Preparation and response behaviour of wormlike micelles in response to CO2 stimulation

Low-permeability reservoirs have a lot of reserves, but there is the phenomenon that gas injection is prone to gas flushing during the development process. CO2 foam drive combines the dual advantages of CO2 drive and foam drive, which can significantly lessen CO2 gas flushing and expand the wave efficiency of the replacement phase. The conventional CO2 foam system contains a large number of foaming agents and foam stabilizers. Still, there are issues such as high viscosity of the extracted fluid, serious emulsification, and difficulty in foam defoaming, which leads to the difficulty and high cost of treating the extracted fluid. In this study, the best performing wormlike micelles system of 0.6 wt% DOAPA@NaSal-H+ to stabilise the CO2 foam system was prepared by preferring N, N-dimethyl-3-oleamidopropylamine (DOAPA) and sodium salicylate (NaSal), using foam performance as an indicator. Analytical tests include conductivity test, rheological property test, surface tension test, Cryo-SEM, DLS are employed. According to the findings, the system under the influence of CO2 exhibits an increase in the chemical shift of hydrogen atoms near the N atom, an increase in the conductivity of the system, a lamellar mesh microstructure, and an average particle size of micelles of 104.6 nm. The surface tension of DOAPA@NaSal-H+ decreases with the increase of concentration, and the apparent viscosity decreases with the increase of shear rate, which exhibits the typical viscoelastic fluid behaviour. It is important to study the stimulus-response rows of CO2 stimulus responsive wormlike micelles, which provides theoretical support for the stabilization of CO2 foams by wormlike micelles.