Experimental investigation of cuttings bed erosion in horizontal wells using water and drag reducing fluids

An experimental study was conducted to investigate the mechanisms of solid particle removal from bed deposits (i.e. bed erosion) in horizontal wells using water and a drag reducing fluid. The cuttings bed erosion experiments were conducted using a 9 m long horizontal flow loop with concentric annular geometry (Outer Pipe ID=95 mm, Inner Pipe OD=38 mm, ID/OD ratio=0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). Water and two drag reducing fluids with 0.07% V/V and 0.1% V/V PHPA concentrations were used. Critical velocities for the initiation of cuttings movement with rolling, saltation/dunes, and suspension modes were determined and compared when using water and drag reducing fluids as a carrier fluid. Critical velocities for the initiation of cuttings movement were found to be lower with water than that of drag reducing fluid in all transport modes.