Title: Rheological and Hydraulic Properties of Welan Gum Fluids in Straight and Coiled Tubings
Author(s): Adedeji Asubiaro, and Subhash N. Shah, Mewbourne School of Petroleum and Geological Engineering, Well Construction Technology Center, The University of Oklahoma
Journal: Journal of Fluids Engineering, August 2008, Vol. 130
Introduction:
Welan gum is a commercially available biopolymer developed by Kelco, Division of Merck Co. Inc. USA in 1985 with a trade name Biozan. It is found to be suitable for drag reduction and viscosity enhancement purposes in many oil and gas production operations including hydraulic fracturing, acidizing, wellbore cleanup, cementing, and drilling. It possesses good thermal stability and is stable in the presence of calcium ions, high pH conditions, and in solutions containing high levels of glycols. The molecular structure of welan gum is shown in Fig. 1.
In recent years, coiled tubing has gained popularity in various petroleum engineering applications due to its numerous operational advantages. Polymeric fluids including welan gum have been pumped through both the straight and coiled sections of coiled tubing in production operations. Due to secondary flow effects caused by centrifugal forces in curved flow geometry, fluid flow behavior in coiled tubing differs significantly from that in straight tubing. It has been observed that friction pressure losses in coiled tubing are much higher when compared to straight tubing under the same flow conditions [1].
Several investigators [2–7] have conducted studies on welan gum fluids. Most of these investigations involved rheological characterization of welan gum fluids and their comparison with other polymeric fluids. To date, there has been no comprehensive investigation of the hydraulic properties of welan gum fluids of concentrations typically used in oilfield applications, especially in coiled tubing. This study, therefore, is the industry’s first effort, focused toward experimentally determining the effect of polymer concentration and coiled tubing curvature ratio on welan gum fluids. The correlations developed in this study are applicable for flow in both straight and coiled tubings and would be of benefit for the prediction of friction factor of welan gum fluids.
