Low damage fracturing fluids are normally utilized for better fracture dimensions confinement and lower residue. This leads to not only longer fracture lengths, but also, higher fracture conductivity. Slick-water fracturing technology - developed in the 1980s - is less expensive than gel treatments. Fluid and proppant volumes can be reduced and treatment flow rates can be significantly increased. When compared to conventional gel treatments, slick-water fracturing can generate similar or better production responses.

In frac treatments, slick-water is pumped through straight as well as coiled tubing. As a result of secondary flow, friction pressure losses in CT are higher than in straight tubing. Determining these losses is of utmost importance for successful treatments. Customarily, laboratory generated flow data are used to develop correlations to predict friction pressure of fluids flowing in ST and CT. These correlations are then, without verification, applied to field application which employ much larger conduit sizes.

The present study is aimed to experimentally investigate the hydraulic properties of the commonly used drag reducer; Nalco ASP-820 in larger tubing sizes. It is a modified partially-hydrolyzed polyacrylamide, PHPA. Previously, we reported flow data gathered employing a ½-in. ST and CT (varying curvature ratio) and the correlations developed to predict friction losses of fluids in ST and CT. In this investigation, the large-scale flow data acquired from 200-ft ST and 1,000, 2,000, and 3,000-ft, 1½-in. CT, and 1,000-ft 2⅜- and 2⅞-in. CT are compared with the predictions from the correlations developed from ½-in. pipe data. The effects of shear intensity, shear duration, and pipe roughness on flow properties of ASP fluid are also investigated.

Results show significantly lower drag reduction in CT than in ST due to secondary flow caused by the tubing curvature. Polymer degradation because of shear (shear intensity and duration) and/or tubing roughness can significantly reduce drag reduction. The results are discussed in light of a recently developed "Drag Reduction Envelope" to evaluate the drag reduction characteristics of slick-water fluid in ST and CT.

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