Abstract: An exemplary method of the present invention for performing an injection operation includes providing a water-soluble relative permeability modifier, introducing the water-soluble relative permeability modifier into a subterranean formation; and injecting an aqueous injection fluid into the subterranean formation after introducing the water-soluble relative permeability modifier. An exemplary permeability-modifying injection fluid of the present invention contains water-soluble relative permeability modifier. The water-soluble relative permeability modifiers of the present invention include hydrophobically modified water-soluble polymers, hydrophilically modified water-soluble polymers, and water-soluble polymers without hydrophobic or hydrophilic modification.

Abstract: The present invention provides drilling fluids that comprise a base fluid and a water-soluble relative permeability modifier. In addition, the present invention provides methods of reducing the permeability of a subterranean formation to aqueous-based fluids during the drilling phase that comprises providing a water-soluble relative permeability modifier; and placing the water-soluble relative permeability modifier into the subterranean formation during the drilling phase. The present invention provides methods of drilling a well bore in a subterranean formation comprising providing a drilling fluid that comprises a base fluid and a water-soluble relative permeability modifier, and placing the drilling fluid in the subterranean formation. The water-soluble relative permeability modifiers of the present invention generally may comprise hydrophilically modified polymers, hydrophobically modified polymers, or water-soluble polymers without hydrophobic or hydrophilic modification.

Abstract: The present invention provides a method of stimulating a subterranean formation penetrated by a well. The formation has a water-bearing section and a hydrocarbon-bearing section. The method includes the steps of: (a) introducing into the formation an aqueous treatment fluid containing a hydrophobically-modified relative permeability modifier, and (b) introducing an acidizing treatment fluid into the formation. The hydrophobically-modified RPM can be formed and introduced into the formation in several ways. For example, the hydrophobically-modified RPM can be the reaction product of a hydrophilic polymer and a hydrophobic compound that are capable of reacting with each other. The hydrophilic polymer is a polymer containing reactive amino groups in the polymer backbone or as pendant groups, which are capable of reacting with a hydrophobic alkyl halide compound.