it's adding up, page-27

Roger - that would the gas if the medium - in this case gas - was free to flow.

The problem here is it isn't.

Its trapped within the geology - hence the fracturing required to free the gas.

If ALL the rock layer could be fractured from a single point - then you'd be right - but also I'm assuming by your knowledge of pressure and force is that the further an object is from a force, the less force that will receive given the fact that other rock between itself and the point of fracture is absorbing that energy - hence you need multiple points of fracture.

Hope that helps.