Method for preparing functional composite microsphere with multi-layer core-shell structure and application thereof

The invention discloses a method for preparing functional composite microsphere with a multi-layer core-shell structure and application thereof, and relates to the technical fields of functional macromolecular microsphere preparation and petroleum exploitation, in particular to the technical field of deep profile control water shutoff during high water-cut period of petroleum exploitation. The functional composite microsphere is prepared by a dispersion polymerization method which comprises the following steps: forming a core part by polymerization of a styrene monomer, and forming a cation shell part by copolymerization of acrylamide, the cation monomer and a crosslinking agent; and forming an anion shell part by copolymerization of acrylamide, anion monomer and the crosslinking agent. The functional composite microsphere is characterized in that the size of the microsphere is between 1,500 and 2,000nm and the microsphere is white solid powder or polymer emulsion; the expansion multiplying power of the microsphere is improved by 20 to 50 times after 5-day hydration; and therefore, the functional composite microsphere can be used for effective plugging at the pore throat of a bottom high permeability zone during high water-cut period of the petroleum exploitation.