Use of reducing agents to control scale deposition from high temperature brine
AssigneeUnion Oil Company of California
InventorsDarrell L. Gallup, John W. Jost
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Abstract
The deposition of metal-containing scale, such as iron silicate scale, from a hot aqueous geothermal brine, or the like, is controlled by blending into the brine sufficient reducing agent effective for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions to cause an overall decrease in scale deposition, especially of iron silicate scale. Preferably, from 2 to 7 times the stoichiometric amount of reducing agent is used to effect a 70 to 90 percent reduction in the formation of iron silicate scale.
Claims30
A method for treating an aqueous geothermal fluid having a pH between about 5 and about 7 and containing disolved ferric cations and siliceous material which tend to interact to form insoluble, iron-rich silicates, said method comprising adding to said fluid a reducing agent effective for substantally lowering the concentration of said dissolved ferric cations so as to substantially reduce the formation of said insoluble silicates which would otherwise form in the absence of adding the reducing agent while changing the pH of the geothermal fluid by less than about 0.1 pH unit, said reducing agent being selected from the group consisting of carbon monoxide, sodium formate, formaldehyde, starch, dextrose, sucrose, corn syrup, glyoxal, acetaldehyde, butyraldehyde, methanol, ethylene glycol, t-butanol, phenol, hydroquinone, potassium cyanide, urea, urea hydrochloride, formamide, formamide hydrochloride, ascorbic acid, formic acid, oxalic acid, potassium iodide, stannous chloride, iron wire, aluminum, hydrazine hydrochloride, arsenious acid, hydrogen, animal glue, glycine, carbon black, elemental zinc and elemental iron.
The method as defined in claim a wherein the reducing agent comprises dextrose.
A method for treating an aqueous geothermal fluid having a pH of less than about 5 and coantaining disolved ferric cations and siliceous material which tend to interact to form insoluble, iron-rich silicates, said method comprising adding to said aqueous geothermal fluid a reducing agent effective for substantially lowering the concentration of said disolved ferric cations so as to substantially reduce the formation of said insoluble silicates which would otherwise form in the absence of adding the reducing agent while changing the pH of the geothermal fluid by less than about 0.1 pH unit, said reducing agent being selected from the group consisting of stannous cloride, iron wire, aluminum, animal glue, glycine, carbon black, elemental iron and elemental zinc.
Dependencies are inferred from the claim text.