )* 0.8 (transport/marketing) / 1.35 (AUD/USD)
= ~AUD$ 15.9 million per annum.

So 5.18/15.9 * 365 = ~ 118 day pay back period.

Even ignoring falls in production over time (have they releases the production curves) those are some highly profitable wells. And we can just rinse and repeat.