| 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. |