Abstract
Cuttings transport has been a subject of active theoretical and experimental research for decades, both due to its operational significance and because it is an extremely complex physical process. Although developments in computer technology has paved the way for more detailed and comprehensive CFD simulations, flow loop experiments are still necessary for model validation. There is also still a need for practical correlations and models which can be used to predict hole cleaning efficiency with reasonable accuracy, and how this efficiency depends on operational parameters. While physics-based models exist for non-rotating drillstring, there are very few published models and correlations accounting for the effect of drillstring rotation. Yet, except for CT drilling, in most cases the drillstring is rotated while drilling. Being able to predict an optimal combination of pump flow rate and drill string rotary speed is important to ensure that pressures are kept within margin, keeping at the same time an acceptable ROP and adequate hole cleaning performance., We present a simple correlation for the effect of drillstring rotation on cuttings holdup in horizontal wells, based on flow loop experiments with real water-based and oil-based fluids. Experiments were conducted both with fully eccentric drillstring without lateral constraints, and with drillstring fixed at 50 percent eccentricity. We argue that, using appropriate dimensionless numbers the cuttings holdup versus drillstring rotation speed for different fluids can be represented by a single master curve. The present work represents a first step towards this goal.