Аннотация
Drilling fluids are complex non-Newtonian fluids that require accurate rheological characterization for reliable hydraulic calculations and wellbore stability. This paper presents a comparative analysis of four rheological models – Bingham plastic, Power Law (Ostwald-de Waele), Casson, and Herschel-Bulkley – using experimental data from four water-based drilling fluids with densities of 1.15-1.65 g·cm-3. Rheological measurements were performed using a six-speed rotational viscometer (Fann 35 type) at 25 °C, with shear rates ranging from 5 to 1022 s-1. Model parameters were estimated via linear and nonlinear regression, and accuracy was quantified using average absolute percentage error (AAPE). Results demonstrate that the three-parameter Herschel-Bulkley model consistently provides the best fit across all fluids, with AAPE values of 1.8-2.9%. Its superior performance stems from simultaneously capturing finite yield stress (3.12-9.95 Pa) and shear-thinning behavior (flow index n = 0.59-0.68). The two-parameter Bingham model overpredicts low-shear stresses (AAPE >= 8%), while the Power Law model, lacking yield stress, performs poorly at low shear rates (AAPE up to 11.7%). The Casson model offers intermediate accuracy (AAPE 6-9%). These findings have practical implications for annular pressure loss prediction, ECD management, cuttings transport, and barite sag prevention. Adoption of the Herschel-Bulkley model with parameters from nonlinear regression on full viscometer data is recommended for precise hydraulic modeling in complex drilling operations.