Layer Modeling for Cuttings Transport in Highly Inclined Wellbores

Abstract

A review is presented on the state-of-the-art of mechanistic cuttings transport modeling. Cuttings transport predictions are essential for the planning of directional and horizontal drilling. It is suggested that field requirements (the need for fast, easy to use, simulators) point towards the use of a combination of two distinct modeling strategies, which are layer-models for the flow along the wellbore, and full numerical solutions in given cross-sectional areas. The layer model approach is developed in detail, yielding a two-layer model that simulates a moving bed of packed cuttings below a heterogeneous layer of mud and cuttings. Some key points on which more research is needed are highlighted. The model has been used to perform numerical simulations, predicting cuttings bed heights, pressure drops, and transport velocities at different rate of penetrations and mudflow rates. Results have been compared to predictions by correlation-based models. The observed differences are discussed and improvements on the current model are proposed.