초록 ▼

Methods and compositions for reducing the precipitation of fluoride compounds following the contact of an aluminum containing subterranean formation with an acid solution containing hydrofluoric acid are provided. In accordance with the methods, a hydroxy carboxylic acid is combined with the hydrofl

Methods and compositions for reducing the precipitation of fluoride compounds following the contact of an aluminum containing subterranean formation with an acid solution containing hydrofluoric acid are provided. In accordance with the methods, a hydroxy carboxylic acid is combined with the hydrofluoric acid solution and the subterranean formation is contacted with the resulting acid solution.

대표청구항 ▼

1. A method of reducing the precipitation of aluminum fluoride complexes following the acidizing of a sandstone formation with an acid solution containing hydrofluoric acid produced by protonation of a fluoride salt comprising the steps of: combining at least one hydroxy carboxylic acid selected

1. A method of reducing the precipitation of aluminum fluoride complexes following the acidizing of a sandstone formation with an acid solution containing hydrofluoric acid produced by protonation of a fluoride salt comprising the steps of: combining at least one hydroxy carboxylic acid selected from the group consisting of lactic acid and hydroxyacetic acid with said acid solution in an amount in the range of from about 5% to about 15% by weight of the resulting solution; and then contacting said sandstone formation with the resulting acid solution. 2. The method of claim 1 wherein said acid solution includes hydrochloric acid in an amount sufficient to protonate the source of said hydrofluoric acid. 3. A composition for acidizing an aluminum containing subterranean formation without substantial aluminum fluoride complexes precipitation comprising: a) water; b) hydrofluoric acid; and c) at least one hydroxy carboxylic acid selected from the group of lactic acid and hydroxyacetic acid present in an amount in the range of from about 5% to about 20% by weight of said composition. 4. The composition of claim 3 which further comprises hydrochloric acid. 5. The composition of claim 3 wherein said hydrofluoric acid is present in said composition in an amount in the range of from about 0.1% to about 6% by weight of said composition. 6. The composition of claim 3 which further comprises hydrochloric acid present in said composition in an amount in the range of from about 0.1% to about 6% by weight of said composition. 7. The composition of claim 3 wherein said hydroxy carboxylic acid is present in said composition in an amount in the range of from about 5% to about 15% by weight of said composition. 8. A method of acidizing an aluminum containing sandstone formation without substantial aluminum fluoride complexes precipitation comprising: contacting said formation with a preflush solution including: water; at least one compound selected from the group consisting of ammonium chloride and hydrochloric acid; and at least one hydroxy carboxylic acid present in said preflush solution in an amount in the range of from about 0.2% to about 20% by weight of said preflush solution; and after contacting said formation with said preflush solution, contacting said formation with an acidizing composition including: water; hydrofluoric acid; and at least one hydroxy carboxylic acid selected from the group of lactic acid and hydroxyacetic acid present in said acidizing composition in an amount in the range of from about 5% to about 20% by weight of said acidizing composition. 9. A method of acidizing an aluminum containing sandstone formation without substantial aluminum fluoride complexes precipitation comprising: contacting said formation with an acidizing composition including: water; hydrofluoric acid; and at least one hydroxy carboxylic acid selected from the group of lactic acid and hydroxyacetic acid present in said acidizing composition in an amount in the range of from about 5% to about 20% by weight of said acidizing composition; and after contacting said formation with said acidizing composition, contacting said formation with an overflush solution including: water; at least one compound selected from the group consisting of ammonium chloride and hydrochloric acid; and at least one hydroxy carboxylic acid present in said overflush solution in an amount in the range of from about 0.2% to about 20% by weight of said overflush solution. 10. The method of claim 9 wherein said hydroxy carboxylic acid present in said overflush solution is selected from the group consisting of citric acid, tartaric acid, malic acid, lactic acid and hydroxyacetic acid.