Investigation of cutting transport in horizontal/deviated annulus using visualization and pressure drop techniques for two-phase slurry flow

Inadequate hole-cleaning in an annulus leads to several problems such as mechanical pipe sticking, premature bit wear, formation fracturing, and/or slow drilling. However, the literature suggests a lack of experimental analysis of the impact of various parameters on cutting transport. Therefore, the present study investigates the impact of various hydrodynamic and operational parameters on the cuttings transport for two-phase Newtonian and non-Newtonian slurry flow using pressure drop and visualization techniques. Several annular flow experiments were performed in 6.16 m (20.2 ft) long horizontal pipe with 2.5 '' (6.4 cm) inner and 4.5 '' (11.4 cm) outer diameter with varying pipe eccentricity (0-30%), drill pipe rotational speeds (0-120 RPM), fluid rheology (Newtonian and non-Newtonian fluids), and pipe inclination (0-5 degrees from Horizontal) for different mass flow rates (170-350 kg/min). Furthermore, novel correlations were developed using the original experimental data and were validated with two independent data sets from literature. Results revealed that mass flow rate and drill pipe rotation positively impact cuttings transport, whereas eccentricity and higher non-Newtonian concentration have a negative impact. Solid in-situ bed height significantly impacts pressure drop and determines its trend. The developed empirical correlations are simpler and quicker tools as compared to the existing models, with a MAPE of 8.18% for the power-law model that can be effectively used during real-time drilling operations. Moreover, the presented experimental and modeling results can tremendously augment the current understanding of the impact of various parameters on cutting transport.