Effect of Barite on the Performance of Oil-Based Drilling Fluids and Its Mechanism

Barite is a critical weighting agent in oil-based drilling fluids (OBDFs), yet the mechanism by which its physicochemical properties influence fluid performance remains insufficiently understood. Unlike previous studies that often treat Barite as a uniform material, this work highlights the significant heterogeneity among commercial Barites and its impact on OBDFs. Four types of Barite were applied as weighting agents to compare their performance, with No. 4 Barite yielding the best comprehensive results─characterized by moderate viscosity and superior sedimentation stability. To reveal the underlying mechanism, this study correlates the interfacial properties, particle size, morphology, and elemental composition of the Barites with their fluid performance. The findings indicate that high amphiphilicity, surface roughness, crystallinity, and oxygen content are key factors enhancing sedimentation stability. Mechanistically, hydroxyl groups on the Barite surface were found to establish a three-dimensional network structure through hydrogen bonding, thereby increasing viscosity. Furthermore, a moderate particle size and distribution were identified as critical for balancing sedimentation stability and rheological properties.