Preparation And Properties Of Core-shell Polyacrylamide Copolymer Microsphere Profile Control Agent

In order to enlarge the water injection volume and increase the utilization rate of water injection and prolong the stable production period,it is necessary to use profile control agent to adjust the water injection profile of reservoir formation.Plugging agents tend to migrate along the high permeability layer of heterogeneous reservoirs,and it is difficult to ent er low permeability areas.Therefore,deep profile control technology is of great significance.The polymer microsphere profile control technique is a relatively effective method in deep profile control technology.However,the size of the ordinary microspheres often needs to be matched with the formation hole roaring size.In view of this problem,we have designed a nuclear shell type cation / anion microsphere,through the different structure of the core shell.Different microspheres can be coalesced to expand their application and improve its plugging effect.By using the advantages of the dispersion polymerization,the product microspheres were prepared by one pot reaction and two step feeding.The core layer cationic PAM microspheres were prepared first.This part only has the cationic charge.The concentration of monomers,the concentration of initiator,the concentration of dispersant and agitate are studied by the orthogonal experiment.The optimum reaction conditions were obtained by the effect of mixing rate and reaction temperature on the conversion rate of polymerization monomer and the index of particle size.Under the optimum conditions,controlling the reaction conditions unchanged,by controlling the shell of reaction liquid,adding further to the reaction vessel,continue to react to the end,the core-shell cationic / anionic PAM copolymer microspheres with different particle sizes were obtainedThe composition,thermal properties,particle size and size distribution,morphology and water absorption and expansion process of the samples were characterized and evaluated by Fourier transform infrared(FT-IR),thermogravimetric analyzer(TGA),laser particle size analyzer(DLS),cold field scanning electron microscope(SEM)and polarized transmission electron microscope.The results showed that the microspheres had core-shell structure and a certain degree of sphericity.The diameter of the microspheres was monodisperse and distributed evenly,and the size was between 8 ?m ~15 ?m.The experimental study on the actual plugging performance of the microspheres using a high temperature and high pressure core flow test instrument is carried out.It is concluded that the blocking efficiency of the core shell positive / anionic PAM copolymer microspheres is better,and the blocking rate is about 95 %.Therefore,the synthesized microspheres prepared by this method have achieved good results,and enhance the plugging effect.