Application of Cassia Gum in Enhanced Oil Recovery.

The objective of this study was to develop an innovative biopolymer, cassia gum, for enhanced oil recovery (EOR) applications. The gum was extracted from the seeds of Cassia grandis, a native Brazilian tree, using a novel method that achieved an average yield of 24.4 ± 1.7 wt %. Structural characterization identified cassia gum as a nonionic galactomannan with an average molar mass (Mw) of 8.07 × 10(5) ± 1.44 × 10(5) g/mol and an organic matter content of 80.32%. A cassia gum-saline solution at 3,000 mg/L, prepared using injection water containing 29,711 mg/L of total dissolved solids, exhibited shear-thinning rheological behavior and viscoelastic properties, with a viscosity of 21.38 cP at 60 °C, closely matching crude oil viscosity. Viscoelastic testing revealed a transition from viscous to elastic behavior, enhancing EOR efficiency by improving sweep and microscopic oil displacement. Contact angle tests with API 25 oil demonstrated that cassia gum could alter carbonate rock wettability from oil-wet to intermediate-wet. Coreflooding experiments under reservoir conditions showed that cassia gum-saline fluid achieved an additional oil recovery of 13.6% OOIP, following 38.5% OOIP recovery during waterflooding. These results establish cassia gum as a promising biopolymer for EOR applications.