Abstract: Methods of temporarily reducing the permeability of one or more selected sections of a subterranean formation penetrated by a horizontal well bore and the flow of water or water and hydrocarbons or hydrocarbons therefrom are provided. The methods comprise the steps of preparing or providing an aqueous treating fluid comprising water and a water-soluble formation permeability reducing agent, introducing the aqueous treating fluid into one or more selected sections and when required, contacting the one or more selected sections with an aqueous treating fluid comprising water and a formation permeability restoring chemical.