What does aquifer drawdown from CBNG development mean?
Ground water flows through coal seams due to water pressure, or hydrostatic head. When the pump in a well is turned on, the amount of water than can be produced is controlled in part by the static water level, which is the original hydrostatic head in the well. As the pump withdraws water from the aquifer and discharges it at the surface (whether it is to a stock tank, house, or CBNG discharge point) the water pressure (head) in the aquifer is reduced. The greatest reduction in water pressure is near the well, with progressively less change at increasing distances from the well. If we could see this reduction in water pressure it would be shaped like a funnel or cone with the spout in the well. This area of reduced water pressure is called the cone-of-depression. When the pump is turned off, water flowing through the coal aquifer replaces the discharged water, and the water pressure returns to static conditions. Within the cone-of-depression, there is less water pressure in the aquifer
