Effect of drillpipe rotation on cuttings transport using computational fluid dynamics (CFD) in complex structure wells

摘要

Effective cuttings transport is one of the most major concerns in designing hydraulic parameters during drilling complex structure wells. It is important and essential to study critical parameters how to influence cuttings bed development, especially the drillpipe rotation effects on cuttings transport behavior. In this study, cuttings transport simulations were carried out for inclinations from 45° to 90°, for pipe rotation speeds from 80 to 240?rpm, and for flow rates from 30 to 50?L/s. Annular cuttings volume, pressure drop, and cuttings distribution are recorded simultaneously within the simulation proceeding. The CFD simulations show that pipe rotation makes cuttings presented in asymmetric distribution along the wellbore and significantly improves the drag effects on drilling fluid in the tangential direction. At a low or medium flow rate, pipe rotation has a significant impact on annular cuttings volume and pressure drop. However, there is no additional contribution of pipe rotation after reaching critical speed at high flow rates. Buckingham-π theorem combined with least square method was applied to establish the empirical correlations for estimating cuttings concentration and annular pressure drop.