Abstract: A copolymer of sodium vinyl sulfonate and polyalkylene glycol mono- or di-methacrylate and a process for inhibiting scale deposition, particularly inorganic sulfate such as barium sulfate. An aqueous fluid present in or produced from a subterranean formation is contacted with an aqueous solution having the copolymer dissolved therein. The aqueous fluid has an acidic pH and the copolymer has a molecular weight of from about 2,000 to about 30,000.

Abstract: A relatively high molecular weight polyvinyl sulfonate and a process for inhibiting scale deposition, particularly inorganic sulfate such as barium sulfate, wherein an aqueous fluid present in or produced from a subterranean formation is contacted with an aqueous solution having a relatively high molecular weight polyvinyl sulfonate dissolved therein. The aqueous fluid has a pH equal to or less than 6.0 and the polyvinyl sulfonate has a molecular weight of from about 9,000 to about 30,000.

Abstract: A method of gravel packaging a well penetrating and in fluid communication with a subterranean formation or zone by sealing the apertures of a gravel pack liner, except near the bottom of the liner, against entry of slurry fluid. This prevents gravel from clogging the apertures or bridging the annulus between the liner and the well bore. An immobile gel provides the sealing function, and a breaker eventually breaks the gel, thereby permitting removal of the gel and unblocking the apertures. The gel is formed from a suitable liquid composition containing the gel breaker, and may be applied to the liner prior to lowering the liner and wash pipe into the well bore.

Abstract: A composition for treating a subterranean formation and a method of treatment. An aqueous gel composition is formed by mixing a carboxylate-containing polymer with a crosslinking agent comprised of chromic carboxylate. Ethylenediaminetetraacetic and is incorporated as a single-component gel breaker. When introduced into a permeable formation, the solution forms a gel which makes the formation impermeable. After a predetermined period of time the gel breaker breaks the gel to a predetermied degree which restores partial or limited permeability to the formation.

Abstract: A composition for treating a subterranean formation and a method of treatment. An aqueous gel composition is formed by mixing a carboxylate-containing polymer with a crosslinking agent comprised of chromic carboxylate. Ethylenediaminetetraacetic acid is incorporated as a single-component gel breaker. When introduced into a permeable formation, the solution forms a gel which makes the formation impermeable. After a predetermined period of time the gel breaker breaks the gel to a predetermined degree which restores partial or limited permeability to the formation.

Abstract: A method of preventing flow of formation fluid and crude oil into a well bore during an electric resistivity logging operation. A readily flowable liquid gellation composition containing a breaker is of contrasting resistivity to that of the formation water. Fluids in the well bore are displaced by the liquid composition and the composition is allowed to gel. The gel may be of a highly viscous, moderately flowable state, which prevents ingress of formation fluids and crude oil but permits logging equipment to be moved therethrough. Alternatively, the gel in the well bore may be removed while leaving the gel in the adjoining formation in place, and the removed gel replaced with fresh water prior to the logging operation. After effecting the log a breaker in the gel composition causes the gel to revert to a liquid, which is removed from the well bore.

Abstract: A method of protecting a permeable formation penetrated by a well bore against damage by subsequent treatment operations. In protecting the formation against damage by cement used in installing a casing, a well bore is drilled through the formation and liquid composition capable of gelling is introduced into the area of the formation. After the gel is formed it is drilled out, leaving a sufficient amount still plugging the voids in the formation wall. Subsequently, after installing the casing, the gel reverts to liquid form, leaving the permeable formation in condition for production of the well. Preferably, the gel contains a breaker to cause the gel to revert to liquid form after a predetermined period of time.

Abstract: A method of preventing intrusion of fluid into a horizontal well bore. A quantity of liquid composition capable of gelling and containing a breaker is introduced into a horizontal well bore up to a point corresponding to the bottom of the intrusion zone. After the liquid composition gels into a temporary gel, a second liquid composition capable of gelling into a permanent gel is introduced into the zone to shut off fluid flow from the zone. The temporary gel prevents flow of the permanent gel into the horizontal well bore. Thereafter the breaker in the temporary gel causes the gel to revert to a liquid, which is removed from the horizontal well bore upon production of the well.

Abstract: A process employing a polymer gel in oil recovery applications. A gel is prepared by mixing a single aqueous gelation solution at the surface made up of a chromium acetate complex crosslinking agent and a mixture of an acrylamide polymer and guar gum polymer. The solution is injected into a desired treatment region and gelled to completion in situ.

Abstract: A polymer gel is formulated by adding a cross-linking agent containing a polyvalent metal cation to an aqueous solution of undried partially hydrolyzed polyacrylamide. The resulting gel is dissolved or suspended in an aqueous medium and injected via a well into a subterranean hydrocarbon-bearing formation to improve oil recovery from the formation.

Abstract: A reducing agent is added to an aqueous medium containing a mixture of undried partially hydrolyzed polyacrylamide and an oxidizing agent. The reducing agent and oxidizing agent act as a redox catalyst system to cross link the polymer and form a polymer gel. Gelation time is controlled by maintaining the components of the gel-forming mixture at predetermined concentrations, reaction ratios and pH. The gel-forming mixture is applied to a porous matrix such as a subterranean hydrocarbon-bearing formation where the mixture gels in situ at a controlled rate to reduce the permeability of the porous matrix.

Abstract: Highly permeable zones in a subterranean formation are selectively plugged by injecting an aqueous solution of an acrylamide polymer, a phenol and an aldehyde via a well into the highly permeable zones. The solution forms a non-flowing, water insoluble polymer resin in situ at a temperature of from about 50.degree. C. to 100.degree. C. and an alkaline pH over a period of from about 1 to 10 days. The polymer resin plugs the highly permeable zones of the formation.

Abstract: Highly permeable zones in a subterranean formation vertically bounded by a relatively less permeable zone are selectively plugged by injecting an emulsion of melamine and formaldehyde in an alcohol medium via a well into the highly permeable zones. The emulsion is hydrocarbon soluble are preferentially envelops the highly permeable zones where it reacts to form a resin at a temperature of from about 80.degree. C. to about 250.degree. C. and a pH of from about 7 to 12 and over a period of from about 1 to 4 days. The resulting resin substantially plugs the highly permeable zones in the formation.

Abstract: Highly permeable zones in a subterranean formation are selectively plugged by injecting a melamine formaldehyde solution via a well into the highly permeable zones. The solution is water soluble and preferentially enters water-containing zones where it reacts to form a resin at a temperature of from about 25.degree. C. to about 120.degree. C. and a pH of from about 7 to 12 and over a period of from about 1 to 4 days. The resulting resin substantially plugs the highly permeable zones in the formation.

Abstract: Highly permeable zones in a subterranean formation are selectively plugged by injecting an aqueous solution of urea, an aldehyde and an acrylamide polymer via a well into the highly permeable zones. The solution forms a polymer resin in situ at a temperature of from about 20.degree. C. to 75.degree. C. and a pH of from about 3 to 9 and over a period of from about 2 to 72 hours. The resulting polymer resin either partially or completely plugs the highly permeable zones in the formation.

Abstract: The highly permeable zones of a subterranean formation are selectively plugged by injecting an aqueous solution of an acrylamide polymer, an aldehyde and a borate salt via a well into the highly permeable zones. The solution forms a non-flowing, water-soluble polymer gel in situ at a temperature of from about 20.degree. C. to 100.degree. C. at an alkaline pH over a period of from about 2 to 72 hours. The polymer gel plugs the highly permeable zones.

Abstract: A process for selectively reducing the permeability of a subterranean formation penetrated by a well bore and having an injection surface plugged by crosslinked dry polymer. The process comprises the sequential injection of an aqueous solution containing an oxidizing agent, an aqueous spacer medium, and an aqueous solution having at least one dry polymer dissolved therein. Sequential injection of these aqueous solutions can be repeated to achieve the desired degree of injectivity and permeability reduction.

Abstract: Hydrolyzed and neutralized acrylonitrile is polymerized in solution without isolation to produce a high molecular weight polyacrylamide useful for mobility control in supplemented recovery of petroleum. The polyacrylamide optionally may be hydrolyzed, and/or methylolated and/or sulfomethylated.

Abstract: A preslug of polyalkene oxide, e.g., polyethylene oxide, is injected before injection of a displacement fluid, e.g., a micellar dispersion or thickened water, in order to prevent contact between the displacement fluid and polyvalent, e.g., divalent and trivalent ions in the formation water, which ions are detrimental to many displacement fluids.