Rheological and hydraulic properties of welan gum fluids in straight and coiled tubings

This study involves experimental investigation of the hydraulic characteristics of aqueous based welan gum fluids of concentrations 1.4 kg/m(3), 2.9 kg/m(3), 5.7 kg/m(3), and 8.6 kg/m(3) in both straight and coiled tubings at 21 degrees C, with particular emphasis on the effect of polymer concentration and coiled tubing curvature ratio. The flow loop available at the Well Construction Technology Center of the University of Oklahoma, consisting of 1.27 cm straight and coiled tubings (with curvature ratios of 0.01, 0.019, and 0.031), was utilized. It was observed that for all welan gum fluids investigated, friction losses in coiled tubing were significantly higher than those in straight tubing. In addition, increasing coiled tubing curvature ratio brings about higher friction loss for all fluids investigated. Rheological data for these fluids were obtained using a Model 35 Fann viscometer. Friction pressure data gathered from flow experiments are analyzed and correlations for friction pressure loss prediction of welan gum fluids have been developed for both straight and coiled tubings. These correlations, which represent the industry's first attempt in the fundamental investigation of friction loss prediction of welan gum fluids, are found to provide good accuracy when compared to the experimental data. Flow behavior of welan gum fluids is compared with 4.9 kg/m(3) guar fluid. It is found that in both straight and coiled tubings, the guar fluid exhibited higher drag reduction when compared to the welan gum fluids investigated in this study.