calculations

Has anyone done any calculations on the potential amount of gas may be contained in the Shale areas NWE has?
I'm having a bit of a go at it and I am struggling to find accurate data on the porosity of the shale and therefore the potential yield.

I have looked at the AWE announcements and have not been able to glean a lot of information from them even though they have drilled the same scource rocks they have not released to the market any detailed analysis results.

Also the pressure that the gas would be under in situe.
The other unknown is the average thickness of the entire shale body. I have read that there are areas that are up to 1 kilometre thick .... which is enormous, but what is the average???

I was trying to assertain the potential yield for the fields and therefore the value. I did some calculations on the potential of the Wessex fields in the UK and I would like to start to get a better feel for the Australian reserves.

Regards