Sure, but my wife reckons I explain things to death so don't...

Sure, but my wife reckons I explain things to death so don't roll your eyes!

Myall Creek $A has been drilled down to target depth and cased. They have assessed the depth of the gas-bearing zone as being the final 300 m (but have dug even further as rat hole for debris etc.)
This 300 m is where they plan to hydraulically stimulate. When they fracture this region, the offshoots from the fractures extend into the sandstone and put big splits in it. My research showed that these fractures can extend up to 200 m in this sandstone but may be less, dependant on how tight the sandstone is.
I have given 2 estimations. The first is based on the fractures extending out 200 m from the well bore, the second is at half of this (100 m in case the sandstone is very difficult to fracture). Picture it as a cylinder with the height being 300 m. To work out the radius/diameter I've used the Pi R Sq calc. My computer doesn't have the symbol.
This calculation works out to Pi 3.14 x (200 x 200 = 40,000) = 125,600. Multiply this by the height of 300 m and you'll get 37,680,000 m3.
If the fractures extend out 100 m from the well bore you'll have 3.14 x (100 x 100 = 10,000) = 9,420,000 m3.
This is the total cubic metres of the cylinder of sandstone that is possible to be fractured.
How much gas is in each cubic metre of sandstone is the unknown.
How well this gas flows out of the fractures and up the tubing is unknown, (but they can put pumps down there to assist this).
Now, just for an example of how this works, have a look at Strike Energy STX at the moment who are drilling and stimulating; their figures for gas content is around 5.5 m3 /t. (STX announcement 2/7/18- subsurface).
Good luck, hope you're still awake