Fines-migration-assisted improved gas recovery during gas field depletion

The core permeability decline during corefloods with varying water composition, especially with low salinity water, has been widely reported in the literature. It has often been explained by the lifting, migration and subsequent plugging of pore throats by fine particles, which has been observed in numerous core flood tests with altered water composition. In this work, the concept of using this permeability decline in order to decrease water production during pressure depletion in gas field is investigated. The small volume injection of fresh water into an abandoned watered-up well in order to slow down the encroaching aquifer water is discussed. Equations for two-phase immiscible compressible flow with fines migration and capture have been derived. In large scale approximation, the equations are transformed to the black-oil polymer flooding model. The performed reservoir simulation shows that injection of fresh water bank significantly decreases water production and improves gas recovery.