Selective permeability reduction in a subterranean hydrocarbon-bearing formation using a nonselective gel

Abstract From the Canadian patent

Selective permeability reduction is achieved in a heterogeneous treatment zone of a subterranean hydrocarbon-bearing formation by initially placing a nonselective permeability-reducing material in the high and low permeability regions of the treatment zone. Thereafter a permeability-, restoring agent is placed in the regions behind the permeability-reducing material. The agent contacts all of the material in the low permeability region,reacting with it to restore permeability thereto. However the agent is, consumed by reaction before it contacts all of the material in the high permeability region, thereby leaving a sufficient amount of material in the high permeability region to achieve …