Synthesis And Characterization Of Polyacrylamide Microsphere With High Mechanical Strength

Most of the petroleum reservoirs in China are facing serious heterogeneity caused by the high water-containing,which requires deep profile control.Polymer microspheres,as a newly developed profile-control and water-plugging agent,have controllable size and excellent swelling characteristics,which could plug the big pore and increase oil while decrease water content during the deep profile control process.However,polymer microspheres have a poor mechanical strength and it is easy to be crushed during stratum migration,which would reduce its plugging performance.To solving this problem,P(AM-BA)copolymer microspheres and PAM/OMMT composite microspheres were both synthesized in this research via reverse-phase suspension polymerization method using acrylamide(AM)as the main monomer,butyl acrylate(BA)and modified organic montmorillonite(OMMT)as toughening reagents and N,N-methylene bisacrylamide(MBA)as cross-linking agent,respectively,and the reaction conditions were also optimized.FT-IR,SEM,XRD,EDS,optical microscope and laser particle size analyzer were applied to characterize the molecular structure,surface morphology,particle size distribution and montmorillonite modification condition of the prepared microspheres.The swelling performance and salt resistance of the two microspheres were investigated at different swelling time,temperature and water salinity,and the shear resistance were also tested at different shear rates.Meanwhile,the compressive and tensile resistance of the bulk gel were evaluated using texture analyzer and SEM was also applied to characterize the gel.The experimental results show that the mechanical strength of acrylamide microspheres can be effectively improved by adding BA and OMMT.Compared with PAM microspheres,appropriate amount of BA can reduce the water-uptaking swelling of microspheres,but shows less effect on the salt-resistance,while the adding of a small amount of OMMT can decrease the water-uptaking swelling and improve the salt resistance of microspheres.The adding of two materials can both reduce the damage possibility of microsphere at high shear rate,among which BA provides a higher improvement.The addition of 5wt% BA in the gel can increase the tensile stress by four times,and has little effect on the compressive resistance.The addition of 2wt% OMMT in the gel can increase the tensile stress by about five times and double the compressive resistance.