A gelled formulation suitable for use in the treatment of discontinuities, comprising: phenolsulfonic acid in a concentration of 25-80% by weight guaiacolsulfonic acid in a concentration of 25-80% by weight free sulfuric acid in a concentration of 0 to 32% by weight and water in a concentration of 0 to 3% by weight diluted in a gel comprising colloidal silica to a concentration of 2 to 5% by weight of the gel.