Preparation And Performance Evaluation Of AM Microspheres With Double Cross-linked Structure By Inverse Emulsion Method

The application of polymer microspheres in deep profile control of oil fields is mainly due to its controllable particle size and satisfied swelling property,which can effectively improve the development effect of water flooding.However,the polymer microspheres with a single organic cross-linked structure have poor temperature resistance and cannot meet the deep profile control requirements of high-temperature and high-salt reservoirs.To this end,this paper takes acrylamide(AM)as the main monomer,and introduces temperature-resistant monomers N-vinylpyrrolidone(NVP)and 2-acrylamide-2-methylpropanesulfonic acid(AMPS),and using N,N’-methylenebisacrylamide(MBA)and metal cross-linking agent or PEI cross-linking agent to prepare temperature-resistant polymer microspheres with double cross-linking structure,the factors which affect the synthesis of microspheres by inverse emulsion polymerization were explored,and the morphology,swelling performance,temperature resistance and rheology of the microspheres were studied by optical microscope,scanning electron microscope(SEM)and HAAKE rheometer.The results show that the optimal conditions for the synthesis of microspheres are emulsifier dosage of 10%,oil-water ratio of 2/1,and stirring speed of 550 rpm.The microspheres prepared under this condition are spherical and have a particle size of ranging from 100 nm to 600 nm.The microspheres dispersion system can withstand a temperature of more than 50 days at 120 ℃.The swelling performance and viscosity-increasing performance of the microspheres increase first and then decrease as the swelling time increases.The higher the swelling temperature or the smaller the amount of crosslinking agent,the better the swelling performance of the microspheres,and the oil-water ratio has little effect on the swelling performance of the microspheres.The viscosity-increasing performance becomes better with the amount of cross-linking agent decreasing or with the concentration of microspheres increases.The microsphere dispersion system prepared by the organic Al cross-linked system after swelling at120 ℃ can effectively block the microporous filter membrane with a certain pore size.As the swelling time of the microspheres increases,the concentration increases,and the amount of the organic Al cross-linking agent decreases,the better the microspheres have in blocking the microporous membrane.