Method of preparing microparticles
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Abstract
A method of preparing microparticles comprising an aqueous solution or dispersion of an oil or gas field production chemical encapsulated in a continuous polymeric phase comprising a degradable polymer, which method comprises: (a) preparing a water in oil in water double emulsion or a water in oil in oil double emulsion having an internal aqueous phase comprising an aqueous solution or dispersion of the production chemical and an internal oil phase comprising a solution of a degradable polymer dissolved in a volatile organic solvent wherein the internal aqueous phase is dispersed in the internal oil phase of the double emulsion in the form of droplets having a mean diameter of less than 10 microns; and (b) at least in part evaporating the volatile organic solvent from the double emulsion such that the degradable polymer accumulates around the droplets of the internal aqueous phase and hardens to form microparticles comprising a continuous polymeric phase encapsulating the internal aqueous phase having a mean particle diameter of less than 10 microns.
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Citations
51 Claims
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1-31. -31. (canceled)
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32. A method of introducing an oil or gas field production chemical into a subterranean formation comprising:
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(a) injecting a suspension comprising microparticles suspended in a liquid medium into a formation through an injection well wherein the microparticles have a mean diameter of less than 1 micron and wherein the microparticles comprise an aqueous phase comprising an aqueous solution of a water-soluble oil or gas field production chemical or an aqueous dispersion of water-dispersible oil gas or gas field production chemical encapsulated in a continuous polymeric phase, and the polymer forming the continuous polymer phase is degradable under the conditions encountered in the formation;
(b) allowing the suspension to percolate through the formation towards a production well; and
(c) controllably releasing the aqueous solution of the water-soluble oil or gas field production chemical or the aqueous dispersion of the water-dispersible oil or gas field production chemical from the microparticles into the formation and/or the production well through degradation of the polymer forming the continuous polymeric phase. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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Specification