This paper discusses a transient solid-liquid two-phase flow modelling approach that was applied for real-time drilling hydraulic and cuttings transport calculation. The flow patterns are categorized into seven scenarios, and the flow pattern transition criteria are presented. A generalized transient solid transport model is developed to simulate the transient solid-liquid two-phase flow by combining the transient mechanistic models and the flow pattern prediction method.
Hole cleaning or cuttings transport is one of the major challenges in drilling, especially for extended reach drilling (ERD). The physics behind cuttings transport is solid-liquid, two-phase flow in annulus geometries. A closely related research topic is the solid-liquid, two-phase pipe flow. A critical part of the two-phase flow study for both pipe flow and annulus flow is the understanding of the flow patterns. In engineering applications, a common approach for two-phase flow modelling is to predict the flow pattern and then develop mechanistic models to simulate the flow based on the flow patterns. Accurate flow pattern is the fundamental of the mechanistic models. The predictions from the model may be completely wrong if the flow pattern is not correct.