Effect of Hydrophobic Modification on the Properties of Polymer‐Blended Microemulsion Gels

Phase behavior of sodium oleate (NaOl)/isoamyl alcohol-based lamellar gel phase in cedar oil/water medium in the presence of the nonionic polymer hydroxyethyl cellulose (HEC) and its hydrophobic modified product (HMHEC) is investigated for the development of polymer-embedded surfactant gels. HMHEC is more soluble in oil-in-water (o/w) microemulsions, but nonionic HEC shows limited solubility in the lamellar microemulsion (o/w type). Quantitative estimation of rate of adsorption of the polymer on lamellae bilayers can be easily done by Sudan solubilization and methylene blue complexation methods. Addition of HMHEC to the lamellar gel phase increases the polymer solubilization limit of lamellar gels as well as the viscoelasticity and thermal stability. The polymer-embedded microemulsion gel acts as a “clean gel” since it exhibits good solubilization in different hydrocarbon media at ambient conditions. Elastic modulus of the polymer-embedded gel influences directly the suspension performance of gels at high temperature and yields a reasonable sand-settling velocity acceptable according to fracturing standards. The thermal characteristics and viscoelastic properties of polymer-embedded gel were found to be suitable for moderate-temperature reservoir stimulation where the bottom hole temperature is in the range 70–75 °C. Already a large amount of experimental data on pure microemulsions (without polymer) exists. Our studies indicate that the developed polymer-embedded microemulsion gel has great potential as a model system for the study of polymer–microemulsion interactions.