From a quick Google, the Vu Upper frac sizes were as follows:...

From a quick Google, the Vu Upper frac sizes were as follows:

K1: 500 bbl
K2 and K3: 1800 bbl
Chiffre: 5000 bbl

The Chiffre frac was a monster.

But I think you're over-analysing this. Even if the fracs were identical size, you're talking very low gas rates for a brief period of time, effectively just a puff of gas released during initial dewatering that was never seen again. You would absolutely expect variation between wells and there's not enough information to pin it to any single factor like frac size or higher saturation in lower coals.

If you take out that one day where Chiffre flowed 50-60 Mscfd, the rest of the time during that initial dewatering period it was producing 10-20 Mscfd, vs the Klebb wells producing 3-5 Mscfd. Those rates are so low as to be effectively just background noise. You need that gas rate to be sustained at >100 Mscfd before you can even start thinking about interpreting reservoir effects as opposed to transient flow effects which is what you are seeing there.