Method for inhibiting water permeation in an extraction well of a hydrocarbon oil from an underground reservoir

A polymerizable composition for injection into an underground reservoir of hydrocarbon oil, said composition comprising:

• at least a first monomer selected from an acrylic monomer or a methacrylic monomer;
• and
• at least a second monomer comprising at least one ethylene unsaturation and at least one polyoxoethylene chain;
• at least one hydrophilic initiator of radical polymerization with thermal activation (hydrophilic initiator) having a temperature T1/2 (10 h) in water within the range of 50-150° C.,
• at least one lipophilic initiator of radical polymerization with thermal activation (lipophilic polymerization initiator) having a temperature T1/2 (10 h) in benzene within the range of 50-150° C.,
• said composition being capable apt to form polymers in situ in contact with reservoir water,
• wherein the initiator is hydrophilic if its distribution coefficient between water and 1-octanol is less than zero, and
• the initiator is lipophilic if its distribution coefficient between water and 1-octanol is greater than zero.