Study On Synthesis And Properties Of Temperature Resistance And Salt Tolerance Polyacrylamide Copolymer

According to the requirement of polymer flooding reservoir with high temperature and high salt,partially hydrolyzed polyacrylamide has been difficult to meet the viscosity requirements of high temperature and high salinity reservoir,which is widely used at present.Due to the structure of partially hydrolyzed polyacrylamide,it has serious mechanical degradation,and has some shortcomings in shear stability,acid resistance,temperature resistance and salt tolerance.The research on the temperature and salt resistant polymer as the next generation of oil displacement agent has become the hotspot of research.Acrylamide copolymer containing sulfonic group has high temperature resistance,salt tolerance,and strong hydration ability,It might been synthesized by free radical aqueous solution copolymerization of acrylamide?AM?with sulfonic monomer.The literature shows that 2-acrylamido-2-methylpropanesulfonic acid?AMPS?contain sulfonic group,active double bond and large side radicals.It is easy to form copolymer with AM.The copolymer can increase the rigidity of the copolymer chain,water solubility of copolymer,thermal stability and hydration ability,the copolymer also has good performance in temperature resistance and salt tolerance,and it can reach an appropriate balance point between economic efficiency,environmental friendliness and oil recovery efficiency.The researchers found that adding the third monomer is the effective way to improve the temperature resistance and salt tolerance,the copolymer containing morpholine ring gains widespread attention because of the good performance in the oil field chemicals.Another effective way to improve the temperature resistance and salt tolerance of polymers is to increase the molecular weight of polymers.It is difficult to obtain high molecular weight polymer by using a separate initiator,because the polymerization process of acrylamide is a strong exothermic reaction.It is an important breakthrough to increase the molecular weight of polymer by using the compound initiator system.In the process of polymerization,the compound initiator system is always maintained at a steady low concentration of free radicals.The main research contents include the following aspects:1.P?AM/AMPS?was synthesized by free radical aqueous solution polymeri-zation with different initiator systems.The effects of initiator concentration,initiator ratio,monomer concentration,monomer ratio,reaction temperature and pH value on the apparent viscosity of the polymer was studied.The solid content and compositions of copolymer were determined,and the structure of the polymer was determined by IR and elemental analysis.2,2'-Azobis[2-?2-imidazolin-2-yl?propane]dihydrochloride?AIBI?and potassium persulfate?KPS?constitute a segmented composite initiator system for preparation of polymer.The optimum polymerization conditions and the various influence factors were investigated by orthogonal test.The best properties of copolymers were prepared under the condition:The monomer concentration was 20%,the initiator concentration was 0.05%,the initiator compound ratio KPS:AIBI was 1:2,and the initiation temperature was about 30 ?,the monomer mass ratio of AM:AMPS was 1:1 and the pH value was about 8.The apparent viscosity of AM;AMPS copolymer aqueous solution can reach 110 mPa-s at a concentration of 500 mg/L in 25 ? ambient temperature.3-Dimethylaminopropionitrile?DMAPN?and potassium peroxodisulfate?KPS?constitute amine redox initiator system.The best properties of copolymers were prepared under the condition:Fixed monomer concentration is 20?25 wt%,monomer mass ratio of AM:AMPS is 1:1,the concentration of initiator is 0.015%of the monomer concentration,KPS:DMAPN=1.05:1?molar ratio?,reaction temperature is 42 ?,reaction time is 6 h,pH value was 9.The polymer solution has higher apparent and stronger resistance to Ca²⁺,Mg2.The apparent viscosity of 500 mg/L polymer aqueous solution at a temperature of 25 ? is 96.20 mPa·s;the apparent viscosity of 1500 mg/L polymer in the Ca²⁺,Mg²⁺salt solution?concentration of salt water is 200 mg/L?is 36.54 mPa·s,35.6 mPa·s.N,N,N',N'-tetramethyl-1,6-hexanediamine?TMHD?and potassium peroxodisulfate?KPS?constitute redox bifunctional initiator system.The best properties of copolymers were prepared under the condition:the monomer concentration was 20?25 wt%,the initiator concentration was 0.003%?molar ratio?,the pH value of the polymerization system was from 8 to 9,the monomer mass ratio of AM:AMPS was 1:1,the temperature is 50 ?,the reaction time is about 3 h.The viscosity and salt resistance of the polymer were excellent,and the apparent viscosity of 1500 mg/L polymer solution at a temperature of 25 ? or 85 ? was about 30.09 mPa·s and 18.16 mPa-s in mineralized water with salinity of 32868 mg/L.KPS/AIBI/DMAPMA constitute the three section temperature control multi effect compound initiation system,the apparent viscosity of 1500 mg/L polymer solution at a temperature of 85? was about 18.69 mPa·s in mineralized water with salinity of 32868 mg/L.The results show that the P?AM/AMPS?copolymer has good resistance to temperature and salt,and the use of the composite system is helpful to improve the properties of the polymer.2.The P?AM/AMPS/ACMO?copolymer was prepared by the free radical aqueous solution copolymerization of acrylamide,2-acrylamido-2-methylpropan-esulfonic acid with N-acrylamide morpholine?ACMO?using the complex initiation system.The effects of initiator concentration,initiator ratio,monomer concentration,monomer ratio,reaction temperature,pH value and amount of ACMO on the apparent viscosity of the polymer was studied.The solid content,compositions and the structure of the polymer was determined by IR and elemental analysis.N-[3-?dimethylamino?propyl]methacrylamide?DMAPMA?and KPS constitute functional complex initiation system,which can improve the molecular weight of the polymer by the double effects of initiation and polymerization.The best properties of copolymers were prepared under the condition:the monomer concentration was 20 wt%,the initiator concentration was 0.0010?0.0015%,the pH value of the polymerization system was 9,the monomer mass ratio of AM:AMPS was 1:1,the temperature is 42 ?,the reaction time is about 4 h,the addition amount of ACMO is 5?10%.The viscosity and salt resistance of the polymer were excellent,and the apparent viscosity of 1500 mg/L polymer solution at a temperature of 25 ? or 85 ?was about 28.59 mPa s and 16.72 mPa·s in mineralized water with salinity of 32868 mg/L.DMAPN and KPS constitute amine redox initiator system,which leads to stable and high efficiency.The best properties of copolymers were prepared under the condition:monomer concentration is 25 wt%,monomer mass ratio of AM/AMPS is 1:1,the concentration of initiator is 0.005%,the addition of ACMO was 10%?molar ratio?,reaction temperature is 46?50 ?,reaction time is 6 h,pH value was 9.The apparent viscosity of 1500 mg/L polymer solution at a temperature of 25 ? or 85 0C was about 29.99 mPa-s and 16.63 mPa·s in mineralized water with salinity of 32868 mg/L.The results show that,P?AM/AMPS/ACMO?polymer has high apparent viscosity and excellent temperature and salt resistance with the addition of the third monomer ACMO and the compound initiation system.3.The viscoelastic properties,thermal stability and aging resistance of polymer solution are the main factors affecting oil recovery.The following aspects have been studied:the effect of polymer concentration and the amount of NaCl?CaCl2?MgCl2 on the apparent viscosity of polymer solution,effects of temperature,inorganic salts and frequency on viscoelasticity of polymer solution,the ability of shear and temperature resistance of polymer solution,the aging resistance of polymer solution.Results show that P?AM/AMPS?and P?AM/AMPS/ACMO?copolymer solution have good shearing resistance,temperature resistance,salt resistance and aging resistance.