Thermally responsive aqueous silicate mixture
AssigneeSaudi Arabian Oil Company
InventorsKevin C. Taylor, Hisham A. Nasr-El-Din
Life of this patent
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Abstract
Sealing a zone in a subterranean well-formation is effected with an aqueous silicate solution containing an alkali metal silicate, at least one activator and a mixture of a chelating agent and a phosphonate. This composition greatly increases the divalent ion tolerance of the silicate gelling system.
Claims14
A composition for increasing the gel formation tolerance of aqueous alkali metal silicate solutions for divalent ions present in subterranean formations, which comprises:
- (a) aqueous alkali metal silicate solution;
- (b) a thermally responsive gelation activator;
- and
- (c) a mixture of phosphonate and a chelating agent selected from the group consisting of ethylene diamine tetraacetic acid, propane diamine tetraacetate, diethyltriamine pentaacetate, N-hydroxyethylene diamine triacetate, hydroxyethylimino diacetic acid, nitrilo triacetate and 1,3-propanediamine tetraacetate.
A method of plugging or sealing a zone in a subterranean formation with an aqueous alkali silicate solution which has an increased gel formation tolerance to divalent ions present in said formation, which comprises:
- (a) introducing into said zone an aqueous alkali metal silicate composition comprising,
- (i) an aqueous alkali metal silicate solution,
- (ii) a thermally responsive gelation activator;
- and
- (iii) a mixture of a phosphonate and a chelating agent selected from the group consisting of ethylenediamine tetracetic acid, propane diamine tetracetate, diethyltriamine pentaacetate, N-hydroxyethylenediamine triacetate, hydroxyethylimino diacetic acid, nitrilo triacetate and 1,3-propanediamine tetraacetate;
- and
- (b) activating said gelation activator in response to a thermal change of said composition within said formation whereby said silicate composition forms a gel in said zone.
Dependencies are inferred from the claim text.