Nanoparticle-modified gemini surfactant foams as efficient displacing fluids for enhanced oil recovery

Abstract

Surfactant-nanoparticle stabilized foams hold significant potential in the field of enhanced oil recovery (EOR). This article discusses an experimental methodology to characterize foam fluids containing {N, N′-bis (dimethyltetradecyl)-1,6-hexanediammonium bromide (14-6-14 GS) + silica/boron nitride} and identify optimal formulations, based on physicochemical evaluation. Stability studies revealed half-life time of ~6 h for 14-6-14 GS foam, which dramatically improved to 27 h and 3313 h in the presence of silica (SiO2) and boron nitride (BN) particles respectively. Enhanced stability was achieved in surfactant-nanoparticle fluids owing to strengthened mechanical barrier (electrostatic repulsion + steric) at gas-liquid interfaces. Structural morphologies of foam lamellae were analyzed by macroscopic and microscopic (imaging). Gaussian, Cauchy-Lorentz and Pseudo-Voight probability distribution functions were applied to model bubble size data. Pendant drop analyses showed that oil/brine IFT decreased from 27.2 mN/m to <5 mN/m in surfactant-NP fluids. Contact angle, zeta potential and micro-imaging analyses showed that wetting nature of rock altered from intermediate-wet to strongly water-wet state in the presence of analyzed fluids. Foam fluids exhibited pseudoplastic flow behavior. Viscoelastic profile investigations showed that foams retain their “pull-and-drag” characteristics during oil displacement. In summary, 14-6-14 GS-NP foams prove to be suitable candidates for EOR with robust stability, interfacial activity and rheological properties.