Title: Effects of Solids Loading on Drag Reduction in Polymeric Drilling Fluids Through Straight and Coiled Tubings
Author(s): David Clark, Baker Hughes INTEQ, Mohammad Tareen, The University of Oklahoma, and Subhash N. Shah, The University of Oklahoma
Presentation: Canadian International Petroleum Conference
Location:Calgary, Alberta Canada
Date: June 6-8, 2000
Abstract: Drag-reducing polymers are widely used in the petroleum industry for various applications. Most recently, these polymeric fluids are pumped through reeled coiled tubing (CT) for applications such as drilling, borehole cleaning, and workover/completions. The friction loss of these fluids through coiled tubing on a reel is uniquely different from that in a straight CT because of the secondary flow pattern induced by imbalance between the forces acting in radial direction of pipe coil. While the flow of Newtonian fluids in curved pipes has been the subject of numerous investigators, information in the corresponding flow of non-Newtonian (polymeric) fluids in CT is rather scarce. Furthermore, the friction losses of weighted polymeric (drilling) fluids in straight pipes and reeled CT are almost non-existent.
An experimental study is undertaken to investigate the friction loss and drag reduction phenomena of unweighted and weighted polymeric fluids through straight pipes and reeled coiled tubing. Drag reducing agents such as polysaccharide gum and partially hydrolyzed polyacrylamide dissolved in potassium chloride and sodium formate solutions have been evaluated. The best drag reducing agent from this evaluation is then selected and loaded with barite and bentonite to simulate drill solid cutting. The friction loss data of these fluids in various straight pipes and CT sizes have been gathered. The dimensionless correlation to estimate friction loss values of the unweighted and weighted drilling fluids flowing through the straight pipes and CT has been developed. Significant increase in friction pressures in reeled CT as compared to straight CT is observed. It is also observed that the drag reduction characteristics are adversely affected by the addition of solids with the polymeric fluids.
The new correlation provides an accurate determination of friction pressure losses of unweighted and weighted polymeric fluids in reeled as well as straight coiled tubing.
