Evaluation of Terminalia Mantaly and Arrowroot Biopolymer Blends as Eco-Friendly Viscosifiers in Water-Based Drilling Fluids

Abstract Drilling fluids are essential to efficient oil and gas well drilling operations, particularly as economic, technical, and environmental challenges continue to intensify across various wells and formations. However, insufficient drilling fluid viscosity can severely impair hole cleaning efficiency, leading to poor cuttings transport and suspension, excessive solids sag, wellbore instability, and inadequate cooling and lubrication of the drill string. These issues are further aggravated by excessive API fluid loss, formation damage, and rheological instability under variable temperature, pressure, and contaminant conditions. Consequently, viscosifiers are required; yet conventional materials such as bentonite, organophilic clays, and synthetic polymers including carboxymethyl cellulose (CMC), polyanionic cellulose (PAC), and xanthan gum are often costly and environmentally unsustainable, particularly in developing regions. In response to Nigeria's growing emphasis on local content development and environmental sustainability, this study investigates the rheological performance of biopolymer-based additives in water-based drilling fluids (WBDFs). Natural polymers derived from Terminalia mantaly extract and arrowroot (Maranta arundinacea) starch blends were evaluated as potential viscosifying agents. PAC-R served as the conventional reference material. FTIR characterization was also carried out to identify the functional groups present in the locally sourced materials. Several WBDF formulations were prepared and tested in accordance with API RP 13B-1 standards to determine plastic viscosity, yield point, gel strength, and pH. Results indicated that T. mantaly–arrowroot blends significantly enhanced mud viscosity and gel strength, with optimal performance observed at moderate additive concentrations. Comparative analyses showed rheological behavior comparable to PAC-R, demonstrating strong potential for these bio-based materials as sustainable, cost-effective, and locally available substitutes for imported drilling fluid additives. This study supports Nigeria's local content policy by establishing the technical viability of renewable, plant-based materials for environmentally responsible drilling fluid formulation.