ABSTRACT
Bentonite drilling fluids are essential in various geotechnical applications, where their rheological properties are crucial for excavation stability, material transport and lubrication. Despite international standards, discrepancies often arise between laboratory tests and on-site measurements. The preparation of these fluids involves variables such as bentonite concentration, mixing speed, and duration, which affect the final properties. This article investigates the characteristics of bentonite and drilling fluids, exploring how chemical composition influences preparation methods and rheological properties. The focus is on understanding how different types of bentonites (calcium and sodium) with varying mineralogical compositions affect fluid behavior. X-Ray diffraction and X-ray fluorescence analyses were used to characterize the bentonites, and clay properties were evaluated through swelling index and Atterberg’s limits. Water-based bentonite fluids were prepared at different concentrations and characterized by Marsh viscosity. The study also examines the impact of carboxymethylcellulose (CMC) additives to enhance fluid performance. The study showed that sodium bentonite, due to its higher swelling capacity and liquid limit, significantly enhances viscosity when CMC is added, while calcium bentonite remains mostly unaffected by the same CMC concentration.
