The entrainment of reservoir water from gas reservoirs and the associated precipitation of dissolved salts in the late production stage can impair the productivity and may even result in the abandonment of wells, even in reservoirs without active edge water drive. The causes of precipitation of dissolved salts from the entrained water, the chemical composition and plugging behaviour of the precipitates, as well as stimulation concepts with field results are discussed.

On the basis of the thermodynamic equilibrium between reservoir water and gas, on the one hand, and between the dissolved salts and the reservoir water, on the other hand, the effect of the reservoir pressure on the aqueous phase is investigated, and the mechanisms of the transport and precipitation of salts are explained.

Special emphasis is placed on early identification of downhole salt precipitation on the basis of the chemical composition and derived ionic parameters of wellhead water samples from different gas wells. The results obtained with water from Rotliegende, Dolomite and Bunter reservoirs are discussed. Experience gained in operations and stimulation with the measures thus derived for controlling the salt problems is described.

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