Claims
- 1. A cement for closing off fluid flow to a permeable zone of a formation obtained by a process comprising the steps of:
- a) injecting into said zone an aqueous solution containing a member selected from the group consisting of an alkali metal hydroxide, ammonium hydroxide, or organoammonium hydroxide;
- b) injecting next into said zone a spacer volume of a water-miscible organic solvent selected from the group consisting of methanol, ethanol, higher alcohols, ketones, tetrahydrofuran, and dimethyl sulfoxide; and
- c) injecting thereafter a water-miscible organic solvent containing an alkylpolysilicate in an amount sufficient to react with a member from step a) so as to form a silica cement in-situ.
- 2. The cement as recited in claim 1 where the alkali metal hydroxide comprises ions of sodium, potassium, or lithium, and mixtures thereof.
- 3. The cement as recited in claim 1 where in step a) said hydroxide is contained in the solution in an amount of from about 20 to about 60 weight percent.
- 4. The cement as recited in claim 1 where in step c) said alkylpolysilicate is contained in said solution in an amount of about 10 to about 90 weight percent.
- 5. The cement as recited in claim 1 where the silica cement withstands a temperature in excess of about 200.degree. F. and a pH of less than about 7.
- 6. The cement as recited in claim 1 wherein in step a) the organoammonium hydroxide comprises C.sub.1 to C.sub.10 alkyl or aryl groups in combination with hetero atom containing moieties.
- 7. The cement as recited in claim 1 where in step c) said alkylpolysilicate is the hydrolysis-condensation product of alkylorthosilicate according to the equation below: ##STR2## where n.ltoreq.2 and R=C.sub.1 -C.sub.10.
Parent Case Info
This is a division of copending application Ser. No. 07/810,649, filed on Dec. 19, 1991 U.S. Pat. No. 5,211,232.
US Referenced Citations (13)
Divisions (1)
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Number |
Date |
Country |
Parent |
810649 |
Dec 1991 |
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