Design And Synthesis Of MPAM-type Amphiphilic Molecular System And Its Controllable Emulsification/demulsification Behavior

The emulsified flooding technology is extremely important in the field of tertiary oil recovery.However,with the improvement of emulsion stability,the demulsification of produced liquid becomes more and more difficult,resulting in a huge energy consumption and severe environmental pollution.In this regard,a class of amphiphilic anionic polyacrylamide macromolecular surfactant system was designed and developed in our study.It can not only form a stable oil-water emulsion system with crude oil,but also achieve the goal of rapid emulsion breaking under the trigger of external stimuli.The thesis designs and utilizes micelle polymerization to synthesize amphiphilic modified polyacrylamide?MPAM?.The characterization results by XPS,IR,¹³C-ss NMR and other methods show that it is consistent with the molecular design structure.The average molecular weight is 1.01×10⁶ g/mol and the average square radius is 113nm.The molecular structure has the characteristics of amphiphilic,acid-sensitive and salt sensitivity.The factors affecting the stability and instability of the modified polyacrylamide?MPAM?emulsion and the emulsifying/demulsifying mechanism were studied by the bottle test method,laser confocal,droplet size analysis,aggregate morphology observation method and zeta potential method.The results of the study indicate that the interfacial activity and spatial network structure of amphiphilic molecules are the decisive factors for the formation of stable emulsions.Emulsion stability is affected by the concentration of amphiphilic molecules,the acidity and alkalinity of the medium,and the salt concentration.The increase of the concentration of amphiphilic molecules and the enhancement of the basicity of the medium all increase the stability of the emulsion,while the increase of the salt concentration decreases the stability of the emulsion.Under the condition of pH=5,the acidity and the salt concentration have a synergistic effect.The demulsification mechanism of the modified polyacrylamide?MPAM?emulsion shows that the acidity and alkalinity of the medium and the multi-charged cations are the main factors that cause emulsion demulsification.Under acidic conditions,protonation of the DEA residue in the MPAM molecule increases the charge density on the molecular chain,making it more hydrophilic,inducing the dewetting of the DEA residue from the droplet surface,increasing the interfacial tension,and making the aggregate more loose,resulting in a decline in the stability of the oil-water emulsion,achieve demulsification.The multi-charged Al³⁺is adsorbed on the SA residue of the MPAM molecule and acts as an"ion bridge"in the electrostatic attraction between the amphiphilic molecules to promote emulsion breaking.