Preparation And Performance Evaluation Of Polymer Gel And Polymer Microspheres

To solve the shortcomings of the low permeability heterogeneous reservoir water pluggi ng and profile control for the gel or swellable particles entering the deep reservoir hardly and the relatively shorter water plugging valid period,the development of profile control/water shutoff agents was carried out.Using acrylamide(AM)and N-hydroxymethyl acrylamide(N-MAM)as reactive monomer,N,N-methylene bisacrylamide(MBAA)as crosslinking agent,two kinds of nanoscale cross-linked polymer microspheres were synthesized via the inverse microemulsion polymerization technique.Viscoelastic polymer gel' low temperature polymerization was implemented by using copolymerization cross-linking system which consisted of acrylamide(AM)and N,N-methylene bisacrylamide(MBAA)by aqueous solution polymerization.(1)Using aqueous solution of acrylamide(AM)and N,N-methylene bisacrylamide(MBAA)as the dispersed phase,the combination of an oil soluble emulsifier(Span80)with a water soluble emulsifier(Tween80),kerosene as the continuous phase,the stable inverse microemulsion of kerosene(52.0wt%),Span80/Tween80(7.8wt%,weight ratio4:1),aqueous phase(40.2wt%)was preparaed.With the stirring speed of 1000r/min,nanoscale polymer microspheres cross-linked with N,N-methylene bisacrylamide(MBAA)were synthesized via the inverse microemulsion polymerization technique initiated by ammonium persulfate(APS)at the temperature of 65 ?.Swelling properties and plugging properties of PAM microspheres were investigated.The results show that polymer microspheres have distinct spherical shape,monodispersity,and uniform distribution of particle size about 100 nm.With the increasing of salinity,the apparent swelling ratio increases,which presents fine salt tolerance and high swelling ratio.Polymer microsphere latex has good injectivity,it can enter the low permeability core smoothly,core plugging rate is more than 90.0%.(2)In order to improve the swelling and water absorption performance of polymer microspheres,the functional monomer N-hydroxymethyl acrylamide(N-MAM)was introduced.Using kerosene as the continuous phase,the aqueous solution consists ofN-hydroxymethyl acrylamide(N-MAM),acrylamide(AM)and N,N-methylene bisacrylamide(MBAA)as the dispersed phase,a blend of surfactants(Span80/OP-10)as emulsified system,the stable inverse microemulsion of kerosene(48.8wt%),Span80/Tween80(9.2wt%),aqueous phase(42.0wt%)was preparaed.With the stirring speed of 1000r/min,the AM/N-MAM ratio of 4:1,nanoscale polymer microspheres(P(AM/N-MAM))cross-linked with N,N-methylene bisacrylamide(MBAA)were synthesized via the inverse microemulsion polymerization technique initiated by ammonium persulfate(APS)at the temperature of 65 ?.Swelling properties and plugging properties of P(AM/N-MAM)microspheres were investigated.The results indicate that the binary microspheres has smaller particle size,which is about 80 nm,and it presents the features of higher swelling ratio and better plugging effect for the low permeability core,core plugging rate of binary microspheres can be up to 95.0%.(3)Using acrylamide(AM)as reactive monomer,N,N-methylene bisacrylamide(MBAA)as cross-linking agent,polymer gel within the reservoir situ polymerization was implemented by aqueous solution polymerization initiated by peroxodisulphate/sodium bisulfite(APS/SHS)redox system which can effectively block large cracks.The experimental results of polymer gel show that good viscoelasticity,high strength,fine salt tolerance and swelling properties of polymer gel are given by the product obtained at the optimal condition of the reaction temperature is 30 ?,the APS/SHS ratio is 3:2,the contents of AM,MBAA,APS/SHS are 8wt%,0.15wt% and 0.15wt%.It is indicated that polymer gel exhibits effective profile control/water shutoff for the high permeability reservoir,core plugging rate is more than 92.0%.