Synthesis And Properties Of Core-shell Polyacrylamide Microspheres With Large Particle Size

Polymer microsphere plugging agent,a novel kind of functional material made from polyacrylamide and its derivatives,has been used effectively to enhance oil recovery.Due to the large amounts of hydrophilic functional group,such as amide group,the polymer microsphere can expand and gel to plug the pore throats of underground.However,particle size of which only ranges from 50 nm to 5 ?m,domestic polymer microsphere can hardly plug the high water-penetrating region effectively.Thus,large-particle-size core-shell polymer microspheres are essential to plug the high water-penetrating region with large pore throats and large cracks.Inverse suspension polymerization was used to synthesis the large-particle-size core-shell polymer microspheres.The effect of every technological parameter on the particle size of polymer microspheres was discussed in detail.The results indicate that the particle size of polymer microspheres can be controlled by changing the technological parameters,such as oil-water ratio,stirring rate,stabilizer concentrate,monomer concentrate,initiator concentrate,crosslinker concentrate and so on.Laser particle analyzer,organic element analyzer,scanning electron microscope(SEM),optical microscope,Fourier transformation infrared spectrometer(FT-IR)and thermal gravity analyzer were used to characterize the prepared polymer microsphere.With the chemical composition,structure,morphology,and thermal stability of polymer microsphere studied,how the various parameters affected the expansive behavior of polymer microsphere was also discussed.Besides,the plugging effect of polymer microsphere was evaluated.The results indicate that the prepared microspheres possess obvious core-shell structure and regular surface morphology which can be affected by technical parameters.At 60 oC,besides satisfying thermal stability,the core-shell polymer microspheres performed regular expansive behavior.With outstanding expansive ratio ranged from 15 to 30,the prepared core-shell polymer microspheres effectively plugged the pore throats of sand packed model whose initial water-permeability was 6000 mD.After 10 days,the plugging ratio overpassed 88 % which represented the excellent plugging ability of core-shell polymer microspheres.