Title: Friction pressure correlations for turbulent flow of drag reducing polymer solutions in straight and coiled tubing
Author(s): Felipe Gallego, and Subhash N. Shah, Mewbourne School of Petroleum and Geological Engineering, Well Construction Technology Center, The University of Oklahoma
Journal: Journal of Petroleum Science and Engineering, April 2009, Vol. 65 pages 147-161
Abstract:
Accurate determination of friction pressure losses of dilute drag reducing polymer solutions remains to be a
challenge in many practical applications. These include a wide variety of hydraulic operations performed on a
daily basis in the oil and gas industry. Most drilling, completions, and stimulation jobs require pumping fluids
at high flow rates, which in turn generates high frictional pressure losses, enhanced by the use of small
diameter tubing or coiled tubing. Curvature in this latter is believed to generate secondary flows and thus
extra flow resistance. Therefore, good drag reduction characteristics of fluids are desirable.
In this study, energy dissipation by eddies in turbulent flow of viscoelastic fluids is assumed to be the
mechanism causing drag reduction. Various concentrations of Nalco ASP-700 and Nalco ASP-820 dilute
polymer solutions are tested at ambient temperature in laboratory-scale and full-scale flow loops installed
with straight and coiled tubing sections exhibiting different values of diameter, curvature ratio and pipe
roughness. In addition, flow tests are conducted at 100 °F and 130 °F using the laboratory-scale flow loop.
Effects of concentration, temperature, curvature ratio, and pipe roughness on drag reduction are discussed in
light of Fanning friction factor versus solvent Reynolds number plots. Results show that drag reduction in
coiled tubing is lower than in straight tubing. As curvature ratio increases, drag reduction decreases. The
effect of increasing temperature is to decrease drag reduction in straight tubing and increase it in coiled
tubing. In turn, the effect of increasing pipe roughness is to slightly decrease drag reduction in straight tubing
up to a certain Reynolds number value and then it starts to increase. For coiled tubing, the effect of increasing
pipe roughness is to decrease drag reduction.
In this study, generalized correlations for the prediction of drag reduction in dilute polymer solutions flowing
in straight and coiled tubing are developed on the basis of the energy dissipation of eddies in turbulent flow
field and a shear rate dependent relaxation time. In addition, correlations are validated using experimental
data for a low concentration guar fluid flowing through full-scale flow loop.
© 2009 Elsevier B.V. All rights reserved.
