Buffer regulated mud acid
Patent
·
OSTI ID:6919550
A siliceous material is reacted relatively slowly with an aqueous hydrogen fluoride-containing acid by contacting the material with an aqueous solution of a fluoride salt, a weak acid, and a weak acid salt in proportions that form a significant but low concentration of hydrogen fluoride. The solute concentrations are preferably correlated so that the fluoride salt concentration is equivalent to at least a clay-dissolving concentration of hydrogen fluoride, the weak acid concentration is sufficient to convert at least an effective amount of fluoride salt to hydrogen fluoride, and the weak acid salt concentration is sufficient to provide a ratio of weak acid to weak acid salt that limits the rate of reaction. The composition provides a buffer-regulated mud acid consisting of an aqueous solution of an amount of fluoride salt equivalent to a hydrogen fluoride concentration of from about 0.1 to 3 molar, a concentration of weak acid sufficient to convert a significant proportion of the fluoride salt to hydrogen fluoride, and enough weak acid salt to provide a weak acid to weak acid salt ratio that buffers the pH of the solution at a value of from about 3 to 6. (12 claims)
- Assignee:
- Shell Oil Co.
- Patent Number(s):
- US 3889753
- OSTI ID:
- 6919550
- Country of Publication:
- United States
- Language:
- English
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