Morphology regulation mechanism and oil displacement performance of dendritic mesoporous nanomaterials
Dendritic mesoporous nanomaterials(DMSNs)were prepared by bicontinuous microemulsion method using tetraethyl orthosilicate(TEOS)and urea as raw materials,hexadecyl trimethyl ammonium bromide(CTAB)as template.Then,the acrylamide and 2-acrylamide-2-methylpropanesulfonic acid dibasic polymer P(AM-AMPS)were added to the DMSNs dispersion system at 0.05%(mass fraction,by mass of the DMSNs dispersion system)to form the DMSNs fluid.And the DMSN characterized by FTIR,XRD,SEM,TEM,N2 adsorption-desorption.The effects of reaction time,TEOS addition amount(based on paraxylene volume,the same below),cosolvent,stirring rate and reaction temperature on the properties of DMSNs were analyzed,while the wettability and oil displacement performance of DMSNS nanofluids were further evaluated.Under the optimal conditions of reaction time 6 h,TEOS addition amount 25%,ethylene glycol as cosolvent,stirring rate 1000 r/min and reaction temperature 85℃,the prepared DMSNs showed an average particle size of 91 nm,specific surface area of 1094.75 m2/g,pore volume of 1.862 cm3/g,and average pore size of 6.1 nm.The surface of DMSNs exhibited a special wrinkle morphology,presenting a"flake/layered"flower-like mesoporous structure.The DMSNs nanofluid with 0.10%DMSNs content(based on the mass of deionized water,the same below)could change the rock wettability from oil-wet to water-wet,with the contact angle increased from 0° to 132°,and the change in rock wettability significantly improved the tertiary oil recovery(39.6%).The competitive nucleation and growth mechanism in the formation of DMSNs consisted of three processes,namely initial nucleation,longitudinal growth,and secondary nucleation+lateral growth.
dendritic mesoporous nanomaterialsmesoporous structurecompetitive nucleation and growthwettability alterationenhanced oil recoveryoil field chemicals
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