(55f) Development of Magnetic Surfactants for Oilfield Applications

Commercially available surfactants, including polyethylene oxide ether, aryl sulfonate, and petroleum sulfonate, exhibit stability issues when applying high salinity (120,000-220,000 ppm) and high temperature (≥90^oC) carbonate reservoir. The severe reservoir environment causes surfactant decomposition and decreases their performance in lowering interfacial tension (IFT), altering rocks' wettability, and mobilization.

For addressing surfactant stability issues, magnetic surfactants were synthesized. The chemical structures were confirmed with the aid of NMR (¹H, ¹³C), FTIR, and mass analysis. The heat stability and aqueous solubility tests were assessed using Thermal Gravimetric Analysis (TGA) and aging methods. The spinning drop method was used to identify interfacial tension. The surface tension and critical micelle concentration (cmc) were measured with a force tensiometer (Biolin Scientific). The rheology was performed on the discovery hybrid rheometer (DHR-3).

The surfactants exhibited good solubility, and the TGA graph showed the decomposition temperature of the prepared surfactants above 230 ^oC which is superior to oilfield temperature (≥90^oC). Similarly, the aging technique revealed no change in the chemical structure after putting them in the oven at 90 ^oC for one month. The cmc, surface tension at cmc, and interfacial tension of the surfactants were comparable to industrially applied surfactants. According to rheological data, the storage modulus was decreased by enhancing the surfactant concentration at a lower rate of shear and frequency due to charge screening and polymer interaction.

The developed magnetic surfactants exhibited remarkable aqueous and heat stabilities and demonstrated immense potential in severe carbonate rocks.