Rhamnolipid-Based Nanosized Dispersed Formulation for Enhanced Fracturing-Fluid Flowback: Phase Behavior, Interfacial Properties, and Porous-Media Performance

Fracturing-fluid retention caused by capillary trapping and surfactant loss during transport through porous media can impair post-fracturing productivity in tight reservoirs. In this study, a rhamnolipid/isopropanol/limonene/water nanosized dispersed formulation was developed as a biosurfactant-based flowback aid. Pseudo-ternary phase diagrams, dynamic light scattering, surface- and interfacial-tension measurements, contact-angle measurements, porous-medium transport experiments, and sand-packed drainage tests were employed to evaluate the formulation behavior and flowback-aiding performance. The largest optically clear single-phase region was obtained at a rhamnolipid/isopropanol mass ratio of 3:1. The formulation maintained nanoscale hydrodynamic dimensions at NaCl or CaCl2 concentrations up to 10 g/L, while systems containing ≤80 wt.% water exhibited comparatively stable hydrodynamic sizes during 7 d of aging at 70 °C. The equilibrium surface tension reached 25.87 mN/m at 200 mg/L. After passage through the proppant/rock-powder-packed medium, the formulation retained a surface tension of 32.02 mN/m and produced a water contact angle of 95°, compared with 51.20 mN/m and 67°, respectively, for the rhamnolipid aqueous solution. The maximum relative aiding-drainage enhancement approached 89.2% at 2000 mg/L. These results indicate an association among formulation characteristics, interfacial properties, porous-medium transport behavior, and drainage performance, and support the potential of the rhamnolipid-based dispersed formulation as a flowback-aid candidate under the investigated laboratory conditions.