Study On The Activated Emulsifier Of CO ₂ / N ₂

High stability of heavy oil emulsion is quite essential in oil pipeline, but high demulsion efficiency is also required at pipeline terminal, which becomes the main discrepancy in oil pipeline. CO2-switchable surfactant may solve this problem due to its special switchability.In this paper, we adopt2-(dimethylamino)ethyl methacrylate (DMAEMA) as the switchable monomer to synthesize two kinds of CO2-switchable polymer surfactants (P(DMAEMA-AM) and P(DMAEMA-BMA)) through combining with acrylamide (AM) and butyl methacrylate (BMA) respectively.The emulsion adopting P (DMAEMA-AM) as emulsifier has the best stability at the molar ratio of8:3(DMAEMA:AM) and its viscosity reduction ratio is over99%. The conductivity of the emulsion increased from6.60×10-2mS·cm-1to8.70×10-2mS·cm-1when bubbled with CO2, which illustrates its CO2responsiveness. The changes of Zeta potential and particle size display the morphology changes of the polymers. The CMC of the P (DMAEMA-AM) is5.00g/L and the according surface tension is43.30mN/m. The article discussed the stability of the heavy oil emulsion under different conditions (in different concentrations of the surfactant, temperature, ratio of water to oil and different concentrations of salts). The result shows that the stability of emulsion doesn’t increase obviously when the concentration of the surfactant is over8.00g/L; its dehydration rate (50h later) is5.20%and the resistance of salt is very high. After demuslsiflcation, the oil in water and water in oil are32.22ppm and11.49%respectively.The best molar ratio of P (DMAEMA-BMA) is8:6. The conductivity of the emulsion increased from3.40×10-2mS·cm-1to5.90×10-2mS·cm-1when bubbled with CO2. Its CMC is0.30g/L and the according surface tension is37.30mN/m. The stability of emulsion doesn’t increase obviously when the concentration of the surfactant is over8.00g/L. The emulsion becomes unstable when the temperature is over40℃. The dehydration rate is27.4times faster than that without CO2. After demuslsification, the oil in water and water in oil are240.82ppm and8.13%respectively.