Disclosed is a composition and use thereof for the recovery of hydrocarbon fluids from a subterranean reservoir. More particularly, this invention concerns sulfonated epoxy resin polymers comprising an epoxide-containing compound, a primary amino sulfonate, and optionally one or more of a primary monoamine alkylene oxide oligomer, that modify the permeability of subterranean formations and increase the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.