Abstract: The use of free, aromatic acids which contain at least two aromatic ring systems or at least two acid functions, and/or salts thereof, for influencing rock formations in the exploitation of underground mineral oil and/or natural gas deposits is described. The free acids are used in particular for influencing and especially controlling the flow of acid into rock formations in so-called acidizing methods. Suitable salts of said aromatic acids serve for reducing the rock permeability and in particular reducing the inflow of water into the well bore. In addition to this use, corresponding methods are also claimed.