Study On Aqueous Dispersion Of Salts Tolerant Polymer As Profile Control Agent

With the development of long-term water flooding in reservoirs,the reservoir heterogeneity is aggravated and the water absorption profile is not uniform,which seriously affects the effect of reservoir development.It's important to develop salt-resistant profile control agent,especially for some high salinity wells.In this paper,a new type of salt-resistant polymer microsphere profile control agent was prepared by reverse emulsion polymerization.The initial particle size of the polymer microspheres was small and the apparent viscosity of the polymer microspheres was low.The polymer microspheres could successfully reach the deep formation.At the same time,the microspheres was steady swelling under the action of the salinity and temperature of the formation water,and could move under the action of external force to achieve step by step of plugging,to achieve the effect of decreasing water and increasing oil.In this paper,acrylamide?AM?,acrylic acid?AA?and salt-resistant monomer 2-acrylamido-methylpropanesulfonic acid?AMPS?were used as polymerization monomers,deionized water was used as the dispersed phase and liquid paraffin was used as dispersion medium.Water-soluble oxidation-reduction initiating system ammonium persulfate and sodium bisulfite were used as initiator,Span80 and polymer emulsifier 2296 were used as emulsifier.The AM-AA-AMPS copolymer was prepared by inverse emulsion polymerization.With the fatty alcohol polyoxyethylene ether as the anti-phase agent,the system was transferred,and finally the water-dispersible salt-resistant polymer microspheres were obtained.The effects of reaction conditions such as emulsifier type,oil-water ratio and initiator concentration on the polymerization system were studied by single factor experiment and the optimum synthesis conditions were obtained.The results showed that when the ratio of oil to water was 2:1,the amount of initiator was 0.06wt%,the amount of MBA was 0.04wt%,the content of monomer in water phase was 40⁴5wt%,the pH value was 6⁷,the reaction temperature was 35?,the stirring rate was 350r·min^-1,and under the conditions of reaction 3h can be obtained copolymer microspheres with better stability,and their average particle size was 400 nm.The FTIR and XRD patterns of the copolymer microspheres show that AM,AA and AMPS are all polymerized.TG and DTG graphs show that the copolymer has good heat stability.The microspheres were swollen for 15 days at high temperature and high salinity.The average particle size was swelled from the initial value of 373.4nm to 2453.6nm and the swelling ratio was 6.7 times,indicating that the prepared polymer microspheres have good salt tolerance performance.From the rheological analysis,it can be seen that the polymer microspheres have better viscoelasticity;The polymer microsphere solution have low viscosity and good and have good injectionability,which can ensure microspheres reach the deep formation.The mechanism of water shutoff of polymer microspheres was studied by studying the water swelling performance of polymer microspheres and the role of polymer microspheres in porous media.Through the indoor sand filling test with simulating the high temperature and high salinity formation can find that the polymer microspheres was hydration swelling with the aging time,and the pressure of the sand was increased.It was proved that the prepared polymer microspheres had the effect of profile control water shutoff in high salinity formation.