Study On Preparation And Temperature Resistance Of AM/PF Microspheres Based On Multiple Crosslinked Structures

Polyacrylamide(PAM)microspheres,as an important oil displacement agent in the tertiary oil recovery profile control technologies,have the advantages in accepts of small particle size,swelling property,elasticity,and injection performance.It is important to improve and stabilize crude oil production,but for the development of advanced water blocking materials,including polymer microspheres,long-term high temperature resistance is still a huge challenge.In this paper,based on the synthesis of polymer microspheres of acrylamide(AM)/water-soluble phenolic resin(PF),the surface structure of the microspheres was modified by adding organic metal cross-linking agent LZ and organic cross-linking agents PEI in later to further optimize the temperature resistance of the AM/PF microspheres,and polymer microspheres with multiple crosslinked structures were obtained.The optical microscopy,scanning electron microscopy(SEM),laser particle size analyzer,and Fourier transform infrared spectrometer(FT-IR)were used to characterize the particle size distribution,surface morphology,and microstructure of the polymer microspheres.The temperature resistance and swelling performance of the obtained polymer microspheres were studied,and the temperature resistance mechanism of polymer microspheres and the effect of the amount of oxygen scavenger on the temperature resistance of multiple crosslinked microspheres were also investigated.Experimental results show that the best performance of the obtained AM/PF microspheres is AM/PF=12/8(mass ratio)microspheres.As the AM/PF ratio decreases,the swelling rate of the microspheres decreases and the temperature resistance time prolongs,AM/PF=12/8 microspheres are stable after 30 days under aerobic 150℃.After further optimization,the obtained AM/PF-LZ microspheres containing 0.1% LZ are stable for 45 days under aerobic 150℃ and are stable more than 300 days under anaerobic 150℃.The performance of the AM/PF-PEI microspheres containing 0.1%PEI is the best,it can stay stable for 65 days under aerobic 150℃ and for 165 days under anaerobic 150℃.The temperature resistance performance of the AM/PF-PEI microspheres increases with the increase of the stabilizer content,meanwhile the swelling performance is almost unchanged.AM/PF-LZ microspheres are bonded by multiple small balls wrapped by LZ cross-linking agent,which are wrapped with two kinds of ball with different particle size.The balls with large particle size are AM/PF microspheres and the small ones are phenolic resin microspheres.After a period of temperature resistance experiment,the LZ cross-linking agent wrapping on the both kinds of ball are hydrolyzed,then the AM/PF microspheres begin to hydrolyze.Finally,the remaining phenolic resin microspheres are in a state of binding with the network,the network structure is the hydrolyzed product of LZ crosslinker and acrylamide,in which the phenolic resin skeleton appears after the AM/PF microspheres are completely hydrolyzed.The surface of the AM/PF-PEI microspheres is covered by a continuous solid shell,which contains a 3D network structure.When the microsphere reaches the maximum value of the swelling volume,the crosslinked polymers on the surface of the microspheres begin to hydrolyze after the stable period,the surface begins to sag,and the network structure gradually decomposes.Finally,only the cross-linked skeleton containing spherical protrusions is maintained.