BAS Chart, page-254

In a conventional gas well gas is trapped in the rock ,the micro pockets in the stone are measured in milli darcys .
the wells are drilled vertically penetrating the layers of rock ofter multiple layers may hold gas.

Coal seam gas is similar in that the porous coal particles hold the gas particles .
Drilling is initially drilled vertically then when the coal is encountered it is drilled horizontally and fraccing can commence to release the gas.
Water is usually pumped out first to release the gas .

In the cooper the coal seams are extensive well documented and deep layers but another cost advantage in the deep seams is there is no water needing removal a cost plus .