Rheological Properties Of Wormlike Micelles Formed By Anionic Surfactant And A Applied Study On The Oil Displacement Agents In Enhanced Oil Recovery

In the first two chapters, the rheological properties of wormlike micelles formed by the anionic surfactant were examined in detail.The rheological properties of surfactant aggregates are functions of both the structural arrangement of particles and the various interaction forces which operate in the system. It is very worthy to be considered for the theory and application of surfactants. In this dissertation, the rheological properties of wormlike micelles formed by anionic surfactant sodium oleate(NaOA)/sodium phosphate(Na₃PO₄) were investigated, including the effects of the concentration of surfactants and electrolytes, temperature, alcohols with small molecular weight, octane, inorganic salts, the mineralization of oil field water and polymer on the rheological properties. Some interesting and noticeable results will enrich the rheological studies of surfactant aggregates, and their applications in industrial fields, especially in enhanced oil recovery(EOR).It is found that the wormlike micelles will be formed in anionic surfactant NaOA/Na₃PO₄ solutions with a proper surfactant and salt concentrations by shear viscosity measurements and freeze-fracture TEM micrographs. The characteristics of a pseudo-plastic fluid and zero yield stress were acquired from the steady-shear experiments. In a lower shear rate range, the viscosity of the samples have no obvious change; if the shear rate is high, the network structures of the wormlike micelles can be broken down, which results in a decrease in viscosity. The curves describing storage and loss moduli intersect for the wormlike micelles as the frequency increasing, indicating that the materials are more viscous than elastic at low frequencies and more elastic than viscous at high frequencies. The wormlike micellar solutions are linear viscoelastic fluids in accord with Maxwell model and Cox-Merz rule.The effects of other factors on the rheological properties were investigated generally. Shear viscosity decreases under the condition of increasing temperature, a higher viscosity systems have a smaller shear activation energy. The addition of acohols with small molecular weight or octane can reduce the R_p value and viscosity of the NaOA/Na₃PO₄ system. The mineralization of oil field wate has few effects on the rheological properties of wormlike micelles. HPAM has some interactions with the micellar molecules and is able to restrain the formation of network structures of wormlike micelles.In the third chapter, the oil displacement agents for Shengli Oil Field were studied systematically by the oil-water interfacial tension measurements and core flood test in laboratory. The serial oil displacement agents from Dow Chemistry Company can not be applied in Shengli Oil Field. The reshaped surfactants of natural carboxylic salt(HF-2), the gemini surfactants of natural carboxylic salt(C18) and the wormlike micelles systems are considered to be good oil displacement agents for their abilities of enhancing sweep efficiency and absorption oil effect.