Experimental Investigation of Cuttings Transport in Horizontal Wells Using Aerated Drilling Fluids

Abstract

AbstractAn experimental study has been conducted to investigate the cuttings transport in horizontal wellbores using aerated drilling fluids. An advanced flow loop system with 21 ft. long annular test section composed of 2.91-in. ID transparent casing and 1.85 in. OD inner drill pipe has been used for the experiments.Aerated fluids were composed of air/water and air/drag reducing polymer fluid mixtures. Partially hydrolyzed polyacrylamide (PHPA) copolymer was used as a drag reducing agent. Drag reducing polymer fluids (i.e. water-polymer mixtures)were prepared usingPHPA concentrations of0.05% V/V, 0.07%V/V, and 0.10% V/V. The optimum PHPA concentrationwas found to be 0.07%V/Vresulting maximum drag reduction of 41.88%.Four different flow regimes were identified along with the flow of aerated fluids as bubble, elongated bubble, slug and wavy annular regimes. Adding PHPA polymers in water delayedthe transition from slug to annular wavy flow regime (i.e. for a given liquid flow rate the transition from slug to wavy annular flow regime was observed at higher gas flow rates).The annular area occupied by the cuttings decreased with the increasing liquid(both water and polymer fluid) and gas flow rates. However, increasing the liquid flow rate was more effective in terms reducing the cuttings bed deposition.On average, the use of 0.07% PHPA polymer fluid with air for cuttings transport caused 23.90% drag reduction while reducing the annular area occupied by the cuttings by 4% and cuttings bed height by 13.78%.Though cuttings transport performance of the various flow regimes did not show significant difference, Wavy Annular flow regime seemed to be the most effective flow regime in terms of cuttings transport among the others.