Skin and permeability are not the same thing. Permeability is a...

Skin and permeability are not the same thing. Permeability is a reservoir property, skin is a wellbore property.

And the water rates have already dropped to 700ish despite BHP being very low and gas rates still being low too. If skin and permeability were constant I would expect water rates to increase with drawdown, like GLL saw.

Regardless of what is going on down there the fact remains they are significantly behind their own forecast of a few months ago, which showed the low case gas rates of 500 mscfd for BHP of 600 ish psi.

Rising skin is one thing that would explain the reported behaviour. We'll just have to wait for more data and hope that gas rate continues upwards. There was quite a lot of leeway built into their forecast so they may still reach their commercial threshold.

As for the question about what that threshold is I'm not even going to try to guess. Too many uncertainties around costs and long term well performance. Even a major gas company with a team of commercial analysts would be essentially throwing darts.