Coupled Axial-Rotational Motion of the Pipe on Cuttings Transport via CFD

Inadequate hole cleaning is one of the main reasons for pipe stuck in extended-reach drilling, especially while back reaming. The mechanism of cuttings transport while back reaming is hereby investigated. First, a coupled dynamic layering and sliding method with the Eulerian-Granular approach is established and verified. The sliding mesh method is applied to simulate the pipe rotation, and the layering mesh method is used to simulate the movement in the axial direction. Next, the tripping operation of a connector-furnished pipe is simulated, and the sensitive parameter analysis is conducted. The results demonstrate that cuttings pile up in front of the connector while tripping, which may bring a risk of a stuck pipe. The cuttings pile decreases with the circulation time and rotational speed of the pipe. The tripping velocity has minimal effect on the cuttings distribution after the cuttings pass through the connector. Moreover, the significant flow rate can be more safely employed after the cuttings have passed through the connector furnished with a large diameter, such as the bottom hole assembly. This exploration is an essential guide to predicting and controlling tight spots while tripping.