Hydrophobically Associating Water-soluble Polymer And Surfactant Interaction Studies

Hydrophobically associating water-soluble polymer is a water-soluble polymer with a few hydrophobic groups in the hydrophilic macromolecular chain (hydrophobically associating polymer, HAWP for short). Because of its unique molecular structure, HAWP solution has properties of good resistance to temperature, salt and shear thinning, gradually showing broad application prospects in enhanced oil recovery. In recent years, the interaction between HAWP and surfactants has been the hot point of the research working in the world. Handing the relationship between the macro-regularities of their interaction and solution microstructure has vital practical significance in guiding the application of HAWP/ surfactant flooding system.In this paper, the relationship between the macro-regularities of hydrophobically associating water-soluble polymer AP-P4 solution, its interaction with anionic surfactant SDBS, non-ionic surfactant OP-10 and the solution microstructure is studied by the methods of viscosity, interfacial tension, electric conductivity and fluorescence probe, the experimental results show that:In low concentration solution, hydrophobically associating polymer AP-P4 chains associate intramolecularly, form intramolecular hydrophobic microdomains, which can not increase the apparent viscosity obviously; in high concentration solution, AP-P4 chains associate intermolecularly, and a large number of intermolecular association can develop into a spatial network structure, there is a critical association concentration(CAC for short), which is 1500mg/L; above the CAC, the apparent viscosity of AP-P4 solution increase significantly, showing a strong tackifying propertiy, at the AP-P4 concentration of 4000mg/L, its apparent viscosity is 2 times of HP AM solution which with the same concentration.The research of interaction between surfactants and AP-P4 shows that, when the AP-P4 concentration is 1500mg/L, regardless of SDBS or OP-10, both can significantly increase the apparent viscosity of solution in the surfactant concentration range of 0-100mg/L; fluorescent probe analysis showes that, the I3/I3 of Pyrene obviously increase in the same surfactant concentration range, I3/I1 represents the non-polar intensity of hydrophobic microdomains, indicating the increasing of viscosity is mainly because surfactants enhance the association of hydrophobic microdomains, enlarge the original network structure size and strength in the solution; further increasing surfactant concentration decrease the apparent viscosity of the solution, because the association between excessive surfactants and AP-P4 break the spatial network structure, while the I3/I1 still increase by the formation of free surfactant micelles. The essence of interaction between surfactants and AP-P4 is hydrophobic interaction, the electric charge property difference make the different degree of influence on the solution properties. In the surfactant concentration range of 0-100mg/L, SDBS increase the I3/I1 by 13.8%and the apparent viscosity by 33.4%, while the OP-10 only increase the I3/I1 by 0.33% and Viscosity by 5.2%, the influence of SDBS on the solution properties is far greater than OP-10. The study of electric conductivity to AP-P4/SDBS mixture solution shows that, the electric conductivity curve's slope of mixture solution is smaller than pure SDBS solution, and the higher the AP-P4 concentration in mixture solution, the smaller the slope is, indicating that the surfactants are adsorbed on AP-P4, the adsorption is a un-cooperation and continuous process; at the same time, because of the adsorption of surfactants on AP-P4, the number of free surfactants in solution reduce, which resulting in the interfacial tension of mixture solution larger than pure surfactant solution, the higher the AP-P4 concentration in mixture solution, the larger the interfacial tension is, when the AP-P4 concentration is 500mg/L, the minimum interfacial tension of SDBS increase by 30%, of OP-10 increase by 12.9%; when the AP-P4 concentration is 1500mg/L, the minimum interfacial tension of SDBS increase by 115%, of OP-10 increase by 45.2%.This paper using a variety of methods studies the relationship between the macro-regularities of hydrophobically associating water-soluble polymer interact with different kinds of surfactants and the changes of solution microstructure, there exists close relationship between the two, the study results have some reference and guidance to such systems applied in chemical flooding.