The precipitation time of a precipitate-forming aqueous solution containing a polyvalent metal that precipitates as a gelatinous metal hydroxide and a reactant that raises the pH to cause the precipitation is decreased by dissolving an incompletely dissociated polyvalent acid in the aqueous solution.
A metal hydroxide-thickened well treating fluid comprises an aqueous liquid containing a water-soluble salt of an amphoteric metal and enough water-soluble base to form a viscosifying amount of a hydrated oxide of the metal.
An aqueous solution of a water-soluble polymer which can be cross-linked in the presence of certain ions by adjusting the pH of the solution is disclosed. The aqueous solution contains a cross-linkable water-soluble organic polymer and at least two cross-linking agents (ions) for said polymer, each cross-linking agent (ion) being effective to cross-link the polymer at a different pH value. The pH of the initial solution is adjusted to a value between the two effective pH values where minimal (if any) cross-linking occurs. The pH can be adjusted up or down to within a range which is effective to cross-link the polymer.
A method of precipitating or depositing material within an underground reservoir which comprises introducing into the reservoir in aqueous solution (i) an isolated enzyme and (ii) a substrate for the enzyme, such that the action of the enzyme on the substrate leads to the precipitation or deposition of material within the underground reservoir.
3885065 - Hydrated metal oxide deposition - Owned by Shell Oil Company (Houston, TX) [*] Notice:The portion of the term of this patent subsequent to September 4, 1990 has been disclaimed.
A treating liquid for depositing a hydrated metal oxide comprises a basic aqueous solution of an oxide of an amphoteric metal and a pH reducing reactant that subsequently lowers the pH of the solution to one at which a hydrated oxide of the amphoteric metal is precipitated. The treating liquid can provide a single step process for consolidating or plugging a sand and/or can comprise a sand consolidating or plugging component of a drilling, fracturing, perforating, oil-displacing, or the like, type of fluid.
The invention herein provides a method for the time delayed precipitation of a solid phase of metal from a low pH, metal salt solution comprising adding to the metal solution a substrate, such as an amide, and an enzyme, such as an amidase, which will react with the substrate, which causes a rise in pH upon the reaction of the substrate with the enzyme. The rise in pH causes the metal to precipitate from solution. The precipitated metal is useful for emplacing metal hydroxides for providing sorptive material useful for removing contamination from groundwater.
