Oil-Tolerant Nonionic Worm-like Micellar Solution

[Image: see text] The goal of this work is to study the effect of crude oil on worm-like micelles and identify any oil-tolerant systems. A new class of nonionic surfactants was synthesized that forms viscous worm-like micelles under a wide range of temperature and salinity conditions. Aqueous stability, rheology, cryogenic transmission electron microscopy imaging, and dynamic-light-scattering measurements were performed to understand properties, shape, and size of the micelles formed using these surfactants under different temperatures and salinity conditions and in the presence of hydrocarbons. These micellar solutions maintained high viscosity in the presence of small amounts (up to 8 vol %) of crude oils and pure hydrocarbons. Similar experiments were performed with conventional surfactant systems that were known to form worm-like micelles; they did not show oil tolerance. Larger alkanes and viscous crude oils affect the viscosity and transformation of cylindrical micelles less. These new surfactants are useful for oil and gas operations such as hydraulic fracturing, conformance control, and mobility control as they form viscous worm-like micelles in the presence of small amounts of crude oils.