Method for plugging subterranean formations with siliceous gels
AssigneeConoco Inc.
InventorsLaine E. Summers, Joe D. Allison
Life of this patent
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Abstract
A high pH solution containing a silica material and an inorganic fluoride salt which hydrolyzes to form hydrofluoric acid are introduced into a subterranean zone where the pH is reduced by the acid whereby the silica material forms a gel and plugs the subterranean zone. The pH at which gelling occurs can be increased by adding a soluble inorganic salt to the solution.
Claims7
A process for selectively plugging a permeably zone in a subterranean formation which comprises injecting into said zone a high pH aqueous solution of colloidal silica or alkali metal silicate and an inorganic fluoride salt which hydrolyzes to form hydrofluoric acid, said inorganic fluoride salt being present in sufficient concentration to reduce the pH of the aqueous solution and effect gelling of the colloidal silica or alkali metal silicate in situ.
A process for selectively plugging a permeable zone in a subterranean formation having a temperature above about 82.degree. C. which comprises injecting into said zone a high pH aqueous solution of colloidal silica or alkali metal silicate, a water-soluble inorganic salt, and an inorganic fluoride salt which hydrolyzes to form hydrofluoric acid and an inorganic salt, said inorganic fluoride salt being present in sufficient concentration to reduce the pH of the aqueous solution and effect gelling of the colloidal silica or alkali metal silicate in situ.
Dependencies are inferred from the claim text.