The porosity and fissurization of the rock are ideal prerequisites for storing gas.

Storage reservoirs are underground gas storage facilities in depleted gas or oil deposits as well as in aquifer horizons. Since gas and oil have previously been extracted from these deposits, they have already been well examined before they are used for gas storage and their storage behaviour is known. The caprock layers, which mostly consist of mudstone or rock salt, have been impervious to gas for millions of years and therefore ensure safe storage operations.

Aquifer structures

Aquifers are porous, water-filled rock strata that are covered by impermeable caprock. The injection of storage gas displaces the resident water from the porous spaces and creates an artificial gas deposit. When the gas is withdrawn, the displaced water pushes the stored gas back into the borehole.