The action of stopping drilling to circulate the cuttings out of the well is always a point of controversy among oilfield teams. The practice of circulating periodically the hole may avoid several operational problems during the drilling of a horizontal well. On the other hand, if hydraulic minimum requirements for the cuttings bed removal are not achieved, circulation can be ineffective, time consuming and, in some cases, detrimental to wellbore stability. This paper presents a series of large scale lab experiments which aimed at the investigation of the erosion of a cuttings bed deposited on the lower part of a horizontal annular section. A group of correlations, based on the experimental data, was developed to predict bed height and critical flow rate for bed removal as functions of several independent variables. The proposed methodology, coupled with a cuttings transport numerical simulator, is an useful tool for programming effective circulation of a cuttings bed.

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