Extraction, characterization, and evaluation of galactomannan from Barbatimão Verdadeiro as a potential additive for enhanced oil recovery fluids

Polymers play a crucial role in enhanced oil recovery (EOR) by increasing the viscosity of injection fluids and enhancing oil displacement. The widely used polymer, partially hydrolyzed polyacrylamide (HPAM), faces performance degradation in high-salinity and high-temperature environments. This study explores galactomannan from <i>Stryphnodendron polyphyllum</i> seeds as an alternative viscosifying agent for EOR fluids. An extraction process for galactomannan from Barbatimão Verdadeiro seeds was developed, yielding 23.3% m/m. The biopolymer was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC). Rheological behavior was tested in brines of different salinities, and injectivity/filterability tests were performed following API RP 63:1990 standards. The galactomannan obtained from <i>Stryphnodendron polyphyllum</i> exhibited a mannose-to-galactose ratio of 1.32. Rheological analysis showed pseudoplastic behavior, with viscosities of 38 cP in brine solutions at 7.37 s⁻¹ and 60 °C. Filterability tests demonstrated satisfactory injectivity with factors of 1.09 (8 µm) and 0.67 (1.2 µm). Compared to HPAM, galactomannan exhibited superior viscosity retention in high-salinity conditions, where HPAM dropped to 6 cP. The galactomannan extracted from <i>Stryphnodendron polyphyllum</i> seeds is a promising biopolymer for EOR applications, offering superior performance under harsh conditions compared to traditional HPAM. Its resilience to high salinity and temperature makes it a viable alternative for pre-salt and offshore fields, contributing to more sustainable and efficient oil recovery.