Preparation And Evaluation Of Polymer Composite Microspheres For Profile Control And Displacement

At present,the waterflood development of most oilfields has entered the middle and late stages,profile control technology needs continuous innovation and development to meet the needs of the scene.The multi-functional polymer microspheres profile control technology has become hotspots and difficulties in the development of this field..A reversed-phase core-shell emulsion polymerization method is used to synthesize a polymer microsphere,which is core-shell structure,shell high temperature can be decomposed,after release of nuclear layer has a certain viscosity.First,through the screening experiment of emulsifier,the span80-tween85 mixing system was determined as the surface active agent for the anti-phase emulsion polymerization.Then fixed nuclear reaction,used core-shell two-step generation method and discussed the effects of the amount of acrylamide monomer,initiator,polymerization temperature and polymerization time on the yield and dispersion of microspheres.Last,the optimum conditions of microspheres reaction were determined,Core-shell two-step generation method,the reaction temperature was 65 ?,the amount of shell monomer was 6% of oil phase(styrene: vinyl acetate = 4: 1),the ratio of crosslinking agent to shell monomer was 1:10,the amount of dispersant was 1.2% of oil phase,and the reaction time was 3.5h.Combined with infrared spectroscopy,scanning electron microscopy,transmission electron microscopy,laser particle size analyzer and other instruments,the structure and morphology of the microspheres were described.The results showed that microspheres had a core-shell structure with good dispersibility.The particles were spherical and uniform in size with a size of submicron-micron.The effect of profile control was simulated by displacement test of core,plugging rate was 70% or more,and increase recovery was 22.22%.At 90 ?,salinity of 5000 mg/L conditions,the composite microsphere had 20 times the expansion of the water.The experiment of shell cracking time proved that the composite microspheres could block effectively in the early stage,after about 60 days,it decomposed to release the core material,had a certain viscosity,and played the role of oil displacement.The core-shell polymer composite microsphere is a new type of functional material used in tertiary recovery.It can replace conventional polymer microspheres and replace or partially replace the polymer in tertiary recovery.