Abstract: Demulsification of a water-in-oil, especially a water-in-crude oil, emulsion is effected by contacting it with an aqueous composition having at least one oil-soluble demulsifier and at least one water-soluble surfactant. These aqueous formulations are advantageous over conventional organic formulations of demulsifiers, as the need for toxic and/or flammable/combustible organic solvents is eliminated.

Abstract: A method of inhibiting corrosion of iron and steel alloys in contact with oil-in-brine emulsions is claimed. The method comprises treating the oil-in-brine emulsions with an effective amount of a water soluble polymer having an average molecular weight of at least one million and an effective amount of a nitrogen-containing corrosion inhibitor.

Abstract: A method for separating emulsified oil from water in petroleum production is disclosed. Low molecular weight polymers of dimethylaminoethyl acrylate methyl chloride and benzyl chloride quaternary salt have good activity as reverse emulsion breakers for freeing oil tied up as a oil-in-water emulsion. The polymer reverse emulsion breakers are preferably prepared and used as aqueous solutions to obviate the need for inversion techniques and the use of hydrocarbon compatibilizers and surfactants as required for a latex polymer.

Abstract: A method and apparatus for recovering oil and clarifying waste water from an oil field are disclosed. The method includes the step of treating the waste water with an aqueous de-emulsifying agent comprising wattle tannin, an inorganic coagulant and a synthetic polymer flocculant to destabilize the oil emulsion and rapidly agglomerate the oil particles formed thereby. Efficiency of the present de-emulsifying agent permits use of flotation equipment for rapid clean-up of the waste water and obviates the need for large settling pits.

Abstract: The invention provides a method of recovering water from an acid workover, the water including dispersed solids and emulsified oil. According to the method, the water is treated with an effective amount of a dispersion of a water-soluble cationic polymer.

Abstract: One aspect of the invention provides a method of removing emulsified oil from oil field produced water. According to the method, the oil-containing water is treated with an effective amount of a dispersion of a water-soluble cationic polymer.

Abstract: Improved water quality of overboard waters discharged from off-shore oil producing rigs is obtained by treating oily produced waters from a crude oil separator, and prior to exposure to air, with an effective coalescing amount of a combination of an iron chelating agent and various polymeric coagulating/coalescing agents. The preferred chelating agent is citric acid, or its salts, EDTA, HEDTA, or mixtures thereof. The polymeric coagulating/coalescing agents may be anionic, cationic, ampohoteric, but are most preferably copolymers of acrylamide with at least one of the monomers chosen from the group consisting of acrylic acid, methacrylic acid, DMAEA, DMAEM, or their acid of quaternary salts, DADMAC, MAPTAC, AMPS, and the like.