Abstract: Methods and compositions for altering the water permeability of subterranean formations are provided. The compositions are comprised of water, at least one polymer capable of being gelled when contacted with a crosslinking agent, at least one crosslinking agent comprised of polyvalent metal cation, and a cation reactivity retarding chelating agent which provides anion for chelating the polyvalent metal cation selected from substantially water soluble dicarboxylic acids, hydroxy carboxylic acids, ketocarboxylic acids and the corresponding salts thereof.

Abstract: A process is disclosed for delaying the rate at which water soluble polymers are gelled by an aldehyde and a phenolic compound and for increasing the mechanical strength of these gels which comprises contacting an aqueous solution of said water soluble polymer, aldehyde, phenolic compound, and water with from 0.004 to about 0.049 wt % of a transition metal ion. In addition, novel gelable compositions are disclosed.

Abstract: A gelable composition is provided which can be injected into a well prior to steam treatment of the well. The composition comprises water, a water-dispersible polymer, a water-dispersible first crosslinker and a water-dispersible second crosslinker, wherein the first and second crosslinkers have differing temperature responsive crosslinking characteristics over the temperature range of about 70.degree. F. to about 400.degree. F. so as to enable crosslinking of the polymer and gelation of the composition over substantially the entire temperature range. Injection of the composition into a "cold" well followed by steam treatment of the well causes the polymer to undergo a two stage crosslinking reaction which produces a particularly effective and stable gel in diverting steam from "thief zones" in the formation surrounding the well.

Abstract: A process is disclosed for delaying the rate at which water soluble polymers are gelled by an aldehyde and a phenolic compound and for increasing the mechanical strength of these gels which comprises contacting an aqueous solution of said water soluble polymer, aldehyde, phenolic compound, and water with from 0.004 to about 0.049 wt % of a transition metal ion. In addition, novel gelable compositions are disclosed.

Abstract: A gelable composition is provided which can be injected into a well prior to steam treatment of the well. The composition comprises water, a water-dispersible polymer, a water-dispersible first crosslinker and a water-dispersible second crosslinker, wherein the first and second crosslinkers have differing temperature responsive crosslinking characteristics over the temperature range of about 70.degree. F. to about 400.degree. F. so as to enable crosslinking of the polymer and gelation of the composition over substantially the entire temperature range. Injection of the composition into a "cold" well followed by steam treatment of the well causes the polymer to undergo a two stage crosslinking reaction which produces a particularly effective and stable gel in diverting steam from "thief zones" in the formation surrounding the well.

Abstract: A sulfate-free clear green solution of chromium(III) propionate is prepared by mixing aqueous propionic acid containing up to 55 weight percent propionic acid with a chromium(VI) oxidant, such as a dichromate or chromate, and a sulfur-containing reductant, such as a bisulfite, which on reacting yields two phases: a lower sulfate-containing phase for discard or recycle and an upper phase solution of sulfate-free clear green propionate-sequestered chromium(III), the latter phase being stabilized with additional acid. The upper phase solution is useful for crosslinking polymeric viscosifiers such as partially hydrolyzed acrylamide-based polymers and the like in permeability contrast corrections in enhanced oil recovery operations.

Abstract: A water permeability contrast correction process to improve the sweep efficiency of waterflooding in carbonate-bearing strata which involves a sequential injection of (1) an optional aqueous preflush slug to adjust connate water salinity, (2) a slug of aqueous polymer gelable with polyvalent metal cations, such as an polyacrylamide, (3) an acidic aqueous solution effective to dissolve some of the carbonate and at least therefrom polyvalent metal cations specifically calcium or magnesium or both effective to gel said polymer, wherein said aqueous polymer and acidic solution can be injected together in a single slug, followed by (4) an additional aqueous polymer solution injection, wherein the acidic solution provides polyvalent metal cations in-situ for gelation of said polymer slug to preferentially decrease water permeability in highly permeable thief zones, and (5) an aqueous drive fluid.

Abstract: A water permeability correction process, and composition therefor, to improve the sweep efficiency of waterflooding which involves the sequential injection of (1) an optional aqueous preflush slug to adjust connate water salinity, (2) an aqueous sequestered polyvalent metal cation, such as chromium, wherein the sequestering anion is bactericidal, such as propionate, (3) a gelable polymeric viscosifier, such as polyacrylamide, and, preferably, (4) an aqueous drive fluid.

Abstract: A water permeability correction process, and composition therefor, to improve the sweep efficiency of waterflooding which involves the sequential injection of (1) an optical aqueous preflush slug to adjust connate water salinity, (2) an aqueous sequestered polyvalent metal cation, such as chromium, wherein the sequestering anion is bactericidal, such as propionate, (3) a gelable polymeric viscosifier, such as polyacrylamide, and, preferably, (4) an aqueous drive fluid.