The present invention relates generally to stable percarboxylic acid compositions comprising, inter alia, at least two stabilizing agents, and various uses for water treatments, including water treatments in connection with oil- and gas-field operations. The present invention also relates to slick water compositions and gel based compositions that comprise stable percarboxylic acid compositions and the use thereof in oil- and gas-field operations.

A carbon disulfide-modified amine additive may be introduced to an aqueous stream in an effective amount to separate oil from the water in the aqueous stream, such as separating at least some of the oil from emulsified oil-in-water in a production fluid, where the oil is crude oil. The carbon disulfide-modified amine additive may be produced from a reaction of synthetic amine, natural amines, or chemically modified natural amines with carbon disulfide and an α,β-unsaturated compound and/or an epoxide in one step. In one non-limiting embodiment, the amine is a natural amine or chemically modified natural amine of a polysaccharide containing amino functional group(s). Optionally, a base catalyst is used to make the carbon disulfide-modified amine additive.

Provided herein are oil herding agents, for example, a biocompatible non-ionic functionalized polysaccharide konjac glucomannan radiation-induced degraded konjac glucomannan. Also provided is a method for containing the spread of an oil spill on a water surface at a low water temperature utilizing the oil herding agent. In addition there is provided a method for preparing an oil herder, a radiation-induced degraded konjac glucomannan prepared by the method and a method for increasing a slick thickness ratio of an oil slick on a water surface utilizing the prepared oil herder.

A method of demulsifying an emulsion with an ionic liquid having a nitrogen or phosphorus cation.

The present invention provides improved methods for purifying and/or removing oily particles, and/or contaminants suspended or dissolved in water. In particular the process relates to an additive composition that has the appropriate surfactant characteristics for effectively removing an oil phase from an oil/aqueous mixed phase via foam fractionation. According to the invention, a hydrophobically modified polymer that acts as an associative thickener is combined with surfactant in appropriate ratios to facilitate oil removal for water purification in any of a number of commercial, environmental and industrial applications.

The present invention relates generally to stable percarboxylic acid compositions comprising, inter alia, at least two stabilizing agents, and various uses for water treatments, including water treatments in connection with oil- and gas-field operations. The present invention also relates to slick water compositions and gel based compositions that comprise stable percarboxylic acid compositions and the use thereof in oil- and gas-field operations.

A single-phase microemulsion additive may be introduced to a stream containing mixtures of or emulsions of oil and water in an effective amount to separate oil from the water in the stream and/or separating water from the oil in the stream. The single-phase microemulsion additive is formed by combining at least one demulsifier, at least one water clarifier, at least one surfactant, and optionally at least one solvent.

The present invention provides improved methods for purifying and/or removing oily particles, and/or contaminants suspended or dissolved in water. In particular the process relates to an additive composition that has the appropriate surfactant characteristics for effectively removing an oil phase from an oil/aqueous mixed phase via foam fractionation. According to the invention, a hydrophobically modified polymer that acts as an associative thickener is combined with surfactant in appropriate ratios to facilitate oil removal for water purification in any of a number of commercial, environmental and industrial applications.

A method of improving effluent brine quality, the method (i) providing a mud wash solvent comprising a hydrocarbon having a specific gravity less than that of a desalter brine to be treated; and (ii) adding the mud wash solvent to a mud wash stream of a desalter system to provide a treated effluent brine.

The invention provides methods for treating or disrupting biofilm in wastewater systems comprising the step of adding to the system at least one biofilm disrupting dose of one or more compounds of general formula I: R—O—O—R.sup.1 I wherein, R is selected from C.sub.1-C.sub.8 alkyl, substituted C.sub.1-C.sub.8 alkyl, aryl, substituted aryl, C.sub.1-C.sub.8 acyl, substituted C.sub.1-C.sub.8 acyl, arylacyl and substituted arylacyl; and R.sup.1 is selected from H, M.sup.+, C.sub.1-C.sub.8 alkyl, substituted C.sub.1-C.sub.8 alkyl, aryl, substituted aryl, C.sub.1-C.sub.8 acyl, substituted C.sub.1-C.sub.8 acyl, arylacyl and substituted arylacyl.