I'd like to make a comment on that. One CBM well that is within a mile of my place is 700 metres deep, perfed at 700 metres and also perfed all the way up to 320 metres deep, with 22 separate perforations.
I don't care what kind of cement job you have; you have a vertical communication between 320 metres and 700 metres down or up that well bore. It doesn't matter what kind of cement you have outside the casing: you have communication vertically through the well bore.