2010 年 75 巻 1 号 p. 89-97
The Bingham plastic model and the power law model have been widely used to describe the rheological property of drilling mud. However, the Herschel-Bulkley model, also referred to as the yield-power law model or the modified-power law model, is being recognized to more accurately characterize the mud rheological property in low shear rate range.
The author has developed a transient cuttings transport simulator in previous studies, where the power law model was used as a mud rheological model. In this study, theoretical discussion is made about modification of generalized Reynolds number presented in the constitutive equations of the cuttings transport model to adopt the Herschel-Bulkley rheological model. Then using the modified cuttings transport simulator, the author conducted steady-state simulations of cuttings transport in vertical and horizontal wells to validate the adoption of the Herschel-Bulkley rheological model.
The obtained results were (1) cuttings transport was more effective with mud having larger yield stress of the Herschel-Bulkley model and (2) the power law model and the dual power law model in API RP 13D respectively underestimated and overestimated the cuttings transport efficiency and were inadequate models for mud whose rheology was best described by the Herschel-Bulkley model.