Method of treating underground formations or cavities by microgels

A method of treating formations, wherein the following stages are carried out:

• preparing a liquid composition comprising microgels by mixing in a solvent, under stirring, an amount representing 0.01% to 60% by mass of said composition of:
• either an inverse latex comprising an oil phase, an aqueous phase, at least one water-in-oil (W/O) type emulsifier, at least one oil-in-water (O/W) type emulsifier, 20% to 60% by weight of a crosslinked anionic polyelectrolyte based on either at least one strong acid function monomer copolymerized with at least one neutral monomer crosslinked with a crosslinking agent in a molar proportion expressed in relation to the monomers used of 0.002% to 0.5%, or a weak acid function monomer copolymerized with at least one neutral monomer crosslinked with a crosslinking agent in a molar proportion expressed in relation to the monomers used of 0.002% to 0.5%,
• or a powdered polymer obtained by azeotropic distillation, atomization or precipitation of said inverse latex,
• injecting said composition into the porous and permeable formation.