A process allowing the encapsulation of a polymerization accelerator comprising the steps of: a) providing an reverse emulsion containing, in an oil phase, a water solution/dispersion containing the polymerisation activator, the oil phase including a heat curable mixture of an isocyanate and a polyalkyldiene hydroxylated or polyol, b) pouring the reverse emulsion in a water phase to make a multiple emulsion water/oil/water, containing drops of activators as the internal water phase, and then, c) heating the multiple emulsion obtained in step b) to cure the polyisocyanate in polyurethane and obtain drops of activator enclosed in shells of polyurethane dispersed in water. The invention also relates to aqueous gelling systems comprising the encapsulated polymerization accelerator with water soluble or dispersable monomers and a polymerization initiator dispersed in said monomers, useful i.a. for sealing subterranean environments or consolidation of a soil or sealing of a subterranean structure.

A water-in-oil emulsion that includes an oil phase (O) and an aqueous phase (A) at an O/A ratio of from about 1:8 to about 10:1; wherein the water-in-oil emulsion includes the oil phase as a continuous phase that includes an inert hydrophobic liquid, at least one water-insoluble hydrophobic monomer, and at least one surfactant, and the aqueous phase as a dispersed phase of distinct particles in the oil phase that includes water and a water soluble polymer that includes: (i) at least one acrylamide monomer and (ii) at least one acrylic acid monomer; wherein the water soluble polymer is present in an amount from about 10 to about 35 weight percent of the water-in-oil emulsion. Also provided is water-in-oil emulsion that includes an oil phase (O) and an aqueous phase (A) at an O/A ratio of from about 1:8 to about 10:1; wherein the water-in-oil emulsion includes the oil phase as a continuous phase that includes an inert hydrophobic liquid and at least one surfactant, and the aqueous phase as a dispersed phase of distinct particles in the oil phase that includes water and a water soluble polymer that includes: (i) at least one acrylamide monomer, (ii) at least one acrylic acid monomer, and (iii) at least one water soluble hydrophobic monomer; wherein the water soluble polymer is present in an amount from 10 to 35 weight percent of the water-in-oil emulsion. Methods of treating a portion of a subterranean formation with a water-in-oil emulsion are also provided.