Study On The Stimulated Response Worm - Like Micellar System With CO ₂ Stimulation

CO2responsive worm-like micelles (WLMs) is a way of causing the molecular structure of the materials changed in aqueous solution by introducing of CO2, macroscopic property shows the variation of viscosity. This type of WLMs has advantages such as adjustable, reversible and controllable in viscosity, and this particularity can make it have huge potential as oil displacement agent or fracturing fluid applied in oil and gas field development.In this dissertation, two different alkyl acid amide propyl tertiary amine with long and short chain synthesized by fatty acid and N, N-dimethyl-1,3propylene amide, and then the structure of these products were characterized by IR and1H-NMR.We prepared a sort of CO2responsive WLMs based on long chain N,N-dimethyl oleoaminde-propylamine (DOAPA) and p-methyl benzenesulfonate (SPTS), and optimized the molar ratio was1:1. By rheological property testing, showed that system behave as linear viscoelastic fluid, and the Cole-Cole plots demonstrated the system fit the Maxwell model. Through the cycle of viscosity test showed that system have the CO2responsiveness in viscosity, the viscosity of system could be circulated by bubbling and removing CO2. The conductivity, surface tension and1H-NMR spectra experiments confirmed the structure of amine changed when bubbling of CO2. DLS showed that the average size of micelles increased from3.64nm to81.51nm after introducing of CO2, and the Cryo-TEM indicated the transition of spherical to wormlike micelles.In addition, we chose the anionic surfactant sodium oleate (NaOA) as principle agent, it could be self-assembled to CO2and pH double responsive anionic WLMs by stimulating assistant short chain N, N-dimethyl octylamide-propyl tertiaryamine (DOAPTA), the molar ratio was optimized at1:0.8. During the rheological measurements, Cole-Cole plots and Cox-merz principle exhibited that the system fit the Maxwell model. Its viscosity could be switched three times from "sol" to "gel" while the pH value of system from10.91to9.56, indicating that the viscosity of system has CO2responsiveness. The conductivity, surface tension and1H-NMR spectra experiments confirmed the structure of amine changed when bubbling of CO2. DLS showed that the average size of micelles increased from2.32nm to51.80nm after introducing of CO2, and the Cryo-TEM indicated the transition of spherical to wormlike micelles.