Annular Velocity Effect on the Lifting of Sandstone Cutting Particles in Inclined Rotating Wellbore Pipes using Novel Hydroxyapatite Nanoparticles

Abstract Deviated wellbore regions make cutting transport harder owing to the substantially low annular velocity distribution in these regions. This causes migrating cuttings to deposit on the lower borehole wall, creating cutting beds and thus resulting in drilling problems like pipe sticking. Water-based mud (WBM) that includes nanoparticles (NPs) to remove cuttings still needs further investigation due to the substantial drop in annular velocity of the mud in inclined boreholes. This research, therefore, employed a nanohydroxyapatite (nanoHAp) additive to improve the properties of WBM, including its cutting transport ratio (CTR). All the fluid performances of nanoHAp were compared with those of aluminium oxide NPs (nano-Al2O3). An inclined cutting rig simulator of 4.88 m long, 0.0609 m ID, and 0.0305 m OD was constructed. 0.4–2.0 g of nanoHAp and nano-Al2O3 were used to clean cutting particles that were 0.80–3.60 mm in diameter and at velocities of 1.5, 2.5, and 3.5 m/s and 120 rpm. The pipes were deviated at 40°, 50°, and 60°. The results indicate that nanoHAp particles are mostly 70–600 nm in size and thermally stable at 750 oC. Additionally, the fluid consistency index demonstrates that nanoHAp and nano-Al2O3 increased the viscosity of WBM of 2.114 Pa. s by 15 to 130% and 5.7 to 94.3%, respectively. Also, nano-HAp concentrations decreased the WBM fluid loss from 9.4 mL to 8.1–5.4 mL, and nano-Al2O3 concentrations decreased it to 8.9–8.2 mL. The CTR of all the fluid samples improves with an increase in concentration and annular velocity at all hole angles. NanoHAp increased the CTR by 10.0% to 31.4% at all concentrations, hole angles, and annular velocities, while nano-Al2O3increased it by 4.0% to 27.1%. A higher percentage of CTR was observed with pipe rotation compared to without pipe rotation. The drill pipe's orbiting motion and increasing axial velocity distribution have a positive effect on CTR. Compared with 40° and 60° deviations, 50° wellbore cuttings are the most difficult to clean, while 40° wellbore is the easiest. This research highlights the advantages of nanoHAp over industrial-based nano-Al2O3, offering options for selecting nanoHAp for drilling operations.