Method and composition for limiting permeability of a matrix to limit liquid and gas inflow

A method of limiting or reducing liquid and/or gas inflow through a porous matrix, comprising delivering to said porous matrix a coagulable polymer emulsion or colloid comprising a dispersion of polymer particles for contacting with at least one selected additive which interacts with said polymer emulsion or colloid to form a sealing barrier to reduce liquid and/or gas inflow through the porous matrix wherein said coagulable polymer emulsion or colloid contains at least one selected additive including one or a combination of radiation stabilisers to confer radiation resistance on said sealing barrier;

• wherein said sealing barrier is formed by contacting said polymer emulsion or colloid with a further selected additive to cause coagulation of said polymer emulsion or colloid to a coagulated mass to form said sealing barrier;
• wherein said sealing composition comprises a latex emulsion or colloid comprising a dispersion of latex particles in aqueous solution and a radiation stabiliser selected from the group consisting of carbon black, zinc oxide both in particulate form and essentially insoluble in water;
• ortho di-substituted phenols, hydroxyphenyl propionates, hydroxybenzyl compounds, aromatic amines, sterically hindered amines, phosphites and organic sulphur compounds;
• and wherein said sealing composition forms a containment barrier mechanically resistant to at least 1 MRad.