Abstract: Cationic polymer-containing gels are stable at elevated temperatures in soft and hard waters.

Abstract: Cationic polymer-containing gels are stable at elevated temperatures in soft and hard waters.

Abstract: Enhanced gel properties (e.g., faster gel time, higher attainable gel strengths) are achieved by reducing the pH and/or increasing the salt of a monovalent and/or divalent cation concentration of an aqueous reaction medium in which a polymer is reacted with an organic crosslinking agent. In addition, the gelation time of an aqueous composition comprising a polymer and an organic crosslinking agent is reduced by heating the composition above about 48.9.degree. C. (120.degree. F.) prior to injecting the composition into a subterranean formation. Alternatively, the gelation time of the aqueous composition is increased by incorporating a pH increasing agent into the composition.

Abstract: Gels stable in a subterranean formation at a temperature greater than about 175.degree. F. are formed using, inter alia, a stabilizing agent (e.g., a buffer having a buffering capacity at a pH of at least about 8 and/or a chelating agent).

Abstract: Visible gels are formed by mixing an inorganic crosslinking agent with a low viscosity aqueous solution having a low polyacrylamide concentration and devoid of polymers containing a vicinal diol pendant group. The visible gels are employed to reduce the water/hydrocarbon permeability ratio of subterranean formations.

Abstract: The gelation of a gelable composition is delayed by using, inter alia, a crosslinking rate retardant selected from the group consisting of epoxides, ethers, and mixtures thereof.

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Gels containing gas precursors and/or pathways are used to selectively reduce the flow of aqueous fluids with respect to the flow of nonaqueous fluids to enhance the recovery of the nonaqueous fluids from subterranean formations. The gels, while stable at reservoir conditions, are also readily degraded by gel degrading agents such as acids and therefore are also employed as fail-safe gels in subterranean gel treatments. In another embodiment, selective permeability is restored to a previously treated well by injecting a gas into the previous treated portions of the subterranean formation to displace any aqueous fluid obstructing the passage of the nonaqueous fluid through the polymer-coated pores or gel.

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Gels stable in a subterranean formation at a temperature greater than about 175.degree. F. are formed using, inter alia, a stabilizing agent (e.g., a buffer having a buffering capacity at a pH of at least about 8 and/or a chelating agent).

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Visible gels are formed by mixing an inorganic crosslinking agent with a low viscosity aqueous solution having a low polyacrylamide content. The visible gels are employed to reduce the water/hydrocarbon permeability ratio of subterranean formations.

Abstract: Drilling mud is economically disposed of in an environmentally sound manner by mixing the mud with a crosslinkable polymer and a crosslinking agent to form a composition that solidifies at a predetermined time. The composition is injected into a subterranean formation through an abandoned well and, when solidified, is substantially immobilized within the formation.

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Polymers (and especially hydroxyethylcellulose) are crosslinked using a lanthanide as a crosslinking agent. The crosslinked polymers have utility in well completion, well stimulation, enhanced oil recovery, and subterranean fluid containment operations.

Abstract: Pathway-containing foamed gels enhance the recovery of the nonaqueous fluids from subterranean formations by selectively reducing the flow of aqueous fluids with respect to the flow of nonaqueous fluids.

Abstract: Water production from a wellbore is reduced by sequentially or simultaneously injecting (a) a hydrophilic polymer-containing organic carrier fluid and (b) a crosslinking agent-containing fluid into at least a portion of a subterranean formation. The cross-linking agent reacts with the polymer in the presence of water to form a gel in at least a portion of the subterranean formation. The gel obstructs the flow of water in the subterranean formation, thereby reducing the production of water from the wellbore.

Abstract: Gels containing gas precursors and/or pathways are used to selectively reduce the flow of aqueous fluids with respect to the flow of nonaqueous fluids to enhance the recovery of the nonaqueous fluids from subterranean formations. The gels, while stable at reservoir conditions, are also readily degraded by gel degrading agents such as acids and therefore are also employed as fail-safe gels in subterranean gel treatments. In another embodiment, selective permeability is restored to a previously treated well by injecting a gas into the previous treated portions of the subterranean formation to displace any aqueous fluid obstructing the passage of the nonaqueous fluid through the polymer-coated pores or gel.

Abstract: Without interrupting an enhanced oil recovery polymer flood of a subterranean formation, ultrasonic energy is used to maintain the injectivity of a polymer solution during the polymer flood by modifying the properties of the injected polymer solution.