Research on High-Temperature Stability and Optimization of Bentonite Modified with Fiber Polysaccharides/Starch

As oil and gas exploration advances into deep and ultra-deep reservoirs, water-based drilling fluid systems encounter significant stability challenges under high-temperature conditions. Bentonite, a critical component of drilling fluids, governs drilling efficiency and safety through its temperature-dependent performance. Current limitations in bentonite's high-temperature stability hinder its industrial applicability, which this study aims to address. We propose enhancing bentonite stability via material modification, exploring optimization strategies, and analyzing synergistic effects of organic additives such as fiber-polysaccharides and starch. Laboratory experiments systematically evaluated the effects of bentonite particle size, additive specifications, and dosage on rheological properties and fluid loss control. Key parameters—viscosity, fluid loss, and dynamic plasticity ratio—were quantified at 150 and 180 ℃. Results demonstrate that fiber-polysaccharides enhance bentonite stability via molecular cross-linking, reducing fluid loss by 40% compared to unmodified samples at 180 ℃. Starch exhibits effective fluid loss control at 150 ℃, though with reduced efficacy at higher temperatures. A synergistic modification process (physical sieving–thermal treatment–organic cross-linking) quantified factor influences and yielded an optimized 180 ℃ formulation. This work provides a cost-effective strategy for enhancing bentonite stability in deep-well systems, supporting the development of sustainable high-temperature drilling technologies.