Yield-power law model more accurately predicts mud rheology

Abstract

The yield-power law rheological model can calculate yield point much more accurately than that calculated by the Bingham plastic model. The yield-power law (Herschel-Bulkley) model offers many advantages over the Bingham plastic and power law models because it more accurately characterizes mud behavior across the entire shear rate range. The yield-power law model has not found widespread use in the oil field because of the lack of simple analytical solutions for viscometric and hydraulics calculations. These concerns are no longer pertinent, however, because of the rapid spread of personal computers in the field and recent developments in using this model. The paper describes yield stress, the Bingham plastic model, the power law model, the yield-power law model, calculation method, model comparison, mixed metal hydroxide drilling fluids, mud hydraulics, and results from applying the model to these drilling muds.