Selecting the Most Appropriate Model for Rheological Characterization of Synthetic Based Drilling Mud

Several mathematical models used in describing the rheology of non-Newtonian fluids includes but not limited to the following; The Power Law model, the Bingham Plastic Model, the Hershel-Buckley Model and the Casson Model. Selection of the best rheological model that accurately represent the shear stress-shear rate analysis is sine qua non to achieving correct results for pressure drops and hydraulic calculations. Hence, in this study, in an effort to determining the best rheological model that accurately represent the rheology of Synthetic based Muds (SBMs), three different Synthetic based Fluids were used to form different Synthetic based Muds with the same composition throughout. These fluids are; Refined Bleached and Deodorized Coconut Oil (RBDCO), Methanol Trans esterified Palm Kernel Oil (TRANSPKO) and Inter Esterified Palm Kernel Oil(INTERPKO). The rheological properties of these drilling muds were measured by using an automated 8-speed viscometer model 800.The dial readings of the viscometer were then converted to stresses by applying standard conversion factors and different non-Newtonian Models were used in computing the stress values. In order to measure the degree of deviation of each model from the measured stress, two statistical methods were employed. These are; the Absolute Average Percentage Error